J/A+A/623/L11 HR8799e K-band spectrum (Lacour+, 2019)
First direct detection of an exoplanet by optical interferometry,
astrometry and K-band spectroscopy of HR8799e.
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.,
Foerster 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., Zins G.
<Astron. Astrophys. 623, L11 (2019)>
=2019A&A...623L..11L 2019A&A...623L..11L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Spectroscopy
Keywords: stars: individual: HR 8799 - planets and satellites: atmospheres -
planet-star interactions - techniques: interferometric
Abstract:
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.
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.
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
104.3±0.3cm.s2. This corresponds to a radius of
1.17-0.11+0.13RJup and a mass of 10-4+7MJup, 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.
Description:
Observations were made with GRAVITY interferomer, on MJD 58358.24, in
the K spectral band at resolution 500.
Objects:
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RA (2000) DE Designation(s)
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23 07 28.72 +21 08 03.3 HR 8799 = HD 218396
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sp.dat 74 237 K band spectrum of HR8799e
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See also:
J/A+A/623/L12 : sdOB star Feige 46 spectrum (Latour+, 2019)
Byte-by-byte Description of file: sp.dat
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Bytes Format Units Label Explanations
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3- 20 F18.10 0.1nm lambda Wavelength
27- 49 E23.17 W/m2/um Flux Flux
53- 74 E22.17 W/m2/um e_Flux rms uncertainty on Flux
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Acknowledgements:
Sulvestre Lacour, sylvestre.lacour(at)obspm.fr
(End) Patricia Vannier [CDS] 05-Mar-2019