The Herschel first look at protostars in the Aquila Rift

TL;DR

This paper presents Herschel observations of the Aquila Rift, revealing numerous new protostars, especially Class 0 objects, and mapping their distribution and properties to understand early star formation stages.

Contribution

It provides a systematic detection and analysis of protostars in Aquila using Herschel data, discovering many new young stellar objects and comparing with previous Spitzer results.

Findings

Discovered 45-60 Class 0 protostars in Aquila.

Identified three main star-forming sites, with W40/Sh2-64 being the richest.

Herschel protostars are generally younger than those detected by Spitzer.

Abstract

As part of the science demonstration phase of the Herschel mission of the Gould Belt Key Program, the Aquila Rift molecular complex has been observed. The complete ~ 3.3deg x 3.3deg imaging with SPIRE 250/350/500 micron and PACS 70/160 micron allows a deep investigation of embedded protostellar phases, probing of the dust emission from warm inner regions at 70 and 160 micron to the bulk of the cold envelopes between 250 and 500 micron. We used a systematic detection technique operating simultaneously on all Herschel bands to build a sample of protostars. Spectral energy distributions are derived to measure luminosities and envelope masses, and to place the protostars in an M_env - L_bol evolutionary diagram. The spatial distribution of protostars indicates three star-forming sites in Aquila, with W40/Sh2-64 HII region by far the richest. Most of the detected protostars are newly discovered. For a reduced area around the Serpens South cluster, we could compare the Herschel census of protostars with Spitzer results. The Herschel protostars are younger than in Spitzer with 7 Class 0 YSOs newly revealed by Herschel. For the entire Aquila field, we find a total of ~ 45-60 Class 0 YSOs discovered by Herschel. This confirms the global statistics of several hundred Class~0 YSOs that should be found in the whole Gould Belt survey.