Spectropolarimetric observations of active stars

Donati, J.‐F.; Semel, M.; Carter, B. D.; Rees, D. E.; Cameron, A. Collier

doi:10.1093/mnras/291.4.658

Cited by 1,544 publications

(2,193 citation statements)

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“…2, bottom panel Donati et al 1997;Kochukhov et al 2010) with that of a Gaussian concluding that the LSD profile is symmetric with no visible presence of the secondary star, therefore HIP 93511 is a single-line spectroscopic binary (SB1). The line bisector as well did not show the presence of the secondary star.…”

Section: From Observationsmentioning

confidence: 96%

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A seismic and gravitationally bound double star observed byKepler

Appourchaux

Antia

Ball

et al. 2015

A&A

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Context. Solar-like oscillations have been observed by Kepler and CoRoT in many solar-type stars, thereby providing a way to probe stars using asteroseismology. Aims. The derivation of stellar parameters has usually been done with single stars. The aim of the paper is to derive the stellar parameters of a double-star system (HIP 93511), for which an interferometric orbit has been observed along with asteroseismic measurements. Methods. We used a time series of nearly two years of data for the double star to detect the two oscillation-mode envelopes that appear in the power spectrum. Using a new scaling relation based on luminosity, we derived the radius and mass of each star. We derived the age of each star using two proxies: one based upon the large frequency separation and a new one based upon the small frequency separation. Using stellar modelling, the mode frequencies allowed us to derive the radius, the mass, and the age of each component. In addition, speckle interferometry performed since 2006 has enabled us to recover the orbit of the system and the total mass of the system. Results. From the determination of the orbit, the total mass of the system is 2.34 +0.45 −0.33 M . The total seismic mass using scaling relations is 2.47 ± 0.07 M . The seismic age derived using the new proxy based upon the small frequency separation is 3.5 ± 0.3 Gyr. Based on stellar modelling, the mean common age of the system is 2.7-3.9 Gyr. The mean total seismic mass of the system is 2.34-2.53 M consistent with what we determined independently with the orbit. The stellar models provide the mean radius, mass, and age of the stars as R A = 1.82−1.87 R , M A = 1.25−1.39 M , Age A = 2.6-3.5 Gyr; R B = 1.22−1.25 R , M B = 1.08−1.14 M , Age B = 3.35-4.21 Gyr. The models provide two sets of values for Star A: [1.25-1.27] M and [1.34-1.39] M . We detect a convective core in Star A, while Star B does not have any. For the metallicity of the binary system of Z ≈ 0.02, we set the limit between stars having a convective core in the range [1.14-1.25] M .

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Section: From Observationsmentioning

confidence: 96%

“…The spectrum, reduced with the Libre-ESpRIT package 6 (Donati et al 1997), covers the 3700-10 400 Å spectral range with a resolving power of about 80 000.…”

Section: From Observationsmentioning

confidence: 99%

A seismic and gravitationally bound double star observed byKepler

Appourchaux

Antia

Ball

et al. 2015

A&A

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“…To circumvent this problem, we use a multi-line addition technique called Least-Squares Deconvolution (LSD, Donati et al 1997). With the help of this method we were able to decrease noise by a factor of 7-16.…”

Section: Magnetic Field Searchmentioning

confidence: 99%

The search for magnetic fields in mercury-manganese stars

et al. 2010

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Abstract. Mercury-manganese (HgMn) stars were considered to be non-magnetic, showing no evidence of surface spots. However, recent investigations revealed that some stars in this class possess an inhomogeneous distribution of chemical elements on their surfaces. According to our current understanding, the most probable mechanism of spot formation involves magnetic fields. Taking the advantage of a newly-built polarimeter attached to the HARPS spectrometer at the ESO 3.6m-telescope, we performed a high-precision spectropolarimetric survey of a large group of HgMn stars. The main purpose of this study was to find out how typical it is for HgMn stars to have weak magnetic fields. We report no magnetic field detection for any of the studied objects, with a typical precision of the longitudinal field measurements of 10 G and down to 1 Gauss for some of the stars. We conclude that HgMn stars lack large-scale magnetic fields typical of spotted magnetic Ap stars and probably lack any fields capable of creating and sustaining chemical spots. Our study confirms that alongside the magnetically altered atomic diffusion, there must be other structure formation mechanism operating in the atmospheres of late-B main sequence stars.

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“…Data subset 1 is corresponding to the observations made on Nov.18-24 (Xinglong) and Dec. 8-11 (BOAO), 2005, data subset 2 to the observations on Dec.8-11 (BOAO) and Dec.17-22 (Xinglong), 2005. To obtain time series of line profiles with the highest signal to noise ratios from the data for Doppler imaging purpose, we employ the Least-Squares Deconvolution (LSD) method (Donati et al 1997) to combine the profile information from all the observed photospheric lines in each observed spectrum.…”

Section: Image Reconstructionmentioning

confidence: 99%

Doppler imaging of the active star PW And

Cameron

Kim

2009

Proc. IAU

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Abstract. We present spot activity of the K2V pre-main-sequence star PW And based on the high-resolution spectroscopic data obtained at Xinglong station and BOAO in 2005 November and December. Using the Least-Squares Deconvolution method, we have derived time series of composite profiles of PW And with high signal to noise ratio. These have been used to reconstruct its starspot pattern via the Doppler imaging method. The result shows that intermediate to highlatitude spots are the dominant features and weak low-latitude spots also appear. Comparing Doppler images from two data subsets, it can be found that almost no difference between two images exists except the small position evolution of weak low-latitude spots, which suggests that the intermediate to high-latitude spots have longer lifetimes than one month, and the low-latitude spots have shorter lifetimes.

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Spectropolarimetric observations of active stars

Cited by 1,544 publications

References 0 publications

A seismic and gravitationally bound double star observed byKepler

A seismic and gravitationally bound double star observed byKepler

The search for magnetic fields in mercury-manganese stars

Doppler imaging of the active star PW And

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