Properties of hot stars in the Wolf-Rayet galaxy NGC 5253 from ISO-SWS spectroscopy

被引:53
|
作者
Crowther, PA
Beck, SC
Willis, AJ
Conti, PS
Morris, PW
Sutherland, RS
机构
[1] Univ London Univ Coll, Dept Phys & Astron, London WC1E 6BT, England
[2] Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Sch Phys & Astron, Ramat Aviv, Israel
[3] Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA
[4] ESA, Div Astrophys, Sci Operat Ctr, ISO, E-28080 Madrid, Spain
[5] SRON, NL-3584 CA Utrecht, Netherlands
[6] Australian Natl Univ, Mt Stromlo & Siding Spring Observ, Canberra, ACT 0200, Australia
关键词
stars : Wolf-Rayet; galaxies : individual : NGC5253; galaxies : starburst; galaxies : stellar content; infrared : galaxies;
D O I
10.1046/j.1365-8711.1999.02380.x
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
ISO-SWS spectroscopy of the Wolf-Rayet galaxy NGC 5253 is presented, and analysed to provide estimates of its hot young star population. Our approach differs from previous investigations in that we are able to distinguish between the regions in which different infrared fine-structure lines form, using complementary ground-based observations. The high-excitation nebular [S IV] emission is formed in a very compact region, which we attribute to the central super-star nucleus, and lower excitation [Ne Ir] nebular emission originates in the galactic core. We use photoionization modelling coupled with the latest theoretical O-star flux distributions to derive effective stellar temperatures and ionization parameters of T(eff) greater than or equal to 38 kK, log Q similar to 8.25 for the compact nucleus, with T(eff) similar to 35 kK, log Q less than or equal to 8 for the larger core. Results are supported by more sophisticated calculations using evolutionary synthesis models We assess the contribution that Wolf-Rayet stars may make to highly ionized nebular lines (e.g, [O IV]). From our Br alpha flux, the 2-arcsec nucleus contains the equivalent of approximately 1000 O7 V star equivalents and the starburst there is 2-3 Myr old: the 20-arcsec core contains about 2500 O7 V star equivalents, with a representative age of similar to 5 Myr, The Lyman ionizing flux of the nucleus is equivalent to that of the 30 Doradus region. These quantities are in good agreement with the observed mid-infrared dust luminosity of 7.8 x 10(8) L.. Since this structure of hot clusters embedded in cooler emission may be common in dwarf starbursts, observing a galaxy solely with a large aperture may result in confusion. Neglecting the spatial distribution of nebular emission in NGC 5253 implies 'global' stellar temperatures (or ages) of 36 kK (4.8 Myr) and 39 kK (2.9 or 4.4 Myr) from the observed [Ne III/II] and [S IV/III] line ratios, assuming log Q = 8.
引用
收藏
页码:654 / 668
页数:15
相关论文
共 50 条
  • [1] ISO-SWS spectroscopy of NGC 1068
    Lutz, D
    Sturm, E
    Genzel, R
    Moorwood, AFM
    Alexander, T
    Netzer, H
    Sternberg, A
    ASTROPHYSICAL JOURNAL, 2000, 536 (02) : 697 - 709
  • [2] ISO observations of the Wolf-Rayet galaxy NGC 7714 and its companion NGC 7715
    O'Halloran, B
    Metcalfe, L
    Delaney, M
    McBreen, B
    Laureijs, R
    Leech, K
    Watson, D
    Hanlon, L
    ASTRONOMY & ASTROPHYSICS, 2000, 360 (03): : 871 - 877
  • [3] The Wolf-Rayet star population in the dwarf galaxy NGC 625
    Monreal-Ibero, A.
    Walsh, J. R.
    Iglesias-Paramo, J.
    Sandin, C.
    Relano, M.
    Perez-Montero, E.
    Vilchez, J.
    ASTRONOMY & ASTROPHYSICS, 2017, 603
  • [4] The red supergiants and Wolf-Rayet stars of NGC 604
    Eldridge, John J.
    Relano, Monica
    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2011, 411 (01) : 235 - 246
  • [5] Spectroscopic analyses of the Wolf-Rayet stars in NGC 3603
    Schmutz, W
    Drissen, L
    WORKSHOP ON HOT STARS IN OPEN CLUSTERS OF THE GALAXY AND THE MAGELLANIC CLOUDS, 1999, 8 : 41 - 48
  • [6] Hot Gas in the Wolf-Rayet Nebula NGC 3199
    Toala, J. A.
    Marston, A. P.
    Guerrero, M. A.
    Chu, Y. -H.
    Gruendl, R. A.
    ASTROPHYSICAL JOURNAL, 2017, 846 (01)
  • [7] Wolf-Rayet stars detected in five associations of NGC 300
    Breysacher, J
    Azzopardi, M
    Testor, G
    Muratorio, G
    ASTRONOMY & ASTROPHYSICS, 1997, 326 (03) : 976 - 981
  • [8] ISO observations of the Wolf-Rayet galaxies NGC 5430, NGC 6764, Mrk 309 and VII Zw 19
    O'Halloran, B
    McBreen, B
    Metcalfe, L
    Delaney, M
    Coia, D
    ASTRONOMY & ASTROPHYSICS, 2005, 439 (02): : 539 - 550
  • [9] The young starburst nucleus of the Wolf-Rayet LINER galaxy NGC 6764
    Schinnerer, E
    Eckart, A
    Boller, T
    ASTROPHYSICAL JOURNAL, 2000, 545 (01) : 205 - 215
  • [10] A survey of the Wolf-Rayet population of the barred, spiral galaxy NGC 1313
    Hadfield, L. J.
    Crowther, P. A.
    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2007, 381 (01) : 418 - 432