Ground-based observation of ZZ Ceti stars and the discovery of four new variables

Romero, A. D.; Amaral, Larissa Antunes; Klippel, Theylor Schumacher; Sanmartim, David; Ourique, Gustavo; Pelisoli, Ingrid; Lauffer, G. R.; Koester, D.

doi:10.1093/mnras/stz2571

Cited by 15 publications

(16 citation statements)

References 58 publications

(97 reference statements)

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“…Measurements of an anomalous period change can thus be used to estimate the associated axion-electron coupling. From the 250 known variable WDs [145], this has so far only been done for G117-B15A [146][147][148][149][150], R548 [148,151], L19-2 [152], and PG 1351+489 [153]. The reason for this small fraction is that measuring the period change is very difficult: while the periods for the WDs listed here are of the order of a few minutes, their (inherently dimensionless) period changes, Π, are less than about 10 −13 in magnitude.…”

Section: Ubdm Hints: Anomalous White Dwarf Coolingmentioning

confidence: 99%

Astrophysical Searches and Constraints on Ultralight Bosonic Dark Matter

Marsh¹,

Hoof²

2021

Preprint

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Starting from the evidence that dark matter (DM) indeed exists and permeates the entire cosmos, various bounds on its properties can be estimated. Beginning with the cosmic microwave background and large scale structure, we summarize bounds on the ultralight bosonic dark matter (UBDM) mass and cosmic density. These bounds are extended to larger masses by considering galaxy formation and evolution, and the phenomenon of black hole superradiance. We then discuss the formation of different classes of UBDM compact objects including solitons/axion stars and miniclusters. Next, we consider astrophysical constraints on the couplings of UBDM to Standard Model particles, from stellar cooling (production of UBDM) and indirect searches (decays or conversion of UBDM). Throughout, there are short discussions of "hints and opportunities" in searching for UBDM in each area. Astrophysical search channelsAstrophysics and cosmology, as outlined in Chapter 1, give convincing evidence that dark matter (DM) exists in the form of new particles beyond the Standard Model of particle physics. The space of possible theories in Chapter 2, even for the subclass of ultralight bosonic DM (UBDM) models considered in this book, is vast. Beyond the basic fact of the existence of DM, astrophysics can be used to reign in this vast theoretical parameter space, with a view to direct detection and measurement of model parameters.The most basic astrophysical route to constrain UBDM is via the relic density. There are three channels for UBDM production:1. Coherent field oscillations. a. Vacuum realigment. b. Topological defect decay.2. Thermal production. 3. Non-thermal production by direct decay.

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Section: Ubdm Hints: Anomalous White Dwarf Coolingmentioning

confidence: 99%

Astrophysical Searches and Constraints on Ultralight Bosonic Dark Matter

Marsh¹,

Hoof²

2021

Preprint

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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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“…Each pulsation mode propagates in a specific region providing information on that particular zone, where its amplitude is maximum (Tassoul et al 1990). Thus, we can perform an asteroseismic study, where we compare the observed periods with the theoretical period spectrum, computed using representative models, to uncover the inner stellar structure (see e. g. Romero et al 2012Romero et al , 2019.…”

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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Ground-based observation of ZZ Ceti stars and the discovery of four new variables

Cited by 15 publications

References 58 publications

Astrophysical Searches and Constraints on Ultralight Bosonic Dark Matter

Astrophysical Searches and Constraints on Ultralight Bosonic Dark Matter

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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