INTERACTIONS OF THE INFRARED BUBBLE N4 WITH ITS SURROUNDINGS

H. LIU; J. LI; Y. WU; J. YUAN; T. LIU; G. DUBNER; S. PARON; M. ORTEGA; S. MOLINARI; M. HUANG; A. ZAVAGNO; M. SAMAL; Y. HUANG; S. ZHANG

ASTROPHYSICAL JOURNAL

IOP PUBLISHING LTD

Lugar: Londres; Año: 2016 vol. 818

0004-637X

The physical mechanisms that induce the transformation of a certain massof gas in new stars are far from being well understood. Infrared bubblesassociated with HII regions have been considered to be good samples forinvestigating triggered star formation. In this paper we report on theinvestigation of the dust properties of the infrared bubble N4 aroundthe HII region G11.898+0.747, analyzing its interaction with itssurroundings and star formation histories therein, with the aim ofdetermining the possibility of star formation triggered by the expansionof the bubble. Using Herschel PACS and SPIRE images with a widewavelength coverage, we reveal the dust properties over the entirebubble. Meanwhile, we are able to identify six dust clumps surroundingthe bubble, with a mean size of 0.50 pc, temperature of about 22 K, meancolumn density of 1.7 x 10^22 cm^-2,mean volume density of about 4.4x10^4cm^-3, and a mean mass of 320 solar masses. Inaddition, from PAH emission seen at 8 μm, free-free emissiondetected at 20 cm, and a probability density function in specialregions, we could identify clear signatures of the influence of the HIIregion on the surroundings. There are hints of star formation, thoughfurther investigation is required to demonstrate that N4 is thetriggering source.