Results 61 to 70 of about 7,790 (232)

Metallicity, temperature, and gravity scales of M subdwarfs, [PDF]

Astronomy & Astrophysics, 2019
Aims. The aim of the project is to define metallicity/gravity/temperature scales for different spectral types of metal-poor M dwarfs. Methods. We obtained intermediate-resolution ultraviolet (R ∼ 3300), optical (R ∼ 5400), and near-infrared (R ∼ 3900 ...
N. Lodieu, F. Allard, C. Rodrigo, Y. Pavlenko, A. Burgasser, Y. Lyubchik, B. Kaminsky, D. H. Iac, Tenerife, Spain., Ul, La Laguna, C. Lyon, France., Visiting professor at Iac, Cab, Villanueva de la Cañada, Svo, Madrid, Mao, Kiev, Ukraine, University of California at San Diego, Usa, Gottingen Institut fur Astrophysik, H Germany   +25 more
semanticscholar   +1 more source

Spectroscopic and Photometric Analysis of the HW Vir Star PTF1 J011339.09+225739.1

Open Astronomy, 2018
HW Vir systems are rare eclipsing binary systems including a subdwarf B star (sdB) with a faint companion, mostly M-dwarfs. Up to now, 19 HW Vir systems have been published, three of them with substellar companions. We report the spectroscopic as well as
Wolz Maximilian, Kupfer Thomas, Drechsel Horst, Heber Ulrich, Irrgang Andreas, Hermes J.J., Bloemen Steven, Levitan David, Dhillon Vik, Marsh TomR.   +9 more
doaj   +1 more source

HST spectroscopy of chemically peculiar hot subdwarfs: PG 0909+276 and UVO0512–08

Open Astronomy, 2017
High-resolution ultraviolet spectroscopy of two chemically peculiar hot subdwarfs, PG 0909+276 and UVO0512-08, has been obtained using the Hubble Space Telescope.
Wild James, Jeffery Christopher Simon
doaj   +1 more source

Distances, ages, and epoch of formation of globular clusters [PDF]

, 1999
We review the results on distances and absolute ages of galactic globular clusters (GCs) obtained after the release of the Hipparcos catalogue. Several methods for the Population II local distance scale are discussed, exploiting NEW RESULTS for RR Lyraes
Arenou F., Axer M., Bessel M. S., Buonanno R., Caldwell J. A. R., Caloi V., De Marchi G., Eugenio Carretta, Fahlman G. G., Feast M. W., Feast M. W., Fernley J., Fernley J., Ferraro F., Fischer P., Flavio Fusi Pecci, Fuhrmann K., Gisella Clementini, Gratton R. G., Gratton R. G., Hanson R. B., Laney C. D., Laney C. D., Lindgren L., Lynga G., Madau P., Oestreicher M. O., Pandey A. K., Penny A. J., Pont F., Raffaele G. Gratton, Schuster W. J., Skillen I., Storm J., Turner M. S., Udalski A., Udalski A., Van Leeuwen F., Wesselink A. J., Zhao G.   +39 more
core   +2 more sources

New Subdwarf B Star Periods [PDF]

, 2003
4 pages, 2 figures. Uses CRCKAPB.sty. To appear in the Proceedings of the XIII European Workshop on White Dwarfs. NATO Science Series II, Kluwer Academic Publishers.
Morales-Rueda, L., Maxted, P. F. L., Marsh, T. R., North, R. C.   +3 more
openaire   +2 more sources

Origin and pulsation of hot subdwarfs [PDF]

Proceedings of the International Astronomical Union, 2013
AbstractWe briefly introduce hot subdwarfs and their evolutionary status before discussing the different types of known pulsators in more detail. Currently, at least six apparently distinct types of variable are known among hot subdwarfs, encompassing p- as well as g-mode pulsators and objects in the Galactic field as well as in globular clusters. Most
Randall, Suzanna K, Fontaine, Gilles, Charpinet, Stéphane, Van Grootel, Valérie, Brassard, Pierre   +4 more
openaire   +1 more source

Heavy metals in intermediate He-rich hot subdwarfs: the chemical composition of HZ 44 and HD 127493 [PDF]

Astronomy & Astrophysics, 2019
Context. Hot subluminous stars can be spectroscopically classified as subdwarf B (sdB) and O (sdO) stars. While the latter are predominantly hydrogen deficient, the former are mostly helium deficient.
M. Dorsch, M. Latour, U. Heber
semanticscholar   +1 more source

The Formation of Subdwarf B Stars [PDF]

International Astronomical Union Colloquium, 2002
AbstractWe performed full binary evolution calculations and carried out binary population synthesis studies in order to investigate the formation of subdwarf B (sdB) stars via the channels of stable Roche lobe overflow (RLOF), common envelope ejection and helium white dwarf mergers. Our model is successful in the explanation of observational properties
Han, Z, Podsiadlowski, P, Maxted, P, Marsh, T, Ivanova, N   +4 more
openaire   +2 more sources

Detection of stellar oscillations in HWVir

Open Astronomy, 2016
We present our analysis of K2 observations of the binary system, HWVir. We processed the raw Kepler data and used Fourier analysis to search for periodic signals that could be associated with pulsations.
Baran Andrzej S., Østensen Roy H., Telting John H.   +2 more
doaj   +1 more source

Rotation in sdB stars as revealed by stellar oscillations

Open Astronomy, 2018
An interesting opportunity offered by the detection of stellar oscillations is the possibility to infer the internal rotation rate of a star through the so-called rotational splittings. Such seismic measurements remained rather scarce for hot B subdwarf (
Charpinet Stephane, Giammichele Noemi, Zong Weikai, Van Grootel Valérie, Brassard Pierre, Fontaine Gilles   +5 more
doaj   +1 more source