The evolution of far-infrared co emission from protostars
Journal Article
·
· Astrophysical Journal
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005 (India)
- Space Telescope Science Institute, Baltimore, MD (United States)
- Department of Physics and Astronomy, University of Toledo, 2801 West Bancroft Street, OH 43606 (United States)
- The University of Texas at Austin, Department of Astronomy, 2515 Speedway, Stop C1400, Austin, TX 78712-1205 (United States)
- Max-Planck-Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)
- Leiden Observatory, Leiden University, P.O. Box 9513, 2300-RA Leiden (Netherlands)
- Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States)
- NASA Goddard Space Flight Center, Greenbelt, MD (United States)
We investigate the evolution of far-IR CO emission from protostars observed with Herschel/PACS for 50 sources from the combined sample of HOPS and DIGIT Herschel key programs. From the uniformly sampled spectral energy distributions, whose peaks are well sampled, we computed the L{sub bol}, T{sub bol}, and L{sub bol}/L{sub smm} for these sources to search for correlations between far-IR CO emission and protostellar properties. We find a strong and tight correlation between far-IR CO luminosity (L{sub CO}{sup fir}) and the bolometric luminosity (L{sub bol}) of the protostars with L{sub CO}{sup fir} ∝L{sub bol}{sup 0.7}. We, however, do not find a strong correlation between L{sub CO}{sup fir} and protostellar evolutionary indicators, T{sub bol} and L{sub bol}/L{sub smm}. FIR CO emission from protostars traces the currently shocked gas by jets/outflows, and far-IR CO luminosity, L{sub CO}{sup fir}, is proportional to the instantaneous mass-loss rate, M-dot {sub out}. The correlation between L{sub CO}{sup fir} and L{sub bol}, then, is indicative of instantaneous M-dot {sub out} tracking instantaneous M-dot {sub acc}. The lack of a correlation between L{sub CO}{sup fir} and evolutionary indicators T{sub bol} and L{sub bol}/L{sub smm} suggests that M-dot {sub out} and, therefore, M-dot {sub acc} do not show any clear evolutionary trend. These results are consistent with mass accretion/ejection in protostars being episodic. Taken together with the previous finding that the time-averaged mass-ejection/accretion rate declines during the protostellar phase, our results suggest that the instantaneous accretion/ejection rate of protostars is highly time variable and episodic, but the amplitude and/or frequency of this variability decreases with time such that the time-averaged accretion/ejection rate declines with system age.
- OSTI ID:
- 22868529
- Journal Information:
- Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 831; ISSN ASJOAB; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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OSTI ID:22016292
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