Results 21 to 30 of about 1,023 (124)

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

Metallicity, temperature, and gravity scales of M subdwarfs

, 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 ...
Y. Lyubchik, Y. Pavlenko, F. Allard, N. Lodieu, D. Homeier, Kaminsky, B., Lodieu, N., Allard, F., Lyubchik, Y., Pavlenko, Y., Homeier, D., Burgasser, A., A. Burgasser, C. Rodrigo, Rodrigo, C., B. Kaminsky   +15 more
core   +1 more source

M Subdwarfs and the Population II Luminosity Function [PDF]

, 1998
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. We present a spectroscopic classification system for M-dwarfs and M-subdwarfs based on quantitative measures of TiO and CaH features in ...
Gizis, John Evangelos
core   +1 more source

Discovery of the first outbursting hot subdwarf binary: ZTF J0007+4804

Astronomy & Astrophysics
Context. Hot subdwarf binaries with white dwarf companions with orbital periods of less than two hours are progenitor candidates for massive single white dwarfs as well as a variety of thermonuclear explosions. Aims.
Stringer E., Kupfer T., Deshmukh K., Maccarone T., Jackson I., Kosakowski A., Bradshaw C. W., Brown A., Dorsch M., Picco A., Dhillon V. S., Poshyachinda S., Awiphan S.   +12 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

Halo stars harbour few wide ultracool companions

Astronomy & Astrophysics
Aims. Our goal is to provide a wide ultracool companion frequency for metal-poor halo stars for the first time. Methods. We selected nearby halo stars with spectroscopically determined high proper motions and metallicities.
Zhang J.-Y., Lodieu N., Martín E. L.
doaj   +1 more source

A small survey of UV-bright stars around the northern ecliptic pole: seeking new p-mode sdB variables for the TESS mission

Open Astronomy, 2019
Starting in 2019, the TESS mission will monitor the northern ecliptic pole for 1 year. Data will be collected at 30-minute and 2-minute cadences, and only a limited amount of slots will be reserved for targets requiring a 20- second cadence.
Prins Saskia, Telting John, Østensen Roy   +2 more
doaj   +1 more source

Spectral energy distributions and colours of hot subluminous stars

Open Astronomy, 2018
Photometric surveys at optical, ultraviolet, and infrared wavelengths provide ever-growing datasets as major surveys proceed. Colour-colour diagrams are useful tools to identify classes of star and provide large samples.
Heber Ulrich, Irrgang Andreas, Schaffenroth Johannes   +2 more
doaj   +1 more source

Wide B-type hot subdwarf binaries

Astronomy & Astrophysics
Context. Long-period binary systems containing a B-type hot subdwarf (sdB) and a main sequence (MS) companion are thought to originate from binary interactions involving stable mass transfer from the red giant, which is the progenitor of the sdB, to the ...
Molina Francisco, Vos Joris, Bobrick Alexey, Vučković Maja   +3 more
doaj   +1 more source

Deep Bayesian spectral learning for the discovery of hot subdwarf binaries in LAMOST

Astronomy & Astrophysics
Context. Hot subdwarf binaries provide stringent constraints on envelope stripping and binary mass transfer. However, robust identification of these systems in large spectroscopic surveys is hindered by variable data quality and the subtle signatures of ...
Yang Beining, Bu Yude, Zhang Yuhang, Li Qinqin, Lu Guangcheng, Zhang Jiangchuan, Yi Zhenping, Kong Xiaoming, Liu Meng   +8 more
doaj   +1 more source