Edge-on T Tauri stars

Appenzeller, I.; Bertout, C.; Stahl, O.

doi:10.1051/0004-6361:20042217

Cited by 47 publications

(61 citation statements)

References 57 publications

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“…This classification is consistent with its Hα emission profile. Similar Hα line profiles are often observed in accreting TTS (Appenzeller et al 2005). According to the concept of the magnetospheric accretion model, the large line width (several hundred km s −1 ) is indicative of large-scale gas flows, while the inverse P Cygni profile traces the gas infall (Muzerolle et al 2001;Kurosawa et al 2006).…”

Section: Spectral Energy Distributionssupporting

confidence: 65%

Discovery of “isolated” co-moving T Tauri stars in Cepheus

Guillout

Frasca

Klutsch

et al. 2010

A&A

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Context. During the course of a large spectroscopic survey of X-ray active late-type stars in the solar neighbourhood, we discovered four lithium-rich stars packed within just a few degrees on the sky. Although located in a sky area rich in CO molecular regions and dark clouds, the Cepheus-Cassiopeia complex, these very young stars are projected several degrees away from clouds in front of an area void of interstellar matter. As such, they are very good "isolated" T Tauri star candidates. Aims. We present optical observations of these stars conducted with 1-2 m class telescopes. We acquired high-resolution optical spectra as well as photometric data allowing us to investigate in detail their nature and physical parameters with the aim of testing the "runaway" and "in-situ" formation scenarios. Their kinematical properties are also analyzed to investigate their possible connection to already known stellar kinematic groups. Methods. We use the cross-correlation technique and other tools developed by us to derive accurate radial and rotational velocities and perform an automatic spectral classification. The spectral subtraction technique is used to infer chromospheric activity level in the Hα line core and clean the spectra of photospheric lines before measuring the equivalent width of the lithium absorption line. Results. Both physical (lithium content, chromospheric, and coronal activities) and kinematical indicators show that all stars are very young, with ages probably in the range 10-30 Myr. In particular, the spectral energy distribution of TYC 4496-780-1 displays a strong near-and far-infrared excess, typical of T Tauri stars still surrounded by an accretion disc. They also share the same Galactic motion, proving that they form a homogeneous moving group of stars with the same origin. Conclusions. The most plausible explanation of how these "isolated" T Tauri stars formed is the "in-situ" model, although accurate distances are needed to clarify their connection with the Cepheus-Cassiopeia complex. The discovery of this loose association of "isolated" T Tauri stars can help to shed light on atypical formation processes of stars and planets in low-mass clouds.

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Section: Spectral Energy Distributionssupporting

confidence: 65%

Discovery of “isolated” co-moving T Tauri stars in Cepheus

Guillout

Frasca

Klutsch

et al. 2010

A&A

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“…Scattered photons that have escaped the central system along trajectories located well above the disk midplane do not encounter either of these absorbing media and therefore do not exhibit central absorption signatures in the line profiles (cf. Appenzeller et al 2005;Grinin et al 2012). Only the HeI 1083 nm line still displays a pronounced redshifted absorption component in the deep state that is essentially unchanged from the bright state, which is indicative of accretion onto the central star (Fischer et al 2008).…”

Section: Discussionmentioning

confidence: 93%

AA Tauri’s sudden and long-lasting deepening: enhanced extinction by its circumstellar disk

Bouvier

Grankin

Ellerbroek

et al. 2013

A&A

108

143

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Context. AA Tau has been monitored for more than 20 years since 1987 and exhibited a nearly constant brightness level of V = 12.5 mag. We report here that in 2011 it suddenly faded, becoming 2 mag fainter in the V-band, and has remained in this deep state since then. Aims. We investigate the origin of the sudden dimming of the AA Tau system. Methods. We report on new optical and near-IR photometry and spectroscopy obtained during the fading event.Results. The system appears to be much redder and fainter than it was in the bright state. Moreover, the 8.2 d photometric period continuously observed for more than 20 years is not detected during most of the deep state. The analysis of the system's brightness and colors suggests that the visual extinction on the line of sight has increased by about 3-4 mag in the deep state. At optical wavelengths, the system appears to be dominated by scattered light, probably originating from the upper surface layers of a highly inclined circumstellar disk. The profiles of the Balmer lines have significantly changed as well, with the disappearance of a central absorption component regularly observed in the bright state. We ascribe this change to the scattering of the system's spectrum by circumstellar dust. Remarkably, the mass accretion rate in the inner disk and onto the central star has not changed as the system faded. Conclusions. We conclude that the deepening of the AA Tau system is due to a sudden increase of circumstellar dust extinction on the line of sight without concomitant change in the accretion rate. We suggest that the enhanced obscuration may be produced by a nonaxisymmetric overdense region in the disk, located at a distance of 7.7 AU or more, that was recently brought into the line of sight by its Keplerian motion around the central star.

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“…Most research has been conducted in the optical and NIR band including photometry, polarimetry, medium-resolution imaging and high-resolution spectroscopy with ground-based instruments (Vrba et al 1985;Appenzeller et al 2005;Anglada et al 2007) and high-resolution imaging with the Hubble Space Telescope (HST) from outside the atmosphere (B96; C01;Watson & Stapelfeldt 2004, hereafter W04). The SED in the MIR has been measured with ISOCAM/ISO (Stapelfeldt & Moneti 1999;Brandner et al 2000) and refined substantially by observations with IRS on the Spitzer Space Telescope (SST, Furlan et al 2008).…”

Section: Observationsmentioning

confidence: 99%

The circumstellar disk of HH 30

Madlener

Wolf

Dutrey

et al. 2012

A&A

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Context. Circumstellar disks are characteristic for star formation and vanish during the first few Myr of stellar evolution. During this time planets are believed to form in the dense midplane by growth, sedimentation and aggregation of dust. Indicators of disk evolution, such as holes and gaps, can be traced in the spectral energy distribution (SED) and spatially resolved images. Aims. We aim to construct a self-consistent model of HH 30 by fitting all available continuum observations simultaneously. New data sets not available in previous studies, such as high-resolution interferometric imaging with the Plateau de Bure Interferometer (PdBI) at λ = 1.3 mm and SED measured with IRS on the Spitzer Space Telescope in the mid-infrared, put strong constraints on predictions and are likely to provide new insights into the evolutionary state of this object. Methods. A parameter study based on simulated annealing was performed to find unbiased best-fit models for independent observations made in the wavelength domain λ ∼ 1 μm . . . 4 mm. The method essentially creates a Markov chain through parameter space by comparing predictions generated by our self-consistent continuum radiation transfer code MC3D with observations. Results. We present models of the edge-on circumstellar disk of HH 30 based on observations from the near-infrared to mmwavelengths that suggest the presence of an inner depletion zone with ∼45 AU radius and a steep decline of mm opacity beyond 140 AU. Our modeling indicates that several modes of dust evolution such as growth, settling, and radial migration are taking place in this object. Conclusions. High-resolution observations of HH 30 at different wavelengths with next-generation observatories such as ALMA and JWST will enable the modeling of inhomogeneous dust properties and significantly expand our understanding of circumstellar disk evolution.

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Edge-on T Tauri stars

Cited by 47 publications

References 57 publications

Discovery of “isolated” co-moving T Tauri stars in Cepheus

Discovery of “isolated” co-moving T Tauri stars in Cepheus

AA Tauri’s sudden and long-lasting deepening: enhanced extinction by its circumstellar disk

The circumstellar disk of HH 30

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