2009MNRAS.398.1368R

Query : 2009MNRAS.398.1368R

2009MNRAS.398.1368R - Mon. Not. R. Astron. Soc., 398, 1368-1382 (2009/September-3)

SOAR-OSIRIS observations of the Sh 2-307 HII region: triggered star formation beyond the solar circle.

ROMAN-LOPES A.

Abstract (from CDS):

This work aims to study the Sh 2-307 Hii region and related stellar population. Near-infrared imaging and spectroscopic observations in the direction of Sh 2-307 were performed using the Ohio State InfraRed Imager/Spectrometer (OSIRIS) at the Southern Observatory for Astrophysical Research (SOAR) Telescope. The photometric data were analysed from colour-colour and colour-magnitude diagrams, while the spectroscopic results were interpreted from the comparison of the science spectra with those obtained from known OB stars. From J-, H- and K-band spectra of the brightest source in the cluster, we conclude that it has a near-infrared spectrum compatible with those of O9V-O9.5V stars. Using the derived spectral type and the respective J-, H- and K-band photometry, we compute a heliocentric distance of 3.2±0.5kpc, which, for R0= 8kpc, puts this cluster at more than 10kpc from the Galactic Centre. From the Brγ, H2 and continuum narrow-band images we were able to detect both the near-infrared (NIR) counterpart of the associated Hii region and the interface between the ionized and cool molecular gas. Using the 5-GHz continuum flux density taken from the Parkes-MIT-NRAO (PMN) catalogue and the Brγ narrow-band image, we estimate that the Hii region has a mean diameter of 0.94±0.15pc, mean electron density of 550/cm3 and a dynamical age of 1.6x106yr. The large fraction of sources presenting excess emission at 2µm suggests that the stellar population is very young, with many sources still in the pre-main-sequence accreting phase. By the use of theoretical pre-main-sequence tracks we derived a cluster mean age of about 2.5Myr, and from the analyses of the fraction of excess emission sources as a function of their spatial distribution we found evidence for an age spread for the embedded pre-main-sequence stellar population. Finally, from the study of the spatial distribution of the low-mass sources relative to the main cluster source and associated photodissociation zones, we conclude that the O-type star has probably been triggering the star formation process in the region.

Abstract Copyright: © 2009 The Author. Journal compilation © 2009 RAS

Journal keyword(s): stars: pre-main-sequence - H ii regions - Galaxy: structure - infrared: stars

VizieR on-line data: <Available at CDS (J/MNRAS/398/1368): table2.dat>

Nomenclature: Table 2: [R2009] NNN (Nos 1-179).

Simbad objects: 188

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Number of rows : 188
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 [DBS2003] 7 OpC 07 35 24.9 -18 39 12           ~ 21 1
2 [R2009] 151 TT? 07 35 31.3 -18 45 12           ~ 1 0
3 [R2009] 88 * 07 35 31.4 -18 45 55           ~ 1 0
4 [R2009] 145 * 07 35 31.4 -18 45 28           ~ 1 0
5 2MASS J07353146-1845377 TT? 07 35 31.4622830256 -18 45 37.901761848           ~ 2 0
6 [R2009] 144 TT? 07 35 31.6 -18 45 46           ~ 1 0
7 [R2009] 65 TT? 07 35 31.7 -18 45 36           ~ 1 0
8 [R2009] 164 TT? 07 35 31.8 -18 46 14           ~ 1 0
9 [R2009] 166 TT? 07 35 31.8 -18 45 54           ~ 1 0
10 [R2009] 154 TT? 07 35 31.8 -18 45 42           ~ 1 0
11 [R2009] 92 TT? 07 35 31.8 -18 46 10           ~ 1 0
12 2MASS J07353185-1846068 TT? 07 35 31.8539252760 -18 46 06.831719040           ~ 1 0
13 [R2009] 114 TT? 07 35 31.9 -18 46 10           ~ 1 0
14 [R2009] 132 TT? 07 35 31.9 -18 45 51           ~ 1 0
15 [R2009] 44 TT? 07 35 31.9 -18 45 45           ~ 1 0
16 [R2009] 97 TT? 07 35 31.9 -18 45 17           ~ 1 0
17 2MASS J07353194-1845230 TT? 07 35 31.9464684936 -18 45 23.041394064           ~ 1 0
18 [R2009] 161 TT? 07 35 32.0 -18 45 22           ~ 1 0
19 [R2009] 138 TT? 07 35 32.2 -18 46 13           ~ 1 0
20 [R2009] 2 Y*? 07 35 32.3 -18 46 01           ~ 1 0
21 [R2009] 80 TT? 07 35 32.3 -18 45 45           ~ 1 0
22 [R2009] 4 Y*? 07 35 32.4 -18 46 03           ~ 1 0
23 [R2009] 67 TT? 07 35 32.4 -18 45 47           ~ 1 0
24 [R2009] 79 TT? 07 35 32.5 -18 45 10           ~ 1 0
25 [R2009] 143 TT? 07 35 32.6 -18 45 54           ~ 1 0
26 [R2009] 171 TT? 07 35 32.6 -18 45 44           ~ 1 0
27 [R2009] 61 TT? 07 35 32.6 -18 45 37           ~ 1 0
28 [R2009] 25 TT? 07 35 32.6 -18 45 33           ~ 1 0
29 [R2009] 121 TT? 07 35 32.7 -18 46 01           ~ 1 0
30 [R2009] 122 * 07 35 32.7 -18 45 51           ~ 1 0
31 [R2009] 3 * 07 35 32.7 -18 45 35           B2V 1 0
32 [R2009] 179 TT? 07 35 32.7 -18 45 25           ~ 1 0
33 [R2009] 136 TT? 07 35 32.7 -18 45 05           ~ 1 0
34 [R2009] 8 * 07 35 32.8 -18 46 11           B5/8V 1 0
35 [R2009] 165 TT? 07 35 32.8 -18 45 54           ~ 1 0
36 [R2009] 176 TT? 07 35 32.8 -18 45 18           ~ 1 0
37 [R2009] 68 * 07 35 32.8 -18 45 36           ~ 1 0
38 [R2009] 134 TT? 07 35 32.8 -18 45 32           ~ 1 0
39 [R2009] 130 TT? 07 35 32.8 -18 45 44           ~ 1 0
40 [R2009] 100 TT? 07 35 32.9 -18 45 48           ~ 1 0
41 [R2009] 59 TT? 07 35 32.9 -18 45 40           ~ 1 0
42 [R2009] 24 TT? 07 35 32.9 -18 45 35           ~ 1 0
43 SH 2-307 HII 07 35 33 -18 45.6           ~ 61 2
44 2MASS J07353297-1845321 TT? 07 35 32.976 -18 45 32.16           ~ 1 0
45 [R2009] 72 TT? 07 35 33.0 -18 46 11           ~ 1 0
46 [R2009] 82 TT? 07 35 33.0 -18 45 46           ~ 1 0
47 [R2009] 159 * 07 35 33.0 -18 45 10           ~ 1 0
48 [R2009] 163 TT? 07 35 33.0 -18 45 09           ~ 1 0
49 [R2009] 102 TT? 07 35 33.0 -18 45 39           ~ 1 0
50 [R2009] 106 TT? 07 35 33.0 -18 45 53           ~ 1 0
51 [R2009] 73 TT? 07 35 33.1 -18 45 55           ~ 1 0
52 [R2009] 22 TT? 07 35 33.1 -18 45 47           ~ 1 0
53 [R2009] 129 * 07 35 33.1 -18 45 36           ~ 1 0
54 [R2009] 126 TT? 07 35 33.1 -18 45 35           ~ 1 0
55 [R2009] 62 TT? 07 35 33.1 -18 45 25           ~ 1 0
56 [R2009] 26 * 07 35 33.1 -18 45 08           ~ 1 0
57 [R2009] 13 TT? 07 35 33.2 -18 46 14           ~ 1 0
58 [R2009] 110 TT? 07 35 33.2 -18 46 04           ~ 1 0
59 [R2009] 45 TT? 07 35 33.2 -18 45 34           ~ 1 0
60 [R2009] 127 TT? 07 35 33.2 -18 45 26           ~ 1 0
61 [R2009] 177 TT? 07 35 33.2 -18 45 44           ~ 1 0
62 [R2009] 133 TT? 07 35 33.2 -18 45 42           ~ 1 0
63 [R2009] 90 TT? 07 35 33.2 -18 45 32           ~ 1 0
64 [R2009] 21 TT? 07 35 33.3 -18 45 37           ~ 1 0
65 [R2009] 155 TT? 07 35 33.3 -18 45 48           ~ 1 0
66 [R2009] 32 TT? 07 35 33.3 -18 45 36           ~ 1 0
67 [R2009] 128 TT? 07 35 33.3 -18 45 14           ~ 1 0
68 [R2009] 83 * 07 35 33.4 -18 45 55           ~ 1 0
69 [R2009] 57 TT? 07 35 33.4 -18 45 44           ~ 1 0
70 [R2009] 113 TT? 07 35 33.4 -18 45 38           ~ 1 0
71 [R2009] 98 TT? 07 35 33.4 -18 45 31           ~ 1 0
72 [R2009] 58 TT? 07 35 33.4 -18 45 18           ~ 1 0
73 [R2009] 125 TT? 07 35 33.4 -18 45 16           ~ 1 0
74 [R2009] 29 TT? 07 35 33.4 -18 45 40           ~ 1 0
75 [R2009] 116 * 07 35 33.4 -18 45 30           ~ 1 0
76 [R2009] 169 TT? 07 35 33.5 -18 46 13           ~ 1 0
77 [R2009] 119 TT? 07 35 33.5 -18 45 48           ~ 1 0
78 [R2009] 39 TT? 07 35 33.5 -18 45 18           ~ 1 0
79 [R2009] 148 TT? 07 35 33.6 -18 46 14           ~ 1 0
80 [R2009] 46 TT? 07 35 33.6 -18 45 50           ~ 1 0
81 [R2009] 41 TT? 07 35 33.6 -18 45 49           ~ 1 0
82 [R2009] 34 * 07 35 33.6 -18 45 36           ~ 1 0
83 [R2009] 63 TT? 07 35 33.6 -18 45 34           ~ 1 0
84 [R2009] 157 TT? 07 35 33.6 -18 45 31           ~ 1 0
85 [R2009] 156 TT? 07 35 33.6 -18 45 41           ~ 1 0
86 [R2009] 93 TT? 07 35 33.7 -18 45 36           ~ 1 0
87 [R2009] 56 TT? 07 35 33.7 -18 45 15           ~ 1 0
88 [R2009] 142 TT? 07 35 33.8 -18 45 46           ~ 1 0
89 [R2009] 28 TT? 07 35 33.8 -18 45 39           ~ 1 0
90 [R2009] 147 * 07 35 33.8 -18 45 36           ~ 1 0
91 [R2009] 123 TT? 07 35 33.8 -18 45 53           ~ 1 0
92 [R2009] 170 * 07 35 33.8 -18 45 52           ~ 1 0
93 [R2009] 89 TT? 07 35 33.8 -18 45 22           ~ 1 0
94 [R2009] 105 TT? 07 35 33.8 -18 45 08           ~ 1 0
95 [R2009] 111 TT? 07 35 33.9 -18 46 11           ~ 1 0
96 [R2009] 91 TT? 07 35 33.9 -18 46 08           ~ 1 0
97 [R2009] 5 Y*? 07 35 33.9 -18 45 59           ~ 1 0
98 [R2009] 77 TT? 07 35 33.9 -18 45 36           ~ 1 0
99 [R2009] 173 TT? 07 35 34.0 -18 46 07           ~ 1 0
100 [R2009] 64 TT? 07 35 34.0 -18 45 59           ~ 1 0
101 [R2009] 11 * 07 35 34.0 -18 45 58           ~ 1 0
102 [R2009] 109 TT? 07 35 34.0 -18 45 52           ~ 1 0
103 [R2009] 16 TT? 07 35 34.0 -18 45 51           ~ 1 0
104 [R2009] 75 * 07 35 34.0 -18 45 50           ~ 1 0
105 [R2009] 17 TT? 07 35 34.0 -18 45 36           ~ 1 0
106 [R2009] 35 TT? 07 35 34.0 -18 45 31           ~ 1 0
107 [R2009] 117 TT? 07 35 34.0 -18 45 22           ~ 1 0
108 [R2009] 101 TT? 07 35 34.0 -18 45 19           ~ 1 0
109 [R2009] 150 TT? 07 35 34.1 -18 46 08           ~ 1 0
110 [R2009] 124 TT? 07 35 34.1 -18 46 02           ~ 1 0
111 [R2009] 146 TT? 07 35 34.1 -18 45 46           ~ 1 0
112 ALS 17537 * 07 35 34.1 -18 45 38 12.8 13.26 12.47     B0V 7 1
113 [R2009] 118 * 07 35 34.1 -18 45 36           ~ 1 0
114 [R2009] 23 TT? 07 35 34.1 -18 45 31           ~ 1 0
115 TYC 5987-246-1 * 07 35 34.1681854752 -18 45 34.970260320   13.19 12.32     O9/9.5V 1 0
116 [R2009] 84 TT? 07 35 34.2 -18 46 03           ~ 1 0
117 [R2009] 33 TT? 07 35 34.2 -18 45 40           ~ 1 0
118 [R2009] 49 TT? 07 35 34.2 -18 45 45           ~ 1 0
119 [R2009] 86 * 07 35 34.2 -18 45 31           ~ 1 0
120 [R2009] 20 TT? 07 35 34.2 -18 45 27           ~ 1 0
121 [R2009] 108 TT? 07 35 34.2 -18 45 21           ~ 1 0
122 [R2009] 55 TT? 07 35 34.3 -18 45 42           ~ 1 0
123 [R2009] 27 TT? 07 35 34.3 -18 45 31           ~ 1 0
124 [R2009] 53 * 07 35 34.3 -18 45 36           ~ 1 0
125 [R2009] 12 TT? 07 35 34.4 -18 45 31           ~ 1 0
126 [R2009] 71 * 07 35 34.4 -18 46 03           ~ 1 0
127 [R2009] 76 TT? 07 35 34.4 -18 46 03           ~ 1 0
128 [R2009] 36 TT? 07 35 34.4 -18 46 00           ~ 1 0
129 [R2009] 15 TT? 07 35 34.4 -18 45 49           ~ 1 0
130 [R2009] 6 * 07 35 34.4 -18 45 33           B5V 1 0
131 [R2009] 30 Y*? 07 35 34.5 -18 46 17           ~ 1 0
132 [R2009] 137 TT? 07 35 34.5 -18 46 00           ~ 1 0
133 [R2009] 54 TT? 07 35 34.5 -18 45 54           ~ 1 0
134 [R2009] 120 TT? 07 35 34.5 -18 45 39           ~ 1 0
135 [R2009] 70 TT? 07 35 34.5 -18 45 37           ~ 1 0
136 [R2009] 78 TT? 07 35 34.5 -18 45 33           ~ 1 0
137 [R2009] 107 TT? 07 35 34.5 -18 45 29           ~ 1 0
138 [R2009] 96 TT? 07 35 34.5 -18 45 24           ~ 1 0
139 [R2009] 95 TT? 07 35 34.5 -18 45 12           ~ 1 0
140 [R2009] 37 * 07 35 34.5 -18 44 56           ~ 1 0
141 [R2009] 174 TT? 07 35 34.6 -18 45 58           ~ 1 0
142 [R2009] 31 TT? 07 35 34.6 -18 45 49           ~ 1 0
143 2MASS J07353462-1845380 TT? 07 35 34.630 -18 45 38.03           ~ 1 0
144 [R2009] 7 TT? 07 35 34.6372167561 -18 45 46.640089846           ~ 2 0
145 [R2009] 140 * 07 35 34.7 -18 45 38           ~ 1 0
146 [R2009] 66 TT? 07 35 34.7 -18 45 35           ~ 1 0
147 [R2009] 103 TT? 07 35 34.7 -18 46 00           ~ 1 0
148 [R2009] 135 TT? 07 35 34.7 -18 45 54           ~ 1 0
149 [R2009] 139 TT? 07 35 34.7 -18 45 09           ~ 1 0
150 [R2009] 112 TT? 07 35 34.8 -18 46 13           ~ 1 0
151 [R2009] 52 TT? 07 35 34.8 -18 45 53           ~ 1 0
152 [R2009] 160 TT? 07 35 34.8 -18 45 57           ~ 1 0
153 [R2009] 115 TT? 07 35 34.8 -18 45 48           ~ 1 0
154 [R2009] 38 TT? 07 35 34.8 -18 45 14           ~ 1 0
155 2MASS J07353483-1845353 TT? 07 35 34.8426517104 -18 45 35.395815492           ~ 1 0
156 [R2009] 87 TT? 07 35 34.9 -18 46 00           ~ 1 0
157 [R2009] 94 * 07 35 34.9 -18 45 26           ~ 1 0
158 [R2009] 81 TT? 07 35 35.0 -18 45 08           ~ 1 0
159 [R2009] 153 * 07 35 35.0 -18 46 02           ~ 1 0
160 [R2009] 69 * 07 35 35.0 -18 46 01           ~ 1 0
161 [R2009] 85 TT? 07 35 35.0 -18 46 00           ~ 1 0
162 [R2009] 167 TT? 07 35 35.0 -18 45 59           ~ 1 0
163 [R2009] 40 * 07 35 35.0 -18 45 42           ~ 1 0
164 [R2009] 149 TT? 07 35 35.0 -18 45 32           ~ 1 0
165 [R2009] 14 TT? 07 35 35.2 -18 45 52           ~ 1 0
166 [R2009] 47 TT? 07 35 35.3 -18 45 52           ~ 1 0
167 [R2009] 175 TT? 07 35 35.4 -18 46 02           ~ 1 0
168 [R2009] 178 TT? 07 35 35.4 -18 45 50           ~ 1 0
169 [R2009] 158 TT? 07 35 35.4 -18 45 32           ~ 1 0
170 [R2009] 74 TT? 07 35 35.5 -18 46 09           ~ 1 0
171 [R2009] 168 TT? 07 35 35.6 -18 45 50           ~ 1 0
172 [R2009] 152 TT? 07 35 35.6 -18 45 28           ~ 1 0
173 [R2009] 60 TT? 07 35 36.0 -18 46 04           ~ 1 0
174 [R2009] 141 TT? 07 35 36.0 -18 45 59           ~ 1 0
175 [R2009] 99 * 07 35 36.2 -18 45 15           ~ 1 0
176 [R2009] 131 TT? 07 35 36.3 -18 45 08           ~ 1 0
177 2MASS J07353635-1845551 * 07 35 36.3515497560 -18 45 55.206932400           ~ 1 0
178 2MASS J07353637-1845470 * 07 35 36.3813879432 -18 45 47.100526992           ~ 1 0
179 [R2009] 162 TT? 07 35 36.4 -18 46 09           ~ 1 0
180 [R2009] 9 * 07 35 36.5 -18 45 15           ~ 1 0
181 [R2009] 104 TT? 07 35 36.5 -18 45 03           ~ 1 0
182 [R2009] 172 TT? 07 35 36.6 -18 45 28           ~ 1 0
183 HD 93028 SB* 10 43 15.3393101352 -60 12 04.231982304 7.29 8.24 8.30 9.26   O9IV 181 0
184 HD 123056 SB* 14 07 25.6396562448 -60 28 14.155719348 7.54 8.28 8.14 9.00   O9.5IV(n) 68 0
185 * tau Sco * 16 35 52.9528530 -28 12 57.661515 1.55 2.56 2.81 2.93 3.18 B0V 959 0
186 HD 152623 ** 16 56 15.0265311912 -40 39 35.892252936 5.95 8.70 8.64 7.68   O7V(n)((f))z 113 0
187 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 16269 0
188 HD 165246 SB* 18 06 04.6792554840 -24 11 43.890335448 6.90 7.70 7.60 8.77   O8V(n) 93 0

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