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A photometric study of the light variations of the triple system DG Leo
Multi-site and multi-year differential photometry of the triple star DGLeo reveals a complex frequency spectrum that can be modelled as thecombination of at least three δ Scuti type frequencies in therange 11.5-13 c/d (with semi-amplitudes of 2-7 mmag) and a superimposedslow variability of larger amplitude. The period of the slow variationfits very well with half the orbital period of the inner spectroscopicbinary indicating the presence of ellipsoidal variations caused by thetidally deformed components in a close configuration. These findings,together with the results of a recent spectroscopic analysis (showingthat the system consists of a pair of mild Am stars and one A-typecomponent of normal solar composition), infer that DG Leo is anextremely interesting asteroseismic target. Identification of whichcomponent(s) of this multiple system is (or are) pulsating anddetermination of the excited pulsation modes will both contribute to amuch better understanding of the non-trivial link between multiplicity,chemical composition, rotation, and pulsation in the lower part of theclassical Cepheid instability strip.
| An investigation of the spectroscopic-visual triple system 20 Leonis
Stromgren uvby photometry of the spectroscopic-visual triple system 20Leonis was obtained at Mount Laguna Observatory of San Diego StateUniversity. The delta Scuti visual component was found to have only oneperiod of 0.0826 day, although another may be present in the data. Thespectroscopic binary component was found to undergo grazing eclipsesfrom which an inclination of 75 +/- 1 deg was tentatively determined.Radial velocities obtained from the Dominion Astrophysical Observatory1.2-m telescope were combined with Fekel and Bopp's 1977 velocities, andnew orbital elements were calculated. Spectroscopic observations of thevisual component also showed that there has been an observable change inthe system since 1977. The possibility that this system may be anellipsoidal variable rather than an eclipsing binary was alsoinvestigated.
| Erratum : MK classification for F- and G-type stars. II.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970AJ.....75..507H&db_key=AST
| MK classifications for F-and G-type stars. II.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970AJ.....75..165H&db_key=AST
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | אריה |
| התרוממות ימנית: | 09h46m13.24s |
| סירוב: | +20°29'21.1" |
| גודל גלוי: | 7.421 |
| מרחק: | 245.098 פארסק |
| תנועה נכונה: | -14.6 |
| תנועה נכונה: | 6.7 |
| B-T magnitude: | 8.61 |
| V-T magnitude: | 7.52 |
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