We report spectroscopic and differential photometric observations of the A-type system V482 Per, which reveal it to be a rare hierarchical quadruple system containing two eclipsing binaries. One binary has the previously known orbital period of 2.4 days and a circular orbit, and the other a period of 6 days, a slightly eccentric orbit (e=0.11), and shallow eclipses only 2.3% deep. The two binaries revolve around their common center of mass in a highly elongated orbit (e=0.85) with a period of 16.67yr. Radial velocities are measured for all components from our quadruple-lined spectra and are combined with the light curves and measurements of times of minimum light for the 2.4 day binary to solve for the elements of the inner and outer orbits simultaneously. The line-of-sight inclination angles of the three orbits are similar, suggesting they may be close to coplanar. The available observations appear to indicate that the 6 day binary experiences significant retrograde apsidal motion in the amount of about 60 deg per century. We derive absolute masses for the four stars good to better than 1.5%, along with radii with formal errors of 1.1% and 3.5% for the 2.4 day binary and ~9% for the 6 day binary. A comparison of these and other physical properties with current stellar evolution models gives excellent agreement for a metallicity of [Fe/H]=-0.15 and an age of 360Myr.
We present V-band photometry of the 20000 brightest asteroids using data from the All-Sky Automated Survey for Supernovae (ASAS-SN) between 2012 and 2018. We were able to apply the convex inversion method to more than 5000 asteroids with more than 60 good measurements in order to derive their sidereal rotation periods, spin axis orientations, and shape models. We derive unique spin state and shape solutions for 760 asteroids, including 163 new determinations. This corresponds to a success rate of about 15%, which is significantly higher than the success rate previously achieved using photometry from surveys. We derive the first sidereal rotation periods for additional 69 asteroids. We find good agreement in spin periods and pole orientations for objects with prior solutions. We obtain a statistical sample of asteroid physical properties that is sufficient for the detection of several previously known trends, such as the underrepresentation of slow rotators in current databases, and the anisotropic distribution of spin orientations driven by the nongravitational forces. We also investigate the dependence of spin orientations on the rotation period. Since 2018, ASAS-SNhas been observing the sky with higher cadence and a deeper limiting magnitude, which will lead to many more new solutions in just a few years.
We present new photometric observations in Johnson V and B of WR30a, revealing relative dramatic changes in brightness of 0.2mag. These variations occur on a time scale of hours, and are only seen in V. We argue that they are not caused by dust extinction, but either by a dramatic change in the strength of the C IV 5801-12{AA} emission line doublet due to a de-excitation process, or by some unknown continuum effect.
The photoelectric observations in v and b bands for YY Eri are presented. These observations were obtained during four nights in November, 1984, with the 35-cm Cassegrain reflector of the Yunnan Observatory in China.
TT Ari was observed in the 5 passbands VBLUW (544, 430, 384, 362 and 324nm) during 3 nights on the 90cm telescope at ESO (La Silla), between July and November 1988, with an integration time of 16s.
VBLUW photometric observations of 13 eclipsing binary stars carried out by C.J. van Houten with the Walraven 5-color photometer between 1965 and 1978 are presented together with a first analysis of the orbital periods.
The 1982-1985 photometry (VBLUW system) of the O3V+O8V close binary HD 93205 has been rediscussed because of new insights into its true nature and orbital changes. By comparing this data set with the one obtained by Antokhina et al. (2000ApJ...529..463A) in 1993, and using the same ephemeris to construct the light curve in the phase diagram, the effect of the apsidal motion became obvious: a phase shift between the two light curves and a small change of the shape. A phase-locked light variation in the L passband (containing the higher Balmer lines) is clearly present in the 1982-1985 data set and is presumably due to absorption if the O8 star is seen through cooler inter-binary gas, e.g. the bow-shock between the two colliding winds.
We have obtained photometric observations in a 182arcmin^2 area, 25' to the north of the center of the globular cluster {omega} Centauri. The Stroemgren vby and broadband BI filters were used to obtain measurements for some 2500 stars. Preliminary examinations of parts of the data have been presented previously (Hughes & Wallerstein, 2000, Cat. <J/AJ/119/1225>; Hughes, Wallerstein, & van Leeuwen, 2002, in ASP Conf. Ser. 265, 73). Here we present the complete data set, study the giant branches, and use the B-I color index as a tool for assessing the ages of the populations within {omega} Cen.
We present a detailed study of an eclipsing binary which had been classified Ap SrCrEu (Hartoog, 1976ApJ...205..807H) before being known as a binary. Radial velocities measured at the times of both quadratures allow us to obtain precise masses for both components, while the light curve yields the radii. The following ephemeris and fundamental parameters of the system were obtained: HJD=(2447999.7656+/-0.0041) +(3.174990+/-0.000001) E, e=0.00, i=81.9+/-0.1{deg}, M_1_=1.90+/-0.02M_{sun}_, M_2_=1.85+/-0.02M_{sun}_, R_1_=1.63+/-0.03R_{sun}_, R_2_=1.60+/-0.03R_{sun}_, vsini_1_=27.6+/-3.5km/s, vsini_2_=23.6+/-3.6km/s. The projected rotational velocities were determined by fitting a synthetic spectrum convolved with a rotational profile to the observed spectrum. A comparison of the spectra of V392 Car and of the normal A star Cox 98, which has the same colour indices, shows that Sr is not overabundant and the metallicity of V392 Car is the same as that of the other cluster members. Therefore, V392 Car is a normal A2 star rather than an Ap star. The position of V392 Car in the HR diagram is entirely consistent with membership of the cluster NGC 2516. An independent estimate of the distance to this cluster was done using the parameters of the eclipsing system, and found to be in agreement with the Hipparcos one. A comparison of the parameters obtained from observations with predictions of internal structure models leads to a metallicity estimate [M/H]=0+/-0.10dex for NGC 2516. This estimate is completely independent of any spectroscopic or photometric method (except for the T_eff_ determination) but relies on stellar structure models.
