An Einstein Observatory SAO-based catalog of B-type stars
About 4000 X-ray images obtained with the Einstein Observatory are usedto measure the 0.16-4.0 keV emission from 1545 B-type SAO stars fallingin the about 10 percent of the sky surveyed with the IPC. Seventy-fourdetected X-ray sources with B-type stars are identified, and it isestimated that no more than 15 can be misidentified. Upper limits to theX-ray emission of the remaining stars are presented. In addition tosummarizing the X-ray measurements and giving other relevant opticaldata, the present extensive catalog discusses the reduction process andanalyzes selection effects associated with both SAO catalog completenessand IPC target selection procedures. It is concluded that X-rayemission, at the level of Lx not less than 10 exp 30 ergs/s, is quitecommon in B stars of early spectral types (B0-B3), regardless ofluminosity class, but that emission, at the same level, becomes lesscommon, or nonexistent, in later B-type stars.
|
Positional reference stars in the Magellanic Clouds
The equatorial coordinates are determined of 926 stars (mainly ofgalactic origin) in the direction of the Magellanic Clouds at the meanepoch T = 1978.4 with an overall accuracy characterized by the meanvalues of the O-C coordinates, Sa = 0.35 arcsec and Sd = 0.38 arcsec,calculated from the coordinates of the Perth reference stars. Thesevalues are larger than the accuracy expected for primary standard stars.They allow the new positions to be considered as those of reliablesecondary standard stars. The published positions correspond to anunquestionable improvement of the quality of the coordinates provided inthe current catalogs. This study represents an 'astrometric step' in thestarting of a 'Durchmusterung' of the Magellanic Clouds organized by deBoer (1988, 1989).
|
UBV (RI)c standard stars in the E- and F-regions and in the Magellanic Clouds - a revised catalogue.
Not Available
|
UBV(RI)c photometry of some standard sequences in the Harvard F regions and in the Magellanic Clouds
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1988MNRAS.231.1047M&db_key=AST
|
UBV photometry of eclipsing binaries in the LMC
UBV photoelectric observations are presented for three eclipsingbinaries in the LMC: HV 2241, HV 2765, and HV 5943. Prior to solving thelight curves, the photoelectric data were corrected for crowding bystudying models, based on CCD observations, of the fields around thevariables. The brightnesses of contaminating stars, both near thevariables and in the areas selected for sky measurements, weredetermined by simulating aperture photometry on the modeled star fields.The light curves were solved with the Wilson-Devinney program by makinga systematic search of parameter space. Numerical simulations showedthat a search involving only one fixed parameter, the mass ratio,produced systematic errors in the solution elements. However, a searchinvolving two fixed parameters, the mass ratio and surface potential ofthe secondary component, found solution elements that are apparentlyfree of systematic effects and correct within the uncertaintiesestimated for them by the program. Preliminary absolute dimensions arecomputed for the components, and the evolutionary status of the systemsis discussed.
|
Revised UBV photometry of Magellanic Cloud sequences
The old photometry of UBV secondary standards in the Magellanic Clouds(Cousins 1970) has been revised. New measurements made at Sutherland arepresented and analyzed.
|
A distance modulus of the LMC from UVBY beta photometry of B supergiants
Stromgren four-color and H-beta photometry has been obtained for 44 Bsupergiants in the Large Magellanic Cloud. As expected, nearly one-halfof them have beta indices which suggest emission at H-beta. From 24stars which appear to be free from this emission, thebeta/c0/M(v) calibration of Balona and Shobbrook (1984),applied with a correction to the beta index for the mean radial velocityof the LMC stars, indicates a distance modulus of 18.8 + or - 0.3.
|
A classification of star clusters in the Magellanic Clouds
Four-color photometry of the integrated light from 61 star clusters inthe Magellanic Clouds, together with a rediscussion of Danziger'smultivariate spectrophotometric data for some of these same clusters,have made possible for the first time an intelligible classificationscheme for their integrated spectra. It is found that the integratedspectra of populous star clusters in the Magellanic Clouds may bearranged in a one-dimensional sequence in such a way, that on traversingthe sequence, all spectral features behave regularly - not necessarilymonotonically, but as smoothly as can be expected from the magnitude ofobservational error. The character of the spectral variations along thesequence suggests that both cluster age and chemical composition varysmoothly as the sequence is traversed. The newly discovered sequence isdistinctly different from the analogous one for star clusters of theGalaxy, and this fact is interpreted as indicating that the relationbetween epoch and average chemical composition of the interstellarmedium is qualitatively different in different stellar systems.
|
Standard Stars for VRI Photometry with S25 Response Photocathodes
Not Available
|
A photoelectric magnitude sequence in the LMC: 0501-6728.
Abstract image available at:http://adsabs.harvard.edu/abs/1974MNRAS.169..577O
|
Polarization measurements of stars in the Magellanic Clouds.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970AJ.....75..778M&db_key=AST
|
UBV photometry of star clusters in the Magellanic Clouds.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1968AJ.....73..569V&db_key=AST
|
U, B, V, photometry in and near the Magellanic Clouds
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1962MNRAS.124..359W&db_key=AST
|
Southern hemisphere photometry II Photoelectric measures of bright stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1958AJ.....63..118A&db_key=AST
|
INHABITED SKY
