2013A&A...550A..83M


C.D.S. - SIMBAD4 rel 1.7 - 2019.12.06CET15:30:15

2013A&A...550A..83M - Astronomy and Astrophysics, volume 550A, 83-83 (2013/2-1)

Star formation, structure, and formation mechanism of cometary globules: near-infrared observations of CG 1 and CG 2.

MAEKELAE M.M. and HAIKALA L.K.

Abstract (from CDS):

Cometary globule (CG) 1 and CG 2 are ``classic'' cometary globules in the Gum Nebula. They have compact heads and long dusty tails that point away from the centre of the Gum Nebula. We study the structure of CG 1 and CG 2 and the star formation in them to find clues to the CG formation mechanism. The two possible CG formation mechanisms, radiation-driven implosion (RDI) and a supernova blast wave, produce a characteristic mass distribution where the major part of the mass is situated in either the head (RDI) or the tail (supernova blast). CG 1 and CG 2 were imaged in the near infrared (NIR) JsHKs bands. NIR photometry was used to locate NIR excess objects and to create visual extinction maps of the CGs. The AV maps allow us to analyse the large-scale structure of CG 1 and CG 2. Archival images from the WISE and Spitzer satellites and HIRES-processed IRAS images were used to study the globule's small-scale structure. Fits were made to the spectral energy distribution plots of the NIR-excess stars to estimate their age and mass. In addition to the previously known CG 1 IRS 1 we discovered three new NIR-excess objects in IR imaging, two in CG 1 and one in CG 2. CG 2 IRS 1 is the first detection of star formation in CG 2. The objects are young low-mass stars. CG 1 IRS 1 is probably a class I protostar in the head of CG 1. CG 1 IRS 1 drives a bipolar outflow, which is very weak in CO, but the cavity walls are seen in reflected light in our NIR and in the Spitzer 3.6 and 4.5µm images. Strong emission from excited polycyclic aromatic hydrocarbon particles and very small grains were detected in the CG 1 tail. The total mass of CG 1 in the observed area is 41.9M of which 16.8M lies in the head. For CG 2 these values are 31.0M total and 19.1M in the head. The observed mass distribution does not offer a firm conclusion for the formation mechanism of the two CGs: CG 1 is in too evolved a state, and in CG 2 part of the globule tail was outside the observed area. Even though the masses of the two CGs are similar, star formation has been more efficient in CG 1. By now, altogether six young low-mass stars have been detected in CG 1 and only one in CG 2. A possible new outflow was discovered to be emanating from CG 1 IRS 1.

Abstract Copyright:

Journal keyword(s): stars: formation - stars: pre-main sequence - ISM: individual objects: CG 1 - ISM: individual objects: CG 2 - dust, extinction

VizieR on-line data: <Available at CDS (J/A+A/550/A83): table1.dat table2.dat table3.dat>

Simbad objects: 15

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Number of rows : 15

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 [DB2002b] G255.30-14.35 DNe 07 16 01 -43 57.7           ~ 17 1
2 IRAS 07144-4352 FIR 07 16 01.1 -43 58 04           ~ 6 0
3 WISE J071604.50-435742.6 IR 07 16 04.5 -43 57 43           ~ 1 0
4 WISE J071814.71-443420.0 IR 07 18 14.7 -44 34 20           ~ 1 0
5 WISE J071846.52-443252.9 IR 07 18 46.5 -44 32 53           ~ 1 0
6 CG 1 CGb 07 19 21.5 -44 35 03           ~ 38 1
7 2MASS J07192185-4434551 IR 07 19 21.851 -44 34 55.12           ~ 2 0
8 IRAS 07178-4429 mul 07 19 25.8 -44 35 01           ~ 17 0
9 CD-44 3318 Ae* 07 19 28.2886716751 -44 35 11.235575735   10.47 9.99     A1e/F2IIIe 111 0
10 NAME GUM Nebula ISM 07 43 -42.1           ~ 377 1
11 * zet Pup BY* 08 03 35.04754 -40 00 11.3321 0.89 1.98 2.25 2.36 2.58 O4I(n)fp 1083 1
12 * gam02 Vel WR* 08 09 31.95013 -47 20 11.7108 0.64 1.58 1.83 1.85 2.00 WC8+O7.5III-V 829 0
13 NAME HH 46-47 HH 08 25 43.6 -51 00 36           ~ 176 2
14 LDN 1780 DNe 15 39.7 -07 10           ~ 70 0
15 MHO 1411 EmO ~ ~           ~ 2 0

    Equat.    Gal    SGal    Ecl

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2019.12.06-15:30:15

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