NEAR-INFRARED H ₂ AND CONTINUUM SURVEY OF EXTENDED GREEN OBJECTS. II. COMPLETE CENSUS FOR THE NORTHERN GALACTIC PLANE

Abstract

We discuss 94 Extended Green Objects (EGOs) in the northern Galactic plane cataloged by Cyganowski et al, based on near-infrared narrowband H 2 (2.122 µm) and continuum observations from the United Kingdom Infrared Telescope. This data set is three times larger than our previous study, and is unbiased by preselection. As discussed in the previous paper, the morphologies of the 4.5 µm emission generally resemble those of the near-infrared continuum, but are different from those of the H 2 emission. Of our sample, only 28% of EGOs with H 2 emission show similar morphologies between 4.5 µm and H 2 emission. These results suggest that the 4.5 µm emission mainly comes from scattered continuum from the embedded young stellar object (YSO), and partially from H 2 emission. About half of EGOs are associated with H 2 outflows, if the H 2 outflow incompleteness is considered. The H 2 outflow detection rate for EGOs with K-band detections (61%) is significantly higher than for those without K-band detections (36%). This difference may be due to the fact that both H 2 and K-band emissions are associated with outflows, i.e., H 2 emission and K-band continuum are associated with shocks and outflow cavities, respectively. We also compared the correlation between the H 2 outflows and Class I 44 GHz methanol masers from literature. The methanol masers can be located upstream or downstream of the H 2 outflows and some bright H 2 spots or outflows are not associated with methanol masers, suggesting that methanol masers and H 2 emission trace different excitation conditions.

A near-infrared spectroscopic survey of massive jets towards extended green objects

“…Such a variety has been detected in many other surveys of H 2 massive flows (see Kumar et al 2002;Stecklum et al 2009;Varricatt et al 2010;Lee et al 2013), as well as in many low-mass protostellar jets (see e.g. Reipurth & Bally 2001).…”

Protostellar Outflows at the EarliesT Stages (POETS)

“…Assuming an electron temperature of 10 4 K, the spectral energy distribution of source CM1 is well reproduced by a model of homogeneous H ii region with a Strömgren radius (R S ) of 630 au, number of Lyman photons (N Ly ) of 10 45.85 s −1 , electron density (n e ) of 8.8 × 10 4 cm −3 , and emission measure of 4.8 × 10 7 pc cm −6 . L3, page 2 of 8 the IRAC instrument on board Spitzer and classified as an extended green object (EGO) associated with bright 4.5 µm emission, which is a tracer of ambient gas shocked by early outflow activity (Cyganowski et al 2008(Cyganowski et al , 2009Lee et al 2013). Cyganowski et al (2011) made a census of the 8 GHz continuum sources at the center of the IR nebula with the B-configuration of the Very Large Array (VLA).…”

YSO jets in the Galactic plane from UWISH2 – III. Jets and outflows in Cassiopeia and Auriga

“…In this series of papers we are analysing in detail the identified jets and outflows from young stars in this survey as Molecular Hydrogen emission-line Objects (MHOs) defined in Davis et al (2010). Previous works based on UWISH2 data by Ioannidis & Froebrich (2012a,b) have concentrated on the Serpens and Aquila region along the plane, while Lee et al (2012Lee et al ( , 2013 have investigated H2 ouflows from Spitzerdetected extended green objects. This paper is structured as follows: In Sect.…”