A SURVEY OF MOLECULAR HYDROGEN IN THE CRAB NEBULA

Journal Article · Wed Jun 01 00:00:00 EDT 2011 · Astrophysical Journal, Supplement Series

DOI:https://doi.org/10.1088/0067-0049/194/2/30· OSTI ID:21560376

Loh, E D; Baldwin, J A; Curtis, Z K ^[1]; Ferland, G J ^[2]; O'Dell, C R ^[3]; Fabian, A C ^[4]; Salome, Philippe ^[5]

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1. Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824-2320 (United States)
2. Department of Physics, University of Kentucky, Lexington, KY 40506 (United States)
3. Physics and Astronomy Department, Vanderbilt University, Nashville, TN 37240 (United States)
4. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
5. LERMA and UMR8112 du CNRS, Observatoire de Paris, 61 Av. de l'Observatoire, F-75014 Paris (France)

We have carried out a near-infrared, narrowband imaging survey of the Crab Nebula, in the H{sub 2} 2.12 {mu}m and Br{gamma} 2.17 {mu}m lines, using the Spartan Infrared camera on the SOAR Telescope. Over a 2.'8 x 5.'1 area that encompasses about 2/3 of the full visible extent of the Crab, we detect 55 knots that emit strongly in the H{sub 2} line. We catalog the observed properties of these knots. We show that they are in or next to the filaments that are seen in optical-passband emission lines. Comparison to Hubble Space Telescope [S II] and [O III] images shows that the H{sub 2} knots are strongly associated with compact regions of low-ionization gas. We also find evidence of many additional, fainter H{sub 2} features, both discrete knots and long streamers following gas that emits strongly in [S II]. A pixel-by-pixel analysis shows that about 6% of the Crab's projected surface area has significant H{sub 2} emission that correlates with [S II] emission. We measured radial velocities of the [S II] {lambda}6716 emission lines from 47 of the cataloged knots and find that most are on the far (receding) side of the nebula. We also detect Br{gamma} emission. It is right at the limit of our survey, and our Br{gamma} filter cuts off part of the expected velocity range. But clearly the Br{gamma} emission has a quite different morphology than the H{sub 2} knots, following the long linear filaments that are seen in H{alpha} and in [O III] optical emission lines.

• OSTI ID: 21560376
• Journal Information: Astrophysical Journal, Supplement Series, Vol. 194, Issue 2; Other Information: DOI: 10.1088/0067-0049/194/2/30; ISSN 0067-0049
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
CAMERAS
CATALOGS
CRAB NEBULA
EMISSION
FILAMENTS
HYDROGEN
NEAR INFRARED RADIATION
RADIAL VELOCITY
TELESCOPES
COSMIC RADIO SOURCES
DOCUMENT TYPES
ELECTROMAGNETIC RADIATION
ELEMENTS
INFRARED RADIATION
NEBULAE
NONMETALS
RADIATIONS
SUPERNOVA REMNANTS
VELOCITY