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Origin of the hot gas in low-mass protostars: Herschel-PACS spectroscopy of HH 46
- Source :
- Astronomy & Astrophysics, 518. EDP Sciences, Astronomy and Astrophysics-A&A, Astronomy and Astrophysics-A&A, EDP Sciences, 2010, 518, pp.L121. ⟨10.1051/0004-6361/201014615⟩, Astronomy and Astrophysics-A&A, 2010, 518, pp.L121. ⟨10.1051/0004-6361/201014615⟩, Astronomy & astrophysics, 518:L121. EDP Sciences
- Publication Year :
- 2010
-
Abstract
- 'Water in Star-forming regions with Herschel' (WISH) is a Herschel Key Programme aimed at understanding the physical and chemical structure of young stellar objects (YSOs) with a focus on water and related species. The low-mass protostar HH 46 was observed with the Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space Observatory to measure emission in H2O, CO, OH, [OI], and [CII] lines located between 63 and 186 um. The excitation and spatial distribution of emission can disentangle the different heating mechanisms of YSOs, with better spatial resolution and sensitivity than previously possible. Far-IR line emission is detected at the position of the protostar and along the outflow axis. The OH emission is concentrated at the central position, CO emission is bright at the central position and along the outflow, and H2O emission is concentrated in the outflow. In addition, [OI] emission is seen in low-velocity gas, assumed to be related to the envelope, and is also seen shifted up to 170 km/s in both the red- and blue-shifted jets. Envelope models are constructed based on previous observational constraints. They indicate that passive heating of a spherical envelope by the protostellar luminosity cannot explain the high-excitation molecular gas detected with PACS, including CO lines with upper levels at >2500 K above the ground state. Instead, warm CO and H2O emission is probably produced in the walls of an outflow-carved cavity in the envelope, which are heated by UV photons and non-dissociative C-type shocks. The bright OH and [OI] emission is attributed to J-type shocks in dense gas close to the protostar. In the scenario described here, the combined cooling by far-IR lines within the central spatial pixel is estimated to be 2 \times 10-2 L_sun, with 60-80% attributed to J- and C-type shocks produced by interactions between the jet and the envelope.<br />Accepted for publication in Astronomy and Astrophysics (Herschel special issue)
- Subjects :
- Experimental Physics
Young stellar object
FOS: Physical sciences
Astrophysics
I
01 natural sciences
Luminosity
0103 physical sciences
Protostar
WATER
Solar and Stellar Astrophysics
OUTFLOW
14. Life underwater
Spectroscopy
010303 astronomy & astrophysics
Solar and Stellar Astrophysics (astro-ph.SR)
Line (formation)
Envelope (waves)
QB
Physics
stars: formation
010308 nuclear & particles physics
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR]
astrochemistry
Astronomy and Astrophysics
HH-46/47
[PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR]
ISM: molecules
ISM: jets and outflows
Astrophysics - Solar and Stellar Astrophysics
13. Climate action
Space and Planetary Science
ISM: individual objects: HH 46
JETS
SHOCK
Outflow
Low Mass
EMISSION
Subjects
Details
- Language :
- English
- ISSN :
- 00046361
- Database :
- OpenAIRE
- Journal :
- Astronomy & Astrophysics, 518. EDP Sciences, Astronomy and Astrophysics-A&A, Astronomy and Astrophysics-A&A, EDP Sciences, 2010, 518, pp.L121. ⟨10.1051/0004-6361/201014615⟩, Astronomy and Astrophysics-A&A, 2010, 518, pp.L121. ⟨10.1051/0004-6361/201014615⟩, Astronomy & astrophysics, 518:L121. EDP Sciences
- Accession number :
- edsair.doi.dedup.....c4e68f05e7fa6d590a25bea4a15fb3fb