3137 III/137 Spectroscopically Identified Hot Subdwarf Stars D Kilkenny U Heber J S Drilling S.Afr. Astron. Obs. Circ. 12 1-80 1988 1988SAAOC..12....1K Stars, population II The catalog contains data for 1225 spectroscopically classified hot subdwarf stars. It excludes central stars of planetary nebulae but includes stars in binary systems. The data assembled include, where available, alternative designations, accurate coordinates, UBV and uvby photometry, spectral types and determinations of effective temperature and surface gravity.

Prior to 1986 there were around 200 spectroscopically classified hot subdwarf stars. The Palomar-Green survey (Green et al., 1986) detected over 900 hot subdwarfs, mostly in the North Galactic Cap and mostly previously unknown objects; the Kitt-Peak_Downes survey found another 60 near the Galactic Plane (Downes, 1986). These form the basis of the present catalog but new subdwarfs are continually being found by spectroscopic surveys of photographically discovered faint blue star samples; examples are the work of Wegner and his co-workers on the Kiso survey (Wegner et al., 1985, 1986, 1987) and of Kilkenny and Muller (1987) on southern discoveries by Luyten and collaborators (e. g. Haro and Luyten, 1962; Luyten and Anderson, 1958, 1959, 1967). Only stars for which a spectroscopic classification exists have been included. There is a significant probability that stars with only photometric classifications can be normal high-latitude B stars, white dwarfs or cataclysmic variable, for example. Hot subdwarfs in binary systems have been included but not planetary nebulae nuclei classified 'sd' since the latter have been cataloged elsewhere. Although there is not a universally accepted classification scheme for hot subdwarfs, it is fairly clear that the main criterion is a surface gravity higher than that of hot main sequence stars but less than that of hot white dwarfs. Also, hot subdwarf stars typically show helium abundance anomalies.

ID Star identification The star name from the original discovery catalog, unless a more common name (such as an HD designation) exists. This has been done even when the discovery catalog gave a 'faint blue object' type rather than a spectroscopic classification because much of the published literature naturally uses the 'discovery' name. Some stars in the data file occupy multiple records. In this case, ID and desig are repeated for all applicable records. --- desig RA/Dec designation Where an RA/Dec designation exists, this has been included using the convention RA (hours, minutes, decimal minutes), sign, Dec (degrees, minutes) with truncation for the last figure in RA and Dec (this avoids occasional rounding ambiguities). The Kiso surveys (Noguchi et al., 1980; Kondo et al., 1984) use rounding to determine the RA/Dec type nomenclature and this has been retained in this catalog to avoid confusing the identifi- cation in published material. Thus, there are sometimes small differences between the KUV and PG names; in this case, both are given. --- RAh Right Ascension (1950) hours h RAm Right Ascension (1950) minutes min n_RAm Right Ascension (1950) sec. or decimal min. Coordinates for 1950 quoted to second and arcsecond accuracy where possible. More accurate co-ordinates can sometimes be found in the source catalogues. If byte 28 is blank, then value in this field is Right Ascension seconds. If byte 28 contains a decimal point, then this field is a continuation of RAm. --- DE- Declination (1950) sign --- DEd Declination (1950) degrees deg DEm Declination (1950) arcminutes arcmin n_DEm Declination (1950) arcsec or decimal arcmin If byte 38 is blank, then value in this field is Declination seconds. If byte 38 contains a decimal point, then this field is a continuation of DEm. --- Name Alternative name for star Alternative names. The authors have tried to include as many common names as possible for each object but have not exhaustively cross-indexed all possible catalogs. Durchmusterung designations for HD stars are not included although such will almost always exist. --- V V magnitude The Johnson or Stroemgren photometry. Because these data occupy the same columns, the immediate way to tell which is which is that the UBV photometry has three quantities; the uvby has four. Hence, where partial information is available in the literature (E.g. V and (B-V) or V, (b-y) and m1) only the magnitude has been listed in this catalog and the original reference must be consulted for the data. Occasionally, a reference will contain other photometric information such as RI or even infrared photometry, so it is always worth checking the original source. mag u_V Uncertainty flag on V --- color1 (B-V) or (b-y) mag u_color1 Uncertainty flag on color1 --- color2 (U-B) or m1 mag u_color2 Uncertainty flag on color2 --- color3 c1 or blank mag r_V A reference for the photometry --- Sp Spectral type Spectral type quoted directly from the literature. No attempt has been made to put the classifications on a uniform system. Probably this should be left until a clear picture of the evolution of hot subdwarf stars emerges. Originally the classes 'sd B' and 'sd O' were recognized by broad Balmer line absorption and the early confluence of the Balmer series; B types were classified by weak or non-existent helium lines and O types by the presence of HeII 4686 or other HeII lines (see e. g. Sargent and Searle 1968). Liebert (1987) accept the sd B, OB, O sequence as one of increasing temperature and helium abundance but propose a new 'hot sd' category with Teff > 60000 K which overlaps with planetary nebula nuclei, PG 1159 stars and hot white dwarfs. Recent spectroscopic analyses (Heber and Hunger 1987, Mendez et al. 1988) indicate that there is indeed an overlap of hot sdO stars with central stars of planetary nebulae and vice versa. In the Palomar-Green survey, Green et al. (1986) use a scheme which is worth summarizing here because the PG-classified stars are a substantial fraction of our catalogue. Briefly: sd B = broad Balmer series absorption sd B-O = sd B stars with very weak HeI 4471 sd OA = strong Balmer absorption with HeI 4471 and often HeI 4026 sd OB = dominated by HeI and HeII lines; often Balmer absorption present sd OC = dominated by HeII absorption; possibly weak HeI 4471 and Balmer series blended with HeII Brackett lines sd OD = 'pure' HeI absorption; weak or absent H and HeII sd O = HeII 4686 and often HeI 4471 present but signal/noise too poor for further classification sd = broad Balmer series absorption but signal/noise too poor for further classification However, the PG classification 'sdOB' is a helium-rich sdO star quite different from the Baschek and Norris (1975) helium-weak 'sdOB'. To separate the authors have introduced the nomenclature sdO(A), sdO(B), sdO(C) and sdO(D) to replace the PG sdOA, ...... , sdOD subtypes. --- r_Sp A reference for the spectral type --- l_Teff Limit flag on Teff --- Teff Log of effective temperature log (effective temperature). Often this is published as K temperature; we have given the logarithm to two decimal places only --- u_Teff Uncertainty flag on Teff --- l_log(g) Limit flag on log(g) --- log(g) Log of surface gravity --- u_log(g) Uncertainty flag on log(g) --- r_Teff Reference for Teff and log(g) --- ref Reference code Code as it appears in r_* fields of data.dat --- text Text of reference --- Julie Anne Watko ADC/SSDOO 1996May22The catalogue was sent to the ADC by Dr. Kilkenny for which we thank him. This document is nearly a verbatim copy of the published text with the exception of the format tables by Julie Anne Watko, and minor changes, particularly the elimination of the first-person references. III_137.xml