Astrocat Starcat Homepage

lwd : Luyten's Catalogue of White Dwarfs

Contents

                                                                          
Table name:       LWD
Records:          6546
Spectral Band:    OPT,Photo,Rband
Kind of Object:   White Dwarfs,Star
Mode:             Astrometry,Proper Motion,Photometry
PreView:
Coordinates:      B1950

Reference

Description

See the Introduction Texts.

Fields

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

1970 INTRO

The catalogue contains 2934 entries and includes all probable white dwarfs and degenerate stars found in the Proper-Motion and Faint-Blue Star Surveys. For the vast majority I first made the proper motion as well as the color determination. However, there are also included those stars which were found blue by others and for which I subsequently determined the proper motion (such as the HZ and the Feige stars) and the few stars which I identified as blue stars but for which proper motions were measured elsewhere. Finally, a handful of objects is included --- largely for reasons of statistcal completeness --- where I merely re-determined the previously known motions and colors: examples are the Greenwich white dwarfs, north of declination +70, W 672, etc. In all these cases I have, of course, retained the original designations.

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   18.3
I 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.

1977 INTRO

The continuation of the first list published in 1970 contains 3033 entries. The arrangement differs slightly from that of the previous one in that the first column gives the star's designation, generally my LP number. The 1950 position is now given to 1s in R.A. and 0'.1 in Dec. The next three columns give the red, and photographic magnitudes, and the estimated color or spectral class. The last two columns give the total proper motion to 0".001 and the direction in degrees. Footnotes provide additional information -- mainly about components of double stars with common proper motion.

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.