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Title: L1448-MM OBSERVATIONS BY THE HERSCHEL KEY PROGRAM, ''DUST, ICE, AND GAS IN TIME'' (DIGIT)

We present Herschel/Photodetector Array Camera and Spectrometer (PACS) observations of L1448-MM, a Class 0 protostar with a prominent outflow. Numerous emission lines are detected at 55 <λ < 210 μm including CO, OH, H{sub 2}O, and [O I]. We investigate the spatial distribution of each transition to find that lines from low energy levels tend to distribute along the outflow direction while lines from high energy levels peak at the central spatial pixel. Spatial maps reveal that OH emission lines are formed in a relatively small area, while [O I] emission is extended. According to the rotational diagram analysis, the CO emission can be fitted by two (warm and hot) temperature components. For H{sub 2}O, the ortho-to-para ratio is close to 3. The non-LTE large velocity gradient (LVG) calculations suggest that CO and H{sub 2}O lines could instead be formed in a high kinetic temperature (T > 1000 K) environment, indicative of a shock origin. For OH, IR-pumping processes play an important role in the level population. The molecular emission in L1448-MM is better explained with a C-shock model, but the atomic emission of PACS [O I] and Spitzer/Infrared Spectrograph [Si II] emission is not consistent with C-shocks, suggesting multiplemore » shocks in this region. Water is the major line coolant of L1448-MM in the PACS wavelength range, and the best-fit LVG models predict that H{sub 2}O and CO emit (50%-80%) of their line luminosity in the PACS wavelength range.« less
Authors:
;  [1] ;  [2] ; ;  [3] ;  [4] ;  [5] ; ;  [6] ;
  1. Department of Astronomy and Space Science, Kyung Hee University, Yongin-shi, Kyungki-do 449-701 (Korea, Republic of)
  2. Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)
  3. Department of Astronomy, University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, TX 78712-1205 (United States)
  4. Korea Astronomy and Space Science Institute, 776 Daedeokdaero, Yuseong, Daejeon 305-348 (Korea, Republic of)
  5. Harvard-Smithsonian Center for Astrophysics, MS78, Cambridge, MA 02138 (United States)
  6. Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen (Denmark)
Publication Date:
OSTI Identifier:
22273291
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal, Supplement Series; Journal Volume: 209; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; CAMERAS; CARBON MONOXIDE; ENERGY LEVELS; INFRARED SPECTRA; JETS; LUMINOSITY; MOLECULES; PERTURBED ANGULAR CORRELATION; PROTOSTARS; SILICON IONS; SPATIAL DISTRIBUTION; STARS; WATER