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• W1999848878 endingPage "1094" @default.
• W1999848878 startingPage "1074" @default.
• W1999848878 abstract "We present ISO Short-Wavelength Spectrometer observations of H_2 pure-rotational line emission from the disks around low- and intermediate-mass pre-main-sequence stars as well as from young stars thought to be surrounded by debris disks. The pre-main-sequence sources have been selected to be isolated from molecular clouds and to have circumstellar disks revealed by millimeter interferometry. We detect ��warm (T ≈100-200 K) H_2 gas around many sources, including tentatively the debris-disk objects. The mass of this warm gas ranges from ~ 10^(-4) M_☉ up to 8 x 10^(-3) and can constitute a nonnegligible fraction of the total disk mass. Complementary single-dish ^(12)CO 3-2/^(13)CO 3-2, and ^(12)CO 6-5 observations have been obtained as well. These transitions probe cooler gas at T ≈ 20-80 K.Most objects show a double-peaked CO emission profile characteristic of a disk in Keplerian rotation,consistent with interferometer data on the lower J lines. The ratios of the ^(12)CO 3-2/^(13)CO 3-2 integratedfluxes indicate that ^(12)CO 3-2 is optically thick but that ^(13)CO 3-2 is optically or at most moderatelythick. The ^(13)CO 3-2 lines have been used to estimate the cold gas mass. If a H_2/CO conversion factor of 1 x 10^(-4) is adopted, the derived cold gas masses are factors of 10-200 lower than those deduced from 1.3 millimeter dust emission assuming a gas/dust ratio of 100, in accordance with previous studies. These findings confirm that CO is not a good tracer of the total gas content in disks since it can be photodissociated in the outer layers and frozen onto grains in the cold dense part of disks, but that it isa robust tracer of the disk velocity field. In contrast, H_2 can shield itself from photodissociation even in low-mass ��optically thin debris disks and can therefore survive longer. The warm gas is typically 1%-10% of the total mass deduced from millimeter continuum emission, but it can increase up to 100% or more for the debris-disk objects. Thus, residual molecular gas may persist into the debris-disk phase. No significant evolution in the H_2 CO, or dust masses is found for stars with ages in the range of 10^6-10^7 yr, although a decrease is found for the older debris-disk star β Pictoris. The large amount ofwarm gas derived from H_2 raises the question of the heating mechanism(s). Radiation from the central star as well as the general interstellar radiation field heat an extended surface layer of the disk, but existingmodels fail to explain the amount of warm gas quantitatively. The existence of a gap in the disk canincrease the area of material influenced by radiation. Prospects for future observations with ground- andspace-borne observations are discussed." @default.
• W1999848878 created "2016-06-24" @default.
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• W1999848878 date "2001-11-10" @default.
• W1999848878 modified "2023-09-27" @default.
• W1999848878 title "H₂and CO Emission from Disks around T Tauri and Herbig Ae Pre–Main‐Sequence Stars and from Debris Disks around Young Stars: Warm and Cold Circumstellar Gas" @default.
• W1999848878 cites W1580997327 @default.
• W1999848878 cites W1584082008 @default.
• W1999848878 cites W1590874663 @default.
• W1999848878 cites W1620503833 @default.
• W1999848878 cites W1668940687 @default.
• W1999848878 cites W176257361 @default.
• W1999848878 cites W1965861082 @default.
• W1999848878 cites W1970716866 @default.
• W1999848878 cites W1972551044 @default.
• W1999848878 cites W1975985072 @default.
• W1999848878 cites W1977521416 @default.
• W1999848878 cites W1983103860 @default.
• W1999848878 cites W1984310872 @default.
• W1999848878 cites W1986287730 @default.
• W1999848878 cites W1987892460 @default.
• W1999848878 cites W1996883839 @default.
• W1999848878 cites W1998759826 @default.
• W1999848878 cites W2004718660 @default.
• W1999848878 cites W2005737883 @default.
• W1999848878 cites W2014488392 @default.
• W1999848878 cites W2016301569 @default.
• W1999848878 cites W2021657959 @default.
• W1999848878 cites W2022154208 @default.
• W1999848878 cites W2025976467 @default.
• W1999848878 cites W2027455535 @default.
• W1999848878 cites W2028855598 @default.
• W1999848878 cites W2029780970 @default.
• W1999848878 cites W2029879978 @default.
• W1999848878 cites W2042157478 @default.
• W1999848878 cites W2042484924 @default.
• W1999848878 cites W2042967366 @default.
• W1999848878 cites W2045125693 @default.
• W1999848878 cites W2047379513 @default.
• W1999848878 cites W2049106187 @default.
• W1999848878 cites W2049896064 @default.
• W1999848878 cites W2052596987 @default.
• W1999848878 cites W2055268292 @default.
• W1999848878 cites W2055281353 @default.
• W1999848878 cites W2055504759 @default.
• W1999848878 cites W2057906648 @default.
• W1999848878 cites W2059079048 @default.
• W1999848878 cites W2061294857 @default.
• W1999848878 cites W2061613524 @default.
• W1999848878 cites W2062925626 @default.
• W1999848878 cites W2068433364 @default.
• W1999848878 cites W2069199724 @default.
• W1999848878 cites W2069627637 @default.
• W1999848878 cites W2072697696 @default.
• W1999848878 cites W2073614690 @default.
• W1999848878 cites W2073663120 @default.
• W1999848878 cites W2077447312 @default.
• W1999848878 cites W2081363656 @default.
• W1999848878 cites W2082649481 @default.
• W1999848878 cites W2086744064 @default.
• W1999848878 cites W2094844733 @default.
• W1999848878 cites W2099559854 @default.
• W1999848878 cites W2100614057 @default.
• W1999848878 cites W2101024055 @default.
• W1999848878 cites W2105150351 @default.
• W1999848878 cites W2111511689 @default.
• W1999848878 cites W2122216910 @default.
• W1999848878 cites W2123144427 @default.
• W1999848878 cites W2130768068 @default.
• W1999848878 cites W2131287406 @default.
• W1999848878 cites W2157721384 @default.
• W1999848878 cites W2242874704 @default.
• W1999848878 cites W3045781907 @default.
• W1999848878 cites W3098904422 @default.
• W1999848878 cites W3100630914 @default.
• W1999848878 cites W3101286584 @default.
• W1999848878 cites W3102115841 @default.
• W1999848878 cites W3105451511 @default.
• W1999848878 cites W3124737761 @default.
• W1999848878 cites W3157917098 @default.
• W1999848878 cites W343244306 @default.
• W1999848878 cites W4251585788 @default.
• W1999848878 cites W2007116956 @default.
• W1999848878 cites W2100252771 @default.
• W1999848878 doi "https://doi.org/10.1086/323361" @default.
• W1999848878 hasPublicationYear "2001" @default.
• W1999848878 type Work @default.
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