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Published May 10, 2017 | Published + Submitted
Journal Article Open

The Herschel Orion Protostar Survey: Luminosity and Envelope Evolution

Abstract

The Herschel Orion Protostar Survey obtained well-sampled 1.2–870 μm spectral energy distributions (SEDs) of over 300 protostars in the Orion molecular clouds, home to most of the young stellar objects (YSOs) in the nearest 500 pc. We plot the bolometric luminosities and temperatures for 330 Orion YSOs, 315 of which have bolometric temperatures characteristic of protostars. The histogram of the bolometric temperature is roughly flat; 29% of the protostars are in Class 0. The median luminosity decreases by a factor of four with increasing bolometric temperature; consequently, the Class 0 protostars are systematically brighter than the Class I protostars, with a median luminosity of 2.3 L_☉ as opposed to 0.87 L_☉. At a given bolometric temperature, the scatter in luminosities is three orders of magnitude. Using fits to the SEDs, we analyze how the luminosities corrected for inclination and foreground reddening relate to the mass in the inner 2500 au of the best-fit model envelopes. The histogram of the envelope mass is roughly flat, while the median-corrected luminosity peaks at 15 L_☉ for young envelopes and falls to 1.7 L_☉ for late-stage protostars with remnant envelopes. The spread in luminosity at each envelope mass is three orders of magnitude. Envelope masses that decline exponentially with time explain the flat mass histogram and the decrease in luminosity, while the formation of a range of stellar masses explains the dispersion in luminosity.

Additional Information

© 2017. The American Astronomical Society. Received 2016 December 2. Accepted 2017 April 12. Published 2017 May 8. Support for this work was provided by the National Aeronautics and Space Administration (NASA) through awards issued by the Jet Propulsion Laboratory/California Institute of Technology (JPL/Caltech). This work is based on observations made with the Spitzer Space Telescope, which is operated by JPL/Caltech under a contract with NASA; it is also based on observations made with the Herschel Space Observatory, a European Space Agency Cornerstone Mission with significant participation by NASA. We include data from the Atacama Pathfinder Experiment, a collaboration between the Max-Planck Institut für Radioastronomie, the European Southern Observatory, and the Onsala Space Observatory. Finally, this publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/Caltech, funded by NASA and the National Science Foundation. This work was supported by NASA Origins of Solar Systems grant 13-OSS13-0094. The work of W.J.F was supported in part by an appointment to the NASA Postdoctoral Program at Goddard Space Flight Center, administered by the Universities Space Research Association through a contract with NASA. J.J.T. acknowledges past support from grant 639.041.439 from the Netherlands Organisation for Scientific Research (NWO) and from NASA through Hubble Fellowship grant #HST-HF-51300.01-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. A.S. is thankful for funding from the "Concurso Proyectos Internacionales de Investigación, Convocatoria 2015" (project code PII20150171) and the BASAL Centro de Astrofísica y Tecnologías Afines (CATA) PFB-06/2007. M.O. acknowledges support from MINECO (Spain) grant AYA2014-57369-C3 (co-funded with FEDER funds).

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Published - Fischer_2017_ApJ_840_69.pdf

Submitted - 1704.05847.pdf

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Additional details

Created:
August 21, 2023
Modified:
October 25, 2023