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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 731933.0, MPI für Astronomie / Publikationen_mpia
The evolution of far-infrared CO emission from protostars
Authors:Manoj, P.; Green, J. D.; Megeath, S. T.; Evans, N. J.; Stutz, A. M.; Tobin, J. J.; Watson, D. M.; Fischer, W. J.; Furlan, E.; Henning, T.
Date of Publication (YYYY-MM-DD):2016
Title of Journal:The Astrophysical Journal
Issue / Number:1
Start Page:id. 69 (11 pp)
Audience:Not Specified
Abstract / Description: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}{bol}, {T}{bol}, and {L}{bol}/{L}{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}{CO}{fir}) and the bolometric luminosity ({L}{bol}) of the protostars with {L}{CO}{fir} \propto {L}{bol} 0.7. We, however, do not find a strong correlation between {L}{CO}{fir} and protostellar evolutionary indicators, {T}{bol} and {L}{bol}/{L}{smm}. FIR CO emission from protostars traces the currently shocked gas by jets/outflows, and far-IR CO luminosity, {L}{CO}{fir}, is proportional to the instantaneous mass-loss rate, {\dot{M}}{out}. The correlation between {L}{CO}{fir} and {L}{bol}, then, is indicative of instantaneous {\dot{M}}{out} tracking instantaneous {\dot{M}}{acc}. The lack of a correlation between {L}{CO}{fir} and evolutionary indicators {T}{bol} and {L}{bol}/{L}{smm} suggests that {\dot{M}}{out} and, therefore, {\dot{M}}{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.
Free Keywords:ISM: jets and outflows; stars: jets; stars: protostars; stars: winds; outflows
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-637X %R 10.3847/0004-637X/831/1/69
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