The nature of VX Sagitarii

Tabernero, H. M.; Dorda, R.; Negueruela, I.; Marfil, E.

doi:10.1051/0004-6361/202039236

Cited by 26 publications

(22 citation statements)

References 102 publications

(180 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To derive the stellar parameters, effective temperature (T eff ), surface gravity (log g), and metallicity (rFe{Hs), we chose to fit the combined spectrum of L 98-59 A constructed using 61 ESPRESSO spectra (S {N " 1063 at 7580 Å) with the latest version of the spectral synthesis code SteParSyn (Tabernero et al 2018;Tabernero et al 2021, see Appendix A.1.1 for more details). We adopted the estimates provided by SteParSyn except for the uncertainty on T eff , which we identified as underestimated (see Appendix A.1).…”

Section: Stellar Atmospheric Parametersmentioning

confidence: 99%

“…In addition, we took the instrumental broadening into account by means of a Gaussian kernel (R " 140 000). We used the latest version of the SteParSyn code (Tabernero et al 2018;Tabernero et al 2021) to infer the stellar parameters. We fit the combined spectrum of L 98-59 A that was constructed using 61 ESPRESSO spectra (S {N " 1063 at 7580 Å).…”

Section: Appendix A12: Machine-learning Regression With Odusseasmentioning

confidence: 99%

See 1 more Smart Citation

Warm terrestrial planet with half the mass of Venus transiting a nearby star

Demangeon

Osorio

Alibert

et al. 2021

A&A

Self Cite

View full text Add to dashboard Cite

In recent years, the advent of a new generation of radial velocity instruments has allowed us to detect planets with increasingly lower mass and to break the one Earth-mass barrier. Here we report a new milestone in this context by announcing the detection of the lowest-mass planet measured so far using radial velocities: L 98-59 b, a rocky planet with half the mass of Venus. It is part of a system composed of three known transiting terrestrial planets (planets b–d). We announce the discovery of a fourth nontransiting planet with a minimum mass of 3.06−0.37+0.33 M⊕ and an orbital period of 12.796−0.019+0.020 days and report indications for the presence of a fifth nontransiting terrestrial planet. With a minimum mass of 2.46−0.82+0.66 M⊕ and an orbital period 23.15−0.17+0.60 days, this planet, if confirmed, would sit in the middle of the habitable zone of the L 98-59 system. L 98-59 is a bright M dwarf located 10.6ṗc away. Positioned at the border of the continuous viewing zone of the James Webb Space Telescope, this system is destined to become a corner stone for comparative exoplanetology of terrestrial planets. The three transiting planets have transmission spectrum metrics ranging from 49 to 255, which undoubtedly makes them prime targets for an atmospheric characterization with the James Webb Space Telescope, the Hubble Space Telescope, Ariel, or ground-based facilities such as NIRPS or ESPRESSO. With an equilibrium temperature ranging from 416 to 627 K, they offer a unique opportunity to study the diversity of warm terrestrial planets without the unknowns associated with different host stars. L 98-59 b and c have densities of 3.6−1.5+1.4 and 4.57−0.85+0.77 g cm−3, respectively, and have very similar bulk compositions with a small iron core that represents only 12 to 14% of the total mass, and a small amount of water. However, with a density of 2.95−0.51+0.79 g cm−3 and despite a similar core mass fraction, up to 30% of the mass of L 98-59 d might be water.

show abstract

Section: Stellar Atmospheric Parametersmentioning

confidence: 99%

Section: Appendix A12: Machine-learning Regression With Odusseasmentioning

confidence: 99%

Warm terrestrial planet with half the mass of Venus transiting a nearby star

Demangeon

Osorio

Alibert

et al. 2021

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…VX Sgr is a semi-regular variable that at times behaves like a fundamental mode pulsator (a Mira variable) with deep minima, fading by 5 to 6 magnitudes. Although some authors suggest VX Sgr may be a "super AGB" star (Tabernero et al 2021) based on its Mira-like variability, its fundamental mode pulsation does not rule out a core burning supergiant (Heger et al 1997). Current distance estimates 3 ranging from 1.5 to 1.7 kpc due to possible association with SgrOB1 and the Sgr spiral arm (Humphreys 1975) to 1.3 to 1.4 kpc (Tabernero et al 2021) indicate a luminosity well above the AGB limit, even taking into account the possibility that a few AGB stars occasionally having luminosities above the AGB limit (García-Hernández et al 2009).…”

Section: Evidence For Gaseous Outflows From Other Rsgsmentioning

confidence: 99%

Episodic Gaseous Outflows and Mass Loss from Red Supergiants

Humphreys,

Jones

2022

Preprint

View full text Add to dashboard Cite

The red hypergiant VY CMa and the more typical red supergiant Betelgeuse provide clear observational evidence for discrete, directed gaseous outflows in their optical and infrared imaging, spectra, and light curves. In the very luminous VY CMa, mass loss estimates from the infrared bright knots and clumps, not only dominate its measured overall mass loss, but explain it. In the lower luminosity Betelgeuse, similar mass estimates of its circumstellar condensations show that they contribute significantly to its measured mass loss rate. We present new measurements for both stars and discuss additional evidence for gaseous ejections in other red supergiants. Gaseous outflows are the dominant mechanism for the most luminous RSGs and an important contributor to the more typical red supergiants like Betelgeuse. We conclude that gaseous outflows, related to magnetic fields and surface activity, comparable to coronal mass ejections, are a major contributor to mass loss from red supergiants and the missing component in discussions of their mass loss mechanism.

show abstract

“…One further effort to re-determine the fundamental stellar parameters uniformly for the entire CARMENES GTO sample will be presented in a forthcoming publication by Marfil et al (2021), using the spectral analysis software SteParSyn (Tabernero et al 2018(Tabernero et al , 2021. SteParSyn is an automatic code designed to infer the stellar atmospheric parameters T eff , log g, [Fe/H] 9 , and v sin i of late-type stars (FGKM) following the spectral synthesis method using a Markov Chain Monte Carlo algorithm.…”

Section: Fits Using Alternative Stellar Parametersmentioning

confidence: 99%

The CARMENES search for exoplanets around M dwarfs: Not-so-fine hyperfine-split vanadium lines in cool star spectra

Shan,

Reiners,

Fabbian

et al. 2021

Preprint

View full text Add to dashboard Cite

Context. M-dwarf spectra are complex and notoriously difficult to model, posing challenges to understanding their photospheric properties and compositions in depth. Vanadium (V) is an iron-group element whose abundance supposedly closely tracks that of iron, but has origins that are not completely understood. Aims. Our aim is to characterize a series of neutral vanadium atomic absorption lines in the 800-910 nm wavelength region of high signal-to-noise, high-resolution, telluric-corrected M-dwarf spectra from the CARMENES survey. Many of these lines are prominent and exhibit a distinctive broad and flat-bottom shape, which is a result of hyperfine structure (HFS). We investigate the potential and implications of these HFS split lines for abundance analysis of cool stars. Methods. With standard spectral synthesis routines, as provided by the spectroscopy software iSpec and the latest atomic data (including HFS) available from the VALD3 database, we modeled these striking line profiles. We used them to measure V abundances of cool dwarfs. Results. We determined V abundances for 135 early M dwarfs (M0.0 V to M3.5 V) in the CARMENES guaranteed time observations sample. They exhibit a [V/Fe]-[Fe/H] trend consistent with that derived from nearby FG dwarfs. The tight (±0.1 dex) correlation between [V/H] and [Fe/H] suggests the potential application of V as an alternative metallicity indicator in M dwarfs. We also show hints that neglecting to model HFS could partially explain the temperature correlation in V abundance measurements observed in previous studies of samples involving dwarf stars with T eff 5300 K. Conclusions. Our work suggests that HFS can impact certain absorption lines in cool photospheres more severely than in Sun-like ones. Therefore, we advocate that HFS should be carefully treated in abundance studies in stars cooler than ∼ 5000 K. On the other hand, strong HFS split lines in high-resolution spectra present an opportunity for precision chemical analyses of large samples of cool stars. The V-to-Fe trends exhibited by the local M dwarfs continue to challenge theoretical models of V production in the Galaxy.

show abstract

The nature of VX Sagitarii

Cited by 26 publications

References 102 publications

Warm terrestrial planet with half the mass of Venus transiting a nearby star

Warm terrestrial planet with half the mass of Venus transiting a nearby star

Episodic Gaseous Outflows and Mass Loss from Red Supergiants

The CARMENES search for exoplanets around M dwarfs: Not-so-fine hyperfine-split vanadium lines in cool star spectra

Contact Info

Product

Resources

About