The population of hot subdwarf stars studied with <i>Gaia</i>

Culpan, Richard; Geier, S.; Reindl, N.; Pelisoli, Ingrid; Fusillo, Nicola Gentile; Vorontseva, A.

doi:10.1051/0004-6361/202243337

Cited by 37 publications

(30 citation statements)

References 163 publications

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“…Based on Gaia DR2 data, Geier et al (2019) compiled a candidate catalog by means of color, absolute magnitude, and reduced proper motion cuts, in which 39,800 hot sub-luminous candidates were selected, and it proved to be a good input catalog for large photometric and spectroscopic surveys for further study of hot subdwarfs. The number of candidates increased to 61,585 by Culpan et al (2022) as new data were updated from Gaia EDR3 (Gaia Collaboration et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Hot Subdwarf Stars Identified in LAMOST DR8 with Single-lined and Composite Spectra

Lei

Németh

et al. 2023

ApJ

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A total of 222 hot subdwarf stars were identified with LAMOST DR8 spectra, among which 131 stars show composite spectra and have been decomposed, while 91 stars present single-lined spectra. Atmospheric parameters of all sample stars were obtained by fitting hydrogen (H) and helium (He) line profiles with synthetic spectra. Two long-period composite sdB binaries were newly discovered by combining our sample with the non-single-star data from Gaia DR3. One of the new systems presents the highest eccentricity (i.e., 0.5 ± 0.09) among known wide sdB binaries, which is beyond model predictions. A total of 15 composite sdB stars fall in the high-probability binary region of the RUWE−AEN plane and deserve priority follow-up observations to further study their binary nature. A distinct gap is clearly presented among temperatures of cool companions for our composite-spectrum sample, but we could not come to a conclusion as to whether this feature is connected to the formation history of hot subdwarf stars before their binary natures are confirmed.

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Section: Introductionmentioning

confidence: 99%

Hot Subdwarf Stars Identified in LAMOST DR8 with Single-lined and Composite Spectra

Lei

Németh

et al. 2023

ApJ

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“…Based on Gaia DR2 data, Geier et al (2019) compiled a candidates catalog by means of colour, absolute magnitude, and reduced proper motion cuts, in which 39 800 hot sub-luminous candidates were selected, and it proved as a good input catalog for large photometric and spectroscopic surveys for further study of hot subdwarfs. The number of candidates increased to 61 585 by Culpan et al (2022) as new data was updated from Gaia EDR3 (Gaia Collaboration et al 2021).…”

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confidence: 99%

Hot Subdwarf Stars Identified in Gaia DR2 with Spectra of LAMOST DR6 and DR7. I. Single-lined Spectra

Lei

Zhao²,

Németh

et al. 2020

ApJ

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182 single-lined hot subdwarf stars are identified by using spectra from the sixth and seventh data release (DR6 and DR7) of the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) survey. We classified all the hot subdwarf stars using a canonical classification scheme, and got 89 sdB, 37 sdOB, 26 sdO, 24 He-sdOB, 3 He-sdO and 3 He-sdB stars, respectively. Among these stars, 108 hot subdwarfs are newly discovered, while 74 stars were reported by previous catalogs. The atmospheric parameters of these stars were obtained by fitting the hydrogen (H) and helium (He) lines with nonlocal thermodynamic equilibrium (non-LTE) model atmospheres. The atmospheric parameters confirm the two He sequences and the two subgroups of He-sdOB stars in our samples, which were found by previous studies in the T eff -log(nHe/nH) diagram. Our results demonstrate different origins of field hot subdwarf stars and extreme horizontal branch (EHB) stars in globular clusters (GCs), and provide strict observational limits on the formation and evolution models of the different sub-types of these evolved objects. Based on the results, we evaluated the completeness of the Geier et al. (2019) catalog. We found the fraction of hot subwarf stars is between 10% and 60%, depending on the brightness of the sample. A more accurate estimation for the hot subdwarf fraction can be obtained when similar results from composite spectra will become available.

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“…Brown dwarf companion stars are difficult to search from optical band data alone, while M dwarf and hot subdwarf companions are in the majority. Hot subdwarfs are underluminous for their high temperature (Heber 2016;Lei et al 2020;Culpan et al 2022). They are divided into two main spectroscopies: B-type subdwarfs (sdBs; a core helium-burning star and thin hydrogen envelope), and O-type subdwarfs (sdOs).…”

Section: Post-common Envelope Binariesmentioning

confidence: 99%

A Systematic Search for Short-period Close White Dwarf Binary Candidates Based on Gaia EDR3 Catalog and Zwicky Transient Facility Data

Ren¹,

Li²,

Ma³

et al. 2023

ApJS

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Galactic short-period close white dwarf binaries (CWDBs) are important objects for space-borne gravitational-wave (GW) detectors in the millihertz frequency bands. Due to the intrinsically low luminosity, only about 25 identified CWDBs are detectable by the Laser Interferometer Space Antenna (LISA), which are also known as verification binaries (VBs). The Gaia Early Data Release 3 (EDR3) provids a catalog containing a large number of CWDB candidates, which also includes parallax and photometry measurements. We crossmatch the Gaia EDR3 and Zwicky Transient Facility public data release 8, and apply period-finding algorithms to obtain a sample of periodic variables. The phase-folded light curves are inspected, and finally we obtain a binary sample containing 429 CWDB candidates. We further classify the samples into eclipsing binaries (including 58 HW Vir-type binaries, 65 EA-type binaries, 56 EB-type binaries, and 41 EW-type binaries) and ellipsoidal variations (209 ELL-type binaries). We discovered four ultrashort period binary candidates with unique light-curve shapes. We estimate the GW amplitude of all of our binary candidates, and calculate the corresponding signal-to-noise ratio (S/N) for TianQin and LISA. We find two (six) potential GW candidates with S/Ns greater than 5 in the nominal mission time of TianQin (LISA), which increases the total number of candidate VBs for TianQin (LISA) to 18 (31).

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The population of hot subdwarf stars studied with Gaia

Cited by 37 publications

References 163 publications

Hot Subdwarf Stars Identified in LAMOST DR8 with Single-lined and Composite Spectra

Hot Subdwarf Stars Identified in LAMOST DR8 with Single-lined and Composite Spectra

Hot Subdwarf Stars Identified in Gaia DR2 with Spectra of LAMOST DR6 and DR7. I. Single-lined Spectra

A Systematic Search for Short-period Close White Dwarf Binary Candidates Based on Gaia EDR3 Catalog and Zwicky Transient Facility Data

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