LITHIUM ABUNDANCES FROM OPTICAL HIGH-RESOLUTION SPECTROSCOPY OF WEAK-LINE T TAURI STARS

Context. Disk winds play a fundamental role in the evolution of protoplanetary systems. The complex structure and dynamics can be investigated through the emission of atomic and molecular lines detected in high-resolution optical/IR spectra of young stellar objects. Despite their great importance, however, studies connecting the atomic and molecular components are lacking so far. Aims. In the framework of the GIARPS High-resolution Observations of T Tauri stars (GHOsT) project, we aim to characterize the atomic and molecular winds in a sample of classical T Tauri stars (CTTs) of the Taurus-Auriga region, focusing on a statistical analysis of the kinematic properties of the [O I] 630 nm and H2 2.12 μm lines and their mutual relationship. Methods. We analyzed the flux calibrated [O I] 630 nm and H2 2.12 μm lines in a sample of 36 CTTs observed at the Telescopio Nazionale Galileo with the HARPS-N spectrograph (resolving power of R = 115 000) and with the GIANO spectrograph (R = 50 000). We decomposed the line profiles into different kinematic Gaussian components and focused on the most frequently detected component, the narrow low-velocity (vp < 20 km s−1) component (NLVC). Results. We found that the H2 line is detected in 17 sources (~50% detection rate), and [O I] is detected in all sources but one. The NLV components of the H2 and [O I] emission are kinematically linked, with a strong correlation between the peak velocities and the full widths at half maximum of the two lines. Assuming that the line width is dominated by Keplerian broadening, we found that the [O I] NVLC originates from a disk region between 0.05 and 20 au and that of H2 in a region from 2 and 20 au. We also found that H2 is never detected in sources where [O I] originates in regions below 1 au, as well as in sources of early (~F-G) spectral type with a luminosity >1 L⊙. Moreover, in seven sources, both H2 and [O I] have clear blueshifted peaks and prominent [O I] high-velocity components. These components have also been detected in sources with no relevant centroid shift. Finally, we did not find any clear correlation between vp of the H2 and [O I] NVLC and the outer disk inclination. This result is in line with previous studies. Conclusions. Our results suggest that molecular and neutral atomic emission in disk winds originate from regions that might overlap, and that the survival of molecular winds in disks strongly depends on the gas exposure to the radiation from the central star. The presence of jets does not necessarily affect the kinematics of the low-velocity winds. Our results demonstrate the potential of wide-band high-resolution spectroscopy in linking tracers of different manifestations of the same phenomenon.

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High-Resolution Spectroscopy of Winds Associated with T Tauri Stars

Research in Astronomy and Astrophysics ◽

10.1088/1674-4527/16/2/030 ◽

2016 ◽

Vol 16 (2) ◽

pp. 010 ◽

Cited By ~ 2

Author(s):

Naoto Iguchi ◽

Yoichi Itoh

Keyword(s):

High Resolution ◽

T Tauri Stars ◽

High Resolution Spectroscopy ◽

T Tauri

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High-Resolution Spectroscopy of T Tauri Stars

Publications of the Astronomical Society of Japan ◽

10.1093/pasj/61.2.251 ◽

2009 ◽

Vol 61 (2) ◽

pp. 251-258 ◽

Cited By ~ 5

Author(s):

Yuske Taguchi ◽

Yoichi Itoh ◽

Tadashi Mukai

Keyword(s):

High Resolution ◽

T Tauri Stars ◽

High Resolution Spectroscopy ◽

T Tauri

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Variability of young stars: Determination of rotational periods of weak-line T Tauri stars in the Cepheus-Cassiopeia star-forming region

Astronomische Nachrichten ◽

10.1002/asna.200911204 ◽

2009 ◽

Vol 330 (5) ◽

pp. 482-492

Author(s):

A. Koeltzsch ◽

M. Mugrauer ◽

St. Raetz ◽

T.O.B. Schmidt ◽

T. Roell ◽

...

Keyword(s):

T Tauri Stars ◽

Young Stars ◽

Weak Line ◽

Star Forming ◽

T Tauri

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Characterising the surface magnetic fields of T Tauri stars with high-resolution near-infrared spectroscopy

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935695 ◽

2019 ◽

Vol 630 ◽

pp. A99 ◽

Cited By ~ 5

Author(s):

A. Lavail ◽

O. Kochukhov ◽

G. A. J. Hussain

Keyword(s):

Magnetic Field ◽

High Resolution ◽

Magnetic Fields ◽

Large Scale ◽

Near Infrared ◽

Field Measurements ◽

T Tauri Stars ◽

Small Scale ◽

Surface Magnetic Field ◽

T Tauri

Aims. In this paper, we aim to characterise the surface magnetic fields of a sample of eight T Tauri stars from high-resolution near-infrared spectroscopy. Some stars in our sample are known to be magnetic from previous spectroscopic or spectropolarimetric studies. Our goals are firstly to apply Zeeman broadening modelling to T Tauri stars with high-resolution data, secondly to expand the sample of stars with measured surface magnetic field strengths, thirdly to investigate possible rotational or long-term magnetic variability by comparing spectral time series of given targets, and fourthly to compare the magnetic field modulus ⟨B⟩ tracing small-scale magnetic fields to those of large-scale magnetic fields derived by Stokes V Zeeman Doppler Imaging (ZDI) studies. Methods. We modelled the Zeeman broadening of magnetically sensitive spectral lines in the near-infrared K-band from high-resolution spectra by using magnetic spectrum synthesis based on realistic model atmospheres and by using different descriptions of the surface magnetic field. We developped a Bayesian framework that selects the complexity of the magnetic field prescription based on the information contained in the data. Results. We obtain individual magnetic field measurements for each star in our sample using four different models. We find that the Bayesian Model 4 performs best in the range of magnetic fields measured on the sample (from 1.5 kG to 4.4 kG). We do not detect a strong rotational variation of ⟨B⟩ with a mean peak-to-peak variation of 0.3 kG. Our confidence intervals are of the same order of magnitude, which suggests that the Zeeman broadening is produced by a small-scale magnetic field homogeneously distributed over stellar surfaces. A comparison of our results with mean large-scale magnetic field measurements from Stokes V ZDI show different fractions of mean field strength being recovered, from 25–42% for relatively simple poloidal axisymmetric field topologies to 2–11% for more complex fields.

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High-resolution X-ray spectroscopy of T Tauri stars in the Taurus-Auriga complex

Astronomy and Astrophysics ◽

10.1051/0004-6361:20066193 ◽

2007 ◽

Vol 468 (2) ◽

pp. 443-462 ◽

Cited By ~ 61

Author(s):

A. Telleschi ◽

M. Güdel ◽

K. R. Briggs ◽

M. Audard ◽

L. Scelsi

Keyword(s):

High Resolution ◽

T Tauri Stars ◽

X Ray ◽

T Tauri

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Erratum: Magnetic topologies of young suns: the weak-line T Tauri stars TWA 6 and TWA 8A

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1254 ◽

2019 ◽

Vol 486 (4) ◽

pp. 5526-5527

Author(s):

C A Hill ◽

C P Folsom ◽

J-F Donati ◽

G J Herczeg ◽

G A J Hussain ◽

...

Keyword(s):

T Tauri Stars ◽

Weak Line ◽

T Tauri

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Magnetic fields of T Tauri stars and inner accretion discs

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319003740 ◽

2018 ◽

Vol 14 (A30) ◽

pp. 121-121

Author(s):

Jean-Francois Donati

Keyword(s):

Magnetic Fields ◽

Large Scale ◽

Near Infrared ◽

High Sensitivity ◽

T Tauri Stars ◽

Accretion Discs ◽

High Resolution Spectroscopy ◽

T Tauri ◽

Low Mass ◽

The Impact

AbstractMagnetic fields play a key role in the early life of stars and their planets, as they form from collapsing dense cores that progressively flatten into large-scale accretion discs and eventually settle as young suns orbited by planetary systems. Pre-main-sequence phases, in which central protostars feed from surrounding planet-forming accretion discs, are especially crucial for understanding how worlds like our Solar System are born.Magnetic fields of low-mass T Tauri stars (TTSs) are detected through high-resolution spectroscopy and spectropolarimetry (e.g., Johns Krull 2007), whereas their large-scale topologies can be inferred from time series of Zeeman signatures using tomographic techniques inspired from medical imaging (Donati & Landstreet 2009). Large-scale fields of TTSs are found to depend on the internal structure of the newborn star, allowing quantitative models of how TTSs magnetically interact with their inner accretion discs, and the impact of this interaction on the subsequent stellar evolution (e.g., Romanova et al. 2002, Zanni & Ferreira 2013).With its high sensitivity to magnetic fields, SPIRou, the new near-infrared spectropolarimeter installed in 2018 at CFHT (Donati et al. 2018), should yield new advances in the field, especially for young embedded class-I protostars, thereby bridging the gap with radio observations.

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Searching for H2 emission from protoplanetary disks using near- and mid-infrared high-resolution spectroscopy

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308016827 ◽

2007 ◽

Vol 3 (S249) ◽

pp. 359-368

Author(s):

A. Carmona ◽

M. E. van den Ancker ◽

Th. Henning ◽

Ya. Pavlyuchenkov ◽

C. P. Dullemond ◽

...

Keyword(s):

Surface Layer ◽

High Resolution ◽

Near Infrared ◽

Protoplanetary Disks ◽

High Resolution Spectroscopy ◽

Disk Model ◽

Mid Infrared ◽

T Tauri ◽

Hα Emission ◽

Ir Emission

AbstractThe mass and dynamics of protoplanetary disks are dominated by molecular hydrogen (H2). However, observationally very little is known about the H2. In this paper, we discuss two projects aimed to constrain the properties of H2 in the disk's planet forming region (R<50AU). First, we present a sensitive survey for pure-rotational H2 emission at 12.278 and 17.035 μm in a sample of nearby Herbig Ae/Be and T Tauri stars using VISIR, ESO's VLT high-resolution mid-infrared spectrograph. Second, we report on a search for H2 ro-vibrational emission at 2.1228, 2.2233 and 2.2477 μm in the classical T Tauri star LkHα 264 and the debris disk 49 Cet employing CRIRES, ESO's VLT high-resolution near-infrared spectrograph.VISIR project: none of the sources show H2 mid-IR emission. The observed disks contain less than a few tenths of MJupiter of optically thin H2 at 150 K, and less than a few MEarth at T>300 K. % and higher T. Our non-detections are consistent with the low flux levels expected from the small amount of H2 gas in the surface layer of a Chiang and Goldreich (1997) Herbig Ae two-layer disk model. In our sources the H2 and dust in the surface layer have not significantly departed from thermal coupling (Tgas/Tdust<2) and the gas-to-dust ratio in the surface layer is very likely <1000.CRIRES project: The H2 lines at 2.1218 μm and 2.2233 μm are detected in LkHα 264. An upper limit on the 2.2477 μm H2 line flux in LkHα 264 is derived. 49 Cet does not exhibit H2 emission in any of observed lines. There are a few MMoon of optically thin hot H2 in the inner disk (∼0.1 AU) of LkHα 264, and less than a tenth of a MMoon of hot H2 in the inner disk of 49 Cet. The shape of the 1–0 S(0) line indicates that LkHα disk is close to face-on (i<35o). The measured 1–0 S(0)/1–0 S(1) and 2–1 S(1)/1–0 S(1) line ratios in LkHα 264 indicate that the H2 is thermally excited at T<1500 K. The lack of H2 emission in the NIR spectra of 49 Cet and the absence of Hα emission suggest that the gas in the inner disk of 49 Cet has dissipated.

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