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Eleven New γ Doradus Stars
We present new high-dispersion spectroscopic and precise photometricobservations to identify 11 new γ Doradus variables. Seven ofthese new γ Doradus stars appear to be single, three are primariesof single-lined binaries, and one has two distant visual companions;none are double-lined or close visual binaries. Several of the starsshow spectroscopic line-profile and low-amplitude radial velocityvariability indicative of pulsation. All 11 stars are photometricallyvariable with amplitudes between 8 and 93 mmag in Johnson B and periodsbetween 0.398 and 2.454 days. One star is monoperiodic; the rest havebetween two and five independent periods. The variability at all periodsapproximates a sinusoid, although three of the stars exhibitcycle-to-cycle variation in the level of maximum brightness, similar tothe Blazhko effect observed in some RR Lyrae stars. We provide a newtabulation of all 54 γ Doradus stars confirmed to date and listsome of their properties. All are dwarfs or subgiants and lie within awell-defined region of the H-R diagram that overlaps the cool edge ofthe δ Scuti instability strip. Four of the new γ Doradusvariables from this paper also lie within the δ Scuti instabilitystrip but do not exhibit the additional higher frequency variabilitytypical of δ Scuti stars. The variability type of several of thesestars given in the General Catalog of Variable Stars and in SIMBADshould now be revised.
| Photoelectric observations of lunar occultations. XIII
Occultation observations made with the 0.76 m reflector at McDonaldObservatory are presented, for 319 events occurring between Jan. 15,1981 and Feb. 7, 1982. One table reports timings, and a second recordsobservations of 16 double stars, in particular, Nu Gem observationsreveal that the two close components are similar in color. This allowsan estimation of individual visible magnitudes (near 4.60 and 5.32)suggesting that the secondary is a late B-type main-sequence star. SAO158929 observations reveal systematic differences in angular diametervalues. Of the 16 observed double stars, 9 appear to be new discoveries,including SAO 93067, SAO 94595, and SAO 98770. A third table gives fullydarkened angular diameters for the stars SAO 158929, SAO 77516 Y Tau,and SAO 119035 Nu Vir.
| Photoelectric observations of lunar occultations. XII
Occultation observations of 414 events observed between 6 July 1979 and4 September 1980 with the 0.76-m telescope of McDonald Observatory arereported. Timings and data on double stars are given. Angular diameterinformation in six cases is included. The stars concerned with their runnumbers are: SAO 161754 (5270); 94027 (Alpha Tau) (5319, 5381, 5454);159370 (Gamma Lib) (5325, 5571); 162413 (43 Sgr) (5332); 97472 (3 Cnc)(5414); and 93955 (Theta Tau) (5445).
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משמש של הקבוצה הבאה
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | בתולה |
| התרוממות ימנית: | 14h16m48.74s |
| סירוב: | -08°53'04.1" |
| גודל גלוי: | 6.477 |
| מרחק: | 163.132 פארסק |
| תנועה נכונה: | -17.8 |
| תנועה נכונה: | -14.6 |
| B-T magnitude: | 8.068 |
| V-T magnitude: | 6.609 |
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