A dataset provided by the European Space Agency

Name OT2_rvisser_1
Title Variability in high-J CO lines as a proxy for variable accretion in embedded protostars
URL

http://archives.esac.esa.int/hsa/whsa-tap-server/data?retrieval_type=OBSERVATION&observation_id=1342241492&instrument_name=PACS&product_level=LEVEL0&compress=true
http://archives.esac.esa.int/hsa/whsa-tap-server/data?retrieval_type=OBSERVATION&observation_id=1342241493&instrument_name=PACS&product_level=LEVEL0&compress=true
http://archives.esac.esa.int/hsa/whsa-tap-server/data?retrieval_type=OBSERVATION&observation_id=1342241494&instrument_name=PACS&product_level=LEVEL0&compress=true
http://archives.esac.esa.int/hsa/whsa-tap-server/data?retrieval_type=OBSERVATION&observation_id=1342268450&instrument_name=PACS&product_level=LEVEL0&compress=true
http://archives.esac.esa.int/hsa/whsa-tap-server/data?retrieval_type=OBSERVATION&observation_id=1342269524&instrument_name=PACS&product_level=LEVEL0&compress=true
http://archives.esac.esa.int/hsa/whsa-tap-server/data?retrieval_type=OBSERVATION&observation_id=1342269525&instrument_name=PACS&product_level=LEVEL0&compress=true
http://archives.esac.esa.int/hsa/whsa-tap-server/data?retrieval_type=OBSERVATION&observation_id=1342269526&instrument_name=PACS&product_level=LEVEL0&compress=true
http://archives.esac.esa.int/hsa/whsa-tap-server/data?retrieval_type=OBSERVATION&observation_id=1342269551&instrument_name=PACS&product_level=LEVEL0&compress=true
http://archives.esac.esa.int/hsa/whsa-tap-server/data?retrieval_type=OBSERVATION&observation_id=1342269552&instrument_name=PACS&product_level=LEVEL0&compress=true
http://archives.esac.esa.int/hsa/whsa-tap-server/data?retrieval_type=OBSERVATION&observation_id=1342269553&instrument_name=PACS&product_level=LEVEL0&compress=true
http://archives.esac.esa.int/hsa/whsa-tap-server/data?retrieval_type=OBSERVATION&observation_id=1342270643&instrument_name=PACS&product_level=LEVEL0&compress=true
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DOI 10.5270/esa-o0rgh97
Author visser, r.
Description Embedded protostars are underluminous compared to model predictions of constant mass accretion rates from the envelope to the young star. This "luminosity problem" can be explained by episodic accretion: most of the mass is accreted in short bursts, so that most of the protostars are observed in a quiescient, low-luminosity state. The timescale between such accretion bursts is on the order of 10^4--10^5 yr. Smaller brightness variations (factors of at most a few) are seen on shorter timescales (days to years) in the more evolved T Tauri phase. Similar small-scale, short-period variations likely occur in the earlier embedded phases, but they are difficult to observe because of the high extinction through the envelope at UV to IR wavelengths. We propose a novel way of studying variable accretion in the embedded phase by obtaining a second epoch of Herschel-PACS data on rotationally excited CO lines in a sample of 21 previously observed embedded protostars. The high-J CO lines (upwards of 10-9) originate in UV- and shock-heated gas in the inner ~1000 AU of the envelope. The UV field and the shock strength are both tied strongly to the accretion rate, so variability in the high-J CO line fluxes can be used as a proxy for variability in the accretion rate. A second epoch of data on the CO 14-13, 16-15, 24-23 and 30-29 lines will reveal to what extent embedded protostars show variable mass accretion rates on timescales of up to a few years.
Publication
Instrument PACS_PacsLineSpec_point
Temporal Coverage 2012-03-15T21:27:56Z/2013-04-20T20:37:36Z
Version SPG v14.2.0
Mission Description Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 ┬Ám range, bridging the gap between earlier infrared space missions and groundbased facilities.
Creator Contact https://support.cosmos.esa.int/herschel/
Date Published 2013-10-20T20:11:07Z
Publisher And Registrant European Space Agency
Credit Guidelines European Space Agency, 2013-10-20T20:11:07Z, OT2_rvisser_1, SPG v14.2.0. https://doi.org/10.5270/esa-o0rgh97