2000ApJ...540..308D


C.D.S. - SIMBAD4 rel 1.7 - 2021.01.21CET07:39:17

2000ApJ...540..308D - Astrophys. J., 540, 308-315 (2000/September-1)

Ultracompact H II regions in W49N at 500 AU scales: shells, winds, and the water maser source.

DE PREE C.G., WILNER D.J., GOSS W.M., WELCH W.J. and McGRATH E.

Abstract (from CDS):

We have observed the ionized gas in the star-forming region W49N with the National Radio Astronomy Observatory Very Large Array (VLA) at 13 mm and 7 mm, and with the Berkeley Illinois Maryland Association (BIMA) Array at 3.3 mm. These observations vary in resolution from 0".045 to 0".35 (500 AU to 4000 AU at a distance of 11.4 kpc). In addition, we have used the VLA to observe water maser emission towards the bright W49N:G sources over a wide velocity range from -435 to 435 km.s–1. The high-resolution continuum observations reveal the morphologies in the ultracompact sources; most of the sources at 0.045" resolution appear to have shell or ring morphologies. The 3.3 mm emission observed with the BIMA array is dominated by free-free emission in all of the compact sources. There is no evidence for any spectral breaks corresponding to the emergence of a dust component. Of the seven bright sources in W49N for which multifrequency flux densities have been measured, four are observed to have rising spectral indices, with values ranging from α=0.3-1.1 and three are observed to be flat (Sν∝να). Those sources with rising spectral indices (A, B1, B2, G1, and G2) also have the broadest radio recombination lines, with ΔVFWHM>45 km.s–1 in the H66α line (De Pree, Mehringer, & Goss, 1997ApJ...482..307D). High-resolution 1.3 cm continuum images made at the same time as the water maser observations have been used to align the maser positions with the high-resolution 7 mm continuum to within 0".05. The maser positions are closely associated with the G1/G2 sources. The outflow traced by the water masers (Gwinn, Moran & Reid) appears to be centered within 0.2" of the G2 peak, the brightest continuum source in the region, but it remains unclear whether this source drives the outflow.

Abstract Copyright:

Journal keyword(s): ISM: H II Regions - ISM: Individual: Alphanumeric: W49N - ISM: Kinematics and Dynamics - Masers - Radio Lines: ISM

Nomenclature: Fig.2, Table 3: [DJW84] W49 AN (Nos A1-A2, B2) added, [DJW84] W49 ANa (Nos G1a-G1c).

Simbad objects: 35

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Number of rows : 35

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 3C 48 QSO 01 37 41.2995845985 +33 09 35.079126038   16.62 16.20     ~ 2548 2
2 M 42 HII 05 35 17.3 -05 23 28           ~ 3765 0
3 NAME Ori A MoC 05 38 -07.1           ~ 2718 0
4 3C 273 BLL 12 29 06.6996828061 +02 03 08.598846466   13.05 14.830 14.11   ~ 5388 1
5 3C 286 Sy1 13 31 08.2885060664 +30 30 32.960825108   17.51 17.25     ~ 3813 2
6 NGC 6334A HII 17 20 19.3 -35 54 55           ~ 113 0
7 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 1964 1
8 NAME Sgr B2 Main Rad 17 47 20.5 -28 23 06           ~ 345 1
9 4C 09.57 BLL 17 51 32.81857318 +09 39 00.7284829   17.46 16.78 15.57   ~ 825 1
10 [DJW84] W49 A1 Rad 19 10 12 +09 06.2           ~ 7 0
11 [DJW84] W49 A2 Rad 19 10 12 +09 06.2           ~ 8 0
12 [DJW84] W49 A HII 19 10 12.93 +09 06 11.9           ~ 30 0
13 [DJW84] W49 B2 Rad 19 10 13.143 +09 06 12.52           ~ 10 0
14 [DJW84] W49 C HII 19 10 13.19 +09 06 18.8           ~ 18 0
15 W 49n HII 19 10 13.2 +09 06 12           ~ 421 3
16 [DJW84] W49 D HII 19 10 13.26 +09 06 11.4           ~ 17 0
17 [DJW84] W49 B1 Rad 19 10 13.26 +09 06 15.0           ~ 12 0
18 [DJW84] W49 F HII 19 10 13.38 +09 06 21.5           ~ 17 0
19 [DJW84] W49 G2a Rad 19 10 13.417 +09 06 13.14           ~ 12 0
20 [DJW84] W49 G1 HII 19 10 13.42 +09 06 12.8           ~ 19 0
21 [DJW84] W49 G2b Rad 19 10 13.450 +09 06 12.98           ~ 11 0
22 [DJW84] W49 G2 HII 19 10 13.47 +09 06 13.2           ~ 16 0
23 [DJW84] W49 G2c Rad 19 10 13.48 +09 06 13.1           ~ 9 0
24 [DJW84] W49 G3 Rad 19 10 13.55 +09 06 12.1           ~ 11 0
25 [DJW84] W49 G HII 19 10 13.57 +09 06 12.9           ~ 24 0
26 [DJW84] W49 G4 Rad 19 10 13.57 +09 06 13.5           ~ 11 0
27 [DJW84] W49 H HII 19 10 13.64 +09 06 17.2           ~ 11 0
28 [DJW84] W49 G5 Rad 19 10 13.66 +09 06 12.4           ~ 11 0
29 W 49a SFR 19 10 15.7 +09 06 05           ~ 264 2
30 W 49 SFR 19 10 20 +09 07.7           ~ 519 1
31 NAME W 49A South HII 19 10 21.6 +09 05 03           ~ 51 2
32 W 49b SNR 19 11 09.000 +09 06 24.00           ~ 404 1
33 ICRF J192559.6+210626 BLL 19 25 59.60535560 +21 06 26.1620442           ~ 180 1
34 NAME K 3-50A HII 20 01 45.6 +33 32 42           ~ 75 0
35 4C 06.69 QSO 21 48 05.4585565234 +06 57 38.605396596   16.85 16.47 15.06   ~ 605 1

    Equat.    Gal    SGal    Ecl

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2021.01.21-07:39:17

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