A global view on star formation: the GLOSTAR Galactic plane survey

Gisela N Ortiz-León,Andreas Brunthaler,William D Cotton,Henrik Beuther,Michael R Rugel,Sergio A Dzib,Rohit Dokara,Karl M Menten,Hans Nguyen,Friedrich Wyrowski,James S Urquhart,Timea Csengeri,Wolfgang Reich,Nirupam Roy,Yan Gong,Carsten König,Jagadheep D Pandian,Sac Nicté X Medina,Aiyuan Yang

doi:10.1051/0004-6361/202140817

Abstract

The Cygnus X complex is covered by the Global View of Star Formation in the Milky Way (GLOSTAR) survey, an unbiased radio-wavelength Galactic plane survey, in 4–8 GHz continuum radiation and several spectral lines. The GLOSTAR survey observed the 6.7 GHz transition of methanol (CH3OH), an exclusive tracer of high-mass young stellar objects. Using the Very Large Array in both the B and D configurations, we observed an area in Cygnus X of 7° × 3° in size and simultaneously covered the methanol line and the continuum, allowing cross-registration. We detected thirteen sources with Class II methanol maser emission and one source with methanol absorption. Two methanol maser sources are newly detected; in addition, we found four new velocity components associated with known masers. Five masers are concentrated in the DR21 ridge and W75N. We determined the characteristics of the detected masers and investigated the association with infrared, (sub)millimeter, and radio continuum emission. All maser sources are associated with (sub)millimeter dust continuum emission, which is consistent with the picture of masers tracing regions in an active stage of star formation. On the other hand, only five masers (38 ± 17%) have radio continuum counterparts seen with GLOSTAR within ~1″, testifying to their youth. Comparing the distributions of the bolometric luminosity and the luminosity-to-mass ratio of cores that host 6.7 GHz methanol masers with those of the full core population, we identified lower limits LBol ~ 200 L⊙ and LBol/Mcore ~ 1 L⊙M⊙−1 for a dust source to host maser emission.

Highlights

The Cygnus X complex is a nearby (1.4 kpc1; Rygl et al 2012), ∼10◦ wide region rich in molecular clouds that is undergoing active star formation and hosts a number of OB associations that testify to the prodigious star formation that has occurred over the past few million years
Several of the masers are associated with the ridge of dense molecular material that extends from DR21 to W75N, which is the region with the highest degree of star formation activity in Cygnus X and home to numerous high-mass stars
In the SED we show infrared data from the Infrared Array Camera (IRAC) 3.6, 4.5, 5.8, and 8 μm and the Multiband Imaging Photometer for Spitzer (MIPS) 24 μm bands taken as part of the Spitzer Legacy Survey of the Cygnus X Complex (Beerer et al 2010)

Summary

Introduction

The Cygnus X complex is a nearby (1.4 kpc1; Rygl et al 2012), ∼10◦ wide region rich in molecular clouds that is undergoing active star formation and hosts a number of OB associations that testify to the prodigious star formation that has occurred over the past few million years. The vast richness of the present star formation activity in this region is revealed by a multitude of observations of centimeter-wavelength free-free radio emission, (sub)millimeter molecular line emission, dust continuum emission, and infrared-wavelength imaging (see Reipurth & Schneider 2008 for a review). With a total mass of 3−4 × 106 M (Schneider et al 2006), this complex is one of the most massive giant molecular clouds (GMCs) in the extended solar neighborhood

Results

Discussion

Conclusion