dc.contributor.author | Oudmaijer, R.D. | |
dc.contributor.author | Drew, J.E. | |
dc.contributor.author | Barlow, M.J. | |
dc.contributor.author | Crawford, I.A. | |
dc.contributor.author | Proga, D. | |
dc.date.accessioned | 2009-12-01T10:46:38Z | |
dc.date.available | 2009-12-01T10:46:38Z | |
dc.date.issued | 1997 | |
dc.identifier.citation | Oudmaijer , R D , Drew , J E , Barlow , M J , Crawford , I A & Proga , D 1997 , ' Helium absorption and emission towards Theta^1 ORI C ' , Monthly Notices of the Royal Astronomical Society , vol. 291 , no. 1 , pp. 110-120 . | |
dc.identifier.issn | 0035-8711 | |
dc.identifier.other | dspace: 2299/4036 | |
dc.identifier.other | ORCID: /0000-0003-1192-7082/work/62750190 | |
dc.identifier.uri | http://hdl.handle.net/2299/4036 | |
dc.description | Original article can be found at: http://adsabs.harvard.edu/basic_search.html Copyright Royal Astronomical Society [Full text of this article is not available in the UHRA] | |
dc.description.abstract | The Hei absorption and emission systems towards Theta^1Ori C, the exciting star of the Orion Nebula, are investigated. To this end, high-resolution near-infrared long-slit spectra centred on the Hei 1.083-μm and Brgamma lines and an ultra-high-resolution (R~10^6) spectrum of the optical Hei 3889-Angstroms line have been obtained. These data are supplemented by blue high spectral resolution echelle observations of Theta^1Ori C and the other members of the Trapezium. Even at R~10^6, the Hei absorption profile, associated with foreground gas at a heliocentric velocity of +3km s^-1, is very smooth, suggesting a simple broadening mechanism and homogeneity. The combination of the Hei 2^3S column density, deduced from the 3889-Angstroms line, with the non-detection of Brgamma emission at the same velocities sets an upper limit on the electron density in this medium of 10^10 m^-3. The Hei 1.083-μm long-slit spectrum shows the familiar background nebular emission, while a second blueshifted component is visible off-star at the same velocities as the absorption on-star. Several mechanisms to explain this emission are explored. We conclude that it is most probably emission formed behind, and leaking through, the absorbing gas layer. A clue to the origin of this emission is found in its spatial distribution: unlike the bright background nebular emission, the blueshifted component peaks symmetrically around the position of Theta^1Ori C, suggesting a physical association with the star. A possible model for the blueshifted emission is that it arises in a large-scale, dense shock front, provoked in some way by the wind of ^1Ori C. | en |
dc.language.iso | eng | |
dc.relation.ispartof | Monthly Notices of the Royal Astronomical Society | |
dc.title | Helium absorption and emission towards Theta^1 ORI C | en |
dc.contributor.institution | School of Physics, Astronomy and Mathematics | |
dc.description.status | Peer reviewed | |
rioxxterms.type | Journal Article/Review | |
herts.preservation.rarelyaccessed | true | |