2011A&A...531A..25C


C.D.S. - SIMBAD4 rel 1.7 - 2019.08.22CEST12:21:34

2011A&A...531A..25C - Astronomy and Astrophysics, volume 531A, 25-25 (2011/7-1)

Linear and circular spectropolarimetry of diffuse interstellar bands.

COX N.L.J., EHRENFREUND P., FOING B.H., D'HENDECOURT L., SALAMA F. and SARRE P.J.

Abstract (from CDS):

The identification of the carriers of diffuse interstellar bands (DIBs) remains one of the long-standing mysteries in astronomy. The detection of a polarisation signal in a DIB profile can be used to distinguish between a dust or gas-phase carrier. The polarisation profile can give additional information on the grain or molecular properties of the absorber. To measure the polarisation efficiency of the carriers of the diffuse interstellar bands. In order to detect and measure the linear and circular polarisation of the DIBs we observed reddened lines of sight showing continuum polarisation. For this study we selected two stars HD 197770 and HD 194279. We used high-resolution (R∼64000) spectropolarimetry in the wavelength range from 3700 to 10480Å with the ESPaDOnS echelle spectrograph mounted at the CFHT. High S/N and high resolution Stokes V (circular), Q and U (linear) spectra were obtained. We constrained upper limits by a factor of 10 for previously observed DIBs. Furthermore, we analysed ∼30 additional DIBs for which no spectropolarimetry data has been obtained before. This included the 9577Å DIB and the 8621Å DIB. The former is attributed to the C60+ fullerene, which could become aligned in a magnetic field. The latter shows a tight correlation with the amount of dust in the line-of-sight and therefore most likely may show a polarisation signal related the aligned grains. The lack of polarisation in 45 DIB profiles suggests that none of the absorption lines is induced by a grain-type carrier. The strict upper limits, less than ∼0.01%, derived for the observed lines-of-sight imply that if DIBs are due to gas-phase molecules these carriers have polarisation efficiencies which are at least 6 times, and up to 300 times, smaller than those predicted for grain-related carriers.

Abstract Copyright:

Journal keyword(s): astrochemistry - polarization - dust, extinction - ISM: lines and bands - ISM: molecules

VizieR on-line data: <Available at CDS (J/A+A/531/A25): hd194279.dat hd197770.dat>

Simbad objects: 9

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Number of rows : 9

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2019
#notes
1 * rho Oph A * 16 25 35.142 -23 26 49.90 4.3 5.22 5.05     B2/3V 377 0
2 HD 183143 s*b 19 27 26.5636908636 +18 17 45.191198361 8.25 8.08 6.86 5.74 4.79 B6Ia 401 0
3 Ass Cyg OB 9 As* 20 21 +39.9           ~ 111 0
4 NGC 6910 OpC 20 23 08 +40 46.5   7.13 7.4     ~ 159 0
5 HD 194279 s*b 20 23 18.1650257662 +40 45 32.596789171 8.01 8.04 7.01 5.98 5.17 B2Ia 172 0
6 NAME Cyg Complex reg 20 32 +45.0           ~ 504 0
7 V* V379 Cep Al* 20 43 13.6841107658 +57 06 50.370628452 6.17 6.591 6.334     B2III 129 0
8 Ass Cyg OB 7 As* 21 08 +47.6           ~ 187 0
9 Ass Cep OB 2 As* 21 51 +60.0           ~ 276 0

    Equat.    Gal    SGal    Ecl

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2019.08.22-12:21:34

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