Eupen, F., Labadie, L., Grellmann, R., Perraut, K., Brandner, W., Duchene, G., Kohler, R., Sanchez-Bermudez, J., Lopez, R. Garcia, Garatti, A. Caratti O., Benisty, M., Dougados, C., Garcia, P., Klarmann, L., Amorim, A., Baubock, M., Berger, J. P., Caselli, P., Clenet, Y., Foresto, V. Coude du, Zeeuw, P. T. de, Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Filho, M., Ganci, V, Gao, F., Gendron, E., Genzel, R., Gillessen, S., Heissel, G., Henning, Th, Hippler, S., Horrobin, M., Hubert, Z., Jimenez-Rosales, A., Jocou, L., Kervella, P., Lacour, S., Lapeyrere, V, Bouquin, J. B. Le, Lena, P., Ott, T., Paumard, T., Perrin, G., Pfuhl, O., Rodriguez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., van Dishoeck, E., Vincent, F., von Fellenberg, S. D., Widmann, F., Woillez, J. and Wojtczak, A. (2021). The GRAVITY young stellar object survey V. The orbit of the T Tauri binary star WWCha. Astron. Astrophys., 648. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

Context. Close young binary stars are unique laboratories for the direct measurement of pre-main-sequence (PMS) stellar masses and their comparison to evolutionary theoretical models. At the same time, a precise knowledge of their orbital parameters when still in the PMS phase offers an excellent opportunity for understanding the influence of dynamical effects on the morphology and lifetime of the circumstellar as well as circumbinary material. Aims. The young T Tauri star WW Cha was recently proposed to be a close binary object with strong infrared and submillimeter excess associated with circum-system emission, which makes it dynamically a very interesting source in the above context. The goal of this work is to determine the astrometric orbit and the stellar properties of WW Cha using multi-epoch interferometric observations. Methods. We derive the relative astrometric positions and flux ratios of the stellar companion in WW Cha from the interferometric model fitting of observations made with the VLTI instruments AMBER, PIONIER, and GRAVITY in the near-infrared from 2011 to 2020. For two epochs, the resulting uv-coverage in spatial frequencies permits us to perform the first image reconstruction of the system in the K band. The positions of nine epochs are used to determine the orbital elements and the total mass of the system. Combining the orbital solution with distance measurements from Gaia DR2 and the analysis of evolutionary tracks, we constrain the mass ratio. Results. We find the secondary star orbiting the primary with a period of T = 206.55 days, a semimajor axis of a = 1.01 au, and a relatively high eccentricity of e = 0.45. The dynamical mass of M-tot = 3.20 M-circle dot can be explained by a mass ratio between similar to 0.5 and 1, indicating an intermediate-mass T Tauri classification for both components. The orbital angular momentum vector is in close alignment with the angular momentum vector of the outer disk as measured by ALMA and SPHERE, resulting in a small mutual disk inclination. The analysis of the relative photometry suggests the presence of infrared excess surviving in the system and likely originating from truncated circumstellar disks. The flux ratio between the two components appears variable, in particular in the K band, and may hint at periods of triggered higher and lower accretion or changes in the disks' structures. Conclusions. The knowledge of the orbital parameters, combined with a relatively short period, makes WW Cha an ideal target for studying the interaction of a close young T Tauri binary with its surrounding material, such as time-dependent accretion phenomena. Finding WW Cha to be composed of two (probably similar) stars led us to reevaluate the mass of WW Cha, which had been previously derived under the assumption of a single star. This work illustrates the potential of long baseline interferometry to precisely characterize close young binary stars separated by a few astronomical units. Finally, when combined with radial velocity measurements, individual stellar masses can be derived and used to calibrate theoretical PMS models.

Item Type: Journal Article
Creators:
CreatorsEmailORCIDORCID Put Code
Eupen, F.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Labadie, L.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Grellmann, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Perraut, K.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Brandner, W.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Duchene, G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Kohler, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Sanchez-Bermudez, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Lopez, R. GarciaUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Garatti, A. Caratti O.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Benisty, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Dougados, C.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Garcia, P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Klarmann, L.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Amorim, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Baubock, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Berger, J. P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Caselli, P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Clenet, Y.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Foresto, V. Coude duUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Zeeuw, P. T. deUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Drescher, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Duvert, G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Eckart, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Eisenhauer, F.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Filho, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Ganci, VUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Gao, F.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Gendron, E.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Genzel, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Gillessen, S.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Heissel, G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Henning, ThUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Hippler, S.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Horrobin, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Hubert, Z.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Jimenez-Rosales, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Jocou, L.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Kervella, P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Lacour, S.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Lapeyrere, VUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Bouquin, J. B. LeUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Lena, P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Ott, T.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Paumard, T.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Perrin, G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Pfuhl, O.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Rodriguez-Coira, G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Rousset, G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Scheithauer, S.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Shangguan, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Shimizu, T.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Stadler, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Straub, O.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Straubmeier, C.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Sturm, E.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
van Dishoeck, E.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Vincent, F.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
von Fellenberg, S. D.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Widmann, F.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Woillez, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Wojtczak, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
URN: urn:nbn:de:hbz:38-605552
DOI: 10.1051/0004-6361/202039599
Journal or Publication Title: Astron. Astrophys.
Volume: 648
Date: 2021
Publisher: EDP SCIENCES S A
Place of Publication: LES ULIS CEDEX A
ISSN: 1432-0746
Language: English
Faculty: Unspecified
Divisions: Unspecified
Subjects: no entry
Uncontrolled Keywords:
KeywordsLanguage
PRE-MAIN-SEQUENCE; LOW-MASS STARS; CHAMELEON-I; OPTICAL INTERFEROMETRY; CIRCUMSTELLAR DISKS; CIRCUMBINARY DISCS; PULSED ACCRETION; DATA REDUCTION; MULTIPLICITY; POPULATIONMultiple languages
Astronomy & AstrophysicsMultiple languages
URI: http://kups.ub.uni-koeln.de/id/eprint/60555

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