Astronomy and Astrophysics – Astrophysics – Galaxy Astrophysics
Scientific paper
2011-04-23
Astronomy and Astrophysics
Astrophysics
Galaxy Astrophysics
6 pages + 13 pages online material, submitted to A&A
Scientific paper
Context. 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. 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~64.000) spectropolarimetry in the wavelength range from 3700 to 10480 Angstrom with the ESPaDOnS echelle spectrograph mounted at the CFHT. Results. 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 9577 A DIB and the 8621 A DIB. Conclusions. 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.
Cox Nick L. J.
d'Hendecourt Louis
Ehrenfreund Pascale
Foing Bernard H.
Salama Farid
No associations
LandOfFree
Linear/circular spectropolarimetry of diffuse interstellar bands does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Linear/circular spectropolarimetry of diffuse interstellar bands, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Linear/circular spectropolarimetry of diffuse interstellar bands will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-484357