Peering into the formation history of beta Pictoris b with VLTI/GRAVITY long baseline interferometry
| Autor: | GRAVITY Collaboration, Nowak, M., Lacour, S., Mollière, P., Wang, J., Charnay, B., van Dishoeck, E. F., Abuter, R., Amorim, A., Berger, J. P., Beust, H., Bonnefoy, M., Bonnet, H., Brandner, W., Buron, A., Cantalloube, F., Collin, C., Chapron, F., Clenet, Y., Foresto, V. Coude du, de Zeeuw, P. T., Dembet, R., Dexter, J., Duvert, G., Eckart, A., Eisenhauer, F., Schreiber, N. M. Forster, Fédou, P., Lopez, R. Garcia, Gao, F., Gendron, E., Genzel, R., Gillessen, S., Haußmann, F., Henning, T., Hippler, S., Hubert, Z., Jocou, L., Kervella, P., Lagrange, A. -M., Lapeyrere, V., Bouquin, J. -B. Le, Lena, P., Maire, A. -L., Ott, T., Paumard, T., Paladini, C., Perraut, K., Perrin, G., Pueyo, L., Pfuhl, O., Rabien, S., Rau, C., Rodriguez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., Vincent, F., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Ziegler, D. |
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| Rok vydání: | 2019 |
| Předmět: | |
| Zdroj: | A&A 633, A110 (2020) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/201936898 |
| Popis: | Our objective is to estimate the C/O ratio in the atmosphere of beta Pictoris b and obtain an estimate of the dynamical mass of the planet, as well as to refine its orbital parameters using high-precision astrometry. We used the GRAVITY instrument with the four 8.2 m telescopes of the Very Large Telescope Interferometer to obtain K-band spectro-interferometric data on $\beta$ Pic b. We extracted a medium resolution (R=500) K-band spectrum of the planet and a high-precision astrometric position. We estimated the planetary C/O ratio using two different approaches (forward modeling and free retrieval) from two different codes (ExoREM and petitRADTRANS, respectively). Finally, we used a simplified model of two formation scenarios (gravitational collapse and core-accretion) to determine which can best explain the measured C/O ratio. Our new astrometry disfavors a circular orbit for $\beta$ Pic b ($e=0.15^{+0.05}_{-0.04}$). Combined with previous results and with Hipparcos/GAIA measurements, this astrometry points to a planet mass of $M = 12.7\pm{}2.2\,M_\mathrm{Jup}$. This value is compatible with the mass derived with the free-retrieval code petitRADTRANS using spectral data only. The forward modeling and free-retrieval approches yield very similar results regarding the atmosphere of beta Pic b. In particular, the C/O ratios derived with the two codes are identical ($0.43\pm{}0.05$ vs $0.43^{+0.04}_{-0.03}$). We argue that if the stellar C/O in $\beta$ Pic is Solar, then this combination of a very high mass and a low C/O ratio for the planet suggests a formation through core-accretion, with strong planetesimal enrichment. Comment: 14 pages + 7 page appendix, 7 figures, accepted for pulication |
| Databáze: | arXiv |
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