Table name: LWD Records: 6546 Spectral Band: OPT,Photo,Rband Kind of Object: White Dwarfs,Star Mode: Astrometry,Proper Motion,Photometry PreView: Coordinates: B1950
Name Type Meaning name c13 Designation of the star note c1 R if a remark exists in the original catalogue r_a F Right Ascension (was given to 0.1mn in 1970 edition) dec F Declination (was given to 1' in 1970 edition) pm F Total proper motion in arcsec/yr pma F Angle of proper motion in degrees sp c3 Color class pmag F Photographic magnitude rmag F Red magnitude (only given in WhiteDwarf II). An unknown magnitude has the value 99.9 Derived Values _ra F J2000 Right Ascension (epoch + equinox J2000) _de F J2000 Declination _lii F Galactic Longitude _bii F Galactic Latitude
Since parallaxes are known for at most a few dozen white dwarfs, and photoelectric colors and spectra for no more than a few hundred, the only valid selection criteria we can use depend on proper motions and crude estimations of color. As a guideline for inclusion into the catalogue I have used the data in the following table which gives minimum values for H = m + 5 + 5 log (mu) for the various color classes :
Min. H Min. H b 13.5 g 17.0 a 14.4 g-k 17.7 f 15.5 k 18.3I have tried to adhere to these limits as closely as possible and have included stars with smaller values of H only if a) evidence from photoelectric colors or spectra indicate the object is a degenerate star (such as LB 3303) or b) the object is close to the antapex (as for many stars found on P234 centered at 21h +42 deg).
The bluest stars in the lists, those of color classes b or a, will probably prove to be mainly genuine white dwarfs but among the yellower objects high-velocity "intermediates" and subdwarfs will probably become more numerous and the attrition, or perhaps we should say, the casualties will b greatest among color class k. Still, owing to the large cosmic dispersion in tangential velocity and the observational errors in the colors (two of the Greenwich white dwarfs were originally classified as "k" on the Palomar survey plates) I believe that the present limits for H are not only reasonably accurate but also statistically sound.
I might point out that, after all, the present catalogue containing 2934 entries represents a first screening from among well over 100,000,000 stars which passed in review in the blink microscope --- thus representing a selection of only 1 out of more than 30,000. Those who make the follow-up spectroscopic or photoelectric observations should not object, therefore, even if one fourth of the present number of probable white dwarfs were to turn out "duds".
I am indebted to the National Science Foundation for two grants, GP 8082 and 9506, which made this research and itrs publication possible.
The catalogue gives data for 3513 stars but it should be emphasized that while the large majority of stars listed with colors "b" and "a" are probbly genuine white dwarfs, the percentage of those which are high-velocity subdwarfs, or main-sequence red dwarfs with strong H and K emission lines increases rapidly with increasing color. Probably no more than 40% of the stars with color "k" will prove to be genuine yellow degenerates.
The large majority of the stars were found on, and the data determined on plates taken with the 48 inch Schmidt telescope of the Palomar Observatory. I am indebted to the Hale Observatories for numerous Guest-Investigatorships during which the needed plates were taken. The processing of the plates was done on the automated-computerized plate scanner and measuring machine built by Control Data Corporation under a contract with the National Aeronotics and Space Administration. Grants from the National Science Foundation made the compilation of the data and the publication of the catalogue possible.