The GRAVITY Young Stellar Object survey — IX. Spatially resolved kinematics of hot hydrogen gas in the star/disk interaction region of T Tauri stars. (arXiv:2210.13095v3 [astro-ph.SR] UPDATED)

The GRAVITY Young Stellar Object survey — IX. Spatially resolved kinematics of hot hydrogen gas in the star/disk interaction region of T Tauri stars. (arXiv:2210.13095v3 [astro-ph.SR] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Collaboration_GRAVITY/0/1/0/all/0/1">GRAVITY Collaboration</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wojtczak_J/0/1/0/all/0/1">J. A. Wojtczak</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Labadie_L/0/1/0/all/0/1">L. Labadie</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Perraut_K/0/1/0/all/0/1">K. Perraut</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Tessore_B/0/1/0/all/0/1">B. Tessore</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Soulain_A/0/1/0/all/0/1">A. Soulain</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Ganci_V/0/1/0/all/0/1">V. Ganci</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Bouvier_J/0/1/0/all/0/1">J. Bouvier</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Dougados_C/0/1/0/all/0/1">C. Dougados</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Alecian_E/0/1/0/all/0/1">E. Alécian</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Nowacki_H/0/1/0/all/0/1">H. Nowacki</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Cozzo_G/0/1/0/all/0/1">G. Cozzo</a> (2,15), <a href="http://arxiv.org/find/astro-ph/1/au:+Brandner_W/0/1/0/all/0/1">W. Brandner</a> (3), <a href="http://arxiv.org/find/astro-ph/1/au:+Garatti_A/0/1/0/all/0/1">A. Caratti o Garatti</a> (3,6,7), <a href="http://arxiv.org/find/astro-ph/1/au:+Garcia_P/0/1/0/all/0/1">P. Garcia</a> (9,10), <a href="http://arxiv.org/find/astro-ph/1/au:+Lopez_R/0/1/0/all/0/1">R. Garcia Lopez</a> (3,6,11), <a href="http://arxiv.org/find/astro-ph/1/au:+Sanchez_Bermudez_J/0/1/0/all/0/1">J. Sanchez-Bermudez</a> (3,8), <a href="http://arxiv.org/find/astro-ph/1/au:+Amorim_A/0/1/0/all/0/1">A. Amorim</a> (9,12), <a href="http://arxiv.org/find/astro-ph/1/au:+Benisty_M/0/1/0/all/0/1">M. Benisty</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Berger_J/0/1/0/all/0/1">J.-P. Berger</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Bourdarot_G/0/1/0/all/0/1">G. Bourdarot</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Caselli_P/0/1/0/all/0/1">P. Caselli</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Clenet_Y/0/1/0/all/0/1">Y. Clénet</a> (13), <a href="http://arxiv.org/find/astro-ph/1/au:+Zeeuw_P/0/1/0/all/0/1">P. T. de Zeeuw</a> (4,14), <a href="http://arxiv.org/find/astro-ph/1/au:+Davies_R/0/1/0/all/0/1">R. Davies</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Drescher_A/0/1/0/all/0/1">A. Drescher</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Duvert_G/0/1/0/all/0/1">G. Duvert</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Eckart_A/0/1/0/all/0/1">A. Eckart</a> (1,5), <a href="http://arxiv.org/find/astro-ph/1/au:+Eisenhauer_F/0/1/0/all/0/1">F. Eisenhauer</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Eupen_F/0/1/0/all/0/1">F. Eupen</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Foster_Schreiber_N/0/1/0/all/0/1">N. M. Föster-Schreiber</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Gendron_E/0/1/0/all/0/1">E. Gendron</a> (13), <a href="http://arxiv.org/find/astro-ph/1/au:+Gillessen_S/0/1/0/all/0/1">S. Gillessen</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Grant_S/0/1/0/all/0/1">S. Grant</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Grellmann_R/0/1/0/all/0/1">R. Grellmann</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Heissel_G/0/1/0/all/0/1">G. Heißel</a> (13), <a href="http://arxiv.org/find/astro-ph/1/au:+Henning_T/0/1/0/all/0/1">Th. Henning</a> (3), <a href="http://arxiv.org/find/astro-ph/1/au:+Hippler_S/0/1/0/all/0/1">S. Hippler</a> (3), <a href="http://arxiv.org/find/astro-ph/1/au:+Horrobin_M/0/1/0/all/0/1">M. Horrobin</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Hubert_Z/0/1/0/all/0/1">Z. Hubert</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Jocou_L/0/1/0/all/0/1">L. Jocou</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Kervella_P/0/1/0/all/0/1">P. Kervella</a> (13), <a href="http://arxiv.org/find/astro-ph/1/au:+Labour_S/0/1/0/all/0/1">S. Labour</a> (13), <a href="http://arxiv.org/find/astro-ph/1/au:+Lapeyrere_V/0/1/0/all/0/1">V. Lapeyrère</a> (13), et al. (17 additional authors not shown)

Aims: We aim to spatially and spectrally resolve the Br-gamma hydrogen
emission line with the methods of interferometry in order to examine the
kinematics of the hydrogen gas emission region in the inner accretion disk of a
sample of solar-like young stellar objects. The goal is to identify trends and
categories among the sources of our sample and to discuss whether or not they
can be tied to different origin mechanisms associated with Br-gamma emission in
T Tauri stars, chiefly and most prominently magnetospheric accretion.

Methods: We observed a sample of seven T Tauri stars for the first time with
VLTI GRAVITY, recording spectra and spectrally dispersed interferometric
quantities across the Br-gamma line in the NIR K-band. We use them to extract
the size of the Br-gamma emission region and the photocenter shifts. To assist
in the interpretation, we also make use of radiative transfer models of
magnetospheric accretion to establish a baseline of expected interferometric
signatures if accretion is the primary driver of Br-gamma emission.

Results: From among our sample, we find that five of the seven T~Tauri stars
show an emission region with a half-flux radius in the range broadly expected
for magnetospheric truncation. Two of the five objects also show Br-gamma
emission primarily originating from within the corotation radius, while two
other objects exhibit extended emission on a scale beyond 10 R$_*$, one of them
even beyond the K~band continuum half-flux radius of 11.3 R$_*$.

Conclusions: We find strong evidence to suggest that for the two weakest
accretors in the sample, magnetospheric accretion is the primary driver of
Br-gamma radiation. The results for the remaining sources imply either partial
or strong contributions coming from spatially extended emission components in
the form of outflows, such as stellar or disk winds.

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