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Register a new userNew multisite observations of Delta Scuti stars V624 Tauri and HD 23194
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Added by
Lester Fox Machado Dr
Publication date
2008
fields
Physics
and research's language is
English
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The preliminary results of STEPHI 2006 campaign are reported.
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We present the results of multisite observations spanning two years on the pre--main-sequence (PMS) star V351 Ori. A total of around 180 hours of observations over 29 nights have been collected, allowing us to measure five different periodicities, most likely related to the delta Scuti variability of V351 Ori. Comparison with the predictions of linear nonadiabatic radial pulsation models put stringent constraints on the stellar parameters and indicate that the distance to V351 Ori is intermediate between the lower limit measured by Hipparcos (210 pc) and that of the Orion Nebula (450 pc). However, radial pulsation models are unable to reproduce all of the observed frequencies with a single choice of (M, L, and Te), suggesting the presence of additional nonradial modes.
HD 220392 (HR 8895), the brightest member of the visual double star CCDM 23239-5349, is a new short-period variable bright star, probably of the Delta Scuti type. The period analysis performed on the complete set of definitive Geneva photometry as well as on the data obtained at the ESO 0.5m telescope shows two periodicities of about 4.7 and 5.5 cycles per day (cpd) with amplitudes of 0.014 and 0.011 mag respectively. A similar period search on the (smaller) dataset obtained for the 1 mag fainter B-component, HD 220391, however shows no periodicity with an amplitude significantly above the noise level of the data (about 0.006 mag). This difference in variability behaviour is discussed from the consideration that both stars form a common origin pair and are located in the Delta Scuti instability strip.
MOST observations and model analysis of the Herbig Ae star HD 34282 (V1366 Ori) reveal {delta}-Scuti pulsations. 22 frequencies are observed, 10 of which confirm those previously identified by Amado et al. (2006), and 12 of which are newly discovered in this work. We show that the weighted-average frequency in each group fits the radial p-mode frequencies of viable models. We argue that the observed pulsation spectrum extends just to the edge to the acoustic cut-off frequency and show that this also is consistent with our best-fitting models.
Preliminary results on the discovery and follow-up observations of a new $delta$ Scuti pulsator in the Cygnus field are presented. The variability of the star HD 207331 was detected while testing a Stromgren spectrophotometer attached to the H.L. Johnson 1.5-m telescope at the San Pedro Martir observatory, Mexico. CCD photometric data acquired soon after confirmed its variability. A few hours of $uvby$ differential photoelectric photometry during three nights revealed at least two beating periods. A two-site observational campaign carried out during one week in 2009 confirms the multi-periodic nature of this new $delta$ Scuti pulsator.
While testing a Stromgren spectrophotometer attached to the 1.5-m telescope at the San Pedro Martir observatory, Mexico, a number of A-type stars were observed, one of which, HD 207331, presented clear indications of photometric variability. CCD photometric data acquired soon after, confirmed its variability. In order to determine its pulsation behaviour more accurately, uvby differential photoelectric photometry was carried out for three nights. As a result of the period analysis of the light curves we have found a dominant pulsation mode at 21.1 c/d with an amplitude of 6 mmag. This strongly suggests that HD 207331 is a new Delta Scuti-type pulsating star.
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