High resolution profiles of chromospheric lines in M dwarf stars

Worden, S. P.; Schneeberger, T. J.; Giampapa, M. S.

doi:10.1086/190741

Cited by 20 publications

(14 citation statements)

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“…This is in line with the central peak in the IM Lup data. In the samples of Worden et al (1981) and Robinson et al (1990), there is not a single case in which Hα is in emission, where simultaneously broad absorption is present. The same is true for WTTS, which have narrow emission lines of symmetric shape (Fang et al 2009).…”

Section: Mass Accretion?mentioning

confidence: 99%

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The disk-bearing young star IM Lupi

Guenther¹,

Schmitt²,

Guêdel³

et al. 2010

A&A

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Context. Classical T Tauri stars (CTTS) differ in their X-ray signatures from older pre-main sequence stars, e.g., weak-lined TTS (WTTS). CTTS exhibit a soft excess and deviations from the low-density coronal limit in the He-like triplets. Aims. We test whether these features correlate with either accretion or the presence of a disk by observing IM Lup, a disk-bearing object apparently in transition between CTTS and WTTS without obvious accretion. Methods. We analyse a Chandra grating spectrum and additional XMM-Newton data of IM Lup and accompanying optical spectra, some of which where taken simultaneously with the X-ray observations. We fit the X-ray emission lines and decompose the Hα emission line into different components. Results. In X-rays, IM Lup has a bright and hot active corona, where elements with low first-ionisation potential are depleted. The He-like Ne ix triplet is in the low-density state, but because of the small number of counts in the data a high-density scenario cannot be excluded at the 90% confidence level. In terms of all its X-ray properties, IM Lup resembles a main-sequence star, but is also compatible with CTTS signatures at the 90% confidence level, thus we cannot decide whether the soft excess and deviations from the low-density coronal limit for the He-like triplets in CTTS are produced by accretion or only the presence of a disk. The star IM Lup is chromospherically active, which accounts for most of its emission in Hα. Despite its low equivalent width, the complexity of the Hα line profile is reminiscent of CTTS. We estimate the mass accretion rate to be 10 −11 M yr −1 .

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Section: Mass Accretion?mentioning

confidence: 99%

“…Other M dwarfs with active chromospheres also have Hα emission, typically with an equivalent width of a few Å (Worden et al 1981;Robinson et al 1990), that is similar to IM Lup. Their Ca H and K lines often have very narrow emission peaks.…”

Section: Mass Accretion?mentioning

confidence: 99%

The disk-bearing young star IM Lupi

Guenther¹,

Schmitt²,

Guêdel³

et al. 2010

A&A

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“…This line appears to be in absorption which gives interesting constraints on model atmospheres, especially about the lower chromosphere where the Paschen lines are formed (Short & Doyle 1998, Papers II and III). Worden et al (1981) also observed the Nai doublet for which they detected a core emission. Pettersen (1989) has observed a number of chromospheric lines of interest for AU Mic.…”

Section: Au Mic (Gl 803)mentioning

confidence: 92%

“…Herbst & Layden (1987) derived photometrically an H α equivalent width of -1.90 Å. Worden et al (1981) also obtained high resolution observations of the Balmer lines. They measured equivalent widths of -8.70 Å and -1.56 Å for H α .…”

Section: Au Mic (Gl 803)mentioning

confidence: 93%

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Observation and modelling of main sequence star chromospheres

Houdebine¹,

Junghans²,

Heanue

et al. 2009

A&A

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Aims. We report on high resolution observations of chromospheric lines for M and K dwarfs. Methods. We observed up to 13 spectral lines per star: the H α , H β , H , Pa , Pa 8 , CaII H, CaII IR triplet, CaI 6572Å, NaI D 1 /D 2 and HeI D 3 lines. We observed two dMe stars, one dM(e) star, 5 dM stars and 3 dK stars. Results. We observed a self-reversal in the emission core of the CaII H line for the brightest stars only, indicating a rather optically thick region of formation. We present original spectra of the NaI doublet and the CaII IR triplet for active dMe stars and less active dM stars. Core emission is detected in the Sodium lines and the CaII IR triplet lines for the most active M dwarf AU Mic. We investigate the difference spectra between active dMe stars and dM stars and show that these provide interesting new constraints for the NLTE-radiation transfer modelling of the chromospheres. In our sample, emission H α profiles have a rather homogeneous FWHM of about 1.5 Å. This, according to our previous modelling, can be interpreted as the signature of a rather constant temperature break in the chromosphere. We found that one of our targets (MCC 332) is a binary with a faint but active H α emission component. For the first time we detect the Pa line for six dwarfs. It appears as weak absorption with possible weak wing emission in AU Mic. The region of the Pa 8 line was observed but the line was not detected.

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Stellar Analogs of Solar Activity: The Sun in A Stellar Context

Giampapa

Saas-Fee Advanced Courses

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High resolution profiles of chromospheric lines in M dwarf stars

Cited by 20 publications

References 0 publications

The disk-bearing young star IM Lupi

The disk-bearing young star IM Lupi

Observation and modelling of main sequence star chromospheres

Stellar Analogs of Solar Activity: The Sun in A Stellar Context

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