L1448-MM observations by the Herschel key program, "Dust, Ice, and Gas in Time" (DIGIT)

TY - JOUR

T1 - L1448-MM observations by the Herschel key program, "Dust, Ice, and Gas in Time" (DIGIT)

AU - Lee, Jinhee

AU - Lee, Jeong-Eun

AU - Lee, Seokho

AU - Green, Joel D.

AU - Evans II, Neal J.

AU - Choi, Minho

AU - Kristensen, Lars

AU - Dionatos, Odyssefs

AU - Jørgensen, Jes Kristian

AU - Team, DIGIT

PY - 2013/11/1

Y1 - 2013/11/1

N2 - 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, H2O, 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 H2O, the ortho-to-para ratio is close to 3. The non-LTE large velocity gradient (LVG) calculations suggest that CO and H2O 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 multiple 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 H2O and CO emit (50%-80%) of their line luminosity in the PACS wavelength range.

AB - 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, H2O, 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 H2O, the ortho-to-para ratio is close to 3. The non-LTE large velocity gradient (LVG) calculations suggest that CO and H2O 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 multiple 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 H2O and CO emit (50%-80%) of their line luminosity in the PACS wavelength range.

KW - ISM

KW - individual objects

KW - L1448-MM - ISM

KW - jets and outflows - ISM

KW - molecules - stars

KW - protostars techniques

KW - spectroscopic

U2 - 10.1088/0067-0049/209/1/4

DO - 10.1088/0067-0049/209/1/4

M3 - Journal article

SN - 0067-0049

VL - 209

JO - Astrophysical Journal, Supplement Series

JF - Astrophysical Journal, Supplement Series

IS - 1

M1 - 4

ER -