PolarBase: A Database of High-Resolution Spectropolarimetric Stellar Observations

Petit, P.; Louge, Thierry; Théado, S.; Paletou, F.; Manset, N.; Morin, J.; Marsden, S. C.; Jeffers, S. V.

doi:10.1086/676976

Cited by 149 publications

(107 citation statements)

References 26 publications

(36 reference statements)

Supporting

Mentioning

107

Contrasting

Order By: Relevance

“…As a reference, we use here the standard Ap star α 2 CVn and a NARVAL observation downloaded from PolarBase (Petit et al 2014b) and already used by Silvester et al (2014). The star α 2 CVn is bright and variable A0p with v sin i = 18 ± 0.5 km s −1 , an effective temperature of 11 600 ± 500 K, and a logarithmic surface gravity equal to 3.9 ± 0.1 (Silvester et al 2014).…”

Section: Methods Outlinementioning

confidence: 99%

Detection of ultra-weak magnetic fields in Am stars:βUrsae Majoris andθLeonis

Blazère

Petit

Lignières

et al. 2016

A&A

Self Cite

View full text Add to dashboard Cite

Context. An extremely weak circularly polarized signature was recently discovered in spectral lines of the chemically peculiar Am star Sirius A. A weak surface magnetic field was proposed to account for the observed polarized signal, but the shape of the phaseaveraged signature, dominated by a prominent positive lobe, is not expected in the standard theory of the Zeeman effect. Aims. We aim at verifying the presence of weak circularly polarized signatures in two other bright Am stars, β UMa and θ Leo, and investigating the physical origin of Sirius-like polarized signals further. Methods. We present here a set of deep spectropolarimetric observations of β UMa and θ Leo, observed with the NARVAL spectropolarimeter. We analyzed all spectra with the least squares deconvolution multiline procedure. To improve the signal-to-noise ratio and detect extremely weak signatures in Stokes V profiles, we co-added all available spectra of each star (around 150 observations each time). Finally, we ran several tests to evaluate whether the detected signatures are consistent with the behavior expected from the Zeeman effect. Results. The line profiles of the two stars display circularly polarized signatures similar in shape and amplitude to the observations previously gathered for Sirius A. Our series of tests brings further evidence of a magnetic origin of the recorded signal. Conclusions. These new detections suggest that very weak magnetic fields may well be present in the photospheres of a significant fraction of intermediate-mass stars. The strongly asymmetric Zeeman signatures measured so far in Am stars (featuring a dominant single-sign lobe) are not expected in the standard theory of the Zeeman effect and may be linked to sharp vertical gradients in photospheric velocities and magnetic field strengths.

show abstract

Section: Methods Outlinementioning

confidence: 99%

Detection of ultra-weak magnetic fields in Am stars:βUrsae Majoris andθLeonis

Blazère

Petit

Lignières

et al. 2016

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…In addition to the newly observed epochs, all prior observations of τ Boötis with the NARVAL instrument were retrieved from the Polarbase 4 (Petit et al 2014) database, and we calculated values of the S-index for each normalised individual exposure of τ Boötis, making four data points for each spectropolarimetric sequence. These are shown in Figure 2.…”

Section: Ca II H and K Activity Proxymentioning

confidence: 99%

The evolving magnetic topology of τ Boötis

Mengel

Farès

Marsden

et al. 2016

Mon. Not. R. Astron. Soc.

Self Cite

108

View full text Add to dashboard Cite

We present six epochs of spectropolarimetric observations of the hot-Jupiter-hosting star τ Boötis that extend the exceptional previous multi-year data set of its large-scale magnetic field. Our results confirm that the large-scale magnetic field of τ Boötis varies cyclicly, with the observation of two further magnetic reversals; between December 2013 and May 2014 and between January and March 2015. We also show that the field evolves in a broadly solar-type manner in contrast to other F-type stars. We further present new results which indicate that the chromospheric activity cycle and the magnetic activity cycles are related, which would indicate a very rapid magnetic cycle. As an exemplar of long-term magnetic field evolution, τ Boötis and this longterm monitoring campaign presents a unique opportunity for studying stellar magnetic cycles.

show abstract

“…The hotter targets (V2062 Oph, V1149 Sco, and Par 2441) do not have strong enough spectral features in this K-band wavelength setting. Instead, for V1149 Sco and Par 2441, we used strong optical unblended Fe i lines with low g eff values in R = 65000 archival ESPaDOnS spectra retrieved from the PolarBase database (Petit et al 2014). The ESPaDOnS instrument is a high-resolution spectropolarimeter mounted on the 3.6 m Canada-France-Hawaii Telescope.…”

Section: Determination Of Mean Field Modulusmentioning

confidence: 99%

Magnetic fields of intermediate mass T Tauri stars

Lavail

Kochukhov

Hussain³

et al. 2017

A&A

View full text Add to dashboard Cite

Aims. In this paper, we aim to measure the strength of the surface magnetic fields for a sample of five intermediate mass T Tauri stars and one low mass T Tauri star from late-F to mid-K spectral types. While magnetic fields of T Tauri stars at the low mass range have been extensively characterized, our work complements previous studies towards the intermediate mass range; this complementary study is key to evaluate how magnetic fields evolve during the transition from a convective to a radiative core. Methods. We studied the Zeeman broadening of magnetically sensitive spectral lines in the H-band spectra obtained with the CRIRES high-resolution near-infrared spectrometer. These data are modelled using magnetic spectral synthesis and model atmospheres. Additional constraints on non-magnetic line broadening mechanisms are obtained from modelling molecular lines in the K band or atomic lines in the optical wavelength region. Results. We detect and measure mean surface magnetic fields for five of the six stars in our sample: CHXR 28, COUP 107, V2062 Oph, V1149 Sco, and Par 2441. Magnetic field strengths inferred from the most magnetically sensitive diagnostic line range from 0.8 to 1.8 kG. We also estimate a magnetic field strength of 1.9 kG for COUP 107 from an alternative diagnostic. The magnetic field on YLW 19 is the weakest in our sample and is marginally detected, with a strength of 0.8 kG.Conclusions. We populate an uncharted area of the pre-main-sequence HR diagram with mean magnetic field measurements from high-resolution near-infrared spectra. Our sample of intermediate mass T Tauri stars in general exhibits weaker magnetic fields than their lower mass counterparts. Our measurements will be used in combination with other spectropolarimetric studies of intermediate mass and lower mass T Tauri stars to provide input into pre-main-sequence stellar evolutionary models.

show abstract

PolarBase: A Database of High-Resolution Spectropolarimetric Stellar Observations

Cited by 149 publications

References 26 publications

Detection of ultra-weak magnetic fields in Am stars:βUrsae Majoris andθLeonis

Detection of ultra-weak magnetic fields in Am stars:βUrsae Majoris andθLeonis

The evolving magnetic topology of τ Boötis

Magnetic fields of intermediate mass T Tauri stars

Contact Info

Product

Resources

About