Discovery of 22 GHz Water Masers in the Serpens South Region

• Published in: The Astronomical journal Vol. 162; no. 2; pp. 68 - 84
• Main Authors: Ortiz-León, Gisela N., Plunkett, Adele L., Loinard, Laurent, Dzib, Sergio A., Rodríguez-Garza, Carolina B., Pillai, Thushara, Gong, Yan, Brunthaler, Andreas
• Format: Journal Article
• Language: English
• Published: Madison The American Astronomical Society 01.08.2021; IOP Publishing
• Subjects: Arrays; Astronomy; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; Asymptotic giant branch stars; ASYMPTOTIC SOLUTIONS; BOLOMETERS; Continuum radiation; DETECTION; EMISSION; Emissions; GHZ RANGE; Interferometers; Low mass stars; LUMINOSITY; MASERS; OTHER INSTRUMENTATION; Protoclusters; PROTOSTARS; SPATIAL DISTRIBUTION; Star forming regions; STARS; WATER; Water masers; Young stellar objects
• ISSN: 0004-6256; 1538-3881; 1538-3881
• DOI: 10.3847/1538-3881/ac052c

Abstract Using the Karl G. Jansky Very Large Array (VLA), we have conducted a survey for 22 GHz, 6 1,6 –5 2,3 H 2 O masers toward the Serpens South region. The masers were also observed with the Very Long Baseline Array following the VLA detections. We detect for the first time H 2 O masers in the Serpens South region that are found to be associated to three Class 0–Class I objects, including the two brightest protostars in the Serpens South cluster, known as CARMA-6 and CARMA-7. We also detect H 2 O masers associated to a source with no outflow or jet features. We suggest that this source is most probably a background asymptotic giant branch star projected in the direction of Serpens South. The spatial distribution of the emission spots suggest that the masers in the three Class 0–Class I objects emerge very close to the protostars and are likely excited in shocks driven by the interaction between a protostellar jet and the circumstellar material. Based on the comparison of the distributions of bolometric luminosity of sources hosting 22 GHz H 2 O masers and 162 young stellar objects covered by our observations, we identify a limit of L Bol ≈ 10 L ⊙ for a source to host water masers. However, the maser emission shows strong variability in both intensity and velocity spread, and therefore masers associated to lower-luminosity sources may have been missed by our observations. We also report 11 new sources with radio continuum emission at 22 GHz.