Herschel/HIFI observations of high-J CO lines in the NGC 1333 low-mass star-forming region
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Herschel/HIFI observations of high-J lines (up to Ju = 10) of
12CO, 13CO and C18O are presented
toward three deeply embedded low-mass protostars, NGC 1333 IRAS 2A, IRAS
4A, and IRAS 4B, obtained as part of the Water In Star-forming regions
with Herschel (WISH) key program. The spectrally-resolved HIFI data are
complemented by ground-based observations of lower-J CO and isotopologue
lines. The 12CO 10-9 profiles are dominated by broad (FWHM
25-30 km s-1) emission. Radiative transfer models are used to
constrain the temperature of this shocked gas to 100-200 K. Several CO
and 13CO line profiles also reveal a medium-broad component
(FWHM5-10 km s-1), seen prominently in H2O lines.
Column densities for both components are presented, providing a
reference for determining abundances of other molecules in the same gas.
The narrow C18O 9-8 lines probe the warmer part of the
quiescent envelope. Their intensities require a jump in the CO abundance
at an evaporation temperature around 25 K, thus providing new direct
evidence for a CO ice evaporation zone around low-mass protostars.
Herschel is an ESA space observatory with science instruments provided
by European-led Principal Investigator consortia and with important
participation from NASA.Appendices and acknowledgements (pages 5 to 7)
are only available in electronic form at http://www.aanda.org
Originalsprog | Engelsk |
---|---|
Tidsskrift | Astronomy & Astrophysics |
Vol/bind | 521 |
Sider (fra-til) | L40 |
Antal sider | 7 |
ISSN | 0004-6361 |
DOI | |
Status | Udgivet - okt. 2010 |
ID: 35114647