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

Lei, Zhenxin; He, Ruijie; Németh, P.; Vos, J.; Zou, Xuan; Hu, Ke; Xiao, Huaping; Yan, Hua-Hui; Zhao, Jingkun

doi:10.3847/1538-4357/aca542

Cited by 15 publications

(7 citation statements)

References 101 publications

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“…By far the hottest star is FBS 0050+358 with a temperature of 26 kK. This finding corresponds well to the spectroscopic surveys collected recently with LAMOST (Luo et al 2021;Lei et al 2023) and the data collection by Geier (2020).…”

Section: A Nearby Pnsupporting

confidence: 88%

The Spatial and Emission Properties of the Large [O iii] Emission Nebula Near M31

Fesen,

Kimeswenger,

Shull

et al. 2023

ApJ

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Drechsler et al. reported the unexpected discovery of a 1.°5 long [O iii] emission nebula 1.°2 southeast of the M31 nucleus. Here we present additional images of this large emission arc, called the Strottner–Drechsler–Sainty Object (SDSO), along with radial velocity and flux measurements from low-dispersion spectra. Independent sets of [O iii] images show SDSO to be composed of broad streaks of diffuse emission aligned northeast–southwest. Deep Hα images reveal no strong coincident emission suggesting a high [O iii]/Hα ratio. We also find no other [O iii] emission nebulosity as bright as SDSO within several degrees of M31 and no filamentary Hα emission connected to SDSO. Optical spectra taken along the nebula’s northern limb reveal [O iii] λ λ4959, 5007 emissions matching the location and extent seen in our [O iii] images. The heliocentric velocity of this [O iii] nebulosity is −9.8 ± 6.8 km s−1 with a peak surface brightness of (4 ± 2) × 10−18 erg s−1 cm−2 arcsec−2 (∼0.55 Rayleigh). We discuss SDSO as a possible unrecognized supernova remnant, a large and unusually nearby planetary nebula, a stellar bow shock nebula, or an interaction of M31's outer halo with Local Group circumgalactic gas. We conclude that galactic origins for SDSO are unlikely and favor instead an extragalactic M31 halo–circumgalactic cloud interaction scenario, despite the nebula’s low radial velocity. We then describe new observations that may help resolve the nature and origin of this large nebulosity so close to M31 in the sky.

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Section: A Nearby Pnsupporting

confidence: 88%

The Spatial and Emission Properties of the Large [O iii] Emission Nebula Near M31

Fesen,

Kimeswenger,

Shull

et al. 2023

ApJ

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“…Hot subdwarf stars of spectral types B and O (sdB/Os) are located around the bluest end of the horizontal branch and roughly between the main sequence (MS) and WD sequence in the Hertzsprung-Russell diagram (reviewed by Heber 2009Heber , 2016. Their surface temperatures and surface gravities are relatively high, i.e., 20,000 K T eff 70,000 K and   ( ) -5.0 log g cm s 6.5 10 2 (Heber 2016;Lei et al 2023). Based on a catalog of 39,800 hot subluminous star candidates, over 1000 sdB/Os have been identified with Large Sky Area Multi-Object Fiber Spectroscopic Telescope spectra (Luo et al 2021;Lei et al 2023).…”

Section: Introductionmentioning

confidence: 99%

“…Their surface temperatures and surface gravities are relatively high, i.e., 20,000 K T eff 70,000 K and   ( ) -5.0 log g cm s 6.5 10 2 (Heber 2016;Lei et al 2023). Based on a catalog of 39,800 hot subluminous star candidates, over 1000 sdB/Os have been identified with Large Sky Area Multi-Object Fiber Spectroscopic Telescope spectra (Luo et al 2021;Lei et al 2023). Geier (2020) compiled an updated catalog of 5874 hot subdwarf stars.…”

Section: Introductionmentioning

confidence: 99%

The Common Envelope Evolution Outcome. II. Short-orbital-period Hot Subdwarf B Binaries Reveal a Clear Picture

Ge,

Tout,

Webbink

et al. 2024

ApJ

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Common envelope evolution (CEE) is vital for forming short-orbital-period compact binaries. It covers many objects, such as double compact merging binaries, Type Ia supernovae progenitors, binary pulsars, and X-ray binaries. Knowledge of the common envelope (CE) ejection efficiency still needs to be improved, though progress has been made recently. Short-orbital-period hot subdwarf B star (sdB) plus white dwarf (WD) binaries are the most straightforward samples with which to constrain CEE physics. We apply the known orbital period–WD mass relation to constrain the sdB progenitors of seven sdB+WD binaries with a known inclination angle. The average CE efficiency parameter is 0.32. This is consistent with previous studies. However, the CE efficiency need not be constant, but a function of the initial mass ratio, based on well-constrained sdB progenitor mass and evolutionary stage. Our results can be used as physical inputs for binary population synthesis simulations of related objects. A similar method can also be applied to study other short-orbital-period WD binaries.

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“…The Large Sky Area Multi-Object Fiber Spectroscopic Telescope spectra survey (LAMOST; Luo et al 2016;Lei et al 2018Lei et al , 2019bLuo et al 2019;Lei et al 2020;Luo et al 2021;Lei et al 2023), Galaxy Evolution Explorer survey (GALEX; Vennes et al 2011;Németh et al 2012), and Transiting Exoplanet Survey Satellite (TESS; Krzesinski et al 2022). Reliable atmospheric parameters (e.g., T eff , g log and (…”

Section: Introductionmentioning

confidence: 99%

Mass Distribution for Single-lined Hot Subdwarf Stars in LAMOST

Lei,

He,

Németh

et al. 2023

ApJ

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Masses for 664 single-lined hot subdwarf stars identified in LAMOST were calculated by comparing synthetic fluxes from spectral energy distribution with observed fluxes from a Virtual Observatory service. Three groups of hot subdwarf stars were selected from the whole sample according to their parallax precision to study the mass distributions. We found that He-poor sdB/sdOB stars present a wide mass distribution from 0.1 to 1.0 M ⊙ with a sharp mass peak at around 0.46 M ⊙, which is consistent with canonical binary model prediction. He-rich sdB/sdOB/sdO stars present a much flatter mass distribution than He-poor sdB/sdOB stars and with a mass peak at around 0.42 M ⊙. By comparing the observed mass distributions to the predictions of different formation scenarios, we concluded that the binary merger channel, including two helium white dwarfs (He-WDs) and He-WD + main-sequence mergers, cannot be the only main formation channel for He-rich hot subdwarfs, and other formation channels, such as the surviving companions from Type Ia supernovae, could also make impacts on producing this special population, especially for He-rich hot subdwarfs with masses less than 0.44 M ⊙. He-poor sdO stars also present a flatter mass distribution with an inconspicuous peak mass at 0.18 M ⊙. The similar mass– Δ RV max distribution between He-poor sdB/sdOB and sdO stars supports the scenario that He-poor sdO stars could be the subsequent evolution stage of He-poor sdB/sdOB stars.

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

Cited by 15 publications

References 101 publications

The Spatial and Emission Properties of the Large [O iii] Emission Nebula Near M31

The Spatial and Emission Properties of the Large [O iii] Emission Nebula Near M31

The Common Envelope Evolution Outcome. II. Short-orbital-period Hot Subdwarf B Binaries Reveal a Clear Picture

Mass Distribution for Single-lined Hot Subdwarf Stars in LAMOST

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