Asteroseismology: Past, Present and Future
D. W. Kurtz
Centre for Astrophysics, University of Central Lancashire, Preston PR1 2HE, UK.
e-mail: dwkurtz@uclan.ac.uk

Abstract. Asteroseismology studies stars with a wide variety of interior and surface conditions. For two decades asteroseismic techniques have been applied to many pulsating stars across the HR diagram. Asteroseismology is now a booming field of research with stunning new discoveries; I highlight a personal selection of these in this review, many of which are discussed in more detail elsewhere in these proceedings. For many years the Nainital–Cape Survey for northern roAp stars has been running at ARIES, so I emphasise new spectroscopic results for roAp stars and point out the outstanding prospects for the planned ARIES 3-m telescope at Devastal. High precision spectroscopy has revolutionised the asteroseismic study of some types of stars – particularly solar-like oscillators and roAp stars – while photometry is still the best way to study the frequency spectra
that are the basic data of asteroseismology. New telescopes, new photo-meters and space missions are revolutionising asteroseismic photometry. In addition to the ground-based potential of asteroseismic spectroscopy, India has the knowledge and capability for space-based asteroseismic photometry. The future for asteroseismology is bright indeed, especially for
Indian astronomers.

Key words. Asteroseismology—stellar pulsation—variable stars.

Theory of Asteroseismology
Hiromoto Shibahashi
Department of Astronomy, University of Tokyo, Tokyo 113 0033, Japan.
e-mail: shibahashi@astron.s.u-tokyo.ac.jp

Abstract. The increasing number of pulsating modes in a star leads to the increase of the amount of information derived from the pulsation. Probing the invisible interior of stars is a dream come true. In this review, I summarize the fundamental properties of stellar pulsations and the excitation mechanisms, emphasizing several cases of recent progress.

Key words. Asteroseismology—stars: pulsation—pulsation: excitation.


Helioseismology
H. M. Antia
Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India.
e-mail: antia@tifr.res.in

Abstract. The sun being the nearest star, seismic observations with high spatial resolution are possible, thus providing accurate measurement of frequencies of about half million modes of solar oscillations covering a wide range of degree. With these data helioseismology has enabled us to study the solar interior in sufficient detail to infer the large-scale structure and rotation of the solar interior. With the availability of high quality helioseismic data over a good fraction of a solar cycle it is also possible to study temporal variations in solar structure and dynamics. Some of these problems and recent results will be discussed.

Key words. Sun: oscillations—sun: interior—sun: rotation.

Excitation of Solar-like Oscillations: From PMS to MS Stellar Models
R. Samadi 1 , M.-J. Goupil 1 , E. Alecian 1 , F. Baudin 2 , D. Georgobiani 3 ,
R. Trampedach 4 , R. Stein 5 & Å. Nordlund 6
1 Observatoire de Paris, 5 place J. Janssen, 92195 Meudon, France.
2 Institut d’Astrophysique Spatiale, Orsay, France.
3 Center for Turbulence Research, Stanford University NASA Ames Research Center, Moffett
Field, USA.
4 Research School of Astronomy and Astrophysics, Mt. Stromlo Observatory, Weston, Australia.
5 Michigan State University, East Lansing, USA.
6 Niels Bohr Institut, Copenhagen, Denmark.

Abstract. The amplitude of solar-like oscillations results from a balance between excitation and damping. As in the sun, the excitation is attributed to turbulent motions that stochastically excite the p modes in the upper-most part of the convective zone. We present here a model for the excitation mechanism. Comparisons between modeled amplitudes and helio and stellar seismic constraints are presented and the discrepancies discussed. Finally the possibility and the interest of detecting such stochastically
excited modes in pre-main sequence stars are also discussed.

Key words. Turbulence—convection—oscillations—excitation—sun, stars: α Cen A—stars: main and pre-main sequence stars.


HD 101065, the Most Peculiar Star: First Results from Precise Radial Velocity Study
D. E. Mkrtichian 1 & A. P. Hatzes 2
1 ARCSEC, Sejong University, Seoul 143 747, Korea and Astronomical Observatory, Odessa
National University, Shevchenko Park, Odessa 65014, Ukraine.
e-mail: david@arcsec.sejong.ac.kr
2 Th¨ uringer Landessternwarte Tautenburg, Sternwarte 5, D-07778, Tautenburg, Germany.

Abstract. In this paper we discuss the prospects for asteroseismology with spatial resolution and motivate studies of the most chemically peculiar roAp star HD 101065. We present the first results from a high-precision radial velocity (RV) study of HD101065 based on data spanning four nights that were acquired using the HARPSechelle-spectrometer at the ESO3.6 m
telescope. The analysis of individual nights showed the amplitude and phase modulation of the dominant mode. The analysis of the whole data set showed the presence of multi-periodic oscillations with two groups of equally-spaced modes. We find ν
=65 2 µHz and δν =7 3 µHz for the large and the small spacing, respectively. HD 101065 is the only roAp star to show the existence of two groups of l =0 2 and l =1 3 excited modes.

Key words. Stars: oscillations, roAp stars.


The Nainital–Cape Survey: A Search for Variability in Ap and Am Stars
Santosh Joshi
Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak,
Nainital 263 129, India.
e-mail: santosh@aries.ernet.in

Abstract. The “Nainital–Cape Survey” program for searching photo-metric variability in chemically peculiar (CP) stars was initiated in 1997 at ARIES, Nainital. We present here the results obtained to date. The Am stars HD98851, HD102480, HD13079 and HD113878 were discovered to exhibit δ Scuti type variability. Photometric variability was also dis-covered
in HD13038, for which the type of peculiarity and variability is not fully explained. The null results of this survey are also presented and discussed.

Key words. Stars: Ap—stars: Am—stars: δ Scuti-individual: HD98851
—stars: individual: HD102480—stars: individual: HD13079— stars:
individual: HD13038—stars: individual: HD113878.


HD12098 and Other Results from Nainital–Cape Survey
V. Girish
Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India.
e-mail: giri@tifr.res.in

Abstract. Nainital–Cape Survey was started with an aim to search for new rapidly oscillating Ap stars in the northern hemisphere. We discovered one new mono-periodic roAp star HD12098. The frequency separation of HD12098 suggests a rotation period of 5.5 days for the star. We summarize here the observations of HD12098 and briefly discuss the results of the
multi-site observation campaign organized to resolve the ambiguity in the determination of the rotation period of HD12098. Other interesting results like non-oscillating Ap stars discovered and two candidate stars in which roAp periodicity is seen but not confirmed are also discussed.

Key words. Stars: roAp stars—stars-individual: HD12098—stars-individual:
HD207561—stars-individual: HD17431—stars-individual:
HD25499—stars-individual: HD38143—stars-individual: HD38817.


Asteroseismic Theory of Rapidly Oscillating Ap Stars
Margarida S. Cunha
Centro de Astrof´ısica da Universidade do Porto, Rua das estrelas, 4150, Porto, Portugal.
e-mail: mcunha@astro.up.pt

Abstract. This paper reviews some of the important advances made over the last decade concerning theory of roAp stars.

Key words. Stars: variable, chemically peculiar, roAp, magnetic.


The Dushak–Erekdag Survey of roAp Stars
Tatyana Dorokhova 1 & Nikolay Dorokhov
Astronomical Observatory, Odessa National University, Ukraine.
1 e-mail: tnd@te.net.ua

Abstract. The search of roAp stars at Mt. Dushak–Erekdag Observatory was started in 1992 using the 0.8 m Odessa telescope equipped with a two-star high-speed photometer. We have observed more than a dozen stars so far and discovered HD 99563 as roAp star while BD +8087 is suspected to have rapid oscillations. Negative results of our observations for the search of rapid oscillations in four stars in NGC 752 are also discussed.

Key words. Stars: chemically peculiar—stars: oscillations—stars:
variables: other—techniques: photometric.


Using the Seismology of Non-magnetic Chemically Peculiar Stars as a Probe of Dynamical Processes in Stellar Interiors
Sylvain Turcotte
Bishop’s University, Lennoxville, Canada, J1M 1Z7.
e-mail: turcotte@apollo.ubishops.ca

Abstract. Chemical composition is a good tracer of the hydrodynamical processes that occur in stars as they often lead to mixing and particle trans-port. By comparing abundances predicted by models and those observed in stars we can infer some constraints on those mixing processes. As pulsations in the stars are often very sensitive to chemical composition, we can
use asteroseismology to probe the internal chemical composition of stars where no direct observations are possible. In this paper I focus on main sequence stars Am, λ Bootis, and HgMn stars and discuss what we can learn of mixing processes in these stars from seismology.

Key words. Variable stars—diffusion.


Asteroseismology of δ Scuti and γ Doradus Stars
Gerald Handler
Institut f ¨ ur Astronomie, Universit ¨ at Wien, T¨ urkenschanzstrasse 17, A 1180 Wien, Austria.
e-mail: handler@astro.univie.ac.at

Abstract. We give an overview of past and present efforts to make seismology  of δ Scuti and γ Doradus stars possible. Previous work has not led to the observational detection and identification of a sufficient number of pulsation modes for these pulsators for the construction of unique seis-mic models. However, recent efforts including large ground-based obser-vational
campaigns, work on pre-main sequence pulsators, asteroseismic satellite missions, theoretical advances on mode identification methods, and the discovery of a star showing simultaneous self-excited δ Scuti and γ Doradus oscillations suggest that we may be able to explore the interiors of these pulsators in the very near future.

Key words. Stars: variables: δ Scuti—stars: oscillations, variables: other.


Asteroseismology of δ Scuti Stars: Problems and Prospects
M.-J. Goupil 1 , M. A. Dupret 1 , R. Samadi 1 , T. Boehm 2 , E. Alecian 1 ,
J. C. Suarez 3 , Y. Lebreton 4 & C. Catala 1
1 LESIA, UMR 8109, Observatoire de Paris, 5 place J. Janssen, 92195 Meudon, France.
2 Observatoire de Midi-Pyr´ en´ ees, Toulouse, France.
3 Instituto de Astrofisica de Andalucia, Granada, Spain.
4 GEPI, UMR 8111,Observatoire de Paris, 5 place J. Janssen, 92195 Meudon, France.

Abstract. We briefly outline the state-of-the-art seismology of δ Scuti stars from a theoretical point of view: why is it so difficult a task? The recent theoretical advances in the field that these difficulties have influenced are also discussed.

Key words. Oscillations—δ Scuti stars—stars: main and pre-main sequence stars.

Pulsations in Subdwarf B Stars
C. Simon Jeffery
Armagh Observatory, College Hill, Armagh BT61 9DG, Northern Ireland.

Abstract. Subdwarf B stars play a significant role in close binary evolution and in the hot star content of old stellar populations, in particular in giant elliptical galaxies. While the question of their origin poses several problems for stellar evolution theory, one of their most fascinating properties is the presence of multi-periodic 2–3 minute oscillations. Interpreting these oscillations optimally requires the correct identification of the modes. Partial identifications can be obtained using high-speed observations
of radial velocity and colour variations. We review some of the several attempts to make such observations, most recently with the Multi-Site Spectroscopic Telescope campaign and with ultracam.

Key words. Stars: oscillations—stars: variables: other (EC14026/
sdBV)—stars: individual: KPD2109 +4401, PB8783, PG1605 +072,
HS0039 +4302, PG0014 +067.

Lessons for Asteroseismology from White Dwarf Stars
Travis S. Metcalfe
High Altitude Observatory, NCAR, P.O. Box 3000, Boulder CO 80307, USA.
e-mail: travis@hao.ucar.edu

Abstract. The interpretation of pulsation data for sun-like stars is currently facing challenges quite similar to those faced by white dwarf modelers ten years ago. The observational requirements for uninterrupted long-term monitoring are beginning to be satisfied by successful multi-site campaigns and dedicated satellite missions. But exploration of the most important physical parameters in theoretical models has been fairly limited, making it difficult to establish a detailed best-fit model for a particular
set of oscillation frequencies. I review the past development and the current  state of white dwarf asteroseismology, with an emphasis on what this can tell us about the road to success for asteroseismology of other types of stars.

Key words. Stars: interiors—stars: oscillations—white dwarfs.


On the Analysis of Light Curves in Asteroseismology
David L. Mary
Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital 263 129, India.
e-mail: dmary@upso.ernet.in

Abstract. We provide a detailed introduction to the main problems arising when analyzing light curves in asteroseismology. Attention is first paid to the signal model delivered by the pulsating stars and to the noise sources corrupting this model in photometric observations. The main pitfalls and ambiguities occurring in Fourier analysis are summarized and illustrated.  Some classical, Least Squares (LS) based methods for spectrum analysis are analyzed and commented on from the point of view of ill-posed problems. The insight that can be gained from such analyses is discussed.

Key words. Fourier analysis—noise sources—ill-posed problems.


Collaborative Research of Open Star Clusters
Alisher S. Hojaev
Ulugh Beg Astronomical Institute, Center for Space Research, Uzbek Academy of Sciences,
Tashkent, Uzbekistan.
e-mail: ash@astrin.uzsci.net

Abstract. Preliminary results on observations of open clusters are pre-sented. The project has been initiated in the framework of the Uzbek– Taiwan and Taiwan–Baltic collaboration, mainly to upgrade and make use of facilities at Maidanak Observatory. We present detailed, multi-wavelength studies of the young cluster NGC 6823 and the associated complex nebulosity, to diagnose the young stellar population and star formation history in the region. In addition, 7 compact open clusters have been monitored for stellar variability. We show how observations like these could feasibly be used to look for exoplanet transit events. We also expect to join the Whole-Earth Telescope effort in future campaigns for asteroseismology.

Key words. Galaxy: open clusters and associations, general—method: observational.


Results from the Whole Earth Telescope – Indian Contributions
S. Seetha 1 ∗, B. N. Ashoka 1 & T. M. K. Marar 2
1 Space Astronomy and Instrumentation Division, ISRO Satellite Centre, Airport Road,
Bangalore 560 017, India.
2 ‘Swathi’ near Valiyalukkal Temple, Kanimangalam, Thrissur 680 027, India.
∗e-mail: seetha@isac.ernet.in

Abstract. The Indian team at ISRO has been part of the Whole Earth Telescope (WET) team since 1988 when we first participated in the campaign on V471 Tau. We have been part of many other observing campaigns over the last decade. This presentation traces the circumstances leading to our joining the WET team and how useful the coverage from the Indian
longitude has been. The results of several pulsators from the WET runs during which we participated are also described. These include PG1159-035 the prototype of the GWVir type of stars, RE J 0751 +14 a cataclysmic variable, PG 1336-018 a binary with an sdB pulsator and finally HR 1217 a roAp star. The paper concludes with what the limitations are in our obser-vations
and how we can overcome them in the future.

Key words. Stars: pulsating—stars: individual: PG1159-035—stars:
individual: RE J 0751 +14—stars: individual: PG 1336-018—stars:
individual: HR 1217.


Upgradation of MOT and its Relevance to WET Campaigns
Alisher S. Hojaev
Ulugh Beg Astronomical Institute, Center for Space Research, Uzbek Academy of Sciences,
Tashkent, Uzbekistan.
e-mail: ash@astrin.uzsci.net

Abstract. The Maidanak One-meter Telescope (MOT) is a Ritchey-Chretien telescope by Carl Zeiss, located atop Maidanak in Uzbekistan, where site parameters indicate excellent atmospheric seeing conditions. An effort to computerize the MOT, jointly made by an Uzbek, Taiwanese and Baltic consortium, is expected to complete in 2005. Monitoring the variability of star clusters will be among the first scientific projects to be carried out. Equipped with sensitive CCD cameras, the MOT, with its
middle-Asia geographic location, will be a desirable addition to the Whole Earth Telescope (WET) network. We describe the upgrade engineering and instrumentation of the telescope and how the system can be used in future campaigns.

Key words. Telescopes—method: observational—stars: oscillation.


Argos: An Optimized Time-Series Photometer
Anjum S. Mukadam 1
∗& R. E. Nather ∗∗
∗Department of Astronomy, University of Washington, Seattle, WA 98195 1580, U.S.A.
e-mail: anjum@astro.washington.edu
∗∗Department of Astronomy, University of Texas at Austin, Austin, TX 78712 0259, U.S.A.
e-mail: nather@astro.as.utexas.edu

Abstract. We designed a prime focus CCD photometer, Argos, optimized for high speed time-series measurements of blue variables (Nather &Mukadam 2004) for the 2.1 mtelescope at McDonald Observatory. Lack of any intervening optics between the primary mirror and the CCD makes the instrument highly efficient. We measure an improvement in sensitivity by a factor of nine over the 3-channel PMT photometers used on the same telescope and for the same exposure time. The CCD frame transfer operation  triggered by GPS synchronized pulses serves as an electronic shutter for the photometer. This minimizes the dead time between exposures, but more importantly, allows a precise control of the start and duration of the exposure. We expect the uncertainty in our timing to be less than 100 µs.

Key words. Photometer—CCD—time-series—variable—instrument.


High Resolution Stellar Spectroscopy with VBT Echelle Spectrometer
N. Kameswara Rao, S. Sriram, K. Jayakumar & F. Gabriel
Indian Institute of Astrophysics, Bangalore 560 034, India.

Abstract. The optical design and performance of the recently commissioned fiber fed echelle spectrometer of 2.34 meter Vainu Bappu Telescope are described. The use of it for stellar spectroscopic studies is discussed.

Key words. High resolution spectroscopy.


Facilities at ARIES for the Nainital–Cape Survey
Ram Sagar 1 & David L. Mary 2
Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak,
Nainital 263 129, India.
1 e-mail: sagar@aries.ernet.in
2 e-mail: dmary@aries.ernet.in

Abstract. A collaborative programme searching for mmag pulsations in chemically peculiar stars in the northern hemisphere was initiated in 1997 between Nainital, India, and Cape Town, South Africa. It was therefore named as the Nainital–Cape Survey programme. The detection limits imposed by the observing conditions (including atmospheric noise and telescope size) at both Manora Peak and Devasthal sites are described. The scintillation noise on the best photometric nights is ≈0 1 to 0.2 mmag for these sites. Both places allow one to detect few mmag variation in bright stars ( ≤12 mag), and are therefore particularly well-suited for carrying out the proposed survey work. The main characteristics of the three-channel photometer developed at ARIES for carrying out the observations are also presented. This excellent instrument has been used extensively since 1999 at the f/13 Cassegrain focus of ARIES’ 104 cm telescope. In particular, it allowed the survey to result in the discovery of δ Scuti like pulsations in four Am stars, in one rapidly oscillating Ap star, and in a number of probable variables so far. The future prospects are then presented, which regard the acquisition of a high speed time series CCD photometer, a project to build a 3-metre class telescope at Devasthal, and collaborative observations with Indian and foreign astronomical sites.

Key words. Stars: chemically peculiar stars—oscillations—δ Scuti— asteroseismology.


The Concordia Station on the Antarctic Plateau: The Best Site on Earth for the 21st Century Astronomers
Eric Fossat
Laboratoire Universitaire d’Astrophysique de Nice, Universit´ e de Nice, France.
e-mail: Eric.Fossat@unice.fr

Abstract. On the Antarctic plateau, a joint project of French and Italian polar programmes is nearing completion: the Concordia station will be open for winter-over operation in 2005. The high altitude and high latitude of this site, the exceptionally cold, clear and stable atmosphere, its incredible astronomical seeing, the almost indefinitely flat snow surface and the not-so- difficult access make this site the most promising on Earth for future ground-based astronomical projects in various fields, including long term photometry, infrared high sensitivity imaging and high angular resolution and high contrast imaging.

Key words. Site testing—astronomical photometry—infrared astronomy—sub-mm astronomy—Antarctic astronomy.