Author name code: rutten-rene
ADS astronomy entries on 2022-09-14
=author:"Rutten, R.G.M." OR =author:"Rutten, Rene G.M." OR =author:"Rutten, Rene"
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Title: An infusion of new blood using the Toptica laser with GeMS:
results of the commissioning and science performance
Authors: Sivo, Gaetano; Marin, Eduardo; Rigaut, François; van Dam,
Marcos; Garrel, Vincent; Neichel, Benoit; Moreno, Cristian; Chirre,
Emmanuel; Araujo, Constanza; Hankla, Allen; Perez, Gabriel; Diaz,
Pablo; Ebbers, Angelic; Collins, Paul; Vergara, Vicente; Hirst, Paul;
Andersen, Morten; Chavez, Joy; Magill, Lindsay; Cunningham, Christine;
Lopez, Ariel; Donahue, Jeff; Carrasco, Rodrigo; Lombardi, Gianluca;
Montes, Vanessa; van der Hoeven, Michiel; Rutten, René; Kleinman,
Scot; Lazo, Manuel
Bibcode: 2018SPIE10703E..0PS
Altcode:
Adaptive Optics (AO) systems aim at detecting and correcting for
optical distortions induced by atmospheric turbulences. The Gemini Multi
Conjugated AO System GeMS is operational and regularly used for science
observations since 2013 delivering close to diffraction limit resolution
over a large field of view. GeMS entered this year into a new era. The
laser system has been upgraded from the old 50W Lockheed Martin Coherent
Technologies (LMCT) pulsed laser to the Toptica 20/2W CW SodiumStar
laser. The laser has been successfully commissioned and is now used
regularly in operation. In this paper we first review the performance
obtained with the instrument. I will go then into the details of the
commissioning of the Toptica laser and show the improvements obtained
in term of acquisition, stability, reliability and performance.
Title: IGRINS at the Discovery Channel Telescope and Gemini South
Authors: Mace, Gregory; Sokal, Kimberly; Lee, Jae-Joon; Oh, Heeyoung;
Park, Chan; Lee, Hanshin; Good, John; MacQueen, Phillip; Oh, Jae
Sok; Kaplan, Kyle; Kidder, Ben; Chun, Moo-Young; Yuk, In-Soo; Jeong,
Ueejeong; Pak, Soojong; Kim, Kang-Min; Nah, Jakyoung; Lee, Sungho;
Yu, Young-Sam; Hwang, Narae; Park, Byeong-Gon; Kim, Hwihyun; Chinn,
Brian; Peck, Alison; Diaz, Ruben; Rutten, Rene; Prato, Lisa; Jacoby,
George; Cornelius, Frank; Hardesty, Ben; DeGroff, William; Dunham,
Edward; Levine, Stephen; Nofi, Larissa; Lopez-Valdivia, Ricardo;
Weinberger, Alycia J.; Jaffe, Daniel T.
Bibcode: 2018SPIE10702E..0QM
Altcode:
The Immersion GRating INfrared Spectrometer (IGRINS) was designed for
high-throughput with the expectation of being a visitor instrument at
progressively larger observing facilities. IGRINS achieves R∼45000 and
> 20,000 resolution elements spanning the H and K bands (1.45-2.5μm)
by employing a silicon immersion grating as the primary disperser
and volume-phase holographic gratings as cross-dispersers. After
commissioning on the 2.7 meter Harlan J. Smith Telescope at McDonald
Observatory, the instrument had more than 350 scheduled nights in
the first two years. With a fixed format echellogram and no cryogenic
mechanisms, spectra produced by IGRINS at different facilities have
nearly identical formats. The first host facility for IGRINS was Lowell
Observatory's 4.3-meter Discovery Channel Telescope (DCT). For the
DCT a three-element fore-optic assembly was designed to be mounted
in front of the cryostat window and convert the f/6.1 telescope beam
to the f/8.8 beam required by the default IGRINS input optics. The
larger collecting area and more reliable pointing and tracking of
the DCT improved the faint limit of IGRINS, relative to the McDonald
2.7-meter, by ∼1 magnitude. The Gemini South 8.1-meter telescope
was the second facility for IGRINS to visit. The focal ratio for
Gemini is f/16, which required a swap of the four-element input optics
assembly inside the IGRINS cryostat. At Gemini, observers have access
to many southern-sky targets and an additional gain of ∼1.5 magnitudes
compared to IGRINS at the DCT. Additional adjustments to IGRINS include
instrument mounts for each facility, a glycol cooled electronics rack,
and software modifications. Here we present instrument modifications,
report on the success and challenges of being a visitor instrument,
and highlight the science output of the instrument after four years
and 699 nights on sky. The successful design and adaptation of IGRINS
for various facilities make it a reliable forerunner for GMTNIRS,
which we now anticipate commissioning on one of the 6.5 meter Magellan
telescopes prior to the completion of the Giant Magellan Telescope.
Title: Dueling lasers! A comparative analysis of two different sodium
laser technologies on sky
Authors: Marin, Eduardo; Sivo, Gaetano; Garrel, Vincent; Andersen,
Morten; Rigaut, Francois; van Dam, Marcos; Neichel, Benoit; Moreno,
Cristian; Chirre, Emmanuel; Hankla, Allen; Carrasco, Rodrigo; Araujo,
Constanza; Perez, Gabriel; Diaz, Pablo; Ebbers, Angelic; Collins,
Paul; Vergara, Vicente; Chavez, Joy; Magill, Lindsay; Lopez, Ariel;
van der Hoeven, Michiel; Rutten, Rene; Hirst, Paul; Lazo, Manuel
Bibcode: 2018SPIE10703E..3NM
Altcode:
Sodium guide star technologies for Adaptive Optics (AO) have been around
for over 20 years. During this time, the technologies for the lasers
used to excite the mesospheric sodium have been in constant development,
with the goals being not only to excite as much sodium as possible,
but to do so efficiently, while producing a round guide star, and while
offering a reliable facility. The first lasers in use were dye lasers
with a liquid gain medium, while these lasers were able to produce
sodium guide stars, the liquid dye used was toxic and flammable. The
second generation of guide star lasers used sum-frequency-mixed
solid-state lasers. These lasers provided excellent return but were
notoriously difficult to calibrate and maintain, requiring a full-time
laser engineer on staff. The current third generation of sodium guide
star lasers use Raman fiber amplification to generate a laser that
is very efficient at exciting sodium with a good spot profile and
offer a high degree of reliability. The Gemini South observatory for
the last few years has been in the process of obtaining one of these
third-generation lasers, a Toptica Sodium Star 20/2 while maintaining
its second-generation Lockheed Martin Coherent Technologies (LMCT) 50W
CW Mode-locked laser. In October of 2017 successful on-sky commissioning
of the Toptica laser was executed while the LMCT laser was still
active and in operations. During the course of the commissioning run
both lasers were used on sky in close in time in possible. We present
a comparative study of the performance of each laser.
Title: Science operations at Gemini Observatory
Authors: Rutten, René; Adamson, Andy; Leggett, Sandy
Bibcode: 2016SPIE.9910E..1MR
Altcode:
Gemini Observatory operates two 8m telescopes, one on Cerro Pachón
in Chile and one on Maunakea Hawaíi, on behalf of an international
partnership. The telescopes, their software and supporting
infrastructure (and some of the instrumentation) are identical at
the two sites. We describe the operation of the observatory, present
some key performance indicators, and discuss the outcomes in terms
of publications and program completion rates. We describe how recent
initiatives have been introduced into the operation in parallel
with accommodating a significant budget reduction and changes in
the partnership.
Title: Phase-resolved spectroscopy and Kepler photometry of the
ultracompact AM CVn binary SDSS J190817.07+394036.4
Authors: Kupfer, T.; Groot, P. J.; Bloemen, S.; Levitan, D.; Steeghs,
D.; Marsh, T. R.; Rutten, R. G. M.; Nelemans, G.; Prince, T. A.;
Fürst, F.; Geier, S.
Bibcode: 2015MNRAS.453..483K
Altcode: 2015arXiv150703926K
Kepler satellite photometry and phase-resolved spectroscopy of
the ultracompact AM CVn type binary SDSS J190817.07+394036.4 are
presented. The average spectra reveal a variety of weak metal lines of
different species, including silicon, sulphur and magnesium as well as
many lines of nitrogen, beside the strong absorption lines of neutral
helium. The phase-folded spectra and the Doppler tomograms reveal an
S-wave in emission in the core of the He I 4471 Å absorption line
at a period of Porb = 1085.7 ± 2.8 s identifying this as
the orbital period of the system. The Si II, Mg II and the core of
some He I lines show an S-wave in absorption with a phase offset of
170° ± 15° compared to the S-wave in emission. The N II, Si III
and some helium lines do not show any phase variability at all. The
spectroscopic orbital period is in excellent agreement with a period
at Porb = 1085.108(9) s detected in the 3 yr Kepler light
curve. A Fourier analysis of the Q6-Q17 short-cadence data obtained
by Kepler revealed a large number of frequencies above the noise
level where the majority shows a large variability in frequency and
amplitude. In an Observed-minus-computed analysis, we measured a \vert
dot{P}\vert ∼ 1.0 × 10-8 s s-1 for some of
the strongest variations and set a limit for the orbital period to
be \vert dot{P}\vert <10^{-10} s s-1. The shape of the
phase-folded light curve on the orbital period indicates the motion of
the bright-spot. Models of the system were constructed to see whether
the phases of the radial velocity curves and the light-curve variation
can be combined to a coherent picture. However, from the measured
phases neither the absorption nor the emission can be explained to
originate in the bright-spot.
Title: First Semester Science Operations with the Gemini Planet Imager
Authors: Tord Rantakyro, Fredrik; Hibon, Pascale; Cardwell, Andrew;
Sadakuni, Naru; Quiroz, Carlos; Rutten, Rene; Gausachs, Gaston;
Galvez, Ramon; Gpi Commissioning Team, Gpies Team
Bibcode: 2015AAS...22543807T
Altcode:
The Gemini Planet Imager (GPI) has now gone through its first six
months of operations at Gemini South, starting in August 1st, 2014 and
finishing in January 31st, 2015. We present here the experiences in
integrating and operating the instrument in mixed queue and classical
modes. A total of 72 hours of observations was accepted out of a total
of proposed 266 hours, out of a total of 2469 hours for all instruments
at Gemini South. The 72 hours were distributed over 12 programs from
almost all partner countries. In addition to the standard classical
and queue time 140 hours was assigned to the GPIES campaign.
Title: PTF1 J191905.19+481506.2—a Partially Eclipsing AM CVn System
Discovered in the Palomar Transient Factory
Authors: Levitan, David; Kupfer, Thomas; Groot, Paul J.; Margon,
Bruce; Prince, Thomas A.; Kulkarni, Shrinivas R.; Hallinan, Gregg;
Harding, Leon K.; Kyne, Gillian; Laher, Russ; Ofek, Eran O.; Rutten,
René G. M.; Sesar, Branimir; Surace, Jason
Bibcode: 2014ApJ...785..114L
Altcode: 2014arXiv1402.7129L
We report on PTF1 J191905.19+481506.2, a newly discovered, partially
eclipsing, outbursting AM CVn system found in the Palomar Transient
Factory synoptic survey. This is only the second known eclipsing AM CVn
system. We use high-speed photometric observations and phase-resolved
spectroscopy to establish an orbital period of 22.4559(3) minutes. We
also present a long-term light curve and report on the normal
and super-outbursts regularly seen in this system, including a
super-outburst recurrence time of 36.8(4) days. We use the presence
of the eclipse to place upper and lower limits on the inclination of
the system and discuss the number of known eclipsing AM CVn systems
versus what would be expected.
Title: Orbital periods and accretion disc structure of four AM
CVn systems
Authors: Kupfer, T.; Groot, P. J.; Levitan, D.; Steeghs, D.; Marsh,
T. R.; Rutten, R. G. M.; Nelemans, G.
Bibcode: 2013MNRAS.432.2048K
Altcode: 2013MNRAS.tmp.1313K; 2013arXiv1303.5610K
Phase-resolved spectroscopy of four AM CVn systems obtained with
the William Herschel Telescope and the Gran Telescopio de Canarias
is presented. SDSS J120841.96+355025.2 was found to have an orbital
period of 52.96 ± 0.40 min and shows the presence of a second bright
spot in the accretion disc. The average spectrum contains strong
Mg I and Si I/II absorption lines most likely originating in the
atmosphere of the accreting white dwarf. SDSS J012940.05+384210.4 has an
orbital period of 37.555 ± 0.003 min. The average spectrum shows the
Stark-broadened absorption lines of the DB white dwarf accretor. The
orbital period is close to the previously reported superhump period
of 37.9 min. Combined, this results in a period excess ɛ = 0.0092 ±
0.0054 and a mass ratio q = 0.031 ± 0.018. SDSS J164228.06+193410.0
displays an orbital period of 54.20 ± 1.60 min with an alias at 56.35
min. The average spectrum also shows strong Mg I absorption lines,
similar to SDSS J120841.96+355025.2. SDSS J152509.57+360054.50 displays
a period of 44.32 ± 0.18 min. The overall shape of the average spectrum
is more indicative of shorter period systems in the 20-35 min range. The
accretor is still clearly visible in the pressure-broadened absorption
lines most likely indicating a hot donor star and/or a high-mass
accretor. Flux ratios for several helium lines were extracted from the
Doppler tomograms for the disc and bright spot region, and compared
with single-slab Local Thermodynamic Equilibrium (LTE) models with
variable electron densities and path lengths to estimate the disc and
bright spot temperature. Good agreement between data and the model in
three out of four systems was found for the disc region. All three
systems show similar disc temperatures of ∼10 500 K. In contrast,
only weak agreement between observation and models was found for the
bright spot region.
Title: GTC observations of ultracompact AM CVn binaries
Authors: Kupfer, T.; Groot, P. J.; Rutten, R. G. M.
Bibcode: 2013RMxAC..42..102K
Altcode:
AM CVn systems are a small group of mass-transferring ultracompact
binaries consisting of a white dwarf primary and a degenerated or
semi-degenerated secondary. They are the endpoints of binary stellar
evolution, having survived two common-envelope phases and showing
orbital periods between 5.4-65 min (Solheim 2010). They are the only
known sources of gravitational waves in the LISA regime and will act
as LISA verification sources.
Title: The first years of GTC science operation, by numbers
Authors: Rutten, R. G. M.
Bibcode: 2013RMxAC..42...99R
Altcode:
The 10.4 m Gran Telescopio CANARIAS came into operation in 2009. During
the two years since that date the facility has seen important changes
and improvements that have helped its scientific exploitation. This
paper highlights some of the basic results of these first years of
science operation and briefly sets out aspects of our operational
methodology. Furthermore, some critical aspects of a more strategic
nature are mentioned with the view of maximizing the scientific return
of the facility in future years.
Title: Organizational transformation into the operational phase of
the GTC
Authors: van der Hoeven, Michiel; Rutten, René; Alvarez Martin, Pedro
Bibcode: 2012SPIE.8448E..16V
Altcode:
In this paper we review various organizational issues encountered when
GRANTECAN, the Spanish organization responsible for the construction
and operation of the GTC telescope, evolved from the construction
phase of a large telescope facility into the phase of scientific
operation. GRANTECAN now operates and further develops the 10.4m
segmented telescope, GTC. The advent of operational pressures to
scientifically exploit the telescope enforced a number of organizational
changes as priorities shifted towards achieving the best possible level
of operational effectiveness. In this paper we will treat the GRANTECAN
experience as a case study of the limitations and problems that were
encountered throughout this change. We will focus on the processes
and strategies applied in order to achieve the necessary changes. We
will place our experience in the framework of the McKinsey 7S model,
highlight a number of key performance indicators, and will indicate
the organizational changes that have taken place, that influenced the
way the objectives are achieved. We will present a forward look based
on our experience to date.
Title: Astrophysics on the Edge: New Instrumental Developments at
the ING
Authors: Santander-García, M.; Rodríguez-Gil, P.; Tulloch, S.;
Rutten, R. G. M.
Bibcode: 2010ASSP...14..539S
Altcode: 2010hsa5.conf..539S
Present and future key instruments at the Isaac Newton Group of
Telescopes (ING) are introduced, and their corresponding latest
scientific highlights are presented. GLAS (Ground-layer Laser Adaptive
optics System): The recently installed 515 nm laser, mounted on the WHT
(William Herschel Telescope), produces a bright artificial star at a
height of 15 km. This enables almost full-sky access to Adaptive Optics
observations. Recent commissioning observations with the NAOMI+GLAS
system showed that very significant improvement in image quality
can be obtained, e.g. down to 0.16 arcsec in the H band. QUCAM2 and
QUCAM3: Two Low Light Level (L3) CCD cameras for fast or faint-object
spectroscopy with the twin-armed ISIS spectrograph at the WHT. Their
use opens a new window of high time-frequency observations, as well as
access to fainter objects. They are powerful instruments for research
on compact objects such as white dwarfs, neutron stars or black holes,
stellar pulsations, and compact binaries.HARPS-NEF (High-Accuracy
Radial-velocity Planet Searcher of the New Earths Facility): An
extremely stable, high-resolution (R ∼ 120, 000) spectrograph for
the WHT which is being constructed for commissioning in 2009-2010. Its
radial velocity stability of < 1 m s- 1 may in the
future be even further improved by using a Fabry-Perot laser-comb,
a wavelength calibration unit capable of achieving an accuracy of 1
cm s- 1. This instrument will effectively allow to search
for earth-like exoplanets.
Title: Optimisation of the range gating and calibration processes
on the GLAS Rayleigh Laser Guide Star at the WHT
Authors: Martin, Olivier; Abrams, Don Carlos; Agócs, Tibor; Benn,
Chris; Bevil, Craige; Cano, Diego; Dipper, Nigel; Gregory, Thomas;
Guerra, Juan Carlos; Morris, Tim; Myers, Richard; Picó, Sergio; Rix,
Samantha; Rutten, René; Skvarc, Jure; Tulloch, Simon
Bibcode: 2008SPIE.7015E..4EM
Altcode: 2008SPIE.7015E.118M
The Laser Guide Star commissioned in 2007 at the WHT on La Palma
is based on Rayleigh backscattering of a 515 nm beam provided by
a diode pumped Q-switched doubled frequency Yb:YAG laser launched
from behind the WHT secondary mirror. At the time the laser beam is
focused at a distance of 15km above the telescope ground and its power
just under 20W. With such a pulsed laser, careful fine tuning of the
range gate system is essential to isolate the most focused part of
the LGS and eliminate parts of the laser plume which would degrade
the Shack-Hartmann spots and consequently AO correction. This is
achieved by an electro-optic shutter using Pockels cells, triggered
by a delay generator synchronised on the laser pulses, and by spatial
filters. Images of 0.15" resolution in J and H bands, very close to
expected performance, have been routinely taken as soon as the third
and fourth commissioning runs. Here we show the performance of the range
gate system as measured and improved over the successive commissioning
runs, as well as the off sky and on sky calibration procedures of the
LGS AO system.
Title: GLAS/NAOMI: ground-layer AO at the William Herschel Telescope
Authors: Benn, Chris; Abrams, Don; Agocs, Tibor; Cano, Diego;
Gregory, Tom; Guerra, Juan Carlos; Martin, Olivier; Morris, Tim;
Myers, Richard; Rix, Samantha; Rutten, Rene; Skillen, Ian; Skvarč,
Jure; Tulloch, Simon
Bibcode: 2008SPIE.7015E..23B
Altcode: 2008SPIE.7015E..54B
GLAS is an upgrade of the William Herschel Telescope's existing
natural-guide-star (NGS) AO system NAOMI to incorporate a 20-W
Rayleigh laser guide star (LGS) projected to an altitude of 15 km. It
is currently being commissioned on-sky, and we review here the current
status of the project. GLAS/NAOMI delivers dramatic improvements in PSF
in both the near-IR (AO-corrected FWHM close to the diffraction limit,
>~ 0.15 arcsec) and in the optical (factor of ~ 2 reduction in
FWHM). The performance is similar to that with NGS, and is consistent
with predictions from modelling. The main advantage over NGS AO is the
large gain in sky coverage (from ~ 1% to ~ 100% at galactic latitude
40°). GLAS provides the first on-sky demonstration of closed-loop
ground-layer AO (GLAO), and is the first Rayleigh LGS AO system to be
offered for general use, at any telescope.
Title: SixPak: a wide-field IFU for the William Herschel Telescope
Authors: Venema, Lars B.; Schoenmaker, Ton; Verheijen, Marc; Trager,
Scott; Rutten, René; Bershady, Matthew; Larsen, Søren; Peletier,
Reynier; Spaans, Marco
Bibcode: 2008SPIE.7014E..0LV
Altcode: 2008SPIE.7014E..19V
We intend to construct SixPak, a wide-field fibre-based IFU for the
4.2-meter William Herschel Telescope on La Palma. The fibre bundle
will consist of 238 fibres, each 3.0 arcsec in diameter, piping light
from the Nasmyth focal plane of the WHT to the existing WYFFOS bench
spectrograph. A total of 217 fibres will be densely packed to span a
hexagonal field of view of 64 × 55 arcsec. The remaining 21 fibres
will collect light from the sky background. SixPak is optimized for
2-dimensional spectroscopy at intermediate resolutions of extended
objects of low surface brightness. At Nasmyth focus, a focal reducer
matches the f-ratio of the telescope (f/11) to the "optimal" f-ratio of
the fibres (f/3) to reduce the losses due to focal ratio degradation in
the fibres. Microlenses convert the output f-ratio of the fibres to the
f-ratio of the WYFFOS collimator (f/8.2). By means of an exchangeable
slit at the pupils of the microlenses, a spectral resolution of R =
10,000 can be achieved. The intention is that SixPak will be open for
general use in order to allow easy access to the broadest possible
astronomical community.
Title: A multicolor near-infrared study of the dwarf nova IP Pegasi
Authors: Ribeiro, T.; Baptista, R.; Harlaftis, E. T.; Dhillon, V. S.;
Rutten, R. G. M.
Bibcode: 2007A&A...474..213R
Altcode: 2007arXiv0708.3099R
We report the analysis of {JHK}s light curves of the
eclipsing dwarf nova IP Peg in quiescence. The light curves are
dominated by the ellipsoidal variation of the mass-donor star, with
additional contributions from the accretion disc and anisotropic
emission from the bright spot. A secondary eclipse is visible in the J
and H light curves, with 2% and 3% of the flux disappearing at minimum
light, respectively. We modeled the observed ellipsoidal variation of
the secondary star (including possible illumination effects on its inner
face) to find a mass ratio of q = 0.42 and an inclination of i = 84.5°,
consistent in the three bands within the uncertainties. Illumination
effects are negligible. The secondary is responsible for 83%, 84%
and 88% of the flux in J, H and K_s, respectively. We fitted a black
body spectrum to the {JHK}s fluxes of the secondary star to
find a temperature of T_bb = 3100 ± 500 K and a distance of d = 115 ±
30 pc to the system. We subtracted the contribution of the secondary
star and applied 3D eclipse mapping techniques to the resulting light
curves to map the surface brightness of a disc with half-opening angle
α and a circular rim at the radius of the bright spot. The eclipse
maps show enhanced emission along the stream trajectory ahead of the
bright spot position, providing evidence of gas stream overflow. The
inferred radial brightness-temperature distribution in the disc is flat
for R < 0.3 R_L1 with temperatures ≃3500 K and colors consistent
with those of cool opaque radiators.
Title: The European LGS test facility
Authors: Myers, R. M.; Bonaccini Calia, D.; Devaney, N.; Esposito, S.;
Goodsell, S. J.; Goncharov, A.; Guerra, J. C.; Guillet de Chatellus,
H.; Harrison, M. A.; Holzloehner, R.; Marchetti, E.; Morris, T. J.;
Pinna, E.; Pique, J. -P.; Rabien, S.; Reyes, M.; Ribak, E.; Rutten,
R. G. M.; Schnetler, H.; Strachan, M.; Stuik, R.; Talbot, R. G.;
Tulloch, S. M.
Bibcode: 2007SPIE.6691E..0QM
Altcode: 2007SPIE.6691E..19M
A European Laser Guide Star (LGS) test facility is proposed for the
4.2m William Herschel Telescope (WHT) on La Palma. It will test the
next-generation Adaptive Optics (AO) LGS technologies to aid risk
mitigation of Extremely Large Telescope (ELT) LGS AO systems. In
particular, critical scaling of current LGS AO technologies to
ELT dimensions will be tested. For example, experiments addressing
increased spot elongation, cone effect and the order of correction
required. A pan-European consortium proposes to construct test
facility infrastructure on the WHT for a number of risk mitigating
experiments. The infrastructure includes the construction of a Nasmyth
platform based controlled environment 'Ground-based Adaptive optics
Innovative Laboratory' (GRAIL), an experimental test environment
'Testbed integration facility' (TIF) and some common-experiment
equipment such as the Common Re-Imaging AO System. Experiments that
are proposed for this facility cover the areas of laser technologies,
spot elongation, LGS wavefront sensing, parallel launch concepts,
Multi-Object AO, atmospheric characterisation, co-phasing and real-time
control system risk mitigation.
Title: Mapping of the Disc Structure of the Neutron Star X-ray
Binary X1822-371
Authors: Giannakis, O.; Harlaftis, E. T.; Niarchos, P. G.; Kitsionas,
S.; Barwig, H.; Still, M.; Rutten, R. G. M.
Bibcode: 2006Ap&SS.304..321G
Altcode: 2006Ap&SS.tmp..465G
We report the results of simultaneous optical/X-ray observations of
X1822-371 at 0.1 second time resolution. The preliminary analysis
finds no correlation between the optical/X-ray light curves. We aim
to constrain the vertical structure and radius of the accretion disc.
Title: GLAS: engineering a common-user Rayleigh laser guide star
for adaptive optics on the William Herschel Telescope
Authors: Talbot, Gordon; Abrams, Don Carlos; Apostolakos, Nikolaos;
Bassom, Richard; Blackburn, Colin; Blanken, Maarten; Cano Infantes,
Diego; Chopping, Alan; Dee, Kevin; Dipper, Nigel; Elswijk, Eddy;
Enthoven, Bernard; Gregory, Thomas; ter Horst, Rik; Humphreys, Ron;
Idserda, Jan; Jolley, Paul; Kuindersma, Sjouke; McDermid, Richard;
Morris, Tim; Myers, Richard; Pico, Sergio; Pragt, Johan; Rees, Simon;
Rey, Jürg; Reyes, Marcos; Rutten, René; Schoenmaker, Ton; Skvarc,
Jure; Tromp, Niels; Tulloch, Simon; Veninga, Auke
Bibcode: 2006SPIE.6272E..2HT
Altcode: 2006SPIE.6272E..78T
The GLAS (Ground-layer Laser Adaptive-optics System) project is
to construct a common-user Rayleigh laser beacon that will work in
conjunction with the existing NAOMI adaptive optics system, instruments
(near IR imager INGRID, optical integral field spectrograph OASIS,
coronagraph OSCA) and infrastructure at the 4.2-m William Herschel
Telescope (WHT) on La Palma. The laser guide star system will
increase sky coverage available to high-order adaptive optics
from ~1% to approaching 100% and will be optimized for scientific
exploitation of the OASIS integral-field spectrograph at optical
wavelengths. Additionally GLAS will be used in on-sky experiments for
the application of laser beacons to ELTs. This paper describes the full
range of engineering of the project ranging through the laser launch
system, wavefront sensors, computer control, mechanisms, diagnostics,
CCD detectors and the safety system. GLAS is a fully funded project,
with final design completed and all equipment ordered, including the
laser. Integration has started on the WHT and first light is expected
summer 2006.
Title: Performance predictions of the GLAS Rayleigh laser guide star
adaptive optics system for the 4.2-m William Herschel Telescope
Authors: Morris, Timothy J.; Wilson, Richard W.; Myers, Richard M.;
Butterley, Timothy; Rutten, Rene G. M.; Talbot, Gordon
Bibcode: 2006SPIE.6272E..37M
Altcode: 2006SPIE.6272E.100M
Results of numerical simulations of the performance of GLAS
(Ground-layer Laser Adaptive optics System) are presented. GLAS uses
a Rayleigh laser guide star (LGS) created at a nominal distance of
20km from the 4.2m William Herschel Telescope primary aperture and
a semi-analytical model has been used to determine the observed
LGS properties. GLAS is primarily intended for use with the OASIS
spectrograph working at visible wavelengths although a wider-field IR
imaging camera can also use the AO corrected output. Image quality
metrics relating to scientific performance for each instrument are
used showing that the energy inside every OASIS lenslet across the 10"
instrument FOV is approximately doubled, irrespective of atmospheric
conditions or wavelength of observation.
Title: Second generation laser traffic control: algorithm changes
supporting Mauna Kea, La Palma, and future multi-telescope laser sites
Authors: Summers, Douglas; Apostolakos, Nikolaos; Rutten, René;
Talbot, Gordon
Bibcode: 2006SPIE.6272E..44S
Altcode: 2006SPIE.6272E.130S
A Laser Traffic Control System (LTCS) for laser beam avoidance has been
in use at the W. M. Keck observatory on Mauna Kea since 2002. Subsequent
LTCS installations have occurred at Gemini North (2003), and at the
William Herschel Telescope on La Palma, Canary Islands (2005). Gemini
North laser tests in 2005 necessitated algorithm changes to provide
support for multiple laser configurations. Operational differences for
how laser-telescope priority resolutions occur on La Palma vs. Mauna Kea
necessitated algorithm changes to address more generic specification
of priority rules, collision event queries, and better display
feedback. A joint collaboration between the W. M. Keck observatory and
the Isaac Newton Group, to install the LTCS at La Palma and enhance
its priority processing algorithm and display functions, occurred in
2005. The changes made should be sufficient to support LTCS software
implementations at many different sites, current and future, where
multiple laser/telescope configurations are planned. This paper will
describe the algorithm changes, review outstanding issues, and describe
planned development activities supporting a broader use potential to
include sites with ELTs.
Title: Prospects for the GLAS Rayleigh laser beacon on the 4.2-m WHT
Authors: Rutten, René; Blanken, Maarten; McDermid, Richard; Gregory,
Thomas; Jolley, Paul; Morris, Tim; Myers, Richard; Pragt, Johan;
Schoenmaker, Ton; Stuik, Remko; Talbot, Gordon
Bibcode: 2006NewAR..49..632R
Altcode:
The scientific exploitation of adaptive optics (AO) with natural guide
stars is severely constrained by the limited presence of bright guide
stars for wavefront sensing. Use of a laser beam as an alternative
means to provide a source for wavefront sensing has the potential of
drastically improving the sky coverage for AO. For this reason at the
4.2-m William Herschel Telescope a project was started to develop a
Rayleigh laser beacon to work together with the existing NAOMI adaptive
optics instrumentation and the OASIS integral field spectrograph. This
paper presents the rationale for this development, highlights some of
the technical aspects, and gives some expected performance measures.
Title: The 4.2-m William Herschel Telescope as ELT testbed facility
Authors: Rutten, René G. M.; Myers, Richard M.; Morris, Tim J.
Bibcode: 2006IAUS..232..496R
Altcode:
The technical developments required to build the future Extremely
Large Telescopes will be very demanding. Some of these developments,
for instance in the field of Adaptive Optics, will rely on experimental
work to test new techniques and concepts. The 4.2-m William Herschel
Telescope located at a representative high-quality observing site,
and with its stable Nasmyth optical bench for general access and its
common-user Rayleigh laser beacon, is well placed to play a role as
a testbed facility for such activities.
Title: Introduction
Authors: Rutten, René G. M.
Bibcode: 2006NewAR..49..487R
Altcode:
These proceedings are the fruits of a workshop held on the island of
La Palma from 9 to 11 May 2005, hosted by the Isaac Newton Group of
Telescopes. The meeting was inspired by the fact that integral-field
spectroscopy and adaptive optics techniques are coming of age and being
deployed on several telescopes around the world. The combination of
integral-field spectrographs and adaptive optics is still a relatively
unexplored area where the potential benefits for astronomy are huge. The
scientific prospects are particularly promising in the areas of:
the dynamics of the central regions of galaxies and active galactic
nuclei; spectroscopy of gravitationally lensed high-redshift galaxies;
star forming regions and outflow of evolved stars, and the dynamics
of crowded stellar fields.
Title: News from the Roque
Authors: Rutten, R. G. M.
Bibcode: 2005INGN...10...25R
Altcode:
The latest news from the Roque de Los Muchachos Observatory
Title: ING future: Prospects for the William Herschel Telescope
Authors: Rutten, René
Bibcode: 2005A&G....46f...9R
Altcode:
René Rutten, Director of the Isaac Newton Group of Telescopes, sets the
scene for future developments in international astronomy on La Palma.
Title: Progress on the GLAS Rayleigh Laser Beacon System for the
William Herschel Telescope
Authors: Rutten, R. G. M.; Talbot, G.
Bibcode: 2005INGN...10...11R
Altcode:
Although natural guide star operation of the NAOMI adaptive optics
system is now well established, the limited sky coverage for higher
order operation has proven a serious limiting factor in its science
use. For that reason in 2004 a project was embarked upon to develop
a facility class general purpose Rayleigh laser beacon system. The
project acronym, GLAS, stands for Ground-layer Laser Adaptive optics
System. The overall scientific aim of the GLAS project is to drastically
improve the sky coverage for high-order adaptive optics.
Title: ING User Questionnaire - Summary of the Results
Authors: Rutten, R. G. M.
Bibcode: 2005INGN...10...19R
Altcode:
Earlier this year a questionnaire was issued to our community of
telescope users with a number of questions regarding the current and
future use of the telescopes. Many responses were received and these
are of great value to the observatory and have served as input to the
International Review of the ING that was held in July of this year.
Title: ING Workshop on Adaptive-Optics Assisted Integral Field
Spectroscopy
Authors: Rutten, R. G. M.
Bibcode: 2005INGN...10...22R
Altcode:
In May 2005 a three-day workshop took place on adaptive-optics assisted
the above subject. The main reason for organising this workshop was
the commissioning of the OASIS integral field spectrograph on the
WHT and the latest project to augment the use of AO on the WHT with
a laser beacon system.
Title: An IR study of the eclipsing dwarf nova IP Pegasi
Authors: Ribeiro, T.; Baptista, R.; Harlaftis, E. T.; Rutten, R. G. M.;
Dhillon, V. S.
Bibcode: 2005ASPC..330..369R
Altcode:
We report the analysis of JHK light curves of the eclipsing dwarf
nova IP Pegasi obtained with the 4.2m WHT Telescope at La Palma on
1996 October 26-29 while the system was in quiescence. We model the
observed ellipsoidal modulation to estimate the binary parameters
and we apply eclipse mapping techniques to map the surface brightness
distributions of the accretion disc.
Title: NAOMI: adaptive optics at the WHT
Authors: Benn, Chris R.; Blanken, Maarten; Bevil, Craige; Els,
Sebastian; Goodsell, Stephen; Gregory, Tom; Jolley, Paul; Longmore,
Andy J.; Martin, Olivier; Myers, Richard M.; Ostensen, Roy; Rees,
Simon; Rutten, Rene G. M.; Soechting, Ilona; Talbot, Gordon; Tulloch,
Simon M.
Bibcode: 2004SPIE.5490...79B
Altcode:
NAOMI is the AO system of the 4.2-m William Herschel Telescope on La
Palma. It delivers near-diffraction-limited images in the IR, and a
significantly improved PSF at optical wavelengths. The science cameras
currently comprise an IR imager (INGRID), an optical integral-field
spectrograph (OASIS) and a coronagraph which may be placed in the
light path to either instrument. 19 science programmes were observed
during 2002-3. Observing overheads are small, with as much as 60% of
the night spent integrating on science targets. In late 2004 this year,
the WFS will be equipped with a low-noise L3 CCD, giving a gain of a
factor of 2 in S:N for faint guide stars. A Rayleigh laser guide star
is under development, with first light expected summer 2006, providing
a unique facility: AO-corrected optical integral-field spectroscopy
anywhere on the northern sky.
Title: A spectrophotometric study of RW Trianguli
Authors: Groot, P. J.; Rutten, R. G. M.; van Paradijs, J.
Bibcode: 2004A&A...417..283G
Altcode: 2004astro.ph..1029G
On the basis of spectrophotometric observations we reconstruct the
accretion disk of the eclipsing novalike cataclysmic variable RW Tri in
the wavelength region 3600-7000 Å. We find a radial temperature profile
that is, on average, consistent with that expected on the basis of the
theory of optically thick, steady state accretion disks and infer a
mass-accretion rate in RW Tri of ∼10-8 M⊙
yr-1. The line emission is dominated by two areas: one
around the hot-spot region and one near the white dwarf. Both emission
regions have appreciable vertical extension, and seem to be decoupled
from the velocity field in the disk. In our observations RW Tri shows
a number of features that are characteristic of the SW Sex sub-class
of novalike stars. The appearance of a novalike system as a UX UMa/RW
Tri or SW Sex star seems to be mainly governed by the mass-transfer
rate from the secondary at the time of observation.
Title: Instrumentation plans for the William Herschel Telescope
Authors: Rutten, R. G. M.
Bibcode: 2004MmSAI..75..224R
Altcode:
With the advent of 8-m class telescopes the role of the 4-m class
telescopes around the world is being redefined. The development
strategy for the 4.2-m William Herschel Telescope on the island of
La Palma focuses on exploitation of the excellent seeing condition
at the Roque de los Muchachos Observatory site, and of the wide
field capability of the telescope's primary focus. Adaptive optics
developments play a central role in these plans, in particular in
carrying out high spatial resolution integral field spectroscopy at
relatively short wavelengths. At the same time the WHT continues to
play an important role as platform for visiting instruments. Apart from
instrument developments, also attention will focus on optimizing the
overall observing efficiency through queue observing and developing
tools for on-line data quality assessment.
Title: INGRID: A near-infrared camera for the William Herschel
Telescope
Authors: Packham, Christopher; Thompson, Keith L.; Zurita, Almudena;
Knapen, Johan H.; Smail, Ian; Greimel, Robert; Folha, Daniel F. M.;
Benn, Chris; Humphrey, Andrew; Rutten, Rene; Ciardi, David; Bec,
Matthieu; Bingham, Richard; Craig, Simon; Dee, Kevin; Ives, Derek;
Jolley, Paul; Moore, Peter; Pi i Puig, Marti; Rees, Simon; Talbot,
Gordon; Worswick, Sue
Bibcode: 2003MNRAS.345..395P
Altcode:
Rapid developments in near-infrared (NIR) arrays and adaptive
optics systems have driven the development of wide-field and
high-spatial-resolution, high-optical-quality NIR imagers
and spectrographs, providing an unparalleled boost to NIR
observations. Based around a 1024 × 1024 pixel2 Hawaii-1
array, the Isaac Newton Group Red Imaging Device (INGRID) imager
provides a field of view >16 arcmin2 (at the Cassegrain
focus) whilst Nyquist sampling the median summer seeing disc. When
used in conjunction with the Nasmyth Adaptive Optics for Multi-Purpose
Instrumentation (NAOMI) system and a second set of collimation optics,
a high spatial resolution mode (0.04 arcsec pixel-1)
is offered, providing near-diffraction-limited imaging. INGRID
uses an all-refractive design and employs a cold stop to reduce
thermal background emission, critical to the performance as it is
used on the non-infrared optimized 4.2-m William Herschel Telescope
(WHT). We discuss the design and operation of INGRID and illustrate
its performance by discussing commissioning observations of the cluster
Abell 2218 and the spiral galaxies NGC 3351 and 1530.
Title: VizieR Online Data Catalog: CaII and MgII excess flux density
in cool stars (Rutten, 1987)
Authors: Rutten, R. G. M.
Bibcode: 2003yCat..31770131R
Altcode:
The relation between the CaII H and K line-tore flux density and
rotation period is studied for a sample of 313 cool stars of luminosity
classes ranging from II-III to V, and compared to similar relations
for MgII h and k and soft X-ray. (3 data files).
Title: Roche tomography of cataclysmic variables - II. Images of
the secondary stars in AM Her, QQ Vul, IP Peg and HU Aqr
Authors: Watson, C. A.; Dhillon, V. S.; Rutten, R. G. M.; Schwope,
A. D.
Bibcode: 2003MNRAS.341..129W
Altcode: 2003astro.ph..2115W
We present a set of Roche tomography reconstructions of the secondary
stars in the cataclysmic variables AM Her, QQ Vul, IP Peg and HU
Aqr. The image reconstructions show distinct asymmetries in the
irradiation pattern for all four systems that can be attributed to
shielding of the secondary star by the accretion stream/column in AM
Her, QQ Vul and HU Aqr, and increased irradiation by the bright-spot
in IP Peg. We use the entropy landscape technique to derive accurate
system parameters (M1, M2, i and γ) for the
four binaries. In principle, this technique should provide the most
reliable mass determinations available, since the intensity distribution
across the secondary star is known. We also find that the intensity
distribution can systematically affect the value of γ derived from
circular orbit fits to radial velocity variations.
Title: Addendum: ``The Dynamics of M15: Observations of the
Velocity Dispersion Profile and Fokker-Planck Models'' (ApJ, 481, 267 [1997])
Authors: Dull, J. D.; Cohn, H. N.; Lugger, P. M.; Murphy, B. W.;
Seitzer, P. O.; Callanan, P. J.; Rutten, R. G. M.; Charles, P. A.
Bibcode: 2003ApJ...585..598D
Altcode: 2002astro.ph.10588D
It has recently come to our attention that there are axis scale errors
in three of the figures presented in Dull et al. (1997, hereafter
D97). This paper presented Fokker-Planck models for the collapsed-core
globular cluster M15 that include a dense, centrally concentrated
population of neutron stars and massive white dwarfs. These models do
not include a central black hole. Figure 12 of D97, which presents the
predicted mass-to-light profile, is of particular interest, since it
was used by Gerssen et al. (2002) as an input to their Jeans equation
analysis of the Hubble Space Telescope (HST) STIS velocity measurements
reported by van der Marel et al. (2002). On the basis of the original,
incorrect version of Figure 12, Gerssen et al. (2002) concluded that
the D97 models can fit the new data only with the addition of an
intermediate-mass black hole. However, this is counter to our previous
finding, shown in Figure 6 of D97, that the Fokker-Planck models predict
the sort of moderately rising velocity dispersion profile that Gerssen
et al. (2002) infer from the new data. Baumgardt et al. (2003) have
independently noted this apparent inconsistency. We appreciate
the thoughtful cooperation of Roeland van der Marel in resolving this
issue. Using our corrected version of Figure 12 (see below), Gerssen et
al. (2003) now find that the velocity dispersion profile that they infer
from the D97 mass-to-light ratio profile is entirely consistent with
the velocity dispersion profile presented in Figure 6 of D97. Gerssen
et al. (2003) further find that there is no statistically significant
difference between the fit to the van der Marel et al. (2002) velocity
measurements provided by the D97 intermediate-phase model and that
provided by their model, which supplements this D97 model with a
1.7+2.7-1.7×103Msolar black
hole. Thus, the choice between models with and without black holes will
require additional model predictions and observational tests. We
present corrected versions of Figures 9, 10, and 12 of D97. We take
responsibility for the errors in the original versions of these figures
and regret any confusion that these may have caused. We also present
an expanded version of Figure 6, which extends the radial scale to both
smaller and larger values, in order to show the full run of the velocity
dispersion profile. The profile of the intermediate-phase model of
D97 is in good agreement with the HST-STIS velocity dispersion profile
presented by Gerssen et al. (2002). In particular, the central value of
~14 km s-1, predicted by this model, nicely coincides with
their findings. We note that three independent studies have now
demonstrated that there is a dense, central concentration of dark mass
in M15, by use of three alternative methods: Fokker-Planck simulations
(D97), GRAPE-6 simulations (Baumgardt et al. 2003), and Jeans equation
modeling (Gerssen et al. 2002, 2003). The dark mass is proposed to
consist of neutron stars and massive white dwarfs, in the former two
studies, versus a central black hole in the latter. Irrespective of
these different interpretations of the nature of the dark mass, its
presence now appears to be well established on dynamical grounds.
Title: The Faint Sky Variability Survey - I. Goals and data reduction
process
Authors: Groot, P. J.; Vreeswijk, P. M.; Huber, M. E.; Everett,
M. E.; Howell, S. B.; Nelemans, G.; van Paradijs, J.; van den Heuvel,
E. P. J.; Augusteijn, T.; Kuulkers, E.; Rutten, R. G. M.; Storm, J.
Bibcode: 2003MNRAS.339..427G
Altcode: 2002astro.ph.10416G
The Faint Sky Variability Survey is aimed at finding photometric
and/or astrometric variable objects in the brightness range between
~16th and ~24th mag on time-scales between tens of minutes and years
with photometric precisions ranging from 3 millimag for the brightest
to 0.2 mag for the faintest objects. An area of ~23 deg2,
located at mid and high Galactic latitudes, has been covered using the
Wide Field Camera on the 2.5-m Isaac Newton Telescope on La Palma. Here
we describe the main goals of the Faint Sky Variability Survey and
the data reduction process.
Title: The ING telescopes in the GAIA era
Authors: Corradi, R. L. M.; Lennon, D. J.; Rutten, R. G. M.
Bibcode: 2003ASPC..298..387C
Altcode: 2003gsst.conf..387C
No abstract at ADS
Title: Introducing the Isaac Newton Group of Telescopes (invited
review talks)
Authors: Rutten, R. G. M.
Bibcode: 2003ASPC..303....3R
Altcode: 2003ssps.conf....3R
No abstract at ADS
Title: Telescope performance metrics
Authors: Talbot, R. G.; Benn, Chris R.; Rutten, Rene G. M.
Bibcode: 2002SPIE.4844..122T
Altcode:
Telescope performance can be characterised by two kinds of metric: those
which reflect scientific productivity (e.g. citation impact) and those
which monitor technical aspects of performance e.g. shutter open time
and instrument throughput, assumed to impinge on eventual scientific
productivity. These metrics can be used to guide an observatory’s
investment of limited operational resources in such a way as to
maximise long-term scientific productivity. We review metrics used at
the 4.2-m William Herschel Telescope (WHT) on La Palma, and identify
key performance indicators.
Title: A Workshop in Honour of Paul Murdin
Authors: Rutten, R. G. M.
Bibcode: 2002INGN....6...29R
Altcode:
The creation of the Isaac Newton Group of Telescopes, and more generally
of the Roque de los Muchachos Observatory, is intimately related with
the relentless energy of Paul Murdin. In October 2001, after many years,
Paul stepped down from the ING Board, and this was commemorated with a
brief but interesting workshop with the title "Science from La Palma -
Past, Present and Future."
Title: The ING Telescopes in a Changing Landscape
Authors: Rutten, R. G. M. .
Bibcode: 2002INGN....6...19R
Altcode:
Landscapes in geological terms tend to change slowly, unless there is
a land slide. With the UK joining ESO the focus of UK ground-based
astronomy will change in a dramatic way as well, strengthening its
European focus. On December 5th 2001 PPARC Council took a number of
important decisions related to the UK joining ESO. These decisions
will have a profound impact on various existing facilities, including
those of the ING.
Title: Mapping the disc evolution of EX Draconis
Authors: Harlaftis, E. T.; Papadimitriou, C.; Steeghs, D.; Sokoloski,
J. L.; Rutten, R. G. M.; Niarchos, P. G.; Gazeas, K.; Manimanis, V.;
Boffin, H.; Zurita, C.
Bibcode: 2002ASPC..261..481H
Altcode: 2002pcvr.conf..481H
We observed EX Draconis in BV I colours for 40 nights, covering 3
outburst events, with the aim to study the disc evolution. Here,
we present a preliminary eclipse-mapping study of some of the B band
light curves obtained during the outburst in August 2000.
Title: IR light curves of eclipsing dwarf novae
Authors: Harlaftis, E. T.; Baptista, R.; Rutten, R. G. M.; Dhillon,
V. S.
Bibcode: 2002ASPC..261..479H
Altcode: 2002pcvr.conf..479H
We present JHK light curves of eclipsing dwarf novae (IP Peg and HT
Cas) obtained with the 4.2m WHT telescope at La Palma and attempt
experimental fits on the H-band light curve of IP Pegasi.
Title: An International Review of ING
Authors: Rutten, R. G. M.
Bibcode: 2001INGN....5...12R
Altcode:
The volume, quality and impact of science carried out with the ING
telescopes is known to be very high by international standards, which is
now well documented. But with an eye on what is coming, a plan for the
future role of the telescopes, and in particular that of the William
Herschel Telescope, must be developed and assessed. The ING Board set
up an independent international review panel to provide a perspective
on the ING's likely scientific programme over the next 5-10 years.
Title: The accretion Disc evolution of the eclipsing cataclysmic
variable EX Draconis
Authors: Harlaftis, E. T.; Steeghs, D.; Sokoloski, J.; Rutten,
R. G. M.; Niarchos, P.; Gazeas, K.; Papadimitriou, C.; Manimanis, V.
Bibcode: 2001hell.confE..61H
Altcode:
The dwarf nova EX Draconis shows deep and wide eclipses, in addition to
its frequent outburst activity (every 2-3 weeks), which makes it the
ideal target for monitoring a complete outburst cycle. We observed EX
Draconis in BVI colours with the 1.2m telescope at Kryonerion Korinthias
(Greece) between 1 July-20 August 2000 covering 3 outburst events
(1-5 July, 20-30 July and 6-12 August). Here, we present a preliminary
eclipse mapping study of the light curves obtained in August 2000.
Title: SW Sextantis in an excited, low state
Authors: Groot, P. J.; Rutten, R. G. M.; van Paradijs, J.
Bibcode: 2001A&A...368..183G
Altcode: 2000astro.ph.12463G
We present low-resolution spectrophotometric optical observations of
the eclipsing nova-like cataclysmic variable SW Sex, the prototype of
the SW Sex stars. We observed the system when it was in an unusual
low state. The spectrum is characterized by the presence of strong
Heii and Civ emission lines as well as the normal single peaked Balmer
emission lines. The radial temperature profile of the disk follows the
expected T~ R-3/4 only in the outer parts and flattens off
inside 0.5 times the white dwarf Roche lobe radius. The single peaked
emission lines originate in a region above the plane of the disk,
at the position of the hot spot.
Title: Astronomy network will allow every site to shine
Authors: Gredel, Roland; Rutten, Rene
Bibcode: 2001Natur.409..761G
Altcode:
No abstract at ADS
Title: Introducing the Isaac Newton Group of Telescopes
Authors: Rutten, René G. M.
Bibcode: 2001ASPC..249....3R
Altcode: 2001cksa.conf....3R
A brief introduction to the Isaac Newton Group of Telescopes and
the Roque de los Muchachos Observatory on the island of La Palma is
presented. Examples of the excellent observing conditions are given,
and the focus of future instrumentation developments is set out.
Title: Instrumentation development strands at the Isaac Newton Group
of Telescopes
Authors: Rutten, R. G. M.
Bibcode: 2001NewAR..45...49R
Altcode:
The advent of a new generation of large optical/IR telescopes has
dramatically changed the skyline of ground-based astronomy. The role and
future instruments for medium-sized telescopes will have to take account
of these developments. An outline strategy for future development of
the telescopes at the Isaac Newton Group is presented.
Title: Spirals and the size of the disk in EX Dra
Authors: Joergens, V.; Spruit, H. C.; Rutten, R. G. M.
Bibcode: 2000A&A...356L..33J
Altcode: 2000astro.ph..2302J
Observations at high spectral and temporal resolution are presented
of the dwarf nova EX Dra in outburst. The disk seen in the He I line
reconstructed by Doppler tomography shows a clear two-armed spiral
pattern pointing to spiral shocks in the disk. The Balmer and He
Ii maps also give evidence for the presence of spirals. The eclipse
as seen in the red continuum indicates a disk radius of 0.31 times
the orbital separation, which might be large enough to explain the
observed spiral shocks through excitation by the tidal field of the
secondary. The eclipse in the Balmer line profiles, well resolved in
our observations, indicates a somewhat smaller disk size (0.25). We
discuss the possibility that this is related to an optical depth effect
in the lines.
Title: The hot-spot environment of SW Sex in a low state
Authors: Groot, Paul J.; Rutten, René G. M.; van Paradijs, Jan
Bibcode: 2000NewAR..44..137G
Altcode:
Based on observations obtained with the 2.5m Isaac Newton Telescope we
show that the characteristics of the SW Sex stars can be explained
by the dominance of a `hot-spot' like feature in the accretion
disk. In SW Sex this `hot-spot' region is located at a distance of
0.5 RL 1 from the white-dwarf and is best visible at
phase ϕ=0.95. The location of the hot-spot as deduced from spectral
eclipse mapping coincides with the formation site of the main emission
lines. We deduce that this hot-spot region is formed by a shock, which
we speculate to be the consequence of a high mass-transfer rate and
a long spin-period of the non-magnetic white dwarf.
Title: The effect of magnetic fields on γ-ray bursts inferred from
multi-wavelength observations of the burst of 23 January 1999
Authors: Galama, T. J.; Briggs, M. S.; Wijers, R. A. M. J.; Vreeswijk,
P. M.; Rol, E.; Band, D.; van Paradijs, J.; Kouveliotou, C.; Preece,
R. D.; Bremer, M.; Smith, I. A.; Tilanus, R. P. J.; de Bruyn, A. G.;
Strom, R. G.; Pooley, G.; Castro-Tirado, A. J.; Tanvir, N.; Robinson,
C.; Hurley, K.; Heise, J.; Telting, J.; Rutten, R. G. M.; Packham,
C.; Swaters, R.; Davies, J. K.; Fassia, A.; Green, S. F.; Foster,
M. J.; Sagar, R.; Pandey, A. K.; Nilakshi; Yadav, R. K. S.; Ofek,
E. O.; Leibowitz, E.; Ibbetson, P.; Rhoads, J.; Falco, E.; Petry,
C.; Impey, C.; Geballe, T. R.; Bhattacharya, D.
Bibcode: 1999Natur.398..394G
Altcode:
Gamma-ray bursts (GRBs) are thought to arise when an extremely
relativistic outflow of particles from a massive explosion (the nature
of which is still unclear) interacts with material surrounding the site
of the explosion. Observations of the evolving changes in emission at
many wavelengths allow us to investigate the origin of the photons,
and so potentially determine the nature of the explosion. Here we
report the results of γ-ray, optical, infrared, submillimetre,
millimetre and radio observations of the burst GRB990123 and its
afterglow. Our interpretation of the data indicates that the initial
and afterglow emissions are associated with three distinct regions in
the fireball. The peak flux of the afterglow, one day after the burst,
has a lower frequency than observed for other bursts; this explains
the short-lived radio emission. We suggest that the differences
between bursts reflect variations in the magnetic-field strength in
the afterglow-emitting regions.
Title: Spectral Energy Distributions and Light Curves of GRB 990123
and its Afterglow
Authors: Galama, T. J.; Briggs, M. S.; Wijers, R. A. M. J.; Vreeswijk,
P. M.; Rol, E.; Band, D.; van Paradijs, J.; Kouveliotou, C.; Preece,
R. D.; Bremer, M.; Smith, I. A.; Tilanus, R. P. J.; de Bruyn, A. G.;
Strom, R. G.; Pooley, G.; Castro-Tirado, A. J.; Tanvir, N.; Robinson,
C.; Hurley, K.; Heise, J.; Telting, J.; Rutten, R. G. M.; Packham,
C.; Swaters, R.; Davies, J. K.; Fassia, A.; Green, S. F.; Foster,
M. J.; Sagar, R.; Pandey, A. K.; Nilakshi; Yadav, R. K. S.; Ofek,
E. O.; Leibowitz, E.; Ibbetson, P.; Rhoads, J.; Falco, E.; Petry,
C.; Impey, C.; Geballe, T. R.; Bhattacharya, D.
Bibcode: 1999astro.ph..3021G
Altcode:
Gamma-ray bursts (GRBs) are thought to result from the interaction
of an extremely relativistic outflow interacting with a small amount
of material surrounding the site of the explosion. Multi-wavelength
observations covering the gamma-ray to radio wavebands allow
investigations of this `fireball' model. On 23 January 1999 optical
emission was detected while the gamma-ray burst was still underway. Here
we report the results of gamma-ray, optical/infra-red, sub-mm, mm and
radio observations of this burst and its afterglow, which indicate
that the prompt and afterglow emissions from GRB 990123 are associated
with three distinct regions in the fireball. The afterglow one day
after the burst has a much lower peak frequency than those of previous
bursts; this explains the short-lived nature of the radio emission,
which is not expected to reappear. We suggest that such differences
reflect variations in the magnetic-field strengths in the afterglow
emitting regions.
Title: The stream impact region in the disc of WZ SGE
Authors: Spruit, H. C.; Rutten, R. G. M.
Bibcode: 1998MNRAS.299..768S
Altcode:
We report the observation of new features in the spectrum of the
cataclysmic variable WZ Sge. The disc eclipse is seen as a well-defined
structure in the Hα line. From phases 0.25 to 0.5 an absorption
feature of the same shape as the emission S wave is seen in this line,
but redshifted by ~200 kms^-1. Two possible interpretations of this
feature are given, both of which imply that it originates at the
impact point of the stream on the disc edge. In addition, evidence
is found for substructure in the velocity map of the spot. Emission
from line-emitting post-shock material, extending to about 60 deg
downstream from the continuum hotspot, is seen in the Doppler map in
the form of a tail extending from the hotspot. A theoretical estimate
shows that such a tail is to be expected as a consequence of the
post-impact hydrodynamics of the stream. A new determination of the
system parameters is made. They agree with those of Gilliland et al.;
in particular, the data support a high primary mass. The variation
of Hα surface brightness with distance from the primary is flatter,
in the inner regions, than the r^-1.5 dependence found by Horne for
other cataclysmic variables in quiescence.
Title: ^56Ni dredge-up in the type IIp supernova 1995V
Authors: Fassia, A.; Meikle, W. P. S.; Geballe, T. R.; Walton, N. A.;
Pollacco, D. L.; Rutten, R. G. M.; Tinney, C.
Bibcode: 1998MNRAS.299..150F
Altcode: 1998astro.ph..4315F
We present contemporary infrared (IR) and optical spectra of the plateau
type II SN 1995V in NGC 1087 covering four epochs, approximately 22
to 84 d after shock break-out. The data show, for the first time, the
IR spectroscopic evolution during the plateau phase of a typical type
II event. In the optical region P Cygni lines of the Balmer series
and of metals such as ScII, FeII, SrII, CaII and BaII lines were
identified. The IR spectra were largely dominated by the continuum,
but P Cygni Paschen lines and Brackett gamma lines were also clearly
seen. The other prominent IR features are confined to wavelengths
blueward of 11000 Angstroms, and include SrII 10327, FeII 10547,
CI 10695 and HeI 10830 Angstroms. Helium has never before been
unambiguously identified in a type IIp supernova spectrum during the
plateau phase. We demonstrate the presence of HeI 10830 Angstroms on
days 69 and 85. The presence of this line at such late times implies
reionization. A likely reionizing mechanism is gamma-ray deposition
following the radioactive decay of ^56Ni. We examine this mechanism by
constructing a spectral model for the HeI 10830-Angstroms line based on
explosion model s15s7b2f of Weaver & Woosley. We find that this does
not generate the observed line owing to the confinement of the ^56Ni to
the central zones of the ejecta. In order to reproduce the HeI line,
it was necessary to introduce additional upward mixing or `dredge-up'
of the ^56Ni, with ~10^-5 of the total nickel mass reaching above the
helium photosphere. In addition, we argue that the HeI line formation
region is likely to have been in the form of pure helium clumps in the
hydrogen envelope. The study of HeI 10830-Angstroms emission during the
photospheric phase of core-collapse supernovae provides a promising tool
for the constraint of initial mixing conditions in explosion models.
Title: HST spatially resolved spectra of the accretion disc and gas
stream of the nova-like variable UX Ursae Majoris
Authors: Baptista, Raymundo; Horne, Keith; Wade, Richard A.; Hubeny,
Ivan; Long, Knox S.; Rutten, Rene G. M.
Bibcode: 1998MNRAS.298.1079B
Altcode: 1998astro.ph..4002B
Time-resolved eclipse spectroscopy of the nova-like variable UX UMa
obtained with the HST/FOS on 1994 August and November is analysed
with eclipse mapping techniques to produce spatially resolved spectra
of its accretion disc and gas stream as a function of distance from
the disc centre. The inner accretion disc is characterized by a blue
continuum filled with absorption bands and lines, which cross over
to emission with increasing disc radius, similar to that reported
by Rutten et al. at optical wavelengths. The comparison of spatially
resolved spectra at different azimuths reveals a significant asymmetry
in the disc emission at ultraviolet (UV) wavelengths, with the disc
side closest to the secondary star showing pronounced absorption by an
`iron curtain' and a Balmer jump in absorption. These results suggest
the existence of an absorbing ring of cold gas whose density and/or
vertical scale increase with disc radius. The spectrum of the infalling
gas stream is noticeably different from the disc spectrum at the same
radius suggesting that gas overflows through the impact point at the
disc rim and continues along the stream trajectory, producing distinct
emission down to 0.1R_L1. The spectrum of the uneclipsed light shows
prominent emission lines of Lyalpha, Nv lambda1241, Siiv lambda1400,
Civ lambda1550, Heii lambda1640, and Mgii lambda2800, and a UV continuum
rising towards longer wavelengths. The Balmer jump appears clearly
in emission indicating that the uneclipsed light has an important
contribution from optically thin gas. The lines and optically thin
continuum emission are most probably emitted in a vertically extended
disc chromosphere + wind. The radial temperature profiles of the
continuum maps are well described by a steady-state disc model in the
inner and intermediate disc regions (R<=0.3R_L1). There is evidence
of an increase in the mass accretion rate from August to November (from
M^. = 10^-8.3 +/- 0.1 to 10^-8.1 +/- 0.1M/yr^-1), in accordance with the
observed increase in brightness. Since the UXUMa disc seems to be in a
high mass accretion, high-viscosity regime in both epochs, this result
suggests that the mass transfer rate of UX UMa varies substantially
(~= 50 per cent) on time-scales of a few months. It is suggested that
the reason for the discrepancies between the prediction of the standard
disc model and observations is not an inadequate treatment of radiative
transfer in the disc atmosphere, but rather the presence of additional
important sources of light in the system besides the accretion disc
(e.g. optically thin continuum emission from the disc wind and possible
absorption by circumstellar cool gas).
Title: Hubble Space Telescope Eclipse Observations of the Nova-like
Cataclysmic Variable UX Ursae Majoris
Authors: Knigge, Christian; Long, Knox S.; Wade, Richard A.; Baptista,
Raymundo; Horne, Keith; Hubeny, Ivan; Rutten, René G. M.
Bibcode: 1998ApJ...499..414K
Altcode: 1998astro.ph..1206K
We present and analyze Hubble Space Telescope observations of the
eclipsing nova-like cataclysmic variable UX UMa obtained with the
Faint Object Spectrograph. Two eclipses each were observed with the
G160L grating (covering the ultraviolet waveband) in 1994 August and
with the PRISM (covering the near-ultraviolet to near-infrared) in
November of the same year. The system was ~50% brighter in November
than in August, which, if due to a change in the accretion rate,
indicates a fairly substantial increase in Ṁacc by
>~50%. The eclipse light curves are qualitatively consistent with
the gradual occultation of an accretion disk with a radially decreasing
temperature distribution. The light curves also exhibit asymmetries
about mideclipse that are likely due to a bright spot at the disk
edge. Bright-spot spectra have been constructed by differencing the
mean spectra observed at pre- and posteclipse orbital phases. These
difference spectra contain ultraviolet absorption lines and show
the Balmer jump in emission. This suggests that part of the bright
spot may be optically thin in the continuum and vertically extended
enough to veil the inner disk and/or the outflow from UX UMa in some
spectral lines. Model disk spectra constructed as ensembles of stellar
atmospheres provide poor descriptions of the observed posteclipse
spectra, despite the fact that UX UMa's light should be dominated
by the disk at this time. Suitably scaled single temperature model
stellar atmospheres with Teff ~= 12,500-14,500 K actually
provide a better match to both the ultraviolet and optical posteclipse
spectra. Evidently, great care must be taken in attempts to derive
accretion rates from comparisons of disk models to observations. One
way to reconcile disk models with the observed posteclipse spectra
is to postulate the presence of a significant amount of optically
thin material in the system. Such an optically thin component
might be associated with the transition region (``chromosphere'')
between the disk photosphere and the fast wind from the system, whose
presence has been suggested by Knigge & Drew. In any event, the
wind/chromosphere is likely to be the region in which many, if not
most, of the UV lines are formed. This is clear from the plethora of
emission lines that appear in the mideclipse spectra, some of which
appear as absorption features in spectra taken at out-of-eclipse
orbital phases. Based on observations with the NASA/ESA Hubble
Space Telescope, obtained at the Space Telescope Science Institute,
which is operated by the Association of Universities for Research in
Astronomy, Inc., under NASA contract NAS 5-2655.
Title: Optical Follow-Up of GRB 970508
Authors: Galama, T. J.; Groot, P. J.; van Paradijs, J.; Kouveliotou,
C.; Strom, R. G.; Wijers, R. A. M. J.; Tanvir, N.; Bloom, J.;
Centurion, M.; Telting, J.; Rutten, R. G. M.; Smith, P.; Mackey, C.;
Smartt, S.; Benn, C.; Heise, J.; in 't Zand, J.
Bibcode: 1998ApJ...497L..13G
Altcode: 1998astro.ph..2160G
We report on the results of optical follow-up observations of the
counterpart of the gamma-ray burst GRB 970508, starting 7 hr after the
event. Multicolor U-, B-, V-, Rc-, and Ic-band
observations were obtained during the first three consecutive
nights. The counterpart was monitored regularly in Rc until
~4 months after the burst. The light curve after the maximum follows a
decline that can be fitted with a power law with exponent α = -1.141
+/- 0.014. Deviations from a smooth power-law decay are moderate (rms =
0.15 mag). We find no flattening of the light curve at late times. The
optical afterglow fluence is a significant fraction, ~5%, of the GRB
fluence. The optical energy distribution can be well represented by
a power law, the slope of which changed at the time of the maximum
(the spectrum became redder).
Title: 3D eclipse mapping
Authors: Rutten, R. G. M.
Bibcode: 1998A&AS..127..581R
Altcode:
A light curve modelling and fitting program is presented for
cataclysmic variable stars and related objects. It allows modelling
of a three-dimensional disk in conjunction with the Roche-lobe filling
secondary star, thus rendering it a very general tool for light curve
analysis. Optimization of the solution is based on the maximum-entropy
algorithm. Some bench-mark tests are presented, and the general
applicability of the program is explored. The program is used here
to study the problem of reconstructing the brightness distribution
on flaring accretion disks from eclipse light curves, and the results
are compared with those obtained using the well-established standard
technique of flat-disk eclipse mapping. A previous study suggested
that erroneous radial temperature profiles were obtained with flat-disk
eclipse mapping. It is shown here that flat-disk eclipse mapping does
reproduce the radial brightness structure of flared accretion disks
very well, provided that the inner disk is not obscured by the outer
rim of the disk.
Title: A Search for Optical Afterglow from GRB 970828
Authors: Groot, P. J.; Galama, T. J.; van Paradijs, J.; Kouveliotou,
C.; Wijers, R. A. M. J.; Bloom, J.; Tanvir, N.; Vanderspek, R.;
Greiner, J.; Castro-Tirado, A. J.; Gorosabel, J.; von Hippel, T.;
Lehnert, M.; Kuijken, K.; Hoekstra, H.; Metcalfe, N.; Howk, C.;
Conselice, C.; Telting, J.; Rutten, R. G. M.; Rhoads, J.; Cole, A.;
Pisano, D. J.; Naber, R.; Schwarz, R.
Bibcode: 1998ApJ...493L..27G
Altcode: 1997astro.ph.11171G
We report on the results of R-band observations of the error box of
the γ-ray burst of 1997 August 28 made between 4 hr and 8 days after
this burst occurred. No counterpart was found varying by more than 0.2
mag down to R=23.8. We discuss the consequences of this nondetection
for relativistic blast wave models of γ-ray bursts and the possible
effect of redshift on the relation between optical absorption and the
low-energy cutoff in the X-ray afterglow spectrum.
Title: Radio and Optical Follow-up Observations and Improved
Interplanetary Network Position of GRB 970111
Authors: Galama, T. J.; Groot, P. J.; Strom, R. G.; van Paradijs, J.;
Hurley, K.; Kouveliotou, C.; Fishman, G. J.; Meegan, C. A.; Heise,
J.; Zand, J. J. M. in't.; de Bruyn, A. G.; Hanlon, L. O.; Bennett,
K.; Telting, J. H.; Rutten, R. G. M.
Bibcode: 1997ApJ...486L...5G
Altcode: 1997astro.ph..7282G
We report on Westerbork 840 MHz and 1.4 and 5 GHz radio observations
of the improved Interplanetary Network Wide Field Camera (IPN WFC)
error box of the γ-ray burst GRB 970111, between 26.4 hr and 120 days
after the event onset. In the ~13 arcmin2 area defined by
the IPN (BATSE and Ulysses) annulus and the published refined BeppoSAX
WFC error box, we detected no steady sources brighter than 0.56 mJy
(4 σ) and no varying radio emission, down to 1.0 mJy (4 σ). We also
report on B-, V-, R-, and I-band observations of the error box with
the 4.2 m William Herschel Telescope at La Palma.
Title: The Dynamics of M15: Observations of the Velocity Dispersion
Profile and Fokker-Planck Models
Authors: Dull, J. D.; Cohn, H. N.; Lugger, P. M.; Murphy, B. W.;
Seitzer, P. O.; Callanan, P. J.; Rutten, R. G. M.; Charles, P. A.
Bibcode: 1997ApJ...481..267D
Altcode:
We report a new measurement of the velocity dispersion profile within
1' (3 pc) of the center of the globular cluster M15 (NGC 7078), using
long-slit spectra from the 4.2 m William Herschel Telescope at La Palma
Observatory. We obtained spatially resolved spectra for a total of 23
slit positions during two observing runs. During each run, a set of
parallel slit positions was used to map out the central region of the
cluster; the position angle used during the second run was orthogonal to
that used for the first. The spectra are centered in wavelength near the
Ca II infrared triplet at 8650 Å, with a spectral range of about 450
Å. We determined radial velocities by cross-correlation techniques
for 131 cluster members. A total of 32 stars were observed more than
once. Internal and external comparisons indicate a velocity accuracy
of about 4 km s-1. The velocity dispersion profile rises
from about σ = 7.2 +/- 1.4 km s-1 near 1' from the center
of the cluster to σ = 13.9 +/- 1.8 km s-1 at 20". Inside
of 20", the dispersion remains approximately constant at about 10.2
+/- 1.4 km s-1 with no evidence for a sharp rise near the
center. This last result stands in contrast with that of Peterson,
Seitzer, & Cudworth who found a central velocity dispersion of 25
+/- 7 km s-1, based on a line-broadening measurement. Our
velocity dispersion profile is in good agreement with those determined
in the recent studies of Gebhardt et al. and Dubath & Meylan. We have developed a new set of Fokker-Planck models and have fitted
these to the surface brightness and velocity dispersion profiles of
M15. We also use the two measured millisecond pulsar accelerations
as constraints. The best-fitting model has a mass function slope
of x = 0.9 (where 1.35 is the slope of the Salpeter mass function)
and a total mass of 4.9 × 105 M⊙. This model
contains approximately 104 neutron stars (3% of the total
mass), the majority of which lie within 6" (0.2 pc) of the cluster
center. Since the velocity dispersion profile of M15 is well fitted by
this postcollapse model in which the most massive objects are neutron
stars, there appears to be no need to invoke the presence of a massive
central black hole in M15. Based on observations made with the
William Herschel Telescope operated on the island of La Palma by the
Royal Greenwich Observatory in the Spanish Observatorio del Roque de
los Muchachos of the Instituto de Astrofisica de Canarias.
Title: The decay of optical emission from the γ-ray burst GRB 970228.
Authors: Galama, T.; Groot, P. J.; Vanparadijs, J.; Kouveliotou, C.;
Robinson, C. R.; Fishman, G. J.; Meegan, C. A.; Sahu, K. C.; Livio,
M.; Petro, L.; Macchetto, F. D.; Heise, J.; Int Zand, J.; Strom, R. G.;
Telting, J.; Rutten, R. G. M.; Pettini, M.; Tanvir, N.; Bloom, J.
Bibcode: 1997Natur.387..479G
Altcode: 1997astro.ph.12322G
The optical counterpart of the γ-ray burst GRB 970228 appears to be
a transient point source embedded in a region of extended nebulosity,
the latter having been tentatively identified as a high-redshift
galaxy. This would seem to favour models that place γ-ray bursts at
cosmological distances, although a range of mechanisms for producing
the bursts is still allowed. A crucial piece of information for
distinguishing between such models is how the brightness of the optical
counterpart evolves with time. Here the authors re-evaluate the existing
photometry of the optical counterpart of GRB 970228 to construct an
optical light curve for the transient event. They find that between 21
hours and six days after the burst, the R-band brightness decreased
by a factor of ≡40, with any subsequent decrease in brightness
occurring at a much slower rate. As the point source faded, it also
became redder. The initial behaviour of the source appears to be
consistent with the "fireball" model, but the subsequent decrease in
the rate of fading may prove harder to explain.
Title: Transient optical emission from the error box of the γ-ray
burst of 28 February 1997
Authors: van Paradijs, J.; Groot, P. J.; Galama, T.; Kouveliotou,
C.; Strom, R. G.; Telting, J.; Rutten, R. G. M.; Fishman, G. J.;
Meegan, C. A.; Pettini, M.; Tanvir, N.; Bloom, J.; Pedersen, H.;
Nørdgaard-Nielsen, H. U.; Linden-Vørnle, M.; Melnick, J.; Van der
Steene, G.; Bremer, M.; Naber, R.; Heise, J.; in't Zand, J.; Costa,
E.; Feroci, M.; Piro, L.; Frontera, F.; Zavattini, G.; Nicastro, L.;
Palazzi, E.; Bennett, K.; Hanlon, L.; Parmar, A.
Bibcode: 1997Natur.386..686V
Altcode:
For almost a quarter of a century1, the origin of γ-ray
bursts- brief, energetic bursts of high-energy photons-has remained
unknown. The detection of a counterpart at another wavelength has
long been thought to be a key to understanding the nature of these
bursts (see, for example, ref. 2), but intensive searches have not
revealed such a counterpart. The distribution and properties of the
bursts3 are explained naturally if they lie at cosmological
distances (a few Gpc)4, but there is a countervailing
view that they are relatively local objects5, perhaps
distributed in a very large halo around our Galaxy. Here we report
the detection of a transient and fading optical source in the error
box associated with the burst GRB970228, less than 21 hours after the
burst6,7. The optical transient appears to be associated
with a faint galaxy7,8, suggesting that the burst occurred in
that galaxy and thus that γ-ray bursts in general lie at cosmological
distance.
Title: GRB 970111
Authors: Groot, P. J.; Galama, T.; Telting, J.; Rutten, R. G. M.;
van Paradijs, J.
Bibcode: 1997IAUC.6574....1G
Altcode: 1997IAUC.6574Q...1G; 1997IAUC.6574A...1G
P. J. Groot and T. Galama, University of Amsterdam (UoA); J. Telting
and R. G. M. Rutten, ING Telescopes, La Palma; and J. van Paradijs, UoA
and University of Alabama in Huntsville, report: "We have obtained BVI
images of the refined error-box of GRB 970111 (IAUC 6569) on Feb. 28.2
UT with integration times of 930, 405, and 695 s, respectively, and R
images (405 s) on Mar. 1.1, using the 4.2-m William Herschel Telescope
(prime focus) at La Palma. Comparison with the Digital Sky Survey shows
no brightening of sources to V = 19. The three radio sources reported
by Galama et al. (IAUC 6571) show no optical counterpart down to V =
24.0. The GRB error box contains two galaxies, at R.A. = 15h28m15s.2,
Decl. = +19o35'55" (equinox 2000.0), with V = 20.2, B-V = +1.3, V-R =
+0.7, V-I = +1.4; and at R.A. = 15h28m10s.8, Decl. = +19o35'35", with
V = 20.5, B-V = +0.5, V-R = +0.4, V-I = +0.9. These galaxies are not
detected in the radio observations reported by Galama et al."
Title: GRB 970228
Authors: Groot, P. J.; Galama, T. J.; van Paradijs, J.; Strom, R.;
Telting, J.; Rutten, R. G. M.; Pettini, M.; Tanvir, N.; Naber, R.;
Kouveliotou, C.; in 't Zand, J.; Heise, J.; Costa, E.; Feroci, M.;
Piro, L.; Frontera, F.; Zavattini, G.; Nicastro, L.; Palazzi, E.
Bibcode: 1997IAUC.6584....1G
Altcode: 1997IAUC.6584A...1G
P. J. Groot and T. J. Galama, University of Amsterdam (UoA); J. van
Paradijs, UoA and University of Alabama, Huntsville; R. Strom,
Netherlands Foundation for Research in Astronomy and UoA; J. Telting
and R. G. M. Rutten, Isaac Newton Group of Telescopes, La Palma;
M. Pettini and N. Tanvir, Institute of Astronomy, Cambridge; R. Naber,
University of Groningen; C. Kouveliotou, Universities Space Research
Association; J. in 't Zand and J. Heise, Space Research Organization of
the Netherlands, Utrecht; E. Costa, M. Feroci, and L. Piro, Instituto di
Astrofisica Spaziale, CNR; F. Frontera and G. Zavattini, Universita di
Ferrara; and L. Nicastro and E. Palazzi, Instituto Tecnologia e Studie
Radiazione Extraterrestri, CNR, report: "Comparison of the V- and I-band
images of the error box of GRB 970228 (IAUC 6572), taken on Mar. 1.0 UT
(IAUC 6574) and on Mar. 8.9 with the William Herschel Telescope (I band,
900 s) and the Isaac Newton Telescope (V band, 2500 s), reveals one
object with a large brightness variation in both bands. The variable
had V = 21.3 and I = 20.6 on Mar. 1.0 and V > 23.6 and I > 22.2
on Mar. 8.9. Its position is R.A. = 5h01m46s.70, Decl. = +11o46'53".0
(equinox 2000.0; estimated accuracy 1"). Approximately 4" away (at
position end figures 46s.73, 53".0), we find another object, with V =
23.1 and I = 20.5 on Mar. 8.9, whose brightness on Mar. 1.0 (measured
somewhat less accurately because of the nearby variable) differed
by < 0.2 mag from these values. The point-spread function of the
variable, and that of the nearby constant object, is consistent with
those of stars in the images; the two objects are therefore extended
by less than about 1".5. Radio observations at 5 GHz obtained with the
Westerbork Synthesis Radio Telescope on Mar. 1.75 and 2.75 (12 hr each)
show no radio source at the position of the variable above 0.35 mJy (3
sigma). The variable is located within the intersection of the BeppoSAX
WFC error box (IAUC 6572), the BeppoSAX LECS error box (IAUC 6576),
and the Ulysses/BeppoSAX annulus (IAUC 6578); it is more than 1' away
from the radio source reported on IAUC 6576. Its position and rapid
decline contemporaneous with that of the BeppoSAX LECS x-ray transient
(IAUC 6576) indicate that the two are related. If the x-ray transient
is related to GRB 970228, we have detected the first transient optical
signal related to a gamma-ray burst." Corrigendum. On IAUC 6582,
Bloom et al., line 6, for We find V = 21.4, read We find V = 22.4,
Title: GRB 970228
Authors: Groot, P. J.; Galama, T. J.; van Paradijs, J.; Melnick,
J.; van der Steene, G.; Bremer, M.; Tanvir, N.; Bloom, J.; Strom,
R.; Telting, J.; Rutten, R. G. M.; Kouveliotou, C.; in 't Zand, J.;
Heise, J.; Costa, E.; Feroci, M.; Piro, L.; Frontera, F.; Zavattini,
G.; Nicastro, L.; Palazzi, E.; Metzger, M. R.; Kulkarni, S. R.;
Djorgovski, S. G.; Gal, R.; Steidel, C. C.; Frail, D. A.
Bibcode: 1997IAUC.6588....1G
Altcode: 1997IAUC.6588A...1G
P. J. Groot and T. J. Galama, University of Amsterdam (UoA); J. van
Paradijs, UoA and University of Alabama, Huntsville; J. Melnick,
G. van der Steene, and M. Bremer, European Southern Observatory
(ESO); N. Tanvir and J. Bloom, Institute of Astronomy, Cambridge;
R. Strom, Netherlands Foundation for Research in Astronomy; J. Telting
and R. G. M. Rutten, Isaac Newton Group of Telescopes, La Palma;
C. Kouveliotou, Universities Space Research Association; J. in 't
Zand and J. Heise, SRON, Utrecht; E. Costa, M. Feroci, and L. Piro,
Istituto di Astrofisica Spaziale, CNR; F. Frontera and G. Zavattini,
Universita di Ferrara; and L. Nicastro and E. Palazzi, Istituto TESRE,
CNR, report: "An R-band image (3600-s exposure) made with the ESO
New Technology Telescope on Mar. 13.0 UT shows the presence of an
extended object at R = 23.8 +/- 0.2 within 0".2 of the position of the
optical transient reported on IAUC 6584. The object is elongated in the
north-south direction and measures 1".3 x 1".0 (FWHM). The point-spread
function for the image has 1".0 FWHM. This indicates that the object is
a galaxy. The brightness of the nearby star (the position end figures
for which should have been given on IAUC 6584 as 46s.43 and 53".0) is
R = 21.5. R- and B-band images made with the Isaac Newton Telescope on
Mar. 9.9 show an object at the position of the optical transient whose
magnitudes, R = 24.0 and B = 25.4, are likely dominated by the above
galaxy. Low-resolution spectroscopy of the nearby star with the ESO
3.6-m telescope shows the presence of TiO features, which together with
the color index (V-I = +2.6) indicates that it is an early M-type dwarf
unrelated to the optical transient." M. R. Metzger, S. R. Kulkarni,
S. G. Djorgovski, R. Gal, and C. C. Steidel, California Institute of
Technology; and D. A. Frail, National Radio Astronomy Observatory,
communicate: "Examination of an R-band image taken with the Keck II
10-m telescope on Mar. 6.32 UT (cf. IAUC 6582) reveals a faint source
near the position of the optical variable reported on IAUC 6584. This
source appears extended, with R = 24.0 and its center at R.A. =
5h01m46s.59, Decl. = +11o46'53".5 (equinox 2000.0); it is 2".7 away
from a brighter source with R = 22.4 at position end figures 46s.40,
53".3 (+/- 0".2), evidently corresponding to the steady source of Groot
et al. (see above). No other sources are detected within 5" to R =
25.0. The extended source also appears on an I-band image taken on
Mar. 6.19 with the Palomar 1.5-m reflector, near the detection limit
of I = 21.5. From an R-band image taken on Mar. 11.18 at the Palomar
5-m reflector, we find that the extended source has not varied by more
than 0.3 mag in R over the interval."
Title: Roche tomography of the cool star in IP Peg
Authors: Rutten, R. G. M.; Dhillon, V. S.
Bibcode: 1996ASSL..208...21R
Altcode: 1996cvro.coll...21R; 1996IAUCo.158...21R
No abstract at ADS
Title: Temperature structure of the disk in V1315 AQR
Authors: Moreno, C.; Rutten, R. G. M.; Dhillon, V. S.
Bibcode: 1996ASSL..208...15M
Altcode: 1996cvro.coll...15M; 1996IAUCo.158...15M
No abstract at ADS
Title: Spectropolarimetry of the nova-like variable V 1315 Aquilae
Authors: Dhillon, V. S.; Rutten, R. G. M.
Bibcode: 1995MNRAS.277..777D
Altcode: 1995astro.ph..6111D
We present spectropolarimetric observations of the eclipsing nova-like
variable V1315 Aql, obtained with the aim of determining whether the
single-peaked uneclipsed lines observed in this and related nova-like
variables are the result of disc emission scattered into the line of
sight by the wind. The data show linear polarization with a mean value
of 0.11+/-0.02 per cent. There are no significant differences between
the continuum and line polarizations and no significant variations with
wavelength or binary phase. We argue that the measured polarization
may be attributed to scattering in the interstellar medium and hence
conclude that there is no evidence of polarization intrinsic to
V1315 Aql. We discuss alternative models which promise to resolve the
controversy surrounding these objects.
Title: Spectropolarimetry of the dwarf nova IP Peg
Authors: Dhillon, V. S.; Rutten, R. G. M.
Bibcode: 1995MNRAS.274...27D
Altcode:
We present spectropolarimetric observations of the eclipsing dwarf nova
IP Peg in quiescence. The data show linear polarizations with a mean
value of 0.10+/-0.06 per cent. There are no significant differences
between the continuum and line polarizations and no significant
variations with wavelength or binary phase. We argue that the measured
polarization may be attributed to scattering in the interstellar medium
and hence conclude that there is no evidence of polarization intrinsic
to IP Peg.
Title: The orbital period of the pre-cataclysmic binary RE 2013+400
and a study of the atmosphere of the DAO white dwarf primary
Authors: Barstow, M. A.; Burleigh, M. R.; Fleming, T. A.; Holberg,
J. B.; Koester, D.; Marsh, M. C.; Rosen, S. R.; Rutten, R. G. M.;
Sakai, S.; Tweedy, R. W.; Wegner, G.
Bibcode: 1995MNRAS.272..531B
Altcode:
Several pre-cataclysmic binaries, comprising a hot white dwarf with a
red dwarf companion, have been discovered as a result of the optical
identification of EUV sources from the ROSAT all-sky survey. The optical
spectra have the steep blue continuum and Balmer absorption typical of a
hot white dwarf, but there are bright, narrow emission lines of H I (and
sometimes He I and Ca II) superimposed. An intense campaign of follow-up
observations has been devoted to these binary systems. So far, only RE
2013+400 has exhibited any measurable changes in the radial velocities
of the emission components, from which it is possible to estimate that
the binary period is 0.71 d. A clear He II 4886-A absorption feature
is detected, which indicates that, like most PCBs with white dwarfs
hotter than 40 000 K, the white dwarf is a hydrogen-helium hybrid
star (DAO). A combined analysis of the optical, UV and EUV/X-ray data
suggests that the atmospheric He abundance is higher in the optical
line-forming region of the white dwarf photosphere than in the region
where the EUV/X-ray flux is formed. This is an interesting result, in
the light of the recent optical study of a sample of DAO white dwarfs
by Bergeron et al., if representative of DAO white dwarfs in general.
Title: Spectropolarimetry of V1315 Aql
Authors: Dhillon, V. S.; Rutten, R. G. M.
Bibcode: 1995ASSL..205..125D
Altcode: 1995cava.conf..125D
No abstract at ADS
Title: HST spectrally-resolved accretion disk maps of UX UMa in
the ultraviolet
Authors: Baptista, R.; Long, K.; Horne, K.; Hubeny, I.; Mauche, C. W.;
Rutten, R. G. M.; Wade, R. A.
Bibcode: 1994AAS...18511605B
Altcode: 1994BAAS...26.1514B
We present spectrally-resolved eclipse maps of the UX UMa accretion
disk in the spectral region 1170--2400 Angstroms. The analysis is
based on low-dispersion time-resolved spectroscopy during eclipse,
obtained with the HST Faint Object Spectrograph. The out-of-eclipse
spectra show prominent emission lines (CIII lambda 1176, Lyalpha ,
NV lambda 1240, SiIV lambda 1400, CIV lambda 1550) as well as many
absorption features and possibly a broad absorption band centered
at about 1900 Angstroms. HeII lambda 1640 appears as a weak emission
line. At mid-eclipse the continuum flux is reduced by a factor ~ 3,
while the emission lines are much less affected by the eclipse and
some of the lines that are seen in absorption in the out-of-eclipse
spectra appear in emission. UV continuum light curves show significant
flickering activity outside of eclipse, relatively much stronger
than observed in the optical range. The eclipses are deep and steep
in the continuum with an asymmetry in their egress portion, however
no clear evidence of a compact bright spot is seen. The spectra were
divided into passbands ( ~ 40 Angstroms in the continuum and ~ 3000
Km/s in the emission lines) and light curves were extracted for each
one. Maximum-entropy eclipse mapping techniques were used to solve
for a map of the disk brightness distribution and for the flux of
an additional uneclipsed component in each band. Radial brightness
temperature profiles and spatially-resolved disk spectra derived from
these maps are presented and discussed.
Title: Roche tomography: imaging the stars in interacting binaries
Authors: Rutten, R. G. M.; Dhillon, V. S.
Bibcode: 1994A&A...288..773R
Altcode:
A new technique for analysing phase-resolved spectral lines from
the Roche-lobe filling secondary star in cataclysmic variables (CVs)
and related objects is presented. This technique, Roche tomography,
enables mapping of the line intensity distribution on the surface
of the Roche-lobe filling star by employing the shape of the Roche
lobe to model both Doppler shifts and line intensity variations
through the binary orbit. It may be used to analyse emission lines
as well as absorption lines. The intrinsic shape of the spectral
line may be taken into account, and the effects of limb darkening,
instrumental resolution and phase resolution may be incorporated. The
maximum-entropy criterion is used to optimize the fit to the data,
yielding the smoothest possible intensity distribution on the star. The
technique can be used to constrain the mass ratio and inclination
of the binary system, and to study the effects of irradiation, or
other surface inhomogeneities. Experiments on computer generated data
are presented in conjunction with an analysis of Balmer emission line
observations from the secondary star in the nova-like variable DW Ursae
Majoris. DW UMa shows strongly enhanced emissivity in the Balmer lines
close to the L1 point, suggesting irradiation from the central part
of the accretion disk or the bright spot.
Title: The Inner Velocity Dispersion Profile of M15
Authors: Dull, J. D.; Cohn, H. N.; Lugger, P. M.; Murphy, B. W.;
Seitzer, P. O.; Callanan, P. J.; Rutten, R. G. M.; Charles, P. A.
Bibcode: 1994AAS...184.5814D
Altcode: 1994BAAS...26..956D
We report a new measurement of the velocity dispersion profile within 1'
(3 pc) of the center of the globular cluster M15 (NGC 7078), using
long-slit spectra from the 4.2-m William Herschel Telescope at La
Palma Observatory. Spectra for a total of 23 slit positions were
obtained during two observing runs. Each run used a set of parallel
positions to map out the central region of the cluster; the position
angle used during the second run was orthogonal to that used for the
first. The spectra are centered near the Ca II infrared triplet at 8650
Angstroms, with a spectral range of 400 Angstroms. We determined radial
velocities by cross-correlation techniques for 130 cluster members. A
total of 32 stars were observed more than once. Internal and external
comparisons indicate a velocity accuracy of about 4 km s(-1) . The
velocity dispersion profile rises from about sigma =8 {km s^{-1}}
near 1' from the center of the cluster to about sigma =12 {km s^{-1}}
at 20''. Inside of 20'' the dispersion remains approximately constant
with no evidence for a sharp rise near the center. This last result
stands in contrast with that of Peterson et al. \ (1989, ApJ, 347,
251) who found a central velocity dispersion of 25+/-7 {km s^{-1}},
based on a line broadening measurement. Our velocity dispersion profile
is in good agreement with those determined in the recent studies of
Gebhardt et al. \ 1994 (ApJ, in press) and Dubath & Meylan (1994,
A&A, in press). The behavior of the central velocity dispersion
profile of M15 is consistent with the predictions of Fokker-Planck
models developed by Grabhorn et al. \ (1992, ApJ, 392, 86) and Phinney
(1993, ASP Conf. Ser., 50, 141) for globular clusters undergoing core
collapse. These models predict the presence of central populations of a
few times 10(4) degenerate remnants with masses exceeding about 1 M_sun,
of which a few times 10(3) are 1.4 M_sun neutron stars. There appears
to be no need to invoke the presence of a massive central black hole
in M15.
Title: A 60-night campaign on dwarf novae - I. Photometric variability
of SU UMa and YZ Cnc.
Authors: van Paradijs, J.; Charles, P. A.; Harlaftis, E. T.; Arevalo,
M. J.; Baruch, J. E. F.; Callanan, P. J.; Casares, J.; Dhillon, V. S.;
Gimenez, A.; Gonzalez, R.; Martinez-Pais, I. G.; Jones, D. H. P.;
Hassall, B. J. M.; Hellier, C.; Kidger, M. R.; Lazaro, C.; Marsh,
T. R.; Mason, K. O.; Mukai, K.; Naylor, T.; Reglero, V.; Rutten,
R. G. M.; Smith, R. C.
Bibcode: 1994MNRAS.267..465V
Altcode:
A 60-night campaign on SU UMa, YZ Cnc and some secondary targets was
carried out during 1988 December and 1989 January at the Observatorio
del Roque de Los Muchachos (the 1988 International Time Project). The
aim was to study the behaviour of these dwarf novae through their
outburst cycle. Here we present the overall light curves of the main
targets, SU UMa and YZ Cnc, which show that the optical fluxes continue
to decrease after the end of the outburst. For YZ Cnc we find
that, during quiescence, orbital variability is present, which may
be interpreted as modulation caused by the bright-spot region. Near
the end of an outburst, a weak, sinusoidal variation is observed;
we discuss the possibility that this arises either from the secondary
star or the accretion disc.
Title: Spectral eclipse mapping of the accretion disk in the nova-like
variable UX Ursae Majoris.
Authors: Rutten, R. G. M.; Dhillon, V. S.; Horne, K.; Kuulkers, E.
Bibcode: 1994A&A...283..441R
Altcode:
We analyze narrow-band eclipse light curves of the nova-like
cataclysmic variable UX UMa, obtained from low-resolution spectra
spanning lambda lambda 3600-9800 A . The light curves for narrow
bands in the continuum as well as those for individual spectral lines
are treated independently, and are used to construct images of the
accretion disk's brightness distribution using the maximum-entropy
eclipse-mapping technique. Particular attention is paid to the
propagation of statistical uncertainties in the data and to how the
analysis may introduce systematic errors in the final result. From the
many narrrow band images we have reconstructed the spectra from isolated
parts of the accretion disk. These spectra reveal that the inner disk
radiates a continuum spectrum which peaks in the near UV and has the
hydrogen Balmer lines in absorption (with the exception of H-alpha),
whereas the outer disk is much fainter, has a much redder spectrum,
and has Balmer emission lines. Our analysis reveals the presence of an
uneclipsed component of the total light, whose spectrum is very red and
has Balmer lines in emission. This unexpected feature of the eclipse
mapping technique offers a new tool for an independent assessment of
the secondary star's spectrum in eclipsing cataclysmic variables.
Title: A Close-up View of interacting Binaries
Authors: Rutten, R. G. M.
Bibcode: 1994AIPC..308..171R
Altcode: 1994exrb.conf..171R
I review a number of ways how eclipses of accretion disks and white
dwarfs in cataclysmic variable stars have been utilized to provide a
detailed view of these interacting binary star systems. Furthermore, a
number of recent developments are highlighted, such as the possibility
to obtain spectral information across the face of the accretion disk,
and a new technique to image the secondary star in the light of spectral
lines is described.
Title: Optical observations of supernova 1993J from La Palma -
I. Days 2 to 125.
Authors: Lewis, J. R.; Walton, N. A.; Meikle, W. P. S.; Martin, R.;
Cumming, R. J.; Catchpole, R. M.; Arevalo, M.; Argyle, R. W.; Benn,
C. R.; Bunclark, P. S.; Castaneda, H. O.; Centurion, M.; Clegg,
R. E. S.; Delgado, A.; Dhillon, V. S.; Goudfrooij, P.; Harlaftis,
E. H.; Hassall, B. J. M.; Helmer, L.; Hill, P. W.; Jones, D. H. P.;
King, D. L.; Lazaro, C.; Lucey, J. R.; Martin, E. L.; Miller, L.;
Morrison, L. V.; Penny, A. J.; Perez, E.; Read, M.; Rudd, P. J.;
Rutten, R. G. M.; Sharples, R. M.; Unger, S. W.; Vilchez, J.
Bibcode: 1994MNRAS.266L..27L
Altcode:
We present astrometric, photometric and spectroscopic observations
of supernova 1993J in M8 1, obtained with the Isaac Newton Group
telescopes and the Carlsberg Automatic Meridian Circle. The spectral
data set includes the first spectrum ever taken of SN1993J. The
early spectra also yield an estimate of the total visual extinction,
Aν. This is combined with the photometric data to produce a
bolometric light curve. Implications of the latter and of the spectral
development are also discussed. The spectral evolution includes an
infrared excess, which appeared after day 50 and may be indicative of
an IR echo. The unchanging nature of blueshifted oxygen lines in the
spectra argues for asymmetry in the distribution of the line-emitting
region.
Title: The HST Observations of IP Pegasi: A First Look at the Data
Authors: Baptista, R.; Horne, K.; Eracleous, M.; Barwig, H.; Long,
K.; Mantel, K. -H.; Marsh, T. R.; Polidan, R. S.; Raymond, J. C.;
Roginson, E. L.; Rutten, R. G. M.; Shafter, A. W.; Szkody, P.; Wade,
R. A.; Wood, J.; Zhang, E. -H.
Bibcode: 1994ASPC...56..259B
Altcode: 1994ibs..conf..259B
No abstract at ADS
Title: Spectrally resolved eclipse maps of the accretion disk in UX
Ursae Majoris
Authors: Rutten, Rene G. M.; Dhillon, V. S.; Horne, Keith; Kuulkers,
E.; van Paradijs, J.
Bibcode: 1993Natur.362..518R
Altcode:
ACCRETION disks play an important role in many astrophysical
environments, such as active galactic nuclei, protostellar systems,
X-ray binaries and cataclysmic variables. The lack of spatially resolved
information, however, has meant that theoretical models for accretion
disks are in general poorly constrained by observations. Here we use
the shape of the light curves from an eclipsing cataclysmic variable,
UX Ursae Majoris, to reconstruct the spectral energy distribution (in
the range 3,600-10,000 Å) across the face of an accretion disk. The
spectral resolution is sufficient to reveal both the radial dependence
of absorption and emission line features within the disk, and the
spectral details of the bright spot formed at the point where the
accretion stream from the secondary star collides with the disk. Such
detailed reconstructions of accretion-disk spectra should help to
bridge the gap between observations and theoretical models.
Title: Mapping Spectral Lines on the Secondary Star
Authors: Rutten, Rene G. M.
Bibcode: 1993AnIPS..10..309R
Altcode:
No abstract at ADS
Title: Spectrally-Resolved Eclipse Maps of the Accretion Disk in
UX UMa
Authors: Rutten, R. G. M.; Dhillon, V.; Horne, K.; Kuulkers, E.;
van Paradijs, J.
Bibcode: 1993AnIPS..10..137R
Altcode:
No abstract at ADS
Title: OY Carinae revisited: development of the accretion disk during
a normal outburst.
Authors: Rutten, R. G. M.; Kuulkers, E.; Vogt, N.; van Paradijs, J.
Bibcode: 1992A&A...265..159R
Altcode:
The authors re-analyse Vogt's (1983) unique set of white-light eclipse
light curves of the dwarf nova OY Car during a normal outburst,
employing the maximum-entropy eclipse-mapping technique. These
eclipse observations provide snapshots of the accretion disk during
quiescence, during the early rising phase of an outburst, and at maximum
outburst. The basic evolutionary aspects of the disk structure already
presented by Vogt (1983) are placed on a more quantitative basis. In
particular, the radial brightness profile and brightness temprature
profile of the disk during the rise to outburst maximum are presented
and discussed in the light of theoretical outburst models; from the
observed stability of the disk radius and from the absence of an
increase in the luminosity of the bright spot it is concluded that
the current observations do not offer support for the mass-transfer
instability model. Furthermore, the analysis suggests the development of
an extra, uneclipsed component during outburst rise, which contributes
up to ≡15% of the total light at outburst maximum. The authors argue
that this extra component most likely represents luminous material well
above the orbital plane, which may indicate the development of a wind.
Title: Reconstruction of the accretion disk in six cataclysmic
variable stars.
Authors: Rutten, R. G. M.; van Paradijs, J.; Tinbergen, J.
Bibcode: 1992A&A...260..213R
Altcode:
The maximum-entropy eclipse-mapping algorithm is used to reconstruct
images of the accretion disks of the novalike variable stars RW Tri,
UX UMa, SW Sex, LX Ser, V 1315 Aql, and V363 Aur. The 2D disk intensity
maps deduced from the light curves reveal the size of the disk and
its radial intensity dependence. Black-body temperature maps deduced
from the intensity maps at different wavelengths show that the disks
in RW Tri, UX UMa, and V363 Aur have a radial temperature dependence
which closely matches the fundamental theoretical run of the effective
temperature with radial distance from disk center: T(eff) varies as R
exp -3/4. The system V1315 Aql and SW Sex exhibit a much flatter run
of T(R) in the inner region of the disk, while LX Ser appears to hold
a position in between these two extremes. The consequences of these
results for accretion disk models are also discussed.
Title: Magnetic struture in cool stars. XVIII. UV-line emission from
T Tauri stars.
Authors: Lemmens, A. F. P.; Rutten, R. G. M.; Zwaan, C.
Bibcode: 1992A&A...257..671L
Altcode:
The flux densities in the UV spectral emission lines from T Tauri
stars are compared with those from other cool stars. In the flux-flux
diagrams for pairs of UV emission lines the data points for T Tauri
stars extend the relations as defined by main-sequence and evolved stars
towards larger flux densities by a factor of 40. We discuss the large
emission-line flux densities and the relations between flux densities
from different lines in the light of magnetic activity and recent
models of accretion disks in T Tauri stars. The very large emission
fluxes in chromospheric lines may be explained by a large emitting
volume associated with the warm (about 10,000 K) inner disk boundary
layer, but the fluxes and the line broadening in the high-excitation
lines requires the presence of hotter material, with temperatures of
about 200,000 K, which must be attached to the inner disks but which
is not predicted by existing disk models.
Title: Disk Temperature Structure in Six Novalike Variables
Authors: Rutten, R. G. M.
Bibcode: 1992ASPC...29..392R
Altcode: 1992cvs..work..392R
No abstract at ADS
Title: Spectropolarimetry of RW Trianguli
Authors: Rutten, R. G. M.; Dhillon, V. S.
Bibcode: 1992ASPC...29..394R
Altcode: 1992cvs..work..394R
No abstract at ADS
Title: Spectropolarimetry of the nova-like variable RW Trianguli.
Authors: Rutten, R. G. M.; Dhillon, V. S.
Bibcode: 1992A&A...253..139R
Altcode:
The first orbitally-resolved spectropolarimetric observations of
the eclipsing nova-like variable RW Tri, obtained with the aim of
testing the hypothesis that the absence of a deep eclipse in the
Balmer emission lines is the result of disk emission scattered by a
nonisotropic wind are presented. The data show linear polarization of
order about 0.8 percent, which is largely independent of wavelength
and binary phase. This polarization is attributable to scattering
in the interstellar medium, and hence there is no evidence of
electron-scattered light from RW Tri.
Title: Observations of SU UMa through Several Outbursts
Authors: Rutten, R. G. M.; Harlaftis, E. T.; ITP Team
Bibcode: 1992ASPC...29..148R
Altcode: 1992cvs..work..148R
No abstract at ADS
Title: Magnetic structure in cool stars. XVII. Minimum radiative
losses from theouter atmosphere.
Authors: Rutten, R. G. M.; Schrijver, C. J.; Lemmens, A. F. P.;
Zwaan, C.
Bibcode: 1991A&A...252..203R
Altcode:
The emissions in several chromospheric and transition region lines and
in coronal soft X-rays are analyzed for a sample of cool stars. The
nature of the lower-limit flux densities is explored, and evidence is
given for the possibility of a basal, nonmagnetic heating mechanism
being responsible for these emission fluxes up to, and perhaps
including, the upper transition region. It is argued that the excess
flux density, derived by subtraction of the basal flux density from the
observed stellar flux, is the proper measure of magnetic activity. The
level of the basal flux density as a function of color is determined
to be 2 x 10 exp 6 erg/sq cm/s for F-type stars and 2 x 10 exp 5 erg/sq
cm/s for K-type stars.
Title: Optical studies of V404 Cyg, the X-ray transient GS 2023+338
-I. The 1989outburst and decline.
Authors: Casares, J.; Charles, P. A.; Jones, D. H. P.; Rutten,
R. G. M.; Callanan, P. J.
Bibcode: 1991MNRAS.250..712C
Altcode:
The results of optical spectroscopy and photometry of V404Cyg, the
optical counterpart of the recently discovered X-ray transient GS2023 +
338, are presented. Optical spectra were obtained at the Roque de los
Muchachos Observatory with the 2.5-mm Isaac Newton Telescope. The
overall optical light curve was found to be similar to that of an
earlier outburst of this star, which was recorded as Nova Cyg 1938
and classified as a classical nova. However, it is not a classical or
recurrent nova, as the large range in optical brightness and intense
and variable X-ray emission at maximum indicate that the system must
be a low-mass X-ray binary. The reddened spectrum and interstellar
absorption features indicate a probable distance in the range of 1-3
kpc. CCD photometry reveals that the source is variable, but gives
no indication of the orbital period. Multicomponent fitting to the
complex He II 4686-A line and subsequent analysis of various asymmetry
parameters do not show any clear trend or periodicity.
Title: Detection of binaries in the core of the globular cluster
M15 using calcium emission lines
Authors: Murphy, Brian W.; Rutten, Réne G. M.; Callanan, Paul J.;
Seftzer, Patrick; Charles, Philip A.; Cohn, Haldan N.; Lugger,
Phyllis M.
Bibcode: 1991Natur.351..130M
Altcode:
M15 is the prototypical collapsed-core globular cluster. Having
undergone collapse, its core is believed now to be expanding, with
energy for the re-expansion provided by binary stars, which turn
gravitational potential energy into kinetic energy1. Because
these binary stars are generally more massive than single stars,
they will have settled to the centre of the cluster2. We
report here that several of the stars at the core of M15 show Ca II H-
and K-line emission, characteristic of young, rapidly rotating stars
and close binaries3. We argue that the emission from M15
comes from primordial binaries, in which a period of spin-up has led
to magnetic field generation by enhanced dynamo action, which in turn
causes heating of the stellar chromospheres. If this interpretation is
correct, the Ca H and K emission may provide an important diagnostic
tool of the binary population in cluster cores, and thus of the
cluster dynamics.
Title: CA II H and K Measurements Made at Mount Wilson Observatory,
1966--1983
Authors: Duncan, Douglas K.; Vaughan, Arthur H.; Wilson, Olin C.;
Preston, George W.; Frazer, James; Lanning, Howard; Misch, Anthony;
Mueller, Jean; Soyumer, David; Woodard, L.; Baliunas, Sallie L.;
Noyes, Robert W.; Hartmann, Lee W.; Porter, Alain; Zwaan, Cornelis;
Middelkoop, Frans; Rutten, Rene G. M.; Mihalas, Dimitri
Bibcode: 1991ApJS...76..383D
Altcode:
Summaries are presented of the photoelectric measurements of stellar
Ca II H and K line intensity made at Mount Wilson Observatory during
the years 1966-1983. These results are derived from 65,263 individual
observations of 1296 stars. For each star, for each observing season,
the maximum, minimum, mean, and variation of the instrumental H and
K index 'S' are given, as well as a measurement of the accuracy of
observation. A total of 3110 seasonal summaries are reported. Factors
which affect the ability to detect stellar activity variations and
accurately measure their amplitudes, such as the accuracy of the H and K
measurements and scattered light contamination, are discussed. Relations
are given which facilitate intercomparison of 'S' values with residual
intensities derived from ordinary spectrophotometry, and for converting
measurements to absolute fluxes.
Title: Ca II H &K Emission from the Core of M15:Evidence of
Binaries
Authors: Murphy, B. W.; Rutten, R. G. M.; Seitzer, P.; Cohn, H. N.;
Lugger, P. M.; Callanan, P.; Charles, P.
Bibcode: 1990BAAS...22Q1285M
Altcode:
No abstract at ADS
Title: A sixty night campaign on dwarf novae - a progress report.
Authors: Jones, D. H. P.; Charles, P. A.; Dhillon, V. S.; King, D. L.;
Arevalo, M. -J.; Casares, J.; Cepa, J.; Gonzales, I.; Gonzales, R.;
Kidger, M. R.; Lazaro, C.; Baruch, J. E. F.; Johnson, P.; Biernicowicz,
R.; Callanan, P. J.; Harlaftis, E. H.; Gimenez, A.; Hassall, B. J. M.;
Hellier, C.; Mason, K. O.; Mukai, K.; Naylor, T.; Reglero, V.; Rutten,
R. G. M.; van Paradijs, J.
Bibcode: 1990apcb.conf...97J
Altcode: 1990cvlm.proc...97J
No abstract at ADS
Title: The Bright X-Ray Transient GS:2023+338 = V404-CYGNI in Optical
Outburst and Decline
Authors: Charles, P. A.; Casares, J.; Jones, D. H. P.; Broadhurst,
T.; Callanan, P. J.; Carter, D.; Hacking, P.; Hassall, B. J. M.;
Lawrence, A.; Naylor, T.; Rutten, R. G. M.; Sahu, K. C.; Taylor, A.
Bibcode: 1989ESASP.296..103C
Altcode: 1989ttxa.symp..103C
The results of optical spectroscopy and photometry from La Palma
(Canary Islands) of V404 Cyg are presented. They correspond to the
optical counterpart of the new X-ray transient GS2023+338 discovered
by Ginga. The overall light curve is similar to that of the previous
optical outburst of this object, recorded as Nova Cyg 1938 and
classified as a classical nova. It is not a classical or recurrent
nova. The large range in optical brightness and intense X-ray emission
at maximum indicate that the system must be a low-mass X-ray binary. The
optical spectrum is unlike any known LMXB or X-ray transient in that
it displays strong, broad, variable and complex emission lines of H,
He I and He II. The reddened spectrum and interstellar absorption
features indicate a problable distance in the range 1 to 3 kpc. Charged
coupled device photometry reveals that the source is variable, but
gives no indication of the orbital period, there being no eclipse or
regular modulation.
Title: Magnetic structure in cool stars. XVI. Emissions from the
outer atmospheres of M-type dwarfs.
Authors: Rutten, R. G. M.; Schrijver, C. J.; Zwaan, C.; Duncan, D. K.;
Mewe, R.
Bibcode: 1989A&A...219..239R
Altcode:
Consideration is given to emission from the outer atmospheres of M-type
dwarfs in several spectral lines originating from the chromosphere, the
transition-region, and the soft X-ray emission from the corona. It is
shown that M-type dwarfs systematically deviate from relations between
flux densities in soft X-rays and chromospheric and transition-region
emission lines. The quantitative relation between the equivalent width
of H-alpha and the Ca II, H, and K emission index is determined. It
is suggested that the emission in the Balmer spectrum may result from
back heating by coronal soft X-rays.
Title: Magnetic structure in cool stars. XV. The evolution of rotation
ratesand chromospheric activity of giants.
Authors: Rutten, R. G. M.; Pylyser, E.
Bibcode: 1988A&A...191..227R
Altcode:
For cool giants and subgiants the observed dependence of rotational
velocity and Ca II H and K line-core emission on color B-V is
interpreted in terms of changes in the moment of inertia by stellar
evolution. Modeling of the rotational velocity during the evolution
of cool giants with masses between 2.0 and 3.0 solar masses, by
taking into account the change in the moment of inertia and assuming
rigid-body rotation and conservation of angular momentum, describes
the observed decrease of v sin i with B-V. The computed evolution
of the rotational velocity, together with the empirical relation
between the Ca II line-core emission and the rotation rate, explain
the observed drop in the Ca II line-core emission for giants at B-V
= about 0.95. For subgiants with masses of about 1.5 solar mass, the
change in the moment of inertia by itself cannot explain the observed v
sin i distribution: there are indications of loss of angular momentum,
presumably by magnetic braking.
Title: Magnetic activity of cool stars and its dependence on rotation
and evolution
Authors: Rutten, René G M
Bibcode: 1987PhDT.......129R
Altcode:
No abstract at ADS
Title: Magnetic structure in cool stars. XII - Chromospheric activity
and rotation of giants and dwarfs
Authors: Rutten, R. G. M.
Bibcode: 1987A&A...177..131R
Altcode:
The relation between the Ca II H and K line-core flux density
and rotation rate is studied for 313 F- to M-type stars ranging in
luminosity class from II-III to V. The activity-rotation relation for Ca
II is compared with similar relations for Mg II and soft X-rays. Dwarfs
and the majority of the giants studied follow the same color-dependent
relation between the Ca II H and K line-core excess flux density and the
rotation period P. The activity-rotation relations for the Mg II h and
k excess flux density and the soft X-rays flux density are compatible
with the color-dependent relations for Ca II. For rapidly rotating
stars, excess flux density decreases slowly with increasing P, whereas
for longer P the excess flux density decreases much faster with P. The
color-dependent shape of this relation helps explain the existence of
the Vaughan-Preston gap and the absence of this gap beyond B - V = 0.9.
Title: Magnetic structure in cool stars. XIII - Appropriate units
for the rotation-activity relation
Authors: Rutten, R. G. M.; Schrijver, C. J.
Bibcode: 1987A&A...177..155R
Altcode:
The paper compares relations between coronal and chromospheric
emissions, and between activity and stellar rotation, in which the
radiative emissions that measure the magnetic activity of cool stars are
expressed in different units. The surface flux density appears to be the
most suitable unit in which to express the radiative emission measuring
stellar magnetic activity: the luminosity introduces an extra dependence
on stellar radius, whereas the flux density normalized by the bolometric
flux density introduces a dependence on color. The dependence on color
in the relation between rotation period and radiative flux density
cannot be repaired by a simple color-dependent scaling of the rotation
period. For example, dividing the rotation period by the turnover time
of convective eddies cannot yield a single, color-independent relation
between rotation and activity, and this scaling disrupts the similarity
in behavior of dwarfs and giants in the rotation-activity relation.
Title: Magnetic structure in cool stars. XIV. Deficiency in
chromospheric fluxes from M-type dwarfs.
Authors: Schrijver, C. J.; Rutten, R. G. M.
Bibcode: 1987A&A...177..143S
Altcode:
Chromospheric, transition-region and coronal emissions of M-type dwarfs
and of dwarfs of earlier spectral type are compared, and related to
the rotation period. M-type dwarfs depart from the relation between
chromopsheric Ca II H+K excess flux density ΔFCa II and
the coronal soft X-ray flux density FX as defined by stars
of earlier spectral type. The M-type dwarfs also show low chromospheric
emissions in comparison to stars of earlier spectral type and the same
rotation period P. It is shown that these deviations are caused by a
deficiency in the chromopsheric emission, rather than by an increase
in the coronal emission.
Title: Magnetic structure in cool stars. X. The CA II H+K flux
density and rotation rate for main-sequence stars.
Authors: Rutten, R. G. M.
Bibcode: 1986A&A...159..291R
Altcode:
A sample of 55 F3 to M4 main-sequence stars with well determined
rotation periods and Ca II H + K line-core flux densities is
analysed. Single stars and members of synchronized binaries follow the
same tight, color-dependent, linear relations between the Ca II H +
K line-core flux density FCa II and the logarithm of the
rotation period. Emission-line stars follow the same relations. From
early K-type stars onwards the response of FCa II to
rotation rate decreases rapidly towards later spectral type. Hence,
the sample refutes the suggestion by Catalano and Marilli that the
relation between the Ca II line-core luminosity and rotation period is
independent of color. The larger sample of stars for which v sin i is
known, confirms the results based on rotation periods; in addition,
for stars with rotation periods less than about one day FCa
II drops below the value predicted by the relations defined by
other main-sequence stars. Somewhat evolved stars follow approximately
the same relation as unevolved stars, provided that the Ca II flux
density is compared with the rotation period and not with the rotation
velocity. The Ca II H + K line-core flux density depends on rotation
rate for stars with B-V down to 0.38, which suggests that the magnetic
activity due to dynamo action extends down to spectral type F3.
Title: On Stellar Activity, Rotation, and the Reality of the
Vaughan-Preston Gap
Authors: Rutten, R. G. M.; Schrijver, C. J.
Bibcode: 1986LNP...254..120R
Altcode: 1986csss....4..120R
No abstract at ADS
Title: Chromospheric Activity and Rotation of Cool Giants and Dwarfs
Authors: Rutten, R. G. M.
Bibcode: 1986LNP...254..116R
Altcode: 1986csss....4..116R
No abstract at ADS
Title: Magnetic structure in cool stars. VII. Absolute surface flux
in CA IIH and K line cores.
Authors: Rutten, R. G. M.
Bibcode: 1984A&A...130..353R
Altcode:
Middlekoop's (1982) conversion of the relative Ca II H and K line-core
intensity index determined with the Ca II H and K photometer at
Mt. Wilson is revised into the line-core flux per unit area at the
stellar surface. The conversion factor is now established for stars
ranging in luminosity class from V to II-III and in color from B - V =
0.3 to B - V = 1.6. A calibration of the stellar surface-flux units
is derived by means of the solar flux spectrum. These results are
compared with other absolute flux determinations, and the influence of
the pass band on the detected Ca II line-core flux is investigated. The
Ca II line-core surface flux exhibits a color-dependent minimum which
differs between main-sequence stars and giants. There is no conspicuous
dependence of the minimal Ca II H and K flux on metallicity.