2015A&A...582A..70S


C.D.S. - SIMBAD4 rel 1.7 - 2020.01.21CET12:25:34

2015A&A...582A..70S - Astronomy and Astrophysics, volume 582A, 70-70 (2015/10-1)

Grain size limits derived from 3.6 µm and 4.5 µm coreshine.

STEINACKER J., ANDERSEN M., THI W.-F., PALADINI R., JUVELA M., BACMANN A., PELKONEN V.-M., PAGANI L., LEFEVRE C., HENNING T. and NORIEGA-CRESPO A.

Abstract (from CDS):

Recently discovered scattered light from molecular cloud cores in the wavelength range 3-5µm (called ``coreshine'') seems to indicate the presence of grains with sizes above 0.5µm. We aim to analyze 3.6 and 4.5µm coreshine from molecular cloud cores to probe the largest grains in the size distribution. We analyzed dedicated deep Cycle 9 Spitzer IRAC observations in the 3.6 and 4.5µm bands for a sample of 10 low-mass cores. We used a new modeling approach based on a combination of ratios of the two background- and foreground-subtracted surface brightnesses and observed limits of the optical depth. The dust grains were modeled as ice-coated silicate and carbonaceous spheres. We discuss the impact of local radiation fields with a spectral slope differing from what is seen in the DIRBE allsky maps. For the cores L260, ecc806, L1262, L1517A, L1512, and L1544, the model reproduces the data with maximum grain sizes around 0.9, 0.5, 0.65, 1.5, 0.6, and >1.5µm, respectively. The maximum coreshine intensities of L1506C, L1439, and L1498 in the individual bands require smaller maximum grain sizes than derived from the observed distribution of band ratios. Additional isotropic local radiation fields with a spectral shape differing from the DIRBE map shape do not remove this discrepancy. In the case of Rho Oph 9, we were unable to reliably disentangle the coreshine emission from background variations and the strong local PAH emission. Considering surface brightness ratios in the 3.6 and 4.5µm bands across a molecular cloud core is an effective method of disentangling the complex interplay of structure and opacities when used in combination with observed limits of the optical depth.

Abstract Copyright:

Journal keyword(s): dust, extinction - ISM: clouds - infrared: ISM - scattering

Simbad objects: 17

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Number of rows : 17

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 LDN 1498 DNe 04 11.0 +24 58           ~ 243 0
2 LDN 1506C DNe 04 18 50.0 +25 19 15           ~ 8 0
3 NAME Taurus Dark Cloud SFR 04 41.0 +25 52           ~ 3356 0
4 LDN 1517A PoC 04 55 06.3 +30 33 40           ~ 25 0
5 LDN 1517 DNe 04 55 45 +30 33.0           ~ 94 0
6 LDN 1439 DNe 05 00 09 +52 04.9           ~ 76 0
7 LDN 1512 MoC 05 04 09.7 +32 43 09           ~ 159 0
8 LDN 1544 DNe 05 04 16.6 +25 10 48           ~ 661 0
9 [CB88] 28 MoC 05 06 16.0 -03 56 29           ~ 18 0
10 PLCKECC G303.09-16.04 cor 12 54 36.9 -78 54 51           ~ 4 0
11 LDN 183 MoC 15 54 12.2 -02 49 42           ~ 675 1
12 NAME Lupus IV MoC 16 03 12.4 -42 07 43           ~ 123 0
13 [TMF2000] rho Oph 9 PoC 16 32 39.4 -23 52 32           ~ 3 0
14 LDN 260 DNe 16 46 58.2 -09 36 20           ~ 41 0
15 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11166 0
16 LDN 1262 MoC 23 25 47 +74 17.6           ~ 130 0
17 NAME Vela Field reg ~ ~           ~ 145 0

    Equat.    Gal    SGal    Ecl

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2020.01.21-12:25:34

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