INVESTIGATION OF THE ORIGIN OF NEBULAR HeII EMISSION IN THE SPECTRA OF LOW-METALLICITY HII REGIONS FROM THE SLOAN DIGITAL SKY SURVEY

К. Б. Агиенко

Abstract


Primordial stars apparently were very hotand massive and emitted a lot of hard ionizing radiation.Regions of ionized hydrogen are the best places for studyingsuch hard radiation, because of underlying starformation processes. To check a possible links between hard ultravioletradiation and Wolf–Rayet (WR) stars we created a sample of galaxies with nebular emission line of HeII 4686 fromSloan Digital Sky Service. Theoretical models predict decreasing of HeII emission line intensity with metallicity. Datafrom our sample did not show any significant trends. This observation is in good agreement with previous studies.Only a half of spectra from our sample show nebular HeII emission, superposed on broad HeII emission from WRstars. This point concludes that not only WR stars are responsible for origin of nebular HeII emission, but also othermechanisms make a contribution into hard ionizing radiation at HII regions.

Keywords


active processes and star formation in galaxies; intensity of emission lines; Wolf–Rayet stars

References


Abazajian K.N., Adelman-McCarthy J.K. The Seventh Data Release of the Sloan Digital Sky Survey // Ap.J.S. —

— 182. — P. 543–558.

Brinchmann J., Kunth D., Durret F. Galaxies with Wolf-Rayet signatures in the low-redshift Universe. A survey

using the Sloan Digital Sky Survey // Astronomy and Astrophysics. — 2008. — 485. — P. 657–677.

Crowther P.A., Hadfield L.J. Reduced Wolf-Rayet line luminosities at low metallicity // Astronomy and Astrophysics.

— 2006. — 449. — P. 711–722.

Guseva N.G., Izotov Y.I., Thuan T.X. A Spectroscopic Study of a Large Sample Of Wolf-Rayet Galaxies // Astrophys. J. — 2000. — 531, №2. — P. 776–803.

Izotov Y.I. The chemical composition of metal-poor emission-line galaxies in the Data Release 3 of the Sloan Digital Sky Survey // A&A. — 2006. — 448. — P. 955–970.

Maeder A., Conti P. Massive star populations in nearby galaxies // Annual Rev. Astron. and Astrophys. — 1994. —

— P. 227–275.

Meynet G., Maeder A. Stellar evolution with rotation. XI. Wolf-Rayet star populations at different metallicities //

A&A. — 2005. — 429. — P. 581–598.

Pilyugin L.S., Mattsson L. Abundance determination in HII regions from spectra without the [OII]3727+3729 line

// MNRAS. — 2011. — 412. — P. 1145–1150.

Schaerer D., Contini T., Kunth D. Detection of Wolf-Rayet Stars of WN and WC Subtypes in Super–Star Clusters of NGC 5253 // Astrophysical Journal Letters. — 1997. — 481. — P. 75

Schaerer D., Vacca W.D. New models for Wolf-Rayet and O populations in young starbursts // Astrophys. J. — 1998. — 497, №2. — P. 618–644.

Whitford A.E. The law of interstellar reddening // Astron. J. — 1958. — 63. — P. 201–207.


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