CO in Protostars (COPS): <i>Herschel</i>-SPIRE Spectroscopy of Embedded Protostars

Date

2018-06-01

Author

Yang, Yao-Lun
Green, Joel D.
Evans, Neal J.
Lee, Jeong-Eun
Jorgensen, Jes K.
Kristensen, Lars E.
Mottram, Joseph C.
Herczeg, Gregory
Karska, Agata
Dionatos, Odysseas
Bergin, Edwin A.
Bouwman, Jeroen
van Dishoeck, Ewine F.
van Kempen, Tim A.
Larson, Rebecca L.
Yıldız, Umut

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

23
views

0
downloads

Cite This

We present full spectral scans from 200 to 670. mu m of 26 Class 0+I protostellar sources obtained with Herschel-SPIRE as part of the "COPS-SPIRE" Open Time program, complementary to the DIGIT and WISH Key Programs. Based on our nearly continuous, line-free spectra from 200 to 670. mu m, the calculated bolometric luminosities (L-bol) increase by 50%. on average, and the bolometric temperatures (T-bol) decrease by 10%. on average, in comparison with the measurements without Herschel. Fifteen protostars have the same class using Tbol and L-bol/L-smm. We identify rotational transitions of CO lines from J = 4 -> 3to J = 13 -> 12, along with emission lines of (CO)-C-13, HCO+, H2O, and [C I]. The ratios of (CO)-C-12 to (CO)-C-13 indicate that (CO)-C-12 emission remains optically thick for J(up) < 13. We fit up to four components of temperature from the rotational diagram with flexible break points to separate the components. The distribution of rotational temperatures shows a primary population around 100 K with a secondary population at similar to 350 K. We quantify the correlations of each line pair found in our data set and find that the strength of the correlation of CO lines decreases as the difference between J levels between two CO lines increases. The multiple origins of CO emission previously revealed by velocity-resolved profiles are consistent with this smooth distribution if each physical component contributes to a wide range of CO lines with significant overlap in the CO ladder. We investigate the spatial extent of CO emission and find that the morphology is more centrally peaked and less bipolar at high-J lines. We find the CO emission observed with SPIRE related to outflows, which consists of two components, the entrained gas and shocked gas, as revealed by our rotational diagram analysis, as well as the studies with velocity-resolved CO emission.

URI

https://hdl.handle.net/11511/115764

Collections

Department of Physics, Article