Space observations of AA Doradus provide consistent mass determinations. New HW-Vir systems observed with <i>TESS</i>

Baran, A.; Østensen, R. H.; Heber, U.; Irrgang, A.; Sanjayan, Sachu; Telting, J. H.; Reed, M. D.; Ostrowski, Jakub

doi:10.1093/mnras/stab620

Cited by 9 publications

(5 citation statements)

References 61 publications

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“…Once the synthetic spectral energy distribution (SED) of a star is known, we can obtain the model flux density at the stellar surface, F (λ). On the other hand, the observed flux density at the Earth, f (λ), can be obtained by converting photometric magnitudes into flux density (see Heber et al 2018, Baran et al 2021and Schaffenroth et al 2022 for more information). With known F (λ), f (λ) and distance from the Earth, d, one can easily obtain the stellar angular diameter, Θ, and stellar radius, R, by the following equation:…”

Section: Basic Principlementioning

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: Basic Principlementioning

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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“…We note thatBaran et al (2021) concurrently discovered this object to have HW Vir-type variability from our TESS data.…”

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confidence: 65%

New Variable Hot Subdwarf Stars Identified from Anomalous Gaia Flux Errors, Observed by TESS, and Classified via Fourier Diagnostics

Barlow,

Corcoran,

Parker

et al. 2021

Preprint

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Hot subdwarf stars are mostly stripped red giants that can exhibit photometric variations due to stellar pulsations, eclipses, the reflection effect, ellipsoidal modulation, and Doppler beaming. Detailed studies of their light curves help constrain stellar parameters through asteroseismological analyses or binary light curve modeling and generally improve our capacity to draw a statistically meaningful picture of this enigmatic stage of stellar evolution. From an analysis of Gaia DR2 flux errors, we have identified around 1200 candidate hot subdwarfs with inflated flux errors for their magnitudes -a strong indicator of photometric variability. As a pilot study, we obtained 2-min cadence TESS Cycle 2 observations of 187 candidate hot subdwarfs with anomalous Gaia flux errors. More than 90% of our targets show significant photometric variations in their TESS light curves. Many of the new systems found are cataclysmic variables, but we report the discovery of several new variable hot subdwarfs, including HW Vir binaries, reflection effect systems, pulsating sdBV s stars, and ellipsoidally modulated systems. We determine atmospheric parameters for select systems using follow-up spectroscopy from the 3-m Shane telescope. Finally, we present a Fourier diagnostic plot for classifying binary light curves using the relative amplitudes and phases of their fundamental and harmonic signals in their periodograms. This plot makes it possible to identify certain types of variables efficiently, without directly investigating their light curves, and may assist in the rapid classification of systems observed in large photometric surveys.

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“…It was found as an eclipsing sdO/B candidate with a dM/BD companion (HW Vir system) by Schaffenroth et al (2019). The star has been observed by the Transiting Exoplanet Survey Satellite (TESS; Ricker et al 2015); the light curve can be seen in Baran et al (2021). Using the atmospheric parameters we could derive the radius and the mass of the sdB star by combining the fit of the SED with the Gaia parallax (see Schaffenroth et al 2021 for more details on the method).…”

Section: Atl 0518-2308mentioning

confidence: 99%

Multifilter Time-series Observations of Eleven Blue Short-period ATLAS Variable Stars

Koen

Schaffenroth

Knyazev

2023

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Eleven periodic variable stars were observed photometrically through two to four filters from the set UBVR C I C . Phase-folded data for each star cover full cycles of variation. Spectral energy distributions, based on absolute photometry extracted from the literature, are used to inform models of the stars. The stars include four eclipsing systems with hot subdwarfs of spectral type O or B (sdO/B). Periods are in the range 1.8–2.2 hr. Four reflection-effect binaries, with amplitudes as large as 0.5 mag in the R C filter were observed; periods range from 1.6 to 2.4 hr. In two of these latter systems, the primary stars are also sdB stars, while two have white-dwarf components. In all eight of these binaries the companion stars are probably M dwarfs. The remaining three stars are pulsators: one large-amplitude δ Scuti star previously misclassified as an eclipsing system; one field SX Phe star near the Galactic plane; and one multiperiodic high-luminosity star of unknown type. The amplitude is usually a strong function of the wavelength in pulsating stars, but this is not the case for the high-luminosity variable. One possible explanation is that the luminous star has a pulsating companion. The SX Phe and high-luminosity star are both heavily reddened (A V > 5 mag).

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Space observations of AA Doradus provide consistent mass determinations. New HW-Vir systems observed with TESS

Cited by 9 publications

References 61 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

New Variable Hot Subdwarf Stars Identified from Anomalous Gaia Flux Errors, Observed by TESS, and Classified via Fourier Diagnostics

Multifilter Time-series Observations of Eleven Blue Short-period ATLAS Variable Stars

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