A major upgrade of the VALD database

Ryabchikova, T.; Piskunov, Nikolai; Kurucz, Robert L.; Stempels, H. C.; Heiter, U.; Pakhomov, Yu. V.; Barklem, P. S.

doi:10.1088/0031-8949/90/5/054005

Cited by 743 publications

(606 citation statements)

References 21 publications

(28 reference statements)

Supporting

Mentioning

598

Contrasting

Unclassified

Order By: Relevance

“…The quantities V(λ) and I(λ) are the Stokes V and I profiles, respectively, g eff is the effective Landé factor, which was set to 1.25 except for the region of the hydrogen Balmer lines where g eff was set to 1.0 (Bagnulo et al 2012), and C z is equal to 4.67×10 −13 Å −1 G −1 . We validated the employed effective Landé factor of 1.25 by extracting from the VALD database (Ryabchikova et al 2015) the information relative to the lines covered by the FORS2 spectrum. We further calculated the diagnosing null profile N, and hence N z (see Bagnulo et al 2009).…”

Section: Observations Data Reduction and Resultsmentioning

confidence: 99%

Detection of magnetic field in the B2 star ρ Ophiuchi A with ESO FORS2

Pillitteri¹,

Fossati²,

Castro³

et al. 2018

A&A

View full text Add to dashboard Cite

Circumstantial evidence suggests that magnetism and enhanced X-ray emission are likely correlated in early B-type stars: similar fractions of them (∼ 10%) are strong and hard X-ray sources and possess strong magnetic fields. It is also known that some B-type stars have spots on their surface. Yet up to now no X-ray activity associated with spots on early-type stars was detected. In this Letter we report the detection of a magnetic field on the B2V star ρ Oph A. Previously, we assessed that the X-ray activity of this star is associated with a surface spot, herewith we establish its magnetic origin. We analyzed FORS2 ESO VLT spectra of ρ Oph A taken at two epochs and detected a longitudinal component of the magnetic field of order of ∼ 500 G in one of the datasets. The detection of the magnetic field only at one epoch can be explained by stellar rotation which is also invoked to explain observed periodic X-ray activity. From archival HARPS ESO VLT high resolution spectra we derived the fundamental stellar parameters of ρ Oph A and further constrained its age. We conclude that ρ Oph A provides strong evidence for the presence of active X-ray emitting regions on young magnetized early type stars.

show abstract

Section: Observations Data Reduction and Resultsmentioning

confidence: 99%

Detection of magnetic field in the B2 star ρ Ophiuchi A with ESO FORS2

Pillitteri¹,

Fossati²,

Castro³

et al. 2018

A&A

View full text Add to dashboard Cite

show abstract

“…2 In the second panel, we show the spectrum of GX And together with annotations of the most prominent atomic and molecular absorption features seen in M dwarfs. Line positions of atomic lines are taken from VALD (Ryabchikova et al 2015), information on molecular bands was compiled from Cushing et al (2005). We chose to show our observed spectra without applying any Doppler shift so that telluric lines appear at the same position in all panels of our atlas.…”

Section: Spectral Atlasmentioning

confidence: 99%

The CARMENES search for exoplanets around M dwarfs

Reiners

Zechmeister

Caballero

et al. 2018

A&A

193

108

View full text Add to dashboard Cite

The CARMENES radial velocity (RV) survey is observing 324 M dwarfs to search for any orbiting planets. In this paper, we present the survey sample by publishing one CARMENES spectrum for each M dwarf. These spectra cover the wavelength range 520-1710 nm at a resolution of at least R > 80, 000, and we measure its RV, Hα emission, and projected rotation velocity. We present an atlas of high-resolution M-dwarf spectra and compare the spectra to atmospheric models. To quantify the RV precision that can be achieved in low-mass stars over the CARMENES wavelength range, we analyze our empirical information on the RV precision from more than 6500 observations. We compare our high-resolution M-dwarf spectra to atmospheric models where we determine the spectroscopic RV information content, Q, and signal-to-noise ratio. We find that for all M-type dwarfs, the highest RV precision can be reached in the wavelength range 700-900 nm. Observations at longer wavelengths are equally precise only at the very latest spectral types (M8 and M9). We demonstrate that in this spectroscopic range, the large amount of absorption features compensates for the intrinsic faintness of an M7 star. To reach an RV precision of 1 m s −1 in very low mass M dwarfs at longer wavelengths likely requires the use of a 10 m class telescope. For spectral types M6 and earlier, the combination of a red visual and a near-infrared spectrograph is ideal to search for low-mass planets and to distinguish between planets and stellar variability. At a 4 m class telescope, an instrument like CARMENES has the potential to push the RV precision well below the typical jitter level of 3-4 m s −1 .

show abstract

“…As such, the S/N of the polarization signature is greatly improved. To perform the LSD method, we started from a VALD3 linemask (Ryabchikova et al 2015) for a star of 17 000 K and a log g = 4.0 dex, compatible with the literature values for HD 43317 (P12). Hydrogen lines as well as all metal lines blended with hydrogen lines, strong telluric features, and diffuse interstellar bands were removed from the linemask.…”

Section: Zeeman Signaturementioning

confidence: 99%

Magnetic characterization of the SPB/β Cep hybrid pulsator HD 43317

Buysschaert

Neiner

Briquet

et al. 2017

A&A

View full text Add to dashboard Cite

Large-scale magnetic fields at the surface of massive stars do not only influence the outer-most layers of the star, but also have consequences for the deep interior, only observationally accessible through asteroseismology. We performed a detailed characterization of the dipolar magnetic field at the surface of the B3.5V star HD 43317, a SPB/β Cep hybrid pulsator, by studying the rotationally modulated magnetic field of archival and new Narval spectropolarimetry. Additionally, we employed a grid-based approach to compare the Zeeman signatures with model profiles. By studying the rotational modulation of the He lines in both the Narval and HARPS spectroscopy caused by co-rotating surface abundance inhomogeneities, we updated the rotation period to 0.897673 ± 0.000004 d. The inclination angle between the rotation axis and the observer's line of sight remains ill-defined, because of the low level of variability in Stokes V and deformations in the intensity profiles by stellar pulsation modes. The obliquity angle between the rotation and magnetic axes is constrained to β ∈ [67, 90] • , and the strength of the dipolar magnetic field is of the order of 1 kG to 1.5 kG. This magnetic field at the stellar surface is sufficiently strong to warrant a uniformly rotating radiative envelope, causing less convective core overshooting, which should be visible in future forward seismic modeling.

show abstract

A major upgrade of the VALD database

Cited by 743 publications

References 21 publications

Detection of magnetic field in the B2 star ρ Ophiuchi A with ESO FORS2

Detection of magnetic field in the B2 star ρ Ophiuchi A with ESO FORS2

The CARMENES search for exoplanets around M dwarfs

Magnetic characterization of the SPB/β Cep hybrid pulsator HD 43317

Contact Info

Product

Resources

About