J/MNRAS/438/426 Spitzer interstellar bubbles (Hou+, 2014)
A statistical study of gaseous environment of Spitzer interstellar bubbles.
Hou L.G., Gao X.Y.
<Mon. Not. R. Astron. Soc., 438, 426-437 (2014)>
=2014MNRAS.438..426H 2014MNRAS.438..426H
ADC_Keywords: H II regions ; Interstellar medium ; Stars, distances
Keywords: stars: formation - ISM: bubbles - ISM: clouds - HII regions
Abstract:
The expansion of interstellar bubbles is suggested to be an important
mechanism of triggering material accumulation and star formation. In
this work, we investigate the gaseous environment of a large sample of
interstellar bubbles identified by the Spitzer space telescope,
aiming to explore the possible evidence of triggered gas accumulation
and star formation in a statistical sense. By cross-matching 6124
Spitzer interstellar bubbles from the Milky Way Project (MWP) and
more than 2500 Galactic HII regions collected by us, we obtain the
velocity information for 818 MWP bubbles. To study the gaseous
environment of the interstellar bubbles and get rid of the projection
effect as much as possible, we constrain the velocity difference
between the bubbles and the 13CO(1-0) emission extracted from the
Galactic Ring Survey (GRS). Three methods: the mean azimuthally
averaged radial profile of 13CO emission, the surface number density
of molecular clumps and the angular cross-correlation function of MWP
bubbles and the GRS molecular clumps are adopted. Significant over
density of molecular gas is found to be close to the bubble rims. 60
percent of the studied bubbles were found to have associated molecular
clumps. By comparing the clump-associated and the clump-unassociated
MWP interstellar bubbles, we reveal that the bubbles in associations
tend to be larger and thicker in physical sizes. From the different
properties shown by the bubble-associated and bubble-unassociated
clumps, we speculate that some of the bubble-associated clumps result
from the expansion of bubbles. The fraction of the molecular clumps
associated with the MWP bubbles is estimated to be about 20 percent
after considering the projection effect. For the bubble-clump
complexes, we found that the bubbles in the complexes with associated
massive young stellar object(s) (MYSO(s)) have larger physical sizes,
hence the complexes tend to be older. We propose that an evolutionary
sequence might exist between the relatively younger MYSO-unassociated
bubble-clump complexes and the MYSO-associated complexes.
Description:
The interstellar bubble catalogue adopted in this work is from the
recently released MWP (Simpson et al., 2012MNRAS.424.2442S 2012MNRAS.424.2442S, Cat.
J/MNRAS/424/2442), containing 5106 bubbles identified by visual
inspection of the Spitzer/GLIMPSE (Benjamin et al.,
2003PASP..115..953B 2003PASP..115..953B, Cat. II/293) and MIPSGAL (Carey et al.,
2009PASP..121...76C 2009PASP..121...76C) survey images.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 114 818 Matched pairs of MWP bubbles (Milky Way Project,
Simpson et al. 2012MNRAS.424.2442S 2012MNRAS.424.2442S)
and Galactic HII regions
refs.dat 275 50 References
--------------------------------------------------------------------------------
See also:
II/293 : GLIMPSE Source Catalog (I + II + 3D) (IPAC 2008)
J/MNRAS/424/2442 : Catalog of bubbles from Milky Way Project (Simpson+, 2012)
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [MWP]
4- 19 A16 --- MWP MWP name (1GLLLlll+BbbbbbA)
21- 27 F7.3 deg GLON Bubble Galactic longitude
29- 34 F6.3 deg GLAT Bubble Galactic latitude
36- 39 F4.2 arcmin Reff Effective radius
41- 47 F7.3 deg GLON2 Associated HII region Galactic longitude
49- 54 F6.3 deg GLAT2 Associated HII region Galactic latitude
56- 61 A6 --- Ref Reference for associated HII region,
in refs.dat file
63- 69 F7.2 km/s VHII Line-of-sight velocity for HII region (1)
72- 76 F5.2 kpc D0 ? Trigonometric or photometric distance
78- 81 F4.2 kpc e_D0 ? rms uncertainty on D0
83- 88 A6 --- r_D0 Reference for D0, in refs.dat file
92- 96 F5.2 kpc DK ? Kinematic distance (2)
98-101 F4.2 kpc e_DK ? rms uncertainty on DK
103-107 A5 --- Mark Solution of the kinematical distance (3)
109-114 A6 --- r_Mark Reference for Mark, in refs.dat file
--------------------------------------------------------------------------------
Note (1): estimated by considering a velocity uncertainty of ±7km/s.
Note (2): estimated with a flat rotation curve with R0=8.3kpc and
Θ0=239km/s.
Note (3): Marks are:
kfar = the farther kinematic distance is adopted
ktan = the source is located at the tangential point
knear = the nearer kinematic distance is adopted
3kpcn = the source is in the near 3-kpc arm (see e.g.,
Dame & Thaddeus, 2011ApJ...734L..24D 2011ApJ...734L..24D)
3kpcf = the source is in the far 3-kpc arm (see e.g.,
Dame & Thaddeus, 2011ApJ...734L..24D 2011ApJ...734L..24D)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: refs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- Ref Reference code
9- 27 A19 ---- BibCode Bicode
29- 53 A25 --- Aut Author's name
55-275 A221 --- Com Comments
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 27-Nov-2014