******************************************************************* * * * SSSSSS OOOOOO N N GGGGGG N N * * S O O NN N G G NN N * * S O O N N N G N N N ee ee w w sssss * * SSSSSS O O N N N G N N N e e w w s * * S O O N N N G GG N N N eeeee w w w sssss * * S O O N NN G G N NN e w w w s * * SSSSSS OOOOOO N N GGGGGG N N eeeee wwwww sssss * * * ******************************************************************* * * * Issue No. 1 SONGNews 12 July 1996 * * * * Newsletter of the Stellar Oscillations Network Group * * * ******************************************************************* * * * SONGNews is distributed from the National Optical Astronomy * * Observatories - Send articles to be included to song@noao.edu. * * To add your name (or delete) to the SONGNews distribution list * * send email to the same address. Issues are also available via * * the World Wide Web at http://www.noao.edu (click on SONG). * * * ******************************************************************* * * * * * CONTENTS OF THIS ISSUE: * * * * 1. Introducing SONGNews * * 2. Report from Madison - the SONG Special Session at the AAS * * 3. Recent Abstracts in Asteroseismology * * 4. Meeting Announcements * * 5. The Procyon Campaign * * * ******************************************************************* ******************************************************************* 1. Introducing SONGNews We are pleased to distribute this first issue of SONGNews, an electronic newsletter devoted to asteroseismology of solar-type stars. The detection and study of oscillations in solar type stars is a natural extension of the scientific goals of helioseismology. In view of the recent encouraging developments in asteroseismology and the announcement of the first results from the initial operation of the full GONG network at the Madison AAS meeting, it is time to develop a coordinated, community wide effort to achieve the potential that asteroseismology offers for progress in stellar physics, stellar structure, and stellar evolution. An effort of this magnitude can only succeed if it is truly community based. This newsletter is founded to disseminate timely information on programs, meetings, and results related to asteroseismology, and to assist in the development of a world-wide network devoted to the study of acoustic oscillations in solar-type stars. Initially, we hope to distribute SONGNews quarterly. ******************************************************************* ******************************************************************* 2. Report from Madison - the SONG Special Session at the AAS A special session on asteroseismology of solar type stars was organized by the Steering Committee of the Stellar Oscillations Network Group for the Madison meeting of the American Astronomical Society in June, 1996. The program included excellent talks by Pierre Demarque on what we can learn from asteroseismology, Tim Brown on the status of observations, and Sam Barden on instrumentation and techniques. Informal presentations by Bob Noyes and Hans Kjeldsen described some recent results. Following these contributions was a general discussion on the best strategies for setting up an international program for the study of acoustic oscillations in solar type stars. The consensus of those present was that this is a good time to work toward the development of a world-wide collaboration for the study of p-mode oscillations, and that we should proceed both by developing a formal project and by encouraging individual collaborations. The meeting ended with a strong feeling of cooperation and optimism. Many of new results present at the Madison meeting (see below) suggest we are on the verge of major advances in this field. But only by working together can we really achieve the potential that asteroseismology offers for improving our understanding of stellar interiors and evolution. ***************************************************************** ***************************************************************** 3. Recent Abstracts in Asteroseismology TITLE: Observations of Small-Amplitude Oscillations in the Radial Velocity of Arcturus AUTHOR: W. J. Merline High accuracy measurements of variations in the radial velocity of the K giant star Arcturus have been obtained. The observations span 5 years and have a point-to-point repeatability of 5 m s^-1 and night-to-night stability of better than 20 m s^-1. Velocity oscillations of Arcturus were discovered during the course of this work in 1986. Extensive additional data, presented here, indicate that Arcturus is exhibiting global non-radial acoustic oscillations with characteristics similar to those occurring in the Sun. A Fabry-Perot interferometer, used in transmission, is employed to accurately tag the stellar wavelengths. The light is dispersed by a cross-dispersed echelle. About 750 points in the spectrum are monitored over 4250--4750A. All observations were done using the 0.9-m telescope of the University of Arizona on Kitt Peak, which is dedicated half-time for use with this instrument. A dedicated facility was crucial to this work --- because of the changing nature of the oscillations, many observing runs, over several years, were required to understand the star's behavior. Continuous data sets as long as 30 days were acquired. The velocity power spectra are complicated and variable. There is substantial evidence that the variations are solar-like p-mode oscillations. At least 10 frequencies have been identified, over the range 8.3 to 1.7 days. A spectrum of evenly spaced modes is apparent, yielding a value for Delta nu_0 ~= 1.2 mHz. The average power spectrum peaks near 3 days, approximately as expected from the acoustic cut-off frequency. There is a broad envelope of power with a distribution reminiscent of that seen in the Sun. The oscillations do not maintain phase coherence and they show abrupt discontinuities, indicating that something is disrupting them, as in the Sun. Coherence of the modes is estimated to be a few weeks to a few months. Driving is likely to be due to stochastic excitation by turbulent convection. Arcturus may be one of the first analogues of solar-like oscillations and/or the first member of a new class of variable stars. Because Arcturus is an evolved star of approximately solar mass, these oscillations will provide a test for stellar evolution theory, as well as for asteroseismology and the study of driving mechanisms for stellar oscillations. This work was done at the University of Arizona, Department of Planetary Sciences and was supported by grants from NASA and NSF to Dr. Robert S. McMillan. (Presented at the Madison Meeting of the AAS) ***************************************************************** TITLE: The Oscillation Modes of epsilon Cep and tau Peg AUTHORS: Scott Horner (Penn State), Ted Kennelly, Tim Brown, Aaron Sigut (HAO), Sylvain Korzennik, Martin Krockenberger, Pete Nisenson, Robert Noyes (CfA), Stephenson Yang (UVic), and Andrew Walker (UBC) Asteroseismology of delta Scuti Stars offers an attractive prospect for determining the interior properties of main sequence A-F stars. Here we present extensive, spectroscopic, time-series observations of two multiperiodic, rapidly rotating, delta Scuti stars: tau Pegasi and epsilon Cephei. Information about the oscillations is contained within the patterns of line-profile variation. We introduce a new technique with which to extract these patterns, modeling the intrinsic stellar spectrum and broadening functions for each spectrum in the time series. A preliminary analysis of the resulting variations is performed using the technique of Fourier-Doppler Imaging. (Presented at the Madison Meeting of the AAS) *********************************************************** TITLE: Asteroseismology via Equivalent Widths - Tests on Procyon, Eta Bootes, and Alpha Triangulum AUTHORS: J. Harvey, C. Pilachowski, S. Barden, M. Giampapa, C. Keller, and F. Hill (NOAO) Recently, Kjeldsen et al. (1995, AJ, 109, 1313) reported a probable detection of solar-like low-amplitude p-mode oscillations of eta Bootes using equivalent width measurements from low-resolution spectra of the hydrogen Balmer lines. This technique has the potential to provide stellar oscillation measurements good enough to allow the asteroseismic inference of stellar structure. Here we report on the preliminary analysis of data from three observing runs with the Kitt Peak Coude Feed and 2.1-m telescopes in November 1995 (alpha Triangulum), February 1996 (alpha Canus Minorum), and March 1996 (eta Bootes). These runs are being used to develop observing and data reduction techniques, such as a synchronized timing system to maintain evenly spaced temporal samples, a continuous unshuttered CCD readout to increase the duty cycle of the observations, and a simulation of the probability of a detection as a function of observing run length. We observed the region around the H-beta, H-gamma, and H-delta lines with a spectral dispersion of about 0.4 A/pixel, extracted equivalent widths, and performed time series analysis. The acoustic spectrum of alpha Triangulum contains a significant peak around 660 mHz, close to the theoretical prediction. However, we do not yet know the origin of this peak. (Presented at the Madison Meeting of the AAS) ************************************************************ TITLE: A Radial Velocity Search for p-modes in Procyon AUTHORS: T. M. Brown, E. J. Kennelly (HAO), R. W. Noyes, S. G. Korzennik, P. Nisenson (CfA), S. D. Horner (Penn. State U.), and C. Catala (Obs. Meudon) Procyon (alpha CMi F5 IV) has long been a promising candidate for detection of solar-like p-modes. Although several authors have reported evidence for low-amplitude (<= 10 m/s) pulsations in this star, none of the existing observations are conclusive. A clear detection of such pulsations would be a significant step for asteroseismology of Sun-like stars, allowing refined estimates of the star's properties and paving the way for the study of fainter stars of similar spectral type. Identification of oscillation modes in subgiants like Procyon is expected to be difficult, however, because both the amplitudes and the frequency separations of the modes are expected to be small. To address these difficulties, we organized a joint observing campaign involving the AFOE spectrograph located at the Whipple Observatory (Mt. Hopkins, AZ) and the MUSICOS spectrograph located at Pic du Midi. Both instruments are capable of providing Doppler measurements with the required precision of a few m/s, and the 7 hour longitude separation between them allows the acquisition of relatively long uninterrupted data strings. In the event, bad weather prevented more than sporadic observations from Pic du Midi. At Mt. Hopkins, however, we obtained good observations on each of 6 consecutive nights 3-8 Feb 1996, for a total of 47 h of observing time. We discuss here the interpretation of this data set in terms of possible p-mode oscillations. (Presented at the Madison Meeting of the AAS) ************************************************************* TITLE: ON THE NUMERICAL SOLUTION OF HIGH-ORDER GRAVITY MODES IN RAPIDLY ROTATING STARS AUTHOR: Maurice J. Clement (Department of Astronomy, University of Toronto) The slowly pulsating B stars and the line-profile variables on the upper main sequence are now believed to involve nonradial gravity modes of high radial order (n>15, say) and be driven by the ionization zones of the iron group metals. This paper is a progress report on efforts to compute numerically the eigenfunctions of these particular modes for rapidly rotating stars. The computational problem is very challenging for several reasons: (i) high radial orders require very small integration stepsizes to achieve acceptable numerical accuracy and stability, (ii) for a given azimuthal symmetry m, rotation couples or mixes components of different latitudinal symmetry l >= m, each having a radial order which increases rapidly with l, and (iii) in the long-period limit (high n), the g-mode spectrum is so rich or dense that convergence is possible only if the trial eigenfrequency and the trial eigenfunction boundary values are very close to being exact. Moreover, Murphy's Laws apply here in that the modes of greatest observational interest -- the sectorial or l = m ones -- are the most difficult to compute because for a given radial order they have the longest periods and, therefore, lie in the richest part of mode-space. Consequently, I have been successful so far in computing sectorial modes only up to radial order n~10 for slow rotation, far short of what is required observationally. For rapid rotation, the situation is even worse in that it is difficult to isolate modes with order much above n=3 or 4. Some examples will be presented and suggestions offered for improving the numerical method. (Presented at the Madison Meeting of the AAS) ***************************************************************** TITLE: Theoretical Radial Pulsation Properties of Massive Yellow Supergiants AUTHORS: M. S. Soukup, A. N. Cox (Los Alamos Astrophysics) We have studied the theoretical linear nonadiabatic radial pulsation periods and amplitude growth rates of two stellar models with initial masses of 30 and 40 solar masses. The intrinsic variability and dynamical properties of massive stars are very important to the understanding of the evolutionary behavior of these stars, especially those at, or near, the Humphreys-Davidson (H-D) Line, an empirically defined boundary in the upper portion of the H- R Diagram above which no stars are observed thus far to exist. Pulsation model parameters are derived from models we evolved for each initial mass. Initial chemical compositions are Y=0.28 and Z=0.02, and mass loss (according to the de Jager - Nieuwenhuijzen parameterization) and Livermore OPAL opacities are included in the modeling. Evolution was followed to core helium exhaustion, and all models are H-R Diagram first-crossing tracks; no blue loops occurred. Convection is treated using standard mixing length theory. As expected, the models did not exhibit radial pulsations blueward of an effective temperature of 6000 K. As yellow supergiants, we found them unstable to radial pulsation in an extension of the Classical Cepheid instability strip. The initial 30 solar mass model has a blue edge at 5700 K. The fundamental mode nonadiabatic pulsation period is 161 days, with an amplitude growth rate per period of 2%. At 5000 K, the period is 256 days, and the growth rate has greatly increased to 115%. The model's mass in this temperature interval is about 25.3 solar masses, and the luminosity is about 313000 solar luminosities. The initial 40 solar mass model has a blue edge at 5900 K, a period of 195 days, and a growth rate per period of 1.7%. At 4900 K, the period is 357 days, and the growth rate per period is 136%. Mass and luminosity here are about 32.3 and 527000 in solar units, respectively. While yellow supergiants, mass loss has not caused an enhancement of helium in the surface layers. For the initial 40 solar mass model, notable enhancement occurs when the star becomes a red supergiant, but this is not so for the lower initial mass model. For both models near their blue edges, helium ionization dominates as the pulsation driving mechanism. As the models evolve redwards, the pulsational driving contribution from the hydrogen ionization zone increases and becomes significant at about 5000 K. However, time dependent convection calculations may be necessary to model the effects of stronger convection at about this and cooler temperatures on the pulsational driving. If the very high growth rates calculated here indeed occur in real stars, it may be that the rapidly growing pulsations result in episodic ejections of mass of the tenuous outer layers of massive supergiants just below the H-D Line. (Presented at the Madison Meeting of the AAS) ***************************************************************** TITLE: Use of Temperature-Sensitive Line Ratios for Stellar Seismology AUTHORS: R. W. Noyes, S. G. Korzennik, M, Krockenberger, P. Nisenson (CfA); T. Brown, T. Kennelly (HAO); S. Horner (Penn. State U.) The line depths of virtually all stellar spectral lines are sensitive to small changes in stellar temperature T_eff induced by stellar pulsations, with varying degrees (and signs) depending on the mean T_eff and the line ionization and excitation state. This suggests that combining the information in all spectral lines available in high-resolution spectra could yield temperature changes to a precision better than can be obtained from changes in the equivalent width of individual lines or pairs of lines. We have explored this possibility using data from the Advanced Fiber Optic Echelle spectrograph (AFOE), which records a total of about 1600~\AA~of spectra within the range 3920 A to 6600 A, at spectral resolution of about 50000. The method is to compare the observed change of residual intensity Delta I at each wavelength in the spectrum to the predicted temperature sensitivity dI / dT_eff at that wavelength, derived from two Kurucz models of the star with slightly differing values of T_eff. Simulations show that for a G2 star like the sun, AFOE spectra with S/N = 500 analyzed this way should yield temperature changes to 0.08 K rms, while for an F5 star like Procyon, spectra with S/N = 500 should yield changes to about 0.16 K. Since for the sun and Procyon the largest individual p-mode thermal fluctuations are predicted to be about .006 K and .022 K respectively, individual p-mode fluctuations in such stars should then be detectable at the 3-sigma level by combining about 1600 or 500 exposures respectively. However, reduction of a string of AFOE data for the Sun and Procyon gave S/N values that are about five times worse, largely because of slight wavelength and relative intensity differences between the Kurucz models and the actual spectra. Work is under way to repair these defects, in hopes that this approach may prove useful for asteroseismology. (Presented at the Madison meeting fo the AAS) ***************************************************************** TITLE: The Impact of Pulsations and Waves on Hot-Star Wind Variability S. R. Cranmer (Bartol Research Inst., D. Massa (Applied Research Corp.), S. P. Owocki (Bartol Research Inst.) Hot luminous stars (O, B, W-R) are observed to have strong and variable stellar winds, and many classes of these stars are also inferred to pulsate radially or nonradially. It has been suspected for some time that these oscillations can induce periodic modulations in the surrounding stellar wind and produce observational signatures in, e.g., ultraviolet P Cygni line profiles. However, the fact that most low-order and low-degree oscillation modes are evanescent in the photosphere (i.e., damping exponentially instead of propagating sinusoidally) presents a problem to the survival of significant wave amplitude in the wind. We find, though, that the presence of an accelerating wind can provide the necessary impetus for evanescent modes to effectively ``tunnel'' their way out of the interior. First, in the subsonic, or near-static wind, the reference frame of the temporal oscillations is itself beginning to propagate, and this implies that a small degree of group velocity is imparted to the evanescent waves. Second, in the supersonic wind, the density no longer falls off exponentially, but much more slowly, so the effective scale height grows much larger. Frequencies previously evanescent here no longer ``see'' as much of an underlying density gradient, and are free to propagate nearly acoustically. We model the propagation of oscillations into a hot-star wind via a numerical radiation-hydrodynamics code, and we find that evanescence is indeed not a hindrance to producing wind variability correlated with stellar pulsations. Preliminary models of strong (nonlinear) radial wind oscillations of the beta Cephei variable BW Vulpeculae show good agreement between observed and modeled base ``radial velocity curves'' and wind-contaminated UV profile variability. We are currently applying this general modeling technique to other systems, especially those which rotate rapidly and exhibit nonradial oscillations (e.g., zeta Puppis and HD 64760, extensively observed by the IUE MEGA project). (Presented at the Madison Meeting of the AAS) ***************************************************************** TITLE: The Time-Dependence of the Frequency Components in the Light Curve of RV And AUTHORS: R. R. Cadmus Jr., J. B. Rost, and K. A. Young (Grinnell Coll.) The brightness variations of the semiregular variable RV And have been monitored for about 12 years at Grinnell College's Grant O. Gale Observatory as part of a project designed to investigate the mode of pulsation for this class of stars. In the early 1980's the Fourier spectrum of the light curve had only one strong frequency component, but following an apparent mode change in 1986 the Fourier spectrum became more complex, suggesting simultaneous pulsation in two or more modes. Since that time both the strengths and the frequencies of these components have been variable, although there has been a trend back toward a simpler Fourier spectrum. The behavior of the frequency components suggests that the oscillations of these stars may involve complex interactions among several modes of pulsation. (Presented at the Madison Meeting of the AAS) ***************************************************************** TITLE: Beat Cepheid Period Ratios from OPAL Opacities S. M. Morgan (UNIowa), D. L. Welch (McMaster) We present the results of linear non-adiabatic pulsation models for intermediate-mass stars with metallicities typical of Milky Way, LMC, and SMC objects. A total of 1560 models of Milky Way Cepheids and 1470 models of LMC and SMC Cepheids have been analysed for mode excitation and pulsation period. We compare our results with the observed period ratios seen in 12 Milky Way Beat Cepheids and the 45 LMC Beat Cepheids discovered by the MACHO project. The probable range of period ratios for SMC Beat Cepheids is also discussed. (Presented at the Madison Meeting of the AAS) ***************************************************************** TITLE: Multi-periodicity of Zeta Oph from Multi-site Observations AUTHORS: E. Kambe (Department of Geoscience, National Defense Academy, Yokosuka, Kanagawa 239, Japan); R. Hirata (Department of Astronomy, Kyoto University, Kyoto 606-01, Japan); H. Ando (National Astronomical Observatory, Mitaka 181, Japan); J. Cuypers (Belgian Royal Observatory, Brussel, Belgium); M. Katoh (Department of Astronomy, Kyoto University, Kyoto 606-01, Japan); E. J. Kennelly, and G. A. H. Walker (Department of Geophysics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada); S. \v{S}tefl (Astronomical Institute, Academy of Sciences of the Czech Republic, CZ-251 65 Ondrejov, Czech Republic); A. E. Tarasov (Crimean Astrophysical Observatory, Nauchnyj, Crimea, 334413) We present an analysis of the results from the simultaneous multi-site high-resolution spectroscopic and photometric observations of zeta Ophiuchi (HD149757) in May 1993. The spectroscopic observations covered continuous 100 hours. The short-term periodicity variations are more probable in the line profile because of the unprecedented temporal coverage. The line-profile variations of HeI 6678, which are characterized by traveling features from blue to red, are well reproduced by two large amplitude sinusoids and other sinusoids with smaller amplitudes. The period of the sinusoid with the largest amplitude is 2.018 hr (f_1) which differs from the 2.43 hr of previous publications, although it is possible that 2.43 hr is an alias of 2.018 hr. The period of the second largest amplitude is, in agreement with previous studies, 3.337 hr (f_2). Periods of smaller amplitude sinusoids are 2.432 hr (f_3), 1.257 hr (f_1+f_2), 1.008 hr (2f_1), 2.107 hr (f_4), 1.293 hr (f_2+f_4), 1.668 hr (2f_2), all of which have relation to the two main periodicities. The two main periods have a common superperiod of about 10.05 hrs. We have discussed the commensurability and other features of the periodicity. Although our data in the period is limited, our photometric observations confirmed again very small amplitude of the light variations, close to their detection limit. No counterpart of the 2.018 hr and 3.337 hr periods can be reliably detected. (Submitted to ApJ) *************************************************************** TITLE: A Redetermination of the Mass of Procyon AUTHORS: T. M. Girard, H. Wu, J. T. Lee, S. E. Dyson, E. P. Horch, W. F. van Altena (Yale Obs.); C. Ftaclas (Michigan Tech. Univ.); R. L. Gilliland, K. G. Schaefer, and H. E. Bond (Space Telescope Science Inst.) The Procyon binary system consists of an F5 IV-V primary and a white-dwarf secondary in an approximately 40-year orbit. The mass of the F5 primary as determined from stellar-evolution theory does not agree with the value derived astrometrically by K. Aa. Strand in 1951, nor with a more recent determination by A. W. Irwin et al. in 1992 who combined Strand's photographic measures with radial velocity data. We have used the Yale PDS microdensitometer to remeasure the plates used in Strand's analysis as well as a substantial number of additional plates, doubling the total time baseline to over 80 years. These new measures yield improved orbital elements for the astrometric orbit, (i.e. that of the primary relative to the barycenter). In turn, the new elements and PDS measurement of the USNO parallax series for Procyon allow us to derive the trigonometric parallax for the system to within a formal uncertainty of 1.5 milliarcseconds. The final datum needed to calculate the individual component masses is the angular scale of the visual orbit, (i.e. that of the secondary relative to the primary). We make use of two, recent, independent measurements of the primary/white-dwarf separation: 1) a ground-based measure by R. Brown et al. using the CoCo coronograph and the NASA IRTF 3-meter telescope, and 2) a preliminary result based on multiple observations with the WFPC2 Planetary Camera of HST. With these final ingredients, we are able to derive mass estimates for the two components which are free of any possible systematic error associated with the visual measures of the separation made early in this century, an extremely difficult task considering the ~ 10-magnitude difference and 5-arcsecond separation. Our new determination for the mass of Procyon A is in good agreement with the value derived by stellar-evolution models. (Presented at the Madison Meeting of the AAS) ***************************************************************** TITLE: Oscillations in Alpha Cen A AUTHORS: Hans Kjeldsen (Theoretical Astrophysics Center and Aarhus University, Denmark), Soeren Frandsen (Aarhus University), Tim Bedding (University of Sidney), Thomas Dall (Aarhus University), and Joergen Christensen-Dalsgaard (Theoretical Astrophysics Center and Aarhus University) Using a new technique, we recently obtained strong evidence for stellar oscillations in the G subgiant eta Boo (Kjeldsen et al. 1995, AJ, 109, 1313). Our technique involves monitoring temperature fluctuations in a star via their effect on the equivalent widths of Balmer lines (see also Bedding et al. 1996, MNRAS 280, 1155). Here we report observations of alpha Cen A (G2,V) made in April 1995 over six nights with the 3.9-m AAT in Australia and the 3.6-m ESO telescope in Chile. A few hours each night were spent observing Procyon, and we also obtained observations of the daytime sky. The following results are preliminary. Solar data: the power spectrum shows an excess around 3 mHz. The peak amplitude is 4-5 ppm (parts-per-million) and the noise level is 1.6 ppm. The power-of-power shows a clear signal at the expected splitting of 135 muHz. Alpha Cen A: we see a power excess around 2.3 mHz with a peak amplitude of about 7 ppm. The noise level is 2.3 ppm, and this should be reduced by further processing. The power-of-power implies a large separation of 105.48 muHz, close to the value expected for this star. Inspection of the power spectrum shows that we should be able to identify frequencies for about 30 individual p-modes. Procyon: the noise level is about 10 ppm and the window function is very poor. There may be a power excess near 1.5 mHz with an amplitude of 20-25 ppm. The power-of-power shows a signal at a separation of 52.6 muHz, the reality of which we are not yet sure. (Presented during the SONG Special Session at the Madison Meeting of the AAS) ***************************************************************** ***************************************************************** 4. Meeting Announcements IAU SYMPOSIUM 189 FUNDAMENTAL STELLAR PROPERTIES: THE INTERACTION BETWEEN OBSERVATION AND THEORY (A meeting to mark the 80th birthday of Emeritus Prof. R. Hanbury Brown) 13th to 17th January 1997 University of Sydney AUSTRALIA First Announcement Principal Topics: Observational data: distances, angular dimensions, spectra, flux distributions and calibration, oscillation frequencies and amplitudes (including asteroseismology). Fundamental properties: emergent fluxes, effective temperatures, masses, radii, gravities, luminosities, abundances. Stellar atmospheres: opacities, atomic constants, line broadening, atmospheric motions, chromospheres, magnetic fields. Stellar structure: opacities, boundary conditions, equation of state, convection, helium diffusion, rotation, ages. Chemical evolution: abundances, abundance anomalies, mass loss. For all topics: the emphasis will be on the critical assessment of the quality, accuracy, and prospects for improvement of the observational data and models, on the identification of outstanding problems in stellar astrophysics, and on the observational and theoretical targets and capabilities for their solution. Scientific Organising Committee: J. Davis (Chair) (Australia) J. Andersen (Denmark) Y. Balega (Russia) B. Barbuy (Brazil) M. Bessell (Australia) C. Chiosi (Italy) J. Christensen-Dalsgaard (Denmark) R-P. Kudritzki (Germany) D. Lambert (U.S.A.) M. Spite (France) D. Vandenberg (Canada) Contact Information: For more information please contact A. Booth (Chair, Local Organising Committee); e-mail: booth@physics.usyd.edu.au; Phone: (61) 2 351 3849 (please note: (61) 2 9351 3849 from August 1996); Fax: (61) 2 660 2903 (please note: (61) 2 9660 2903 from August 1996). Or visit our Web page http://www.physics.usyd.edu.au/astron/first.html or use anonymous ftp from ftp.physics.usyd.edu.au} in the directory fsp97. Second mailing and call for papers are anticipated for mid-July 1996. Please register for the second mailing using either the Web page or by e-mail to fsp97@physics.usyd.edu.au. Limited funds may be available to assist with travel and conference expenses in exceptional cases. In the first instance applicants should seek funding from all possible alternative sources. Please indicate when registering if you are likely to request assistance. ********************************************************* ********************************************************* 5. An Invitation to Participate in the Procyon Campaign During the last three weeks of January, 1997, the Stellar Oscillations Network Group at NOAO will conduct a campaign to monitor the star Procyon for p-mode oscillations. Observations will be obtained on the coude feed telescope on Kitt Peak, near Tucson, Arizona, at a reciprocal dispersion of 0.4 A/pixel, covering the region from 3800-5200A. Primary emphasis will be on the measurement of the equivalent widths of H-beta, -gamma, and -delta for asteroseismology. The actual dates of the campaign are January 11 - February 1 (UT). Some additional time during the first weeks of February may also be scheduled. We are interested in developing collaborations with other observatories during this period, both to extend coverage to times when Procyon cannot be observed from Kitt Peak, and to monitor the star using other techniques such as Doppler velocity variation or photometric variation. If you are interested in participating in this campaign, please contact one of us at NOAO (S. Barden, M. Giampapa, J. Harvey, F. Hill, C. Keller, or C. Pilachowski) or send email to song@noao.edu for details. ********************************************************* *********************************************************o The National Optical Astronomy Observatories are operated by the Association of Universities for Research in Astronomy, Inc. under cooperative agreement with the National Science Foundation. ************