Delta Scuti Star Newsletter

Issue 6, May 1993

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A catalogue of variable stars in the lower instability strip

by: J.R.Garcia, J.R.Cebral, E.R.Scoccimarro, P.Wahnon, M.Zimmermann, R.Arena, V.Bazterra, C.Krawczenco, F.Marotta, L.Pellizza, A.Risi

Abstract:

Identifications, positions, photometry, spectra, some pulsational features, other astrophysical parameters and literature for 279 pulsating variable stars in the lower instability strip, near the ZAMS, are given. About 169 stars have near homogeneous photometric information in Stroemgren's uvbyBeta photometric system. This catalogue/data base covers information published until July 1992.

Introduction

The instability strip of the H-R diagram presents a region near the ZAMS populated by Am, Delta Del and constant stars, sharing their room with a group of variable stars with ultrashort periods, that, in the past, several authors called dwarf cepheids (attending at the manifestation of some features of cepheid variable stars but in a smaller scale), but now called Delta Scuti and SX Phoenicis (according to their small or large amplitudes, population, metal abundances and other astrophysical features). As we have considered in a previous paper (Garcia et al., 1989), this distinction is not yet well established.

A previous version of this catalogue, covering information for 254 stars, has been published in the Bull. Inform. CDS No.34 (1988). This new version of the catalogue was encouraged by a comment by Kurtz (1990) and other private comments from M. Breger. This release of the second edition of the Catalogue covers identification, position, spectra, photometry, pulsation features and other astrophysical parameters and literature references for 279 variable stars of both types.

In order to have a good description of the general characteristics of these stars, some review papers by Breger (1979), Kurtz (1988, 1990), Shibahashi (1987) and Wolf (1983) can be read.

Structure of the Catalogue/Database

The list is given according to 1950.0 equinox equatorial coordinates. The mean source of information is the 4th Edition of the General Catalogue of Variable Stars (GCVS) by Kholopov et al. (1987) and the Name Lists Nrs. 67, 68, 69 (Kholopov et al., 1985, 1987, 1989) and 70 (Kazarovets and Samus, 1990).

The catalogue is a data base composed by one main menu and eight windows. The software's style used is the point and shot menu driven, all explained in the screen. For this version, the access to the information in the catalogue is read only. The structure is the following:

Windows 1 to 4 are scrolling display fields for choosing the star or the literature by different orders. The stars can be chosen ordered by right ascension or by constellation. Instead, literature can be retrieved by means of its order number or by the first author's surname.

Window 5 has the following fields:

  1. ORDER. The order identification number for the star established by the authors arbitrarily.
  2. HR. Designation from HR Catalogue.
  3. HD. Designation from Henry Draper Catalogue.
  4. STAR'S NAME. According to GCVS or Name Lists.
  5. TYPE. The type of variable star according to GCVS.
  6. PERIOD. The period given here is, as a rule, the fundamental one. The harmonics, secondaries and others are given in the remarks, later in this window.
  7. EPOCH OF MAXIMUM. All epochs given are expressed in days of the Julian period (J.D.). The epoch only corresponds to a moment of maximum light.
  8. RANGE. Magnitudes at maximum and minimum light, and the type of magnitude given. The type of magnitude could be V, B or P, meaning V and B from Johnson's UBV, and P for photographic.
  9. RA. Equatorial coordinate right ascension for the equinox 1950.0 with an accuracy of a second of time.
  10. DEC. Equatorial coordinate declination for the equinox 1950.0 with an accuracy of 0.1 minute of arc.
  11. PREC. IN RA. Precession in right ascension for the equinox 1950.0 with an accuracy of 0.01 of a second of time.
  12. PREC. IN DEC. Precession in declination for the equinox 1950.0 with an accuracy of 0.001 minute of arc.
  13. l. Galactic coordinate longitude l(II) with an accuracy of a hundredth of a degree.
  14. b. Galactic coordinate latitude b(II) with an accuracy of a hundredth of a degree.
  15. SPECTRAL TYPE. If modern two dimensional spectral classification is available for a star, we have attempted to provide it. In the case of several available determinations of spectral type we have preferred more recent studies, taking into account, of course, the reliability of every determination. Two spectral type values separated by the <-> sign mean the limits of spectral type variations of the object during its light changes.
  16. REMARKS. The remarks describe some features of light variability (period variation, changes of the light curve shape). Spectral peculiarities are also noted. Literature references are in the same system as in window 7 field 2. The signs < > show that the quantity between them is a mean value.

The following abbreviations are used:

  • dm, A: amplitude (total, not semiamplitude)
  • const: constant, does not vary
  • P: period
  • Porb: period of orbital motion for close binary systems
  • SB: spectroscopic binary system
  • SB1: a spectroscopic binary with lines of only one component appearing in the spectrum
  • SB2: a spectroscopic binary with lines of both components appearing in the spectrum
  • var: variable, varies
  • VB: visual binary (or double) system
  • Rad.vel.: radial velocity
  • PA: position angle
  • a: semi-major axis of the relative orbit of a binary system
  • e: orbital eccentricity

    For visual binary systems, the symbol VB or a number from a corresponding catalogue, with the variable component indicated, is followed (in brackets) by magnitudes of the components A and B, angular separation of these components and the fainter component position angle, or the semi-major axis of the relative orbit and the period of orbital motion; sometimes the epoch of observation is indicated; then data on other components are given, if necessary. As a rule, Table II gives the limits of variation for combined light, if the variable component is not indicated in the remarks.

    Sometimes, the companion's magnitude is followed by letters n, s, p, f, showing that the companion is to the north (n), to the south (s) of the primary star, is preceding (p) or following (f) it in the diurnal rotation of the celestial sphere.

    Finally, the remarks notice the stars situated in the region of some star cluster.

    Window 6 has the following fields1:
    1. STAR. The same star's name and order given in the window 5.
    2. Amplitude. Amplitude of light variations with an accuracy of a 0.001 mag.
    3. Mv. The absolute magnitude is given according to determinations based on different criteria.We preferred more recent studies taking into account their reliability.
    4. v sin i. Rotational velocity v.sin(i).
    5. b-y. The colour index (b-y) of the uvbyb photometric system.
    6. (b-y)o. The corrected or intrinsic colour index (b-y)0 of the uvbyb photometric system.
    7. m1. The parameter m1 of the uvbyb system.
    8. m0. The dereddened parameter m0 of the uvbyb system.
    9. dm1. The parameter dm1 of the uvbyb system.
    10. d[m1]. The dereddened parameter d[m1] of the uvbyb system.
    11. b. The b magnitude.
    12. E(b-y). The colour excess in (b-y) of the uvbyb system.
    13. c1. The parameter c1 of the uvbyb system.
    14. c0. The dereddened parameter c0 of the uvbyb system.
    15. dc1. The parameter d c1 of the uvbyb system.
    16. d[c1]. The dereddened parameter d[c1] of the uvbyb system.
    17. V. The V magnitude of the Johnson's UBV system.
    18. B-V. The B-V colour index of the UBV system.
    19. U-B. The U-B colour index of the UBV system.

    Window 7 is a list (scrolling) of references in the literature for the star chosen. The list is composed not only of papers contacting about important information of the star, but a finder chart's reference is also given. The contents of the four columns of the list are the following:

    1. STAR'S ORDER. The same as in window 5 field 1.
    2. LITERATURE'S ORDER. This number is a cumulative index which has the following criteria:
      • if the reference appears in the GCVS, the number is the same as in it;
      • if it is not there but it appears in the 67th Name List, the number is the same as in it but plus 50000;
      • if it is not there but it is in the 68th Name List, the number is the same as in it but plus 60000;
      • if it is not there but it appears in the 69th Name List, the number is the same as in it but plus 69000;
      • if it is not there but it is in the 70th Name List, the number is the same as in it but plus 70000;
      • finally, if it is not there, the new numbers start with 90001.
    3. FIRST'S AUTHOR SURNAME.
    4. YEAR OF PUBLICATION.

    Window 8 (View paper's details) has the following fields:

    1. ORDER NUMBER. The same literatureÆs order given in window 7 field 2.
    2. FIRST AUTHOR. The surname of the first author of the article, book, catalogue or atlas.
    3. AUTHORS. The author or the almost complete list of authors of the article, book, catalogue or atlas.
    4. JOURNAL. The abbreviation for the JournalÆs name where the paper was published. The list of abbreviation is the same as in the GCVS.
    5. VOLUME.
    6. NUMBER.
    7. PAGE.
    8. YEAR.

    Availability

    This computer based catalogue has a software for access and retrieval of information from a database, which was made for operating under DOS. Lists of the contents are available also in ASCII form.

    The database is available from Instituto Copernico, upon request, at the only cost for postage and handling (about US $ 6.-).

    We expect that a printed version of the catalogue will be submitted for publication during the second quarter of 1993.

    Presently, we are planning to make a complete data base of literature for these stars, accessible by keywords (covering the most detailed topics).

    If you have papers published that you have not sent before to us or preprints about these stars, please send them as soon as possible. We are waiting for suggestions about the most relevant keywords on this topic.

    Acknowledgements

    We wish to thank to Dr. C. Jaschek, for several comments on the first version of this catalogue. We appreciate the information directly addressed to us from authors of papers mentioned here and specially to Dr. M. Creze for sending us the information available in SIMBAD for these stars. We are in debt for the encouragement given by Dr. D. Kurtz and Dr. M. Breger.

    References:

    1. Breger, M.: 1979, Pubs. Astr. Soc. Pacific, 91, 5.
    2. Garcia, J.R.; Cebral, R.; DiGiorgio, F.; Romano P.; Scoccimarro, E.R.; Wahnon, P.; Zimmermann, M.: 1988, Bull. Inform. CDS nr. 34, 67.
    3. Garcia, J.R.; Cebral, R.; Magaldi, D.; Romano P.; Scoccimarro, E.R.; Wahnon, P.; Zimmermann, M.: Rev.Mex.Astr.Astrof. 21, 395, 1990
    4. Kazarovets, E.V.; Samus, N.N.: IAU Comm. 27 I.B.V.S. 3530, 1990
    5. Kholopov, P.N.; Samus, N.N.; Kazarovets, E.V.; Perova, N.B.: IAU Comm. 27 I.B.V.S. 2681, 1985
    6. Kholopov, P.N.; Samus, N.N.; Kazarovets, E.V.; Kireeva, N.N.: IAU Comm. 27 I.B.V.S. 3058, 1987
    7. Kholopov, P.N. et al.: General Catalogue of Variable Stars, Moscow 4th Edition, 1987
    8. Kholopov, P.N. et al.: IAU Comm 27 I.B.V.S. 3323, 1989
    9. Kurtz, D.W.: Communications in Asteroseismology 21, 5, 1990
    10. Kurtz, D.W.; 1988, in: Multimode Stellar Pulsations, ed. G. Kovacs et al., Konkoly Obs. - Kultura , Budapest, p 95.
    11. Shibahashi, H.: Lecture Notes in Physics, 274, 112, 1987
    12. Wolf, S.C.: The A-type Stars, publ. NASA, Washington, 93, 1983

    sperl@astro.ast.univie.ac.at