Please use this identifier to cite or link to this item:
|Title:||Halo dust detection around NGC 891||Authors:||Bocchio, M.
HUNT, Leslie Kipp
|Issue Date:||2016||Journal:||ASTRONOMY & ASTROPHYSICS||Number:||586||First Page:||A8||Abstract:||Context. Observations of edge-on galaxies allow us to investigate the vertical extent and properties of dust, gas and stellar distributions. NGC 891 has been studied for decades and represents one of the best studied cases of an edge-on galaxy. Aims: We use deep Photoconductor Array Camera and Spectrometer (PACS) data together with Infrared Array Camera (IRAC), Multiband Imaging Photometer for Spitzer (MIPS) and Spectral and Photometric Imaging Receiver (SPIRE) data to study the vertical extent of dust emission around NGC 891. We also test for the presence of a more extended, thick dust component. Methods: By performing a convolution of an intrinsic vertical profile emission with each instrument point spread function (PSF) and comparing it with observations we derived the scale height of a thin and thick dust-disc component. Results: The emission is best fit with the sum of a thin and a thick dust component for all wavelengths considered. The scale height of both dust components shows a gradient goes from 70 μm to 250 μm. This could be due either to a drop in dust heating (and thus the dust's temperature) with the distance from the plane, or to a sizable contribution (~15-80%) of an unresolved thin disc of hotter dust to the observed surface brightness at shorter wavelengths. The scale height of the thick dust component, using observations from 70 μm to 250 μm, has been estimated at (1.44 ± 0.12) kpc, which is consistent with previous estimates (I.e. extinction and scattering in optical bands and mid-infrared (MIR) emission). The amount of dust mass at distances greater than ~2 kpc from the midplane represents 2-3.3% of the total galactic dust mass, and the abundance of small grains relative to large grains is almost halved compared to levels in the midplane. Conclusions: The paucity of small grains high above the midplane might indicate that dust is hit by interstellar shocks or galactic fountains and entrained together with gas. The halo dust component is likely to be embedded in an atomic/molecular gas and heated by a thick stellar disc. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.||URI:||http://hdl.handle.net/20.500.12386/24408||URL:||https://www.aanda.org/articles/aa/abs/2016/02/aa26950-15/aa26950-15.html||ISSN:||0004-6361||DOI:||10.1051/0004-6361/201526950||Bibcode ADS:||2016A&A...586A...8B||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
Show full item record
Files in This Item:
|aa26950-15.pdf||PDF editoriale||1.33 MB||Adobe PDF||View/Open|
checked on Oct 28, 2020
checked on Oct 28, 2020
Items in DSpace are published in Open Access, unless otherwise indicated.