# University of Hertfordshire

## A Herschel study of YSO evolutionary stages and formation timelines in two fields of the Hi-GAL survey

Research output: Contribution to journalArticlepeer-review

### Documents

• pdf

Accepted author manuscript, 318 KB, PDF document

• D. Elia
• E. Schisano
• S. Molinari
• T. Robitaille
• D. Anglés-Alcázar
• J. Bally
• C. Battersby
• M. Benedettini
• N. Billot
• L. Calzoletti
• A. M. Di Giorgio
• F. Faustini
• J. Z. Li
• P. Martin
• L. Morgan
• F. Motte
• J.C. Mottram
• P. Natoli
• L. Olmi
• And 11 others
• F. Piacentini
• M. Pestalozzi
• S. Pezzuto
• D. Polychroni
• M. Smith
• F. Strafella
• G. S. Stringfellow
• L. Testi
• M.A. Thompson
• A. Traficante
• M. Veneziani
Original language English L97 Astronomy and Astrophysics 518 https://doi.org/10.1051/0004-6361/201014651 Published - 11 May 2010

### Abstract

We present a first study of the star-forming compact dust condensations revealed by Herschel in the two 2 \times 2 \degr Galactic Plane fields centered at [l;b] = [30\degr; 0 \degr] and [l;b] = [59\degr; 0 \degr], respectively, and observed during the Science Demonstration Phase for the Herschel infrared Galactic Plane survey (Hi-GAL) Key-Project. Compact source catalogs extracted for the two fields in the five Hi-GAL bands (70, 160, 250, 350 and 500 $\mu$m) were merged based on simple criteria of positional association and spectral energy distribution (SED) consistency into a final catalog which contains only coherent SEDs with counterparts in at least three adjacent Herschel bands. These final source lists contain 528 entries for the l = 30\degr field, and 444 entries for the l = 59\degr field. The SED coverage has been augmented with ancillary data at 24 $\mu$m and 1.1 mm. SED modeling for the subset of 318 and 101 sources (in the two fields, respectively) for which the distance is known was carried out using both a structured star/disk/envelope radiative transfer model and a simple isothermal grey-body. Global parameters like mass, luminosity, temperature and dust properties have been estimated. The Lbol/Menv ratio spans four orders of magnitudes from values compatible with the pre-protostellar phase to embedded massive zero-age main sequence stars. Sources in the l = 59\degr field have on average lower L/M, possibly outlining an overall earlier evolutionary stage with respect to the sources in the l = 30\degr field. Many of these cores are actively forming high-mass stars, although the estimated core surface densities appear to be an order of magnitude below the 1 g cm$^{-2}$ critical threshold for high-mass star formation.

### Notes

Original article can be found at: http://www.aanda.org/ Copyright The European Southern Observatory

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