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Absolute dimensions of detached eclipsing binaries - I. The metallic-lined system WW Aurigae
Maxted, P. F. L.; Southworth, J.; Claret, A. +2 more
WW Aurigae is a detached eclipsing binary composed of two metallic-lined A-type stars orbiting each other every 2.5 d. We have determined the masses and radii of both components to accuracies of 0.4 and 0.6 per cent, respectively. From a cross-correlation analysis of high-resolution spectra we find masses of 1.964 +/- 0.007 Msolar for t…
Hubble Space Telescope spectroscopy of the Balmer lines in Sirius B*
Bond, Howard E.; Barstow, M. A.; Koester, D. +3 more
Sirius B is the nearest and brightest of all white dwarfs, but it is very difficult to observe at visible wavelengths due to the overwhelming scattered light contribution from Sirius A. However, from space we can take advantage of the superb spatial resolution of the Hubble Space Telescope (HST) to resolve the A and B components. Since the closest…
Pushing the ground-based limit: 14-µmag photometric precision with the definitive Whole Earth Telescope asteroseismic data set for the rapidly oscillating Ap star HR1217
Kepler, S. O.; Kawaler, S. D.; Winget, D. E. +43 more
HR1217 is one of the best-studied rapidly oscillating Ap (roAp) stars, with a frequency spectrum of alternating even- and odd-l modes that are distorted by the presence of a strong, global magnetic field. Several recent theoretical studies have found that within the observable atmospheres of roAp stars the pulsation modes are magneto-acoustic with…
What a local sample of spectroscopic binaries can tell us about the field binary population
Schröder, Klaus-Peter; Fisher, James; Smith, Robert Connon
We study a sample of spectroscopic binaries (SBs) in the local solar neighbourhood (d<= 100 pc and MV<= 4) in an attempt to find the distributions of the period, P, the primary mass, m1, and the mass ratio q(=m2/m1), as well as the initial mass function (IMF) of the local population of field binari…
Rotation periods for stars of the TW Hydrae association: the evidence for two spatially and rotationally distinct pre-main-sequence populations
Lawson, Warrick A.; Crause, Lisa A.
We have conducted a photometric study of late-type members of the TW Hydrae association (TWA) and measured the rotation periods for 16 stars in 12 systems. For TWA stars listed by Webb et al. and Sterzik et al. (TWA 1-13 led by TW Hya = TWA 1) we find a median period of 4.7 d. However, for stars that we measured in the TWA 14-19 group identified b…
Tycho-2 stars with infrared excess in the MSX Point Source Catalogue
Lumsden, S. L.; Oudmaijer, R. D.; Clarke, A. J.
Stars of all evolutionary phases have been found to have excess infrared emission due to the presence of circumstellar material. To identify such stars, we have positionally correlated the infrared Mid-Course Space Experiment (MSX) Point Source Catalogue and the Tycho-2 optical catalogue. Near-mid-infrared colour criteria have been developed to se…
Chemical abundances of very metal-poor stars
Zhao, G.; Zhang, H. W.
High-resolution and high signal-to-noise ratio spectra of 32 very metal-poor stars were obtained with the Coudé echelle spectrograph mounted on the 2.16-m telescope at the National Astronomical Observatories (Xinglong, China). Equivalent widths of FeI, FeII, OI, NaI, MgI, AlI, SiI, SiII, KI, CaI, ScII, TiI, VI, CrI, MnI, NiI, CuI and BaII lines we…
85 Peg A: what age for a low-metallicity solar-like star?
Cardini, D.; D'Antona, F.; Montalbán, J. +3 more
We explore the possible evolutionary status of the primary component of the binary 85 Pegasi, listed as a target for asteroseismic observations by the MOST satellite. In spite of the assessed `subdwarf' status, and of the accurate distance determination from the Hipparcos data, the uncertainties in the metallicity and age, coupled with the uncerta…