Query : 2017A&A...605L..10E

2017A&A...605L..10E - Astronomy and Astrophysics, volume 605, L10-10 (2017/9-1)

The 15 273Å diffuse interstellar band in the dark cloud Barnard 68.


Abstract (from CDS):

High obscuration of background stars behind dark clouds precludes the detection of optical diffuse interstellar bands (DIBs) and hence our knowledge of DIB carriers in these environments. Taking advantage of the reduced obscuration of starlight in the near-infrared (NIR) we used one of the strongest NIR DIBs at 15 273Å to probe the presence and properties of its carrier throughout the nearby interstellar dark cloud Barnard 68. We measured equivalent widths (EW) for different ranges of visual extinction AV, using VLT/KMOS H-band (1.46-1.85µm) moderate-resolution (R∼4000) spectra of 43 stars situated behind the cloud. To do so, we fitted the data with synthetic stellar spectra from the APOGEE project and TAPAS synthetic telluric transmissions appropriate for the observing site and time period. The results show an increase of DIB EW with increasing AV. However, the rate of increase is much flatter than expected from the EW-AV quasi-proportionality established for this DIB in the Galactic diffuse interstellar medium. Based on a simplified inversion assuming sphericity, it is found that the volume density of the DIB carrier is 2.7 and 7.9 times lower than this expected average value in the external and central regions of the cloud, which have nH~=0.4 and 3.5x105cm–3, respectively. Further measurements with multiplex NIR spectrographs should allow detailed modeling of such an edge effect of this DIB and other bands and help clarify its actual origin.

Abstract Copyright: © ESO, 2017

Journal keyword(s): line: profiles - ISM: lines and bands - ISM: clouds - dust, extinction - dust, extinction

Simbad objects: 6

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Number of rows : 6
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
1 M 42 HII 05 35 17 -05 23.4           ~ 4036 0
2 HD 62542 * 07 42 37.2147724128 -42 13 47.831717064   8.21 8.03     B3V 150 0
3 LDN 57 DNe 17 22 38.2 -23 49 34           ~ 311 1
4 2MASS J17224159-2350261 * 17 22 41.59 -23 50 26.2           G0/M4III 3 0
5 2MASS J17224313-2350357 NIR 17 22 43.134 -23 50 35.74           ~ 1 0
6 NAME Galactic Bulge reg ~ ~           ~ 4208 0

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