The GRAVITY young stellar object survey: IV. The CO overtone emission in 51 Oph at sub-au scales
Journal article, 2021

Context. 51 Oph is a Herbig Ae/Be star that exhibits strong near-infrared CO ro-vibrational emission at 2.3 μm, most likely originating in the innermost regions of a circumstellar disc. Aims. We aim to obtain the physical and geometrical properties of the system by spatially resolving the circumstellar environment of the inner gaseous disc. Methods. We used the second-generation Very Large Telescope Interferometer instrument GRAVITY to spatially resolve the continuum and the CO overtone emission. We obtained data over 12 baselines with the auxiliary telescopes and derive visibilities, and the differential and closure phases as a function of wavelength. We used a simple local thermal equilibrium ring model of the CO emission to reproduce the spectrum and CO line displacements. Results. Our interferometric data show that the star is marginally resolved at our spatial resolution, with a radius of ∼10.58 ± 2.65R·. The K-band continuum emission from the disc is inclined by 63° ± 1°, with a position angle of 116° ± 1°, and 4 ± 0.8 mas (0.5 ± 0.1 au) across. The visibilities increase within the CO line emission, indicating that the CO is emitted within the dust-sublimation radius. By modelling the CO bandhead spectrum, we derive that the CO is emitted from a hot (T = 1900-2800 K) and dense (NCO = (0.9-9) × 1021 cm-2) gas. The analysis of the CO line displacement with respect to the continuum allows us to infer that the CO is emitted from a region 0.10 ± 0.02 au across, well within the dust-sublimation radius. The inclination and position angle of the CO line emitting region is consistent with that of the dusty disc. Conclusions. Our spatially resolved interferometric observations confirm the CO ro-vibrational emission within the dust-free region of the inner disc. Conventional disc models exclude the presence of CO in the dust-depleted regions of Herbig AeBe stars. Ad hoc models of the innermost disc regions, that can compute the properties of the dust-free inner disc, are therefore required.

Accretion, accretion disks

Stars: pre-main sequence

Stars: individual: 51 Oph

Stars: formation

Techniques: interferometric

Author

M. Koutoulaki

Max Planck Society

European Southern Observatory (ESO)

University College Dublin

Dublin Institute for Advanced Studies

R. Garcia-Lopez

University College Dublin

Max Planck Society

Dublin Institute for Advanced Studies

A. Natta

Dublin Institute for Advanced Studies

Rubén Fedriani

University College Dublin

Dublin Institute for Advanced Studies

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics, Galactic Astrophysics

A. Caratti o. Garatti

Dublin Institute for Advanced Studies

Max Planck Society

University College Dublin

T. P. Ray

Dublin Institute for Advanced Studies

Deirdre Coffey

Dublin Institute for Advanced Studies

Max Planck Society

W. Brandner

Max Planck Society

C. Dougados

Université Grenoble Alpes

P. J.V. Garcia

Instituto Superior Tecnico

University of Porto

European Southern Observatory Santiago

L. Klarmann

Max Planck Society

L. Labadie

University of Cologne

K. Perraut

Université Grenoble Alpes

J. Sanchez-Bermudez

Max Planck Society

Universidad Nacional Autonoma de Mexico

C. C. Lin

University of Hawaii

Max Planck Society

A. Amorim

Instituto Superior Tecnico

University of Lisbon

M. Bauböck

Max Planck Society

M. Benisty

University of Chile (UCH)

Université Grenoble Alpes

J. P. Berger

Université Grenoble Alpes

A. Buron

Max Planck Society

P. Caselli

Max Planck Society

Y. Clénet

Université Paris PSL

V. Coudé Du Foresto

Université Paris PSL

P. T. De Zeeuw

Leiden University

Max Planck Society

G. Duvert

Université Grenoble Alpes

W. J. De Wit

European Southern Observatory Santiago

A. Eckart

Max Planck Society

University of Cologne

F. Eisenhauer

Max Planck Society

M. Filho

Instituto Superior Tecnico

University of Porto

European Southern Observatory Santiago

F. Gao

Max Planck Society

E. Gendron

Université Paris PSL

R. Genzel

Max Planck Society

University of California

S. Gillessen

Max Planck Society

R. Grellmann

University of Cologne

M. Habibi

Max Planck Society

X. Haubois

European Southern Observatory Santiago

F. Haussmann

Max Planck Society

T. Henning

Max Planck Society

S. Hippler

Max Planck Society

Z. Hubert

Université Grenoble Alpes

M. Horrobin

University of Cologne

Alejandra Jimenez-Rosales

Max Planck Society

L. Jocou

Université Grenoble Alpes

P. Kervella

Université Paris PSL

J. Kolb

European Southern Observatory Santiago

S. Lacour

Université Paris PSL

J. B. Le Bouquin

Université Grenoble Alpes

P. Léna

Université Paris PSL

H. Linz

Max Planck Society

T. Ott

Max Planck Society

T. Paumard

Université Paris PSL

G. Perrin

Université Paris PSL

O. Pfuhl

European Southern Observatory (ESO)

M. C. Ramírez-Tannus

Max Planck Society

C. Rau

Max Planck Society

G. Rousset

Université Paris PSL

S. Scheithauer

Max Planck Society

J. Shangguan

Max Planck Society

J. Stadler

Max Planck Society

O. Straub

Max Planck Society

C. Straubmeier

University of Cologne

E. Sturm

Max Planck Society

E. Van Dishoeck

Max Planck Society

Leiden University

F. Vincent

Université Paris PSL

S. von Fellenberg

Max Planck Society

F. Widmann

Max Planck Society

E. Wieprecht

Max Planck Society

M. Wiest

University of Cologne

E. Wiezorrek

Max Planck Society

S. Yazici

Max Planck Society

University of Cologne

G. Zins

European Southern Observatory Santiago

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 645 A50

Subject Categories

Astronomy, Astrophysics and Cosmology

Atom and Molecular Physics and Optics

Geophysics

DOI

10.1051/0004-6361/202038000

More information

Latest update

1/20/2021