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Register a new userMultisite observations of the PMS delta Scuti star V351 Ori
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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.
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The preliminary results of STEPHI 2006 campaign are reported.
CONTEXT: The study of pulsation in Pre--Main--Sequence intermediate-mass stars represents an important tool for deriving information on fundamental stellar parameters and internal structure, as well as for testing current theoretical models. Interest in this class of variable stars has significantly increased during the last decade and about 30 members are presently known in the literature. AIMS: We have constructed the frequency spectrum of the oscillations in V346 Ori. We apply asteroseismic tools to these data to estimate the intrinsic parameters (mass, luminosity, effective temperature) of V346 Ori and to obtain information on its internal structure. METHODS: CCD time series photometry in the Johnson V filter has been obtained for a total of 145.7 h of observations distributed over 36 nights. The resulting light curves have been subjected to a detailed frequency analysis using updated numerical techniques. Photometric and spectroscopic data have also been acquired to determine reliable estimates of the stellar properties. RESULTS: We have identified 13 oscillation frequencies, 6 of which with higher significance. These have been compared with the predictions of non-radial adiabatic models. The resulting best fit model has a mass of 2.1$pm$0.2 $M_{odot}$, luminosity $log{L/L_{odot}}=1.37^{+0.11}_{-0.13}$, and effective temperature 7300$pm$200 K. These values are marginally consistent with the association of V346 Ori to Orion OB1a. Alternatively, V346 Ori could be placed at a slightly larger distance than previously estimated.
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.
We present the results of a photometric multisite campaign on the $delta$ Scuti Pre-Main-Sequence star IP Per. Nine telescopes have been involved in the observations, with a total of about 190 hours of observations over 38 nights. Present data confirms the multiperiodic nature of this star and leads to the identification of at least nine pulsational frequencies. Comparison with the predictions of linear non-adiabatic radial pulsation models allowed us to identify only five of the nine observed frequencies, and to constrain the position of IP Per in the HR diagram. The latter is in good agreement with the empirical determination of the stellar parameters obtained by Miroshnichenko et al. (2001). An initial interpretation of the observed frequencies using the Aarhus non-radial pulsation code suggests that three frequencies could be associated with non-radial ($l$=2) modes. Finally, we present new evolutionary and pulsation models at lower metallicity (Z=0.008) to take into account the possibility that IP Per is metal deficient, as indicated by Miroshnichenko et al. (2001).
The preliminary results of a multisite photometric campaign on the Pleiades Delta Scuti variable V650 Tauri are reported. The star was observed photometrically for 14 days during 2008 November from three observatories distributed in Longitude around the Earth. As a result of the preliminary analysis we have detected in V650 Tauri at least nine oscillation frequencies above a 99% confidence level.
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