Koumpia, E, van der Tak, FFS, Kwon, W et al. (3 more authors) (2016) Evolutionary status of dense cores in the NGC 1333 IRAS 4 star-forming region. Astronomy & Astrophysics, 595. A51. ISSN 0004-6361
Abstract
Context: Protostellar evolution after the formation of the protostar is becoming reasonably well characterized, but the evolution from a prestellar core to a protostar is not well known, although the first hydrostatic core (FHSC) must be a pivotal step.
Aims: NGC 1333 – IRAS 4C is a potentially very young object that we can directly compare with the nearby Class 0 objects IRAS 4A and IRAS 4B. Observational constraints are provided by spectral imaging from the JCMT Spectral Legacy Survey (330−373 GHz). We present integrated intensity and velocity maps of several species, including CO, H₂CO and CH₃OH. CARMA observations provide additional information with which we can distinguish IRAS 4C from other evolutionary stages.
Methods: We present the observational signatures of the velocity of an observed outflow, the degree of CO depletion, the deuterium fractionation of [DCO⁺]/[HCO⁺], and gas kinetic temperatures.
Results: We report differences between the three sources in four aspects: a) the kinetic temperature as probed using the H₂CO lines is much lower toward IRAS 4C than the other two sources; b) the line profiles of the detected species show strong outflow activity toward IRAS 4A and IRAS 4B, but not toward IRAS 4C; c) the HCN/HNC is <1 toward IRAS 4C, which confirms the cold nature of the source; d) the degree of CO depletion and the deuteration are lowest toward the warmest of the sources, IRAS 4B.
Conclusions: IRAS 4C seems to be in a different evolutionary state than the sources IRAS 4A and IRAS 4B. We can probably exclude the FHSC stage becaues of the relatively low Lsmm/Lbol (~6%), and we investigate the earliest accretion phase of Class 0 stage and the transition between Class 0 to Class I. Our results do not show a consistent scenario for either case; the main problem is the absence of outflow activity and the cold nature of IRAS 4C. The number of FHSC candidates in Perseus is ~10 times higher than current models predict, which suggests that the lifespan of these objects is ≥103 yrs, which might be due to an accretion rate lower than 4 × 10⁻⁵ M⊙/yr.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2016, ESO. Reproduced with permission from Astronomy & Astrophysics. |
Keywords: | ISM: abundances; ISM: kinematics and dynamics; ISM: molecules; stars: formation; stars: low-mass; stars: protostars |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) > Astrophysics (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 27 Nov 2018 10:12 |
Last Modified: | 27 Nov 2018 10:12 |
Status: | Published |
Publisher: | EDP Sciences |
Identification Number: | 10.1051/0004-6361/201528042 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:138968 |