2019A&A...623L..11G

Query : 2019A&A...623L..11G

2019A&A...623L..11G - Astronomy and Astrophysics, volume 623, L11-11 (2019/3-1)

First direct detection of an exoplanet by optical interferometry. Astrometry and K-band spectroscopy of HR 8799 e.

GRAVITY COLLABORATION, LACOUR S., NOWAK M., WANG J., PFUHL O., EISENHAUER F., ABUTER R., AMORIM A., ANUGU N., BENISTY M., BERGER J.P., BEUST H., BLIND N., BONNEFOY M., BONNET H., BOURGET P., BRANDNER W., BURON A., COLLIN C., CHARNAY B., CHAPRON F., CLENET Y., COUDE DU FORESTO V., DE ZEEUW P.T., DEEN C., DEMBET R., DEXTER J., DUVERT G., ECKART A., FORSTER SCHREIBER N.M., FEDOU P., GARCIA P., GARCIA LOPEZ R., GAO F., GENDRON E., GENZEL R., GILLESSEN S., GORDO P., GREENBAUM A., HABIBI M., HAUBOIS X., HAUSSMANN F., HENNING T., HIPPLER S., HORROBIN M., HUBERT Z., JIMENEZ ROSALES A., JOCOU L., KENDREW S., KERVELLA P., KOLB J., LAGRANGE A.-M., LAPEYRERE V., LE BOUQUIN J.-B., LENA P., LIPPA M., LENZEN R., MAIRE A.-L., MOLLIERE P., OTT T., PAUMARD T., PERRAUT K., PERRIN G., PUEYO L., RABIEN S., RAMIREZ A., RAU C., RODRIGUEZ-COIRA G., ROUSSET G., SANCHEZ-BERMUDEZ J., SCHEITHAUER S., SCHUHLER N., STRAUB O., STRAUBMEIER C., STURM E., TACCONI L.J., VINCENT F., VAN DISHOECK E.F., VON FELLENBERG S., WANK I., WAISBERG I., WIDMANN F., WIEPRECHT E., WIEST M., WIEZORREK E., WOILLEZ J., YAZICI S., ZIEGLER D. and ZINS G.

Abstract (from CDS):

Aims. To date, infrared interferometry at best achieved contrast ratios of a few times 10^–4 on bright targets. GRAVITY, with its dual-field mode, is now capable of high contrast observations, enabling the direct observation of exoplanets. We demonstrate the technique on HR 8799, a young planetary system composed of four known giant exoplanets.
Methods. We used the GRAVITY fringe tracker to lock the fringes on the central star, and integrated off-axis on the HR 8799 e planet situated at 390mas from the star. Data reduction included post-processing to remove the flux leaking from the central star and to extract the coherent flux of the planet. The inferred K band spectrum of the planet has a spectral resolution of 500. We also derive the astrometric position of the planet relative to the star with a precision on the order of 100µas.
Results. The GRAVITY astrometric measurement disfavors perfectly coplanar stable orbital solutions. A small adjustment of a few degrees to the orbital inclination of HR 8799 e can resolve the tension, implying that the orbits are close to, but not strictly coplanar. The spectrum, with a signal-to-noise ratio of ~=5 per spectral channel, is compatible with a late-type L brown dwarf. Using Exo-REM synthetic spectra, we derive a temperature of 1150±50K and a surface gravity of 10^4.3±0.3cm/s². This corresponds to a radius of 1.17_–0.11^+0.13R_Jup and a mass of 10_–4⁺⁷M_Jup, which is an independent confirmation of mass estimates from evolutionary models. Our results demonstrate the power of interferometry for the direct detection and spectroscopic study of exoplanets at close angular separations from their stars.

Abstract Copyright: © S. Lacour et al. 2019

Journal keyword(s): stars: individual: HR 8799 - planets and satellites: atmospheres - planet-star interactions - techniques: interferometric

VizieR on-line data: <Available at CDS (J/A+A/623/L11): sp.dat>

Simbad objects: 6

Full paper

View the references in ADS

Number of rows : 6

N	Identifier	Otype	ICRS (J2000) RA	ICRS (J2000) DEC	Mag B	Mag V	Mag I	Sp type	#ref 1850 - 2023	#notes
1	NAME Columba Association	As*	06 04 19.4	-22 20 40				~	274	0
2	NAME Luhman 16A	BD*	10 49 14.0238534572	-53 19 05.005159625				L7.5	48	0
3	NAME Luhman 16	**	10 49 18.91536	-53 19 10.0776	16.86	16.20	14.95	L7.5+T0.5	93	0
4	* 51 Peg b	Pl	22 57 27.9804167474	+20 46 07.782240714				~	646	1
5	HD 218396e	Pl	23 07 28.7156905667	+21 08 03.302133882				~	195	1
6	HD 218396	El*	23 07 28.7157209544	+21 08 03.310767492	6.21	5.953		F0+VkA5mA5	1102	0

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