2022A&A...657A..38M


Query : 2022A&A...657A..38M

2022A&A...657A..38M - Astronomy and Astrophysics, volume 657A, 38-38 (2022/1-1)

Accreting protoplanets: Spectral signatures and magnitude of gas and dust extinction at Hα.

MARLEAU G.-D., AOYAMA Y., KUIPER R., FOLLETTE K., TURNER N.J., CUGNO G., MANARA C.F., HAFFERT S.Y., KITZMANN D., RINGQVIST S.C., WAGNER K.R., VAN BOEKEL R., SALLUM S., JANSON M., SCHMIDT T.O.B., VENUTI L., LOVIS C. and MORDASINI C.

Abstract (from CDS):

Context. Accreting planetary-mass objects have been detected at Hα, but targeted searches have mainly resulted in non-detections. Accretion tracers in the planetary-mass regime could originate from the shock itself, making them particularly susceptible to extinction by the accreting material. High-resolution (R > 50 000) spectrographs operating at Hα should soon enable one to study how the incoming material shapes the line profile. Aims. We calculate how much the gas and dust accreting onto a planet reduce the Hα flux from the shock at the planetary surface and how they affect the line shape. We also study the absorption-modified relationship between the Hα luminosity and accretion rate. Methods. We computed the high-resolution radiative transfer of the Hα line using a one-dimensional velocity-density-temperature structure for the inflowing matter in three representative accretion geometries: spherical symmetry, polar inflow, and magnetospheric accretion. For each, we explored the wide relevant ranges of the accretion rate and planet mass. We used detailed gas opacities and carefully estimated possible dust opacities. Results. At accretion rates of M ≥ 3 x 10–6 MJ/yr, gas extinction is negligible for spherical or polar inflow and at most A ≥ 0.5 mag for magnetospheric accretion. Up to M ≃ 3 x 10–4 MJ/yr^, the gas contributes A ≥ 4 mag. This contribution decreases with mass. We estimate realistic dust opacities at Hα to be κ ∼ 0.01-10 cm2 g–1, which is 10-104 times lower than in the interstellar medium. Extinction flattens the L -M relationship, which becomes non-monotonic with a maximum luminosity L ∼ 10–4 L towards M ≃ 10–4 MJ/yr for a planet mass ∼10 MJ. In magnetospheric accretion, the gas can introduce features in the line profile, while the velocity gradient smears them out in other geometries. Conclusions. For a wide part of parameter space, extinction by the accreting matter should be negligible, simplifying the interpretation of observations, especially for planets in gaps. At high M, strong absorption reduces the Hα flux, and some measurements can be interpreted as two M values. Highly resolved line profiles (R ∼ 105) can provide (complex) constraints on the thermal and dynamical structure of the accretion flow.

Abstract Copyright: © G.-D. Marleau et al. 2021

Journal keyword(s): accretion, accretion disks - planets and satellites: gaseous planets - planets and satellites: detection - planets and satellites: formation - methods: analytical - radiative transfer

Simbad objects: 12

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Number of rows : 12
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 SCR J0103-5515C LM* 01 03 35.58 -55 15 54.6           ~ 37 0
2 EM* LkCa 15b Pl 04 39 17.7912813350 +22 21 03.387667491           ~ 76 1
3 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 4094 0
4 CD-40 8434c Pl 14 08 10.1545137760 -41 23 52.576649494           ~ 103 0
5 CD-40 8434b Pl 14 08 10.1545137760 -41 23 52.576649494           ~ 146 0
6 CD-40 8434 TT* 14 08 10.1545500744 -41 23 52.573291080   13.42 12.18 11.71 10.506 K7IVe 267 0
7 2MASS J15383166-1038507 * 15 38 31.6696868832 -10 38 50.716599252           M5/5.5e 8 0
8 NAME Lupus Complex SFR 16 03 -38.1           ~ 642 0
9 NAME Upper Sco Association As* 16 12 -23.4           ~ 1252 1
10 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 3446 1
11 HD 163296 Ae* 17 56 21.2881851168 -21 57 21.871819008 7.00 6.93 6.85 6.86 6.67 A1Vep 1002 0
12 HD 169142 Ae* 18 24 29.7799891464 -29 46 49.327400568   8.42 8.16     F1VekA3mA3_lB? 408 2

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2023.01.30-22:13:14

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