2018A&A...617A..42M


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.13CEST00:10:41

2018A&A...617A..42M - Astronomy and Astrophysics, volume 617A, 42-42 (2018/9-1)

Optical and UV surface brightness of translucent dark nebulae. Dust albedo, radiation field, and fluorescence emission by H2.

MATTILA K., HAAS M., HAIKALA L.K., JO Y.-S., LEHTINEN K., LEINERT C. and VAISANEN P.

Abstract (from CDS):


Context. Dark nebulae display a surface brightness because dust grains scatter light of the general interstellar radiation field (ISRF). High-galactic-latitudes dark nebulae are seen as bright nebulae when surrounded by transparent areas which have less scattered light from the general galactic dust layer.
Aims. Photometry of the bright dark nebulae LDN 1780, LDN 1642, and LBN 406 shall be used to derive scattering properties of dust and to investigate the presence of UV fluorescence emission by molecular hydrogen and the extended red emission (ERE).
Methods. We used multi-wavelength optical photometry and imaging at ground-based telescopes and archival imaging and spectroscopic UV data from the spaceborn GALEX and SPEAR/FIMS instruments. In the analysis we used Monte Carlo RT and both observational data and synthetic models for the ISRF in the solar neighbourhood. The line-of-sight extinctions through the clouds have been determined using near infrared excesses of background stars and the 200/250µm far infrared emission by dust as measured using the ISO and Herschel space observatories.
Results. The optical surface brightness of the three target clouds can be explained in terms of scattered light. The dust albedo ranges from ∼0.58 at 3500Å to ∼0.72 at 7500Å. The spectral energy distribution of LDN 1780 is explained in terms of optical depth and background scattered light effects instead of the original published suggestion in terms of ERE. The far-ultraviolet surface brightness of LDN 1780 cannot be explained by scattered light only. In LDN 1780, H2 fluorescent emission in the wavelength range 1400-1700Å has been detected and analysed.
Conclusions. Our albedo values are in good agreement with the predictions of the dust model of Weingartner and Draine and with the THEMIS CMM model for evolved core-mantle grains. The distribution of H2 fluorescent emission in LDN 1780 shows a pronounced dichotomy with a strong preference for its southern side where enhanced illumination is impinging from the Sco OB2 association and the O star ζ Oph. A good correlation is found between the H2 fluorescence and a previously mapped 21-cm excess emission. The H2 fluorescence emission in LDN 1780 has been modelled using a PDR code; the resulting values for H2 column density and the total gas density are consistent with the estimates derived from CO observations and optical extinction along the line of sight.

Abstract Copyright: © ESO 2018

Journal keyword(s): ISM: clouds - dust, extinction - solar neighborhood - ultraviolet: ISM

Simbad objects: 25

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Number of rows : 25

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 NAME Eridanus Shell sh 02 17 31 +07 49.6           ~ 45 0
2 NAME Perseus Cloud SFR 03 35.0 +31 13           ~ 1061 0
3 Barnard 207 DNe 04 04.6 +26 20           ~ 6 0
4 LDN 1489 DNe 04 04 47.5 +26 19 42           ~ 195 0
5 LDN 1642 MoC 04 35 18 -14 13.9           ~ 137 0
6 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 3479 0
7 NAME Ori A MoC 05 38 -07.1           ~ 2675 0
8 NAME Ori B MoC 05 41 43.0 -01 54 44           ~ 1164 0
9 HD 44179 pA* 06 19 58.2185496 -10 38 14.706068 9.51 9.33 9.02     B9Ib/II 715 0
10 Cl Bochum 15 OpC 07 40 10 -33 32.4   6.74 6.3     ~ 18 0
11 NAME Coalsack Nebula DNe 12 31 19 -63 44.6           ~ 242 0
12 LP 916-15 PM* 15 38 59.6477173130 -28 35 36.970418054   12.19 11.62     A 104 0
13 SA 107- reg 15 39.2 -00 20           ~ 89 0
14 LDN 1780 DNe 15 39.7 -07 10           ~ 70 0
15 LDN 1778 DNe 15 39.9 -07 10           ~ 17 0
16 LDN 169 DNe 15 52.6 -03 19           ~ 23 0
17 LDN 134 MoC 15 53 36.3 -04 35 26           ~ 194 0
18 LDN 183 MoC 15 54 12.2 -02 49 42           ~ 682 1
19 NAME ASSOC II SCO As* 16 15 -24.2           ~ 1120 1
20 * zet Oph Be* 16 37 09.5390545 -10 34 01.529471 1.73 2.58 2.56 2.46 2.50 O9.2IVnn 1724 2
21 LBN 090.02+38.77 HII 16 46 +60.2           ~ 3 0
22 NAME Draco Cloud MoC 16 48 17 +60 11.8           ~ 66 1
23 NAME Draco Nebula RNe 16 52 +61.0           ~ 46 0
24 LSE 259 HS* 16 53 54.5761511888 -56 01 54.752384338     12.54     sdO 30 0
25 NAME Local Bubble ISM ~ ~           ~ 693 0

    Equat.    Gal    SGal    Ecl

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2020.07.13-00:10:41

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