Search Publications
Ca II H+K fluxes from S-indices of large samples: a reliable and consistent conversion based on PHOENIX model atmospheres
Schmitt, J. H. M. M.; Schröder, K. -P.; Mittag, M.
Context. Historic stellar activity data based on chromospheric line emission using O.C. Wilson's S-index reach back to the 1960ies and represent a very valuable data resource both in terms of quantity and time-coverage. However, these data are not flux-calibrated and are therefore difficult to compare with modern spectroscopy and to relate to quan…
Baade-Wesselink distances to Galactic and Magellanic Cloud Cepheids and the effect of metallicity
Groenewegen, M. A. T.
Context. The metallicity dependence of the Cepheid period-luminosity (PL) relation is of importance in establishing the extragalactic distance scale.
Aims: The aim of this paper is to investigate the metallicity dependence of the PL relation in V and K, based on a sample of 128 Galactic, 36 Large Magellanic Cloud (LMC), and 6 Small Magellanic…
The CORALIE survey for southern extrasolar planets. XVII. New and updated long period and massive planets
Alonso, R.; Queloz, D.; Sahlmann, J. +24 more
Context. Since 1998, a planet-search program around main sequence stars within 50 pc in the southern hemisphere has been carried out with the CORALIE echelle spectrograph at La Silla Observatory.
Aims: With an observing time span of more than 14 years, the CORALIE survey is now able to unveil Jovian planets on Jupiter's period domain. This gr…
The asymmetric drift, the local standard of rest, and implications from RAVE data
Watson, F.; Munari, U.; Steinmetz, M. +13 more
Context. The determination of the local standard of rest (LSR), which corresponds to the measurement of the peculiar motion of the Sun based on the derivation of the asymmetric drift of stellar populations, is still a matter of debate. The classical value of the tangential peculiar motion of the Sun with respect to the LSR was challenged in recent…
AKARI/IRC 18 µm survey of warm debris disks
Marshall, J. P.; White, G. J.; Nakagawa, T. +11 more
Context. Little is known about the properties of the warm (Tdust ≳ 150 K) debris disk material located close to the central star, which has a more direct link to the formation of terrestrial planets than does the low-temperature debris dust that has been detected to date.
Aims: To discover new warm debris disk candidates that show …
What do the Mt. Wilson stars tell us about solar activity?
Schmitt, J. H. M. M.; Schröder, K. -P.; Mittag, M. +2 more
We relate the evolutionary status and mass of the Mt. Wilson project stars with the type and strength of stellar activity as established in decades of monitoring their chromospheric Ca II K line emission. We specifically derive their positions in the Hertzsprung-Russell-diagram (HRD) from Hipparcos parallaxes and SIMBAD B - V data, considering and…
Ultraviolet and visual flux and line variations of one of the least variable Bp stars HD 64740
Skarka, M.; Krtička, J.; Janík, J. +4 more
Context. The light variability of hot magnetic chemically peculiar stars is typically caused by the flux redistribution in spots with peculiar abundance. This raises the question why some stars with surface abundance spots show significant rotational light variability, while others do not.
Aims: We study the Bp star HD 64740 to investigate ho…
Low-amplitude rotational modulation rather than pulsations in the CoRoT B-type supergiant HD 46769
Auvergne, M.; Baudin, F.; Poretti, E. +16 more
Aims: We aim to detect and interpret photometric and spectroscopic variability of the bright CoRoT B-type supergiant target HD 46769 (V = 5.79). We also attempt to detect a magnetic field in the target.
Methods: We analyse a 23-day oversampled CoRoT light curve after detrending and spectroscopic follow-up data using standard Fourier anal…
The HIPPARCOS parallax for Polaris
van Leeuwen, F.
This Letter follows a recent claim that the Hipparcos parallax for Polaris could be too small by 2.5 mas. It examines in detail the Hipparcos epoch astrometric data for Polaris, as well as the viability of other observations that were put forward to support a larger parallax. The Hipparcos determination of the Polaris parallax is shown to be suffi…
Masses and age of the chemically peculiar double-lined binary χ Lupi
Ménard, F.; Beust, H.; Le Bouquin, J. -B. +3 more
Aims: We aim at measuring the stellar parameters of the two chemically peculiar components of the B9.5Vp HgMn + A2 Vm double-lined spectroscopic binary HD 141556 (χ Lup), whose period is 15.25 days.
Methods: We combined historical radial velocity measurements with new spatially resolved astrometric observations from PIONIER/VLTI to recon…