Affiliation: AA( jinhuahe@ynao.ac.cn), AB( satoko_t@asiaa.sinica.edu.tw), AC( chenxi@shao.ac.cn)

Publication: The Astrophysical Journal Supplement, Volume 202, Issue 1, article id. 1, 15 pp. (2012). (ApJS Homepage)

Publication Date: 09/2012

Abstract

A northern subsample of 89 Spitzer GLIMPSE extended green objects (EGOs), the candidate massive young stellar objects, are surveyed for molecular lines in two 1 GHz ranges: 251.5-252.5 and 260.188-261.188 GHz. A comprehensive catalog of observed molecular line data and spectral plots are presented. Eight molecular species are undoubtedly detected: H13CO+, SiO, SO, CH3OH, CH3OCH3, CH3CH2CN, HCOOCH3, and HN13C. The H13CO+ 3-2 line is detected in 70 EGOs, among which 37 also show the SiO 6-5 line, demonstrating their association with dense gas and supporting the outflow interpretation of the extended 4.5 μm excess emission. Our major dense gas and outflow tracers (H13CO+, SiO, SO, and CH3OH) are combined with our previous survey of 13CO, 12CO, and C18O 1-0 toward the same sample of EGOs for a multi-line, multi-cloud analysis of linewidth and luminosity correlations. Good log-linear correlations are found among all considered line luminosities, the explanation of which requires a universal similarity of density and thermal structures and probably of shock properties among all EGO clouds. It also requires that the shocks be produced within the natal clouds of the EGOs. Diverse degrees of correlation are found among the linewidths. However, both the linewidth and luminosity correlations tend to progressively worsen across larger cloud subcomponent size scales, depicting the increase of randomness across cloud subcomponent sizes. Moreover, the linewidth correlations among the three isotopic CO 1-0 lines show data scatter as linear functions of the linewidth itself, indicating that the velocity randomness also increases with whole cloud sizes in a regular way.

The SMT observing time was funded by Academia Sinica, Institute of Astronomy and Astrophysics, Taipei.