HD12098 and Other Results from Nainital-Cape Survey
Nainital-Cape Survey was started with an aim to search for new rapidlyoscillating Ap stars in the northern hemisphere. We discovered one newmono-periodic roAp star HD12098. The frequency separation of HD12098suggests a rotation period of 5.5 days for the star. We summarize herethe observations of HD12098 and briefly discuss the results of themulti-site observation campaign organized to resolve the ambiguity inthe determination of the rotation period of HD12098. Other interestingresults like non-oscillating Ap stars discovered and two candidate starsin which roAp periodicity is seen but not confirmed are also discussed.
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The Naini Tal - Cape survey for pulsations in chemically peculiar A-type stars. I. Methods and preliminary results
A new survey for pulsating, chemically peculiar A- and F-type stars inthe northern hemisphere has been initiated using the 1-m telescope atUttar Pradesh State Observatory in Naini Tal. The survey is primarilystructured to reveal high-overtone pulsations in chemically peculiar A-Fstars, but it is also revealing low-overtone delta Scuti-type pulsationsin stars with peculiar colours. This paper describes the scope andmethods of the survey. Preliminary observations of 28 candidate starsare presented and the discovery of three new pulsators, HD 12098, HD13038 and HD 13079, is announced. Null results for the remaining 25stars are also discussed.
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The short-period Cepheid EU Tau. I - New photometric and radial-velocity data
New Johnson UBVRI and Cousins (RI)c photometry of EU Tau from threeobservatories are used to answer the outstanding questions surroundingthe pulsation period of this short-period Cepheid. These data providealmost complete phase coverage of the pulsation cycle. It is confirmedthat EU Tau is pulsating with a single period near 2.1 days in agreementwith that found previously by Fernie. Confusion in the literature aboutthe photometric indices of the comparison star BD 18959 deg near EU Tauis shown to arise largely from misidentifications of BD 18957 deg and BD18959 deg. New radial velocities for EU Tau are reported and compared toearlier observations with CORAVEL. Contemporaneous radial velocities andphotometric data are ideally suited to a surface-brightness analysis ofthis interesting Cepheid.
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Frequency analysis of the short-period Cepheid EU Tauri
New photometric and radial-velocity observations of the short-periodCepheid EU Tauri show systematic deviations from a smooth curve whenplotted in phase according to the accepted period of 2.1025 days. Thesedeviations suggest that the star may be multiperiodic, or now may have asingle period which differs from the older value. Frequency analysis ofthe existing data was undertaken to investigate these possibilities. Itis found that a better fit to the new data is obtained by using arevised primary period, P1 = 2.0895 days. Furthermore, the light andvelocity variations can be reproduced to within the observationalscatter by the sum of only two sinusoids, with periods P1 and P2 = P1/2.This apparent simple harmonic composition of the EU Tau curves is rare,if not unique, among the known short-period Cepheids. It is suggestedthat this could indicate the presence of a 2:1 resonance between thesecond and a higher overtone of pulsation in the star.
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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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Comparison Star Adjustments for the Cepheid EU Tau
Not Available
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UBV photometry of EU Tau
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974A&AS...13...91S&db_key=AST
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