Query : 2019A&A...628A..67E

2019A&A...628A..67E - Astronomy and Astrophysics, volume 628A, 67-67 (2019/8-1)

Updated extraction of the APOGEE 1.5273 µm diffuse interstellar band: a Planck view on the carrier depletion in dense cores.


Abstract (from CDS):

Context. Constraining the spatial distribution of diffuse interstellar band (DIB) carriers and their links with gas and dust are mandatory steps in understanding their role in interstellar chemistry.
Aims. The latest SDSS/APOGEE data release, DR14, has provided an increased number of stellar spectra in the H band and associated stellar models using an innovative algorithm known as the Cannon. We took advantage of these novelties to extract the 15 273Å near-infrared DIB and to study its link with dust extinction and emission.
Methods. We modified our automated fitting methods dedicated to hot stars and used in earlier studies with some adaptations motivated by the change from early- or intermediate-type stars to red giants. A new method has also been developed to quantify the upper limits on DIB strengths. Careful and thorough examinations were carried out of the DIB parameters, the continuum shape, and the quality of the adjustment of the model to the data. We compared our DIB measurements with the stellar extinctions, AV, from the Starhorse database. We then compared the resulting DIB-extinction ratio with the dust optical depth derived from Planck data, both globally and separately for nearby off-plane cloud complexes. Results. Our analysis has led to the production of a catalog containing 124 064 new measurements of the 15273Å DIB, allowing us to revisit the correlation between DIB strength and dust reddening. The new data clearly reveal that the sky-averaged 15273Å DIB strength is linearly correlated with AV over two orders as reported by earlier studies but leveling off with respect to extinction for highly reddened lines of sight behind dense clouds. The comparison with Planck individual optical depths reveals in a conspicuous way this DIB depletion in the dense cores and shows it applies to all off-plane dense clouds. Using selected targets located beyond the Orion, Taurus, and Cepheus clouds, we derived empirical relationships between the DIB-extinction ratio and the Planck dust optical depth for the three cloud complexes. Their average is similar to the DIB carrier depletion measured in the dark cloud Barnard 68.Conclusions. APOGEE measurements confirm the ubiquity of the 15273Å DIB carrier decrease with respect to dust grains in dense cloud cores, in a manner that can be empirically related to the dust optical depth reached in the cloud. They also show that the ratio between the DIB equivalent width and the extinction AV for sightlines with τ(353GHz)≤2x10–5 that do not contain dense molecular gas is about four times higher than the constant limit towards which the ratio tends for very long sightlines with many diffuse and dense phases distributed in distance.

Abstract Copyright: © M. Elyajouri and R. Lallement 2019

Journal keyword(s): ISM: clouds - ISM: lines and bands - dust, extinction - infrared: ISM - ISM: molecules

VizieR on-line data: <Available at CDS (J/A+A/628/A67): catalog.dat>

Status at CDS : All or part of tables of objects will not be ingested in SIMBAD.

Simbad objects: 11

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Number of rows : 11
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 NAME Perseus Cloud SFR 03 35.0 +31 13           ~ 1311 0
2 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 4250 0
3 NAME Ori Region reg 05 35 17.30 -05 23 28.0           ~ 568 0
4 NAME Orion Molecular Cloud MoC 05 56 -01.8           ~ 1065 1
5 HD 62542 * 07 42 37.2147724128 -42 13 47.831717064   8.21 8.03     B3V 149 0
6 NAME Sco-Oph Region reg 16 30.0 -21 00           ~ 74 0
7 LDN 57 DNe 17 22 38.2 -23 49 34           ~ 309 1
8 2MASS J19420307+2317393 RG* 19 42 03.0749004288 +23 17 39.458969664           ~ 6 0
9 NAME Cepheus Region reg 21 20 00.0 +72 30 00           ~ 112 0
10 NAME Cepheus Cloud SFR 22 00.0 +76 30           ~ 139 0
11 NAME Gould Belt PoG ~ ~           ~ 854 1

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