A multiwavelength study of the star forming region IRAS 18544+0112

Abstract

Aims. This work aims at investigating the molecular and infrared components in the massive young stellar object (MYSO) candidate IRAS 18544+0112. The purpose is to determine the nature and the origin of this infrared source. Methods. To analyze the molecular gas towards IRAS 18544+0112, we have carried out observations in a 90 × 90 region around l = 34.• 69, b = −0.• 65, using the Atacama Submillimeter Telescope Experiment (ASTE) in the 12 CO J = 3-2, 13 CO J = 3-2, HCO + J = 4-3 and CS J = 7-6 lines with an angular resolution of 22 . The infrared emission in the area has been analyzed using 2MASS and Spitzer public data. Results. From the molecular analysis, we find self-absorbed 12 CO J = 3-2 profiles, which are typical in star forming regions, but we do not find any evidence of outflow activity. Moreover, we do not detect either HCO + J = 4-3 or CS J = 7-6 in the region, which are species normally enhanced in molecular outflows and high density envelopes. The 12 CO J = 3-2 emission profile suggests the presence of expanding gas in the region. The Spitzer images reveal that the infrared source has a conspicuous extended emission bright at 8 μm with an evident shell-like morphology of ∼1. 5 in size (∼1.4 pc at the proposed distance of 3 kpc) that encircles the 24 μm emission. The non-detection of ionized gas related to IRAS 18544+0112 together with the fact that it is still embedded in a molecular clump suggest that IRAS 18544+0112 has not reached the UCHII region stage yet. Based on near infrared photometry we search for YSO candidates in the region and propose that 2MASS 18565878+0116233 is the infrared point source associated with IRAS 18544+0112. Finally, we suggest that the expansion of a larger nearby HII region, G034.8−0.7, might be related to the formation of IRAS 18544+0112.

Study of the dense molecular gas surrounding the ‘extended green object’ G35.03+0.35

“…The 13 CO J = 3–2 spectrum presents similar features. We conclude that these lines present an absorption dip at ∼51.5 km s −1 which separates both mentioned velocity components, showing that the lines are self‐absorbed as is usually found towards star‐forming regions (Johnstone, Boonman & van Dishoeck 2003; Buckle et al 2010; Ortega et al 2010). The velocity of the 12 CO and 13 CO dip mentioned is coincident (within the errors) with the central velocities of the SiO (5–4), H 13 CO + (3–2) and CH 3 OH (5 2, 3 –4 1, 3 ) lines observed towards the centre of EGOg35 by Cyganowski et al (2009) and with the CS J = 7–6 main component reported in this work.…”

The interstellar medium and the massive stellar content towards the SNR G18.1−0.1 and neighbouring H ii regions

“…Some examples of this spatial coincidence are the field toward W28, with several SNRs and HII regions (e.g. Nicholas et al 2011), the SNR W44 and the HII region G034.8-0.7 (Paron et al 2009;Ortega et al 2010), the luminous blue variable (LBV) star candidate G24.73+0.69, some HII regions and the SNR G24.7+0.6 (Petriella et al 2011(Petriella et al , 2012. Moreover, it is usually observed large amounts of molecular gas in the surroundings of HII regions and SNRs.…”

On the integrated continuum radio spectrum of supernova remnant W44 (G34.7-0.4): New insights from Planck

“…Castelletti et al (2007) noted that exactly at the interface between observed H ii region and W44, as seen in the plane of the sky, a young stellar object is present. In fact, two massive young stellar objects are identified at the border of the H ii region that is evolving within a molecular cloud shocked by the SNR W44 (Paron et al 2009;Ortega et al 2010).…”