Search Publications
AGB variables and the Mira period-luminosity relation
Whitelock, Patricia A.; Feast, Michael W.; Van Leeuwen, Floor
Published data for large-amplitude asymptotic giant branch variables in the Large Magellanic Cloud (LMC) are re-analysed to establish the constants for an infrared (K) period-luminosity relation of the form MK=ρ[log P- 2.38]+δ. A slope of ρ=-3.51 ± 0.20 and a zero-point of δ=-7.15 ± 0.06 are found for oxygen-rich Miras (if a distance mo…
M dwarfs: effective temperatures, radii and metallicities
Casagrande, Luca; Flynn, Chris; Bessell, Michael
We empirically determine effective temperatures and bolometric luminosities for a large sample of nearby M dwarfs, for which high accuracy optical and infrared photometry is available. We introduce a new technique which exploits the flux ratio in different bands as a proxy of both effective temperature and metallicity. Our temperature scale for la…
A catalogue of multiplicity among bright stellar systems
Eggleton, P. P.; Tokovinin, A. A.
We consider the multiplicity of stellar systems with (combined) magnitude brighter than 6.00 in Hipparcos magnitudes. We identify 4559 such bright systems (including the Sun), and the frequencies of multiplicities 1, 2,..., 7 are found to be 2718, 1437, 285, 86, 20, 11 and 2. We discuss the uncertainties, which are substantial. We also consider th…
The luminosities and distance scales of type II Cepheid and RR Lyrae variables
van Leeuwen, Floor; Whitelock, Patricia A.; Feast, Michael W. +2 more
Infrared and optical absolute magnitudes are derived for the type II Cepheids κ Pav and VY Pyx using revised Hipparcos parallaxes and for κ Pav, V553 Cen and SW Tau from pulsational parallaxes. Revised Hipparcos and HST parallaxes for RR Lyrae agree satisfactorily and are combined in deriving absolute magnitudes. Phase-corrected J, H and Ks
The fundamental parameters of the roAp star α Circini
Tuthill, P. G.; Davis, J.; Kurtz, D. W. +12 more
We have used the Sydney University Stellar Interferometer to measure the angular diameter of α Cir. This is the first detailed interferometric study of a rapidly oscillating A (roAp) star, α Cir being the brightest member of its class. We used the new and more accurate Hipparcos parallax to determine the radius to be 1.967 ± 0.066 R⊙. W…
Luminosity-colour relations for thin-disc main-sequence stars
Cabrera-Lavers, A.; Bilir, S.; Yaz, E. +3 more
In this study we present the absolute magnitude calibrations of thin-disc main-sequence stars in the optical , and in the near-infrared . Thin-disc stars are identified by means of Padova isochrones, and absolute magnitudes for the sample are evaluated via the newly reduced Hipparcos data. The obtained calibrations cover a large range of spectral …
Observation and modelling of main-sequence stellar chromospheres - VII. Rotation and metallicity of dM1 stars
Houdebine, E. R.
We have measured v sini and metallicity from high-resolution spectroscopic observations of a selected sample of dM1-type stars.
To measure v sini, we first selected three template stars known for their slow rotation or their very low activity levels and then cross-correlated their spectra with those of our target stars. The excess broadening …Absolute dimensions and apsidal motion of the eccentric binary PT Velorum
Demircan, O.; Bakış, V.; Eker, Z. +1 more
High-resolution (λ/dλ ~ 41000) echelle spectra of the eccentric binary system PT Vel were analysed. Precise spectroscopic orbital elements of the system were obtained by means of cross-correlation technique. According to the solution of radial velocities with Hipparcos and All Sky Automated Survey-3 (ASAS-3) light curves, PT Vel consists of two ma…
Spectroscopic and photometric observations of the selected Algol-type binaries - II. V2080 Cygni and V2365 Ophiuchi
Frasca, A.; Çakırlı, Ö.; Sipahi, E. +9 more
This paper is the second in the planned series of investigations. We present new radial velocities and photometric observations of V2080 Cyg and V2365 Oph. New UBV photometric data and radial velocities were analysed for the systems' parameters. While V2080 Cyg consists of two nearly equal F-type main-sequence stars, V2365 Oph has two different co…
A search for rapid pulsations in the magnetic cool chemically peculiar star HD3980
Hubrig, S.; Kurtz, D. W.; Mathys, G. +2 more
The Ap star HD3980 appears to be a promising roAp candidate based on its fundamental parameters, leading us to search for rapid pulsations with the VLT UV-Visual Echelle Spectrograph (UVES). A precise Hipparcos parallax and estimated temperature of 8100K place HD3980 in the middle of the theoretical instability strip for rapidly oscillating Ap sta…