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Title: HERSCHEL KEY PROGRAM, ''DUST, ICE, AND GAS IN TIME'' (DIGIT): THE ORIGIN OF MOLECULAR AND ATOMIC EMISSION IN LOW-MASS PROTOSTARS IN TAURUS

Six low-mass embedded sources (L1489, L1551-IRS5, TMR1, TMC1-A, L1527, and TMC1) in Taurus have been observed with Herschel-PACS to cover the full spectrum from 50 to 210 μm as part of the Herschel key program, ''Dust, Ice, and Gas In Time''. The relatively low intensity of the interstellar radiation field surrounding Taurus minimizes contamination of the [C II] emission associated with the sources by diffuse emission from the cloud surface, allowing study of the [C II] emission from the source. In several sources, the [C II] emission is distributed along the outflow, as is the [O I] emission. The atomic line luminosities correlate well with each other, as do the molecular lines, but the atomic and molecular lines correlate poorly. The relative contribution of CO to the total gas cooling is constant at ∼30%, while the cooling fraction by H{sub 2}O varies from source to source, suggesting different shock properties resulting in different photodissociation levels of H{sub 2}O. The gas with a power-law temperature distribution with a moderately high density can reproduce the observed CO fluxes, indicative of CO close to LTE. However, H{sub 2}O is mostly subthermally excited. L1551-IRS5 is the most luminous source (Ł{sub bol} = 24.5 Lmore » {sub ☉}) and the [O I] 63.1 μm line accounts for more than 70% of its FIR line luminosity, suggesting complete photodissociation of H{sub 2}O by a J shock. In L1551-IRS5, the central velocity shifts of the [O I] line, which exceed the wavelength calibration uncertainty (∼70 km s{sup –1}) of PACS, are consistent with the known redshifted and blueshifted outflow direction.« less
Authors:
;  [1] ;  [2] ; ;  [3]
  1. Department of Astronomy and Space Science, Kyung Hee University, Yongin-shi, Kyungki-do 449-701 (Korea, Republic of)
  2. Department of Physics and Astronomy, The University of Georgia, Athens, GA 30602-2451 (United States)
  3. Department of Astronomy, University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, TX 78712-1205 (United States)
Publication Date:
OSTI Identifier:
22340160
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal, Supplement Series; Journal Volume: 214; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CALIBRATION; CARBON MONOXIDE; COSMIC DUST; DENSITY; EMISSION; GAS COOLING; ICE; LUMINOSITY; MASS; MOLECULES; NORTHERN HEMISPHERE; PHOTOLYSIS; PROTOSTARS; RED SHIFT; SPECTRA; TEMPERATURE DISTRIBUTION; VELOCITY; WATER; WAVELENGTHS