2016A&A...587A..58B


Query : 2016A&A...587A..58B

2016A&A...587A..58B - Astronomy and Astrophysics, volume 587A, 58-58 (2016/3-1)

First light of the VLT planet finder SPHERE. IV. Physical and chemical properties of the planets around HR 8799.

BONNEFOY M., ZURLO A., BAUDINO J.L., LUCAS P., MESA D., MAIRE A.-L., VIGAN A., GALICHER R., HOMEIER D., MAROCCO F., GRATTON R., CHAUVIN G., ALLARD F., DESIDERA S., KASPER M., MOUTOU C., LAGRANGE A.-M., ANTICHI J., BARUFFOLO A., BAUDRAND J., BEUZIT J.-L., BOCCALETTI A., CANTALLOUBE F., CARBILLET M., CHARTON J., CLAUDI R.U., COSTILLE A., DOHLEN K., DOMINIK C., FANTINEL D., FEAUTRIER P., FELDT M., FUSCO T., GIGAN P., GIRARD J.H., GLUCK L., GRY C., HENNING T., JANSON M., LANGLOIS M., MADEC F., MAGNARD Y., MAUREL D., MAWET D., MEYER M.R., MILLI J., MOELLER-NILSSON O., MOUILLET D., PAVLOV A., PERRET D., PUJET P., QUANZ S.P., ROCHAT S., ROUSSET G., ROUX A., SALASNICH B., SALTER G., SAUVAGE J.-F., SCHMID H.M., SEVIN A., SOENKE C., STADLER E., TURATTO M., UDRY S., VAKILI F., WAHHAJ Z. and WILDI F.

Abstract (from CDS):

The system of four planets discovered around the intermediate-mass star HR8799 offers a unique opportunity to test planet formation theories at large orbital radii and to probe the physics and chemistry at play in the atmospheres of self-luminous young (∼30Myr) planets. We recently obtained new photometry of the four planets and low-resolution (R∼30) spectra of HR8799 d and e with the SPHERE instrument (Paper III). In this paper (Paper IV), we aim to use these spectra and available photometry to determine how they compare to known objects, what the planet physical properties are, and how their atmospheres work. We compare the available spectra, photometry, and spectral energy distribution (SED) of the planets to field dwarfs and young companions. In addition, we use the extinction from corundum, silicate (enstatite and forsterite), or iron grains likely to form in the atmosphere of the planets to try to better understand empirically the peculiarity of their spectrophotometric properties. To conclude, we use three sets of atmospheric models (BT-SETTL14, Cloud-AE60, Exo-REM) to determine which ingredients are critically needed in the models to represent the SED of the objects, and to constrain their atmospheric parameters (Teff, logg, M/H). We find that HR8799d and e properties are well reproduced by those of L6-L8 dusty dwarfs discovered in the field, among which some are candidate members of young nearby associations. No known object reproduces well the properties of planets b and c. Nevertheless, we find that the spectra and WISE photometry of peculiar and/or young early-T dwarfs reddened by submicron grains made of corundum, iron, enstatite, or forsterite successfully reproduce the SED of these planets. Our analysis confirms that only the Exo-REM models with thick clouds fit (within 2σ) the whole set of spectrophotometric datapoints available for HR8799 d and e for Teff=1200K, logg in the range 3.0-4.5, and M/H=+0.5. The models still fail to reproduce the SED of HR8799c and b. The determination of the metallicity, logg, and cloud thickness are degenerate. Our empirical analysis and atmospheric modelling show that an enhanced content in dust and decreased CIA of H2 is certainly responsible for the deviation of the properties of the planet with respect to field dwarfs. The analysis suggests in addition that HR8799c and b have later spectral types than the two other planets, and therefore could both have lower masses.

Abstract Copyright:

Journal keyword(s): instrumentation: high angular resolution - stars: individual: HR8799 - planets and satellites: atmospheres - planets and satellites: detection - techniques: imaging spectroscopy - planets and satellites: fundamental parameters

Simbad objects: 26

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Number of rows : 26
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 2MASS J00470038+6803543 BD* 00 47 00.38664 +68 03 54.3672           L9pec 77 0
2 LEHPM 1481B BD* 01 22 50.86 -24 39 51.6           L4-6 34 0
3 2MASS J02062493+2640237 BD* 02 06 24.93192 +26 40 23.7540           L9pec 18 0
4 HD 44627B BD* 06 19 12.9988086984 -58 03 20.198341332           L1 131 1
5 NAME AB Dor Moving Group MGr 06 38 53.4 -42 50 04           ~ 470 0
6 2MASS J06420559+4101599 BD* 06 42 05.59200 +41 01 59.9988           L9 16 0
7 2MASS J07542987+7909546 BD* 07 54 29.87616 +79 09 54.6084           T2p? 14 0
8 TWA 27B BD* 12 07 33.50 -39 32 54.4           L3 279 0
9 SIPS J1256-1257B BD* 12 56 01.83264 -12 57 27.6912           L7 80 0
10 2MASS J13243553+6358281 BD* 13 24 35.53752 +63 58 28.1532           L8.0+T3.5 49 0
11 NAME beta Pic Moving Group MGr 14 30 -42.0           ~ 768 0
12 2MASS J15164306+3053443 BD* 15 16 43.06536 +30 53 44.3436           L8.0+L9.5 33 0
13 RX J1609.5-2105 Y*O 16 09 30.3075290712 -21 04 58.943800992   14.21 12.77 12.25 10.99 M0.0e 92 0
14 2MASS J16471580+5632057 BD* 16 47 15.80544 +56 32 05.7264           L9pec 33 0
15 WISE J173859.27+614242.1 BD* 17 38 59.27544 +61 42 42.1668           Y/T 8 0
16 2MASS J17410280-4642218 BD* 17 41 02.80656 -46 42 21.8520           L5:gamma 23 0
17 2MASS J21140802-2251358 BD* 21 14 08.02560 -22 51 35.8380           L7.5 108 0
18 HD 203030B BD* 21 18 58.97 +26 13 46.1           L7.5 71 0
19 CFBDS J213926+022023 BD* 21 39 26.76936 +02 20 22.6968           L8.5+T3.5 90 0
20 V* HN Peg B BD* 21 44 28.47168 +14 46 07.7988           T2.5 125 0
21 2MASS J22271087-0045471 BD* 22 27 10.913 -00 45 47.31           L7.0 15 0
22 HD 218396d Pl 23 07 28.7157209544 +21 08 03.310767492           ~ 235 1
23 HD 218396b Pl 23 07 28.7157209544 +21 08 03.310767492           ~ 274 1
24 HD 218396e Pl 23 07 28.7157209544 +21 08 03.310767492           ~ 204 1
25 HD 218396c Pl 23 07 28.7157209544 +21 08 03.310767492           ~ 256 1
26 HD 218396 El* 23 07 28.7157209544 +21 08 03.310767492   6.21 5.953     F0+VkA5mA5 1123 0

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