2000ApJ...538..885S


Query : 2000ApJ...538..885S

2000ApJ...538..885S - Astrophys. J., 538, 885-903 (2000/August-1)

Albedo and reflection spectra of extrasolar giant planets.

SUDARSKY D., BURROWS A. and PINTO P.

Abstract (from CDS):

We generate theoretical albedo and reflection spectra for a full range of extrasolar giant planet (EGP) models, from Jovian to 51 Pegasi class objects. Our albedo modeling utilizes the latest atomic and molecular cross sections, Mie theory treatment of scattering and absorption by condensates, a variety of particle size distributions, and an extension of the Feautrier technique, which allows for a general treatment of the scattering phase function. We find that, because of qualitative similarities in the compositions and spectra of objects within each of five broad effective temperature ranges, it is natural to establish five representative EGP albedo classes. At low effective temperatures (Teff≲150 K) is a class of ``Jovian'' objects (class I) with tropospheric ammonia clouds. Somewhat warmer class II, or ``water cloud'', EGPs are primarily affected by condensed H2O. Gaseous methane absorption features are prevalent in both classes. In the absence of nonequilibrium condensates in the upper atmosphere, and with sufficient H2O condensation, class II objects are expected to have the highest visible albedos of any class. When the upper atmosphere of an EGP is too hot for H2O to condense, radiation generally penetrates more deeply. In these objects, designated class III or ``clear'' because of a lack of condensation in the upper atmosphere, absorption lines of the alkali metals, sodium and potassium, lower the albedo significantly throughout the visible. Furthermore, the near-infrared albedo is negligible, primarily because of strong CH4 and H2O molecular absorption and collision-induced absorption (CIA) by H2 molecules. In those EGPs with exceedingly small orbital distance (``roasters'') and 900 K≲Teff≲1500 K (class IV), a tropospheric silicate layer is expected to exist. In all but the hottest (Teff≳1500 K) or lowest gravity roasters, the effect of this silicate layer is likely to be insignificant because of the very strong absorption by sodium and potassium atoms above the layer. The resonance lines of sodium and potassium are expected to be salient features in the reflection spectra of these EGPs. In the absence of nonequilibrium condensates, we find, in contrast to previous studies, that these class IV roasters likely have the lowest visible and Bond albedos of any class, rivaling the lowest albedos of our solar system. For the small fraction of roasters with Teff≳1500 K and/or low surface gravity (≲103 cm.s–2; class V), the silicate layer is located very high in the atmosphere, reflecting much of the incident radiation before it can reach the absorbing alkali metals and molecular species. Hence, the class V roasters have much higher albedos than those of class IV. In addition, for class V objects, UV irradiation may result in significant alkali metal ionization, thereby further weakening the alkali metal absorption lines. We derive Bond albedos (AB) and Teff estimates for the full set of known EGPs. A broad range in both values is found, with Teff ranging from ∼150 to nearly 1600 K, and AB from ∼0.02 to 0.8. We find that variations in particle size distributions and condensation fraction can have large quantitative, or even qualitative, effects on albedo spectra. In general, less condensation, larger particle sizes, and wider size distributions result in lower albedos. We explore the effects of nonequilibrium condensed products of photolysis above or within principal cloud decks. As in Jupiter, such species can lower the UV/blue albedo substantially, even if present in relatively small mixing ratios.

Abstract Copyright:

Journal keyword(s): Molecular Processes - Stars: Planetary Systems - Scattering

CDS comments: Table 3: HD 199263b is a misprint for HD 192263b.

Simbad objects: 35

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Number of rows : 35
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 * nu. And SB* 00 49 48.8473652 +41 04 44.076380 3.80 4.38 4.53 4.56 4.71 B5V 209 0
2 * ups And c Pl 01 36 47.84216 +41 24 19.6443           ~ 153 1
3 * ups And d Pl 01 36 47.84216 +41 24 19.6443           ~ 159 1
4 * ups And b Pl 01 36 47.84216 +41 24 19.6443           ~ 265 1
5 HD 13445 PM* 02 10 25.9181700303 -50 49 25.465181208   6.945 6.117     K1.5V 438 1
6 HD 13445b Pl 02 10 25.9190575041 -50 49 25.467227759           ~ 97 1
7 * iot Hor b Pl 02 42 33.4664838826 -50 48 01.056222150           ~ 45 1
8 HD 75289b Pl 08 47 40.3895634256 -41 44 12.456269569           ~ 86 1
9 * rho01 Cnc PM* 08 52 35.8111044043 +28 19 50.954994470 7.45 6.82   5.4   K0IV-V 1059 1
10 * rho01 Cnc b Pl 08 52 35.8113282132 +28 19 50.956901366           ~ 251 1
11 * rho01 Cnc c Pl 08 52 35.8113282132 +28 19 50.956901366           ~ 135 1
12 * 47 UMa PM* 10 59 27.9727514012 +40 25 48.920572724   5.66   4.7   G1-VFe-0.5 753 1
13 * 47 UMa b Pl 10 59 27.9738644892 +40 25 48.922388918           ~ 153 1
14 HD 114762C LM* 13 12 19.7410686234 +17 31 01.630334317           ~ 127 0
15 * 70 Vir b Pl 13 28 25.8081883620 +13 46 43.642951116           ~ 108 1
16 * tau Boo Ro* 13 47 15.7381720026 +17 27 24.809555600 5.02 4.98 4.49 4.09 3.85 F7IV-V 953 1
17 * tau Boo b Pl 13 47 15.74340 +17 27 24.8552           ~ 269 1
18 HD 130322b Pl 14 47 32.7265637197 -00 16 53.305928889           ~ 57 1
19 HD 131977 BY* 14 57 28.0007918772 -21 24 55.727265310 7.89 6.83 5.72 4.74 4.19 K4V 470 0
20 HD 131977b Pl? 14 57 28.0008928545 -21 24 55.726897561           ~ 2 0
21 * rho CrB b Pl 16 01 02.6608052290 +33 18 12.642245533           ~ 73 1
22 * 14 Her b Pl 16 10 24.3152754550 +43 49 03.498734567           ~ 76 1
23 HD 168443b Pl 18 20 03.9331764016 -09 35 44.609316076           ~ 93 1
24 * 16 Cyg B PM* 19 41 51.9726777456 +50 31 03.089030916 7.07 6.86 6.20 5.76 5.42 G3V 856 1
25 * 16 Cyg Bb Pl 19 41 51.9731830550 +50 31 03.086127222           ~ 124 1
26 HD 187123b Pl 19 46 58.1122608389 +34 25 10.279867125           ~ 85 1
27 HD 192263b Pl 20 13 59.8455148268 -00 52 00.771665295           ~ 60 1
28 HD 195019b Pl 20 28 18.6366531368 +18 46 10.179936391           ~ 66 1
29 * phi02 Pav PM* 20 40 02.6374808954 -60 32 56.018592211   5.63 5.121     G0VFe-0.8CH-0.5 171 1
30 HD 196378b err 20 40 02.6377 -60 32 56.012           ~ 4 1
31 HD 209458b Pl 22 03 10.7729598762 +18 53 03.548248479           ~ 1741 1
32 HD 210277b Pl 22 09 29.8657193934 -07 32 55.163014863           ~ 51 1
33 BD-15 6290b Pl 22 53 16.7323107416 -14 15 49.303409936           ~ 240 1
34 * 51 Peg b Pl 22 57 27.9804167474 +20 46 07.782240714           ~ 618 1
35 HD 217107b Pl 22 58 15.5411942071 -02 23 43.387117210           ~ 90 1

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2023.01.30-06:14:07

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