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

Koutoulaki, M., Lopez, R. G., Natta, A., Fedriani, R., Garatti, A. C. o., Ray, T. P., et al. (2021). The GRAVITY young stellar object survey: IV. The CO overtone emission in 51 Oph at sub-au scales. Astronomy and Astrophysics, 645: A50. doi:10.1051/0004-6361/202038000.

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Koutoulaki, M., Author
Lopez, R. Garcia, Author
Natta, A., Author
Fedriani, R., Author
Garatti, A. Caratti o, Author
Ray, T. P., Author
Coffey, D., Author
Brandner, W., Author
Dougados, C., Author
Garcia, P. J. V., Author
Klarmann, L., Author
Labadie, L., Author
Perraut, K., Author
Sanchez-Bermudez, J., Author
Lin, C.-C., Author
Amorim, A., Author
Bauböck, M.1, Author              
Benisty, M., Author
Berger, J. P., Author
Buron, A.2, Author              
Caselli, P.3, Author              Clénet, Y., Authordu Foresto, V. Coudé, Authorde Zeeuw, P. T.1, Author              Duvert, G., Authorde Wit, W., AuthorEckart, A., AuthorEisenhauer, F.1, Author              Filho, M., AuthorGao, F.1, Author              Gendron, E., AuthorGenzel, R.1, Author              Gillessen, S.1, Author              Grellmann, R., AuthorHabibi, M.1, Author              Haubois, X., AuthorHaussmann, F.1, Author              Henning, T., AuthorHippler, S., AuthorHubert, Z., AuthorHorrobin, M., AuthorJimenez Rosales, A.1, Author              Jocou, L., AuthorKervella, P., AuthorKolb, J., AuthorLacour, S., AuthorLe Bouquin, J.-B., AuthorLéna, P., AuthorLinz, H., AuthorOtt, T.1, Author              Paumard, T., AuthorPerrin, G., AuthorPfuhl, O., AuthorRamírez-Tannus, M. C., AuthorRau, C.2, Author              Rousset, G., AuthorScheithauer, S., AuthorShangguan, J.1, Author              Stadler, J.1, Author              Straub, O.1, Author              Straubmeier, C., AuthorSturm, E.1, Author              Dishoeck, E. van1, Author              Vincent, F., AuthorFellenberg, S. von1, Author              Widmann, F.1, Author              Wieprecht, E.1, Author              Wiest, M., AuthorWiezorrek, E.1, Author              Yazici, S.1, Author              Zins, G., Author more..
1Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society, ou_159889              
2MPI for Extraterrestrial Physics, Max Planck Society, ou_159888              
3Center for Astrochemical Studies at MPE, MPI for Extraterrestrial Physics, Max Planck Society, ou_1950287              


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 Abstract: 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.


Language(s): eng - English
 Dates: 2021-01-07
 Publication Status: Published online
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: -
 Identifiers: DOI: 10.1051/0004-6361/202038000
Other: LOCALID: 3289603
 Degree: -



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Title: Astronomy and Astrophysics
  Other : Astron. Astrophys.
Source Genre: Journal
Publ. Info: France : EDP Sciences S A
Pages: - Volume / Issue: 645 Sequence Number: A50 Start / End Page: - Identifier: ISSN: 1432-0746
CoNE: https://pure.mpg.de/cone/journals/resource/954922828219_1