Volume 550, February 2013
|Number of page(s)||5|
|Section||Interstellar and circumstellar matter|
|Published online||22 January 2013|
Dust properties in the Galactic bulge⋆
Kapteyn Astronomical Institute,
PO Box 800,
2 Institut d’Astrophysique Spatiale, Paris-Sud 11, 91405 Orsay, France
Received: 22 May 2012
Accepted: 21 December 2012
Context. It has been suggested that the ratio of total-to-selective extinction RV in dust in the interstellar medium differs in the Galactic bulge from its value in the local neighborhood.
Aims. We attempt to test this suggestion.
Methods. The mid-infrared hydrogen lines in 16 Galactic bulge PNe measured by the Spitzer Space Telescope are used to determine the extinction corrected Hβ flux. This is compared to the observed Hβ flux to obtain the total extinction at Hβ. The selective extinction is obtained from the observed Balmer decrement in these nebulae. The value of RV can then be found.
Results. The ratio of total-to-selective extinction in the Galactic bulge is consistent with the value RV = 3.1, which is the same as has been found in the local neighborhood.
Conclusions. The suggestion that RV is different in the Galactic bulge is incorrect. The reasons for this are discussed.
Key words: dust, extinction / planetary nebulae: general / infrared: ISM / radio continuum: ISM
© ESO, 2013
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