New ZZ Ceti Stars from the LAMOST Survey

Su, Jie; Fu, Jian-Ning; Lin, Guo‐Qiang; Chen, Fangfang; Khokhuntod, Pongsak; Li, Chunqian

doi:10.3847/1538-4357/aa88a8

Cited by 8 publications

(8 citation statements)

References 38 publications

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“…With the previous LAM-OST data (including the LK-project's), several independent works have been concentrated on highly evolved compact stars, aiming at the characterization and determination of stellar parameters for white dwarfs (Guo et al 2015;Zhao et al 2013) as well as hot subdwafs (Luo et al 2016). These stars, which are not analyzed by the LASP code, are scientifically valuable when their parameters are derived by specialized outside pipelines or models (see, e.g., Su et al 2017).…”

Section: Discussionmentioning

confidence: 99%

LAMOST Observations in the Kepler Field. II. Database of the Low-resolution Spectra from the Five-year Regular Survey*

Zong

Cat

et al. 2018

ApJS

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The LAMOST-Kepler (LK-) project was initiated to use the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) to make spectroscopic follow-up observations for the targets in the field of the Kepler mission. The Kepler field is divided into 14 subfields that are adapted to the LAMOST circular field with a diameter of 5 degrees. During the regular survey phase of LAMOST, the LK-project took data from 2012 June to 2017 June and covered all the 14 subfields at least twice. In particular, we describe in this paper the second Data Release of the LK-project, including all spectra acquired through 2015 May to 2017 June together with the first round observations of the LK-project from 2012 June to 2014 September. The LK-project now counts 227 870 spectra of 156 390 stars, among which we have derived atmospheric parameters (log g, T eff and [Fe/H]) and heliocentric radial velocity (RV) for 173 971 spectra of 126 172 stars. These parameters were obtained with the most recent version of the LAMOST Stellar Parameter Pipeline v 2.9.7. Nearly one half, namely 76 283 targets, are observed both by LAMOST and Kepler telescopes. These spectra, establishing a large spectroscopy library, will be useful for the entire astronomical community, particularly for planetary science and stellar variability on Kepler targets.

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Section: Discussionmentioning

confidence: 99%

LAMOST Observations in the Kepler Field. II. Database of the Low-resolution Spectra from the Five-year Regular Survey*

Zong

Cat

et al. 2018

ApJS

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“…For the targets with more than one determination for the atmospheric parameters in Table 1, we adopt that obtained from photometry and parallax from Gaia for Figure 1. The sample of ZZ Ceti stars known to date is depicted in this figure, and was extracted from the works of Bognar & Sodor (2016); Hermes et al (2017a); Su et al (2017); Romero et al (2019b); Vincent et al (2020). The values for effective temperature and surface gravity derived from spectroscopy were corrected by 3D convection (Tremblay et al 2013) for all objects (Córsico et al 2019).…”

Section: New Zz Ceti Starsmentioning

confidence: 99%

Discovery of 74 new bright ZZ Ceti stars in the first three years of TESS

Romero,

Kepler,

Hermes

et al. 2022

Preprint

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We report the discovery of 74 new pulsating DA white dwarf stars, or ZZ Cetis, from the data obtained by the Transiting Exoplanet Survey Satellite (TESS) mission, from Sectors 1 to 39, corresponding to the first 3 cycles. This includes objects from the Southern Hemisphere (Sectors 1-13 and 27-39) and the Northern Hemisphere (Sectors 14-26), observed with 120 s-and 20 s-cadence. Our sample likely includes 13 low-mass and one extremely low-mass white dwarf candidate, considering the mass determinations from fitting Gaia magnitudes and parallax. In addition, we present follow-up time series photometry from ground-based telescopes for 11 objects, which allowed us to detect a larger number of periods. For each object, we analysed the period spectra and performed an asteroseismological analysis, and we estimate the structure parameters of the sample, i.e., stellar mass, effective temperature and hydrogen envelope mass. We estimate a mean asteroseismological mass of 𝑀 sis = 0.635± 0.015 M , excluding the candidate low or extremely-low mass objects. This value is in agreement with the mean mass using estimates from Gaia data, which is 𝑀 phot = 0.631± 0.040 M , and with the mean mass of previously known ZZ Cetis of 𝑀 * = 0.644 ± 0.034 M . Our sample of 74 new bright ZZ Cetis increases the number of known ZZ Cetis by ∼20 per cent.

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“…In addition, there are 10 objects in the literature with stellar masses within the range 0.30 ≤ M/M ≤ 0.45 (black-green dots in Fig. 1) that show photometric variability with periods between 200 and 1300 s (Bognar & Sodor 2016;Su et al 2017;Fuchs 2017;Rowan et al 2019). For 4 of them, the uncertainties in the atmospheric parameters are quite large, leading to an uncertainty in stellar mass of 0.1-0.4 M (Su et al 2017;Rowan et al 2019).…”

Section: Introductionmentioning

confidence: 99%

“…1) that show photometric variability with periods between 200 and 1300 s (Bognar & Sodor 2016;Su et al 2017;Fuchs 2017;Rowan et al 2019). For 4 of them, the uncertainties in the atmospheric parameters are quite large, leading to an uncertainty in stellar mass of 0.1-0.4 M (Su et al 2017;Rowan et al 2019). The low number of pulsating low-mass WDs as compared to canonical mass ZZ Ceti stars could be due to some kind of fine tuning during the evolution of the progenitor, but it is most likely due to the lack of studies focused on the search for pulsations for objects in this stellar mass range.…”

Section: Introductionmentioning

confidence: 99%

Uncovering the chemical structure of the pulsating low-mass white dwarf SDSS J115219.99+024814.4

Romero,

Lauffer,

Istrate

et al. 2021

Preprint

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Pulsating low-mass white dwarf stars are white dwarfs with stellar masses between 0.30 M and 0.45 M that show photometric variability due to gravity-mode pulsations. Within this mass range, they can harbour both a helium-and hybrid-core, depending if the progenitor experienced helium-core burning during the pre-white dwarf evolution. SDSS J115219.99+024814.4 is an eclipsing binary system where both components are low-mass white dwarfs, with stellar masses of 0.362±0.014 M and 0.325±0.013 M . In particular, the less massive component is a pulsating star, showing at least three pulsation periods of ∼1314 s, ∼1069 s and ∼582.9 s. This opens the way to use asteroseismology as a tool to uncover its inner chemical structure, in combination with the information obtained using the light-curve modelling of the eclipses. To this end, using binary evolutionary models leading to helium-and hybrid-core white dwarfs, we compute adiabatic pulsations for ℓ = 1 and ℓ = 2 gravity modes with Gyre. We found that the pulsating component of the SDSS J115219.99+024814.4 system must have a hydrogen envelope thinner that the value obtained from binary evolution computations, independently of the inner composition. Finally, from our asteroseismological study, we find a best fit model characterised by T eff = 10 917 K, M=0.338 M , M H = 10 −6 M with the inner composition of a hybrid WD.

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New ZZ Ceti Stars from the LAMOST Survey

Cited by 8 publications

References 38 publications

LAMOST Observations in the Kepler Field. II. Database of the Low-resolution Spectra from the Five-year Regular Survey*

LAMOST Observations in the Kepler Field. II. Database of the Low-resolution Spectra from the Five-year Regular Survey*

Discovery of 74 new bright ZZ Ceti stars in the first three years of TESS

Uncovering the chemical structure of the pulsating low-mass white dwarf SDSS J115219.99+024814.4

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