A New Spectral Classification System for the Earliest O Stars: Definition of Type O2

By N. Walborn, I. Howarth, D. Lennon, Philip Massey, M. Oey, A. Moffat, G. Skalkowski, N. Morrell, L. Drissen, J. Parker. 2002

207 citations recorded by the source corpus.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/a5e6f0fe0a23a02aa2319c9031e4eef4e9ea83c0

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In Astronomy and Astrophysics

1. N. Smith
2. N. Langer
3. P. Crowther
4. S. Smartt
5. Selma de Mink
6. J. Puls
7. D. John Hillier
8. J. Vink

In Instrumentation

1. N. Smith
2. N. Langer
3. J. Puls
4. S. Smartt
5. J. Vink
6. Selma de Mink
7. P. Crowther
8. D. John Hillier

Citations in the corpus

• Stellar and wind parameters of Galactic O-stars - The influence of line-blocking/blanketing (2004, background): “Moreover, according to Walborn et al. (2002), HD 93129A and HD 303308 (prior to knowing that the two stars were binaries; see Nelan et al. 2003, in prep.) have been revised to O2 If∗ and O4 V((f+)), respectively.”
• A census of the Wolf–Rayet content in Westerlund 1 from near-infrared imaging and spectroscopy (2006, unknown): “From membership of WR stars in open clusters, Schild & Maeder (1984) and Massey, DeGioia-Eastwood & Waterhouse (2001) investigated the initial masses of WR stars empirically, from the membership of WR stars in Milky Way clusters, to which we can now add Westerlund 1, which hosts more WR stars than a”
• The Physical Properties and Effective Temperature Scale of O-Type Stars as a Function of Metallicity. II. Analysis of 20 More Magellanic Cloud Stars and Results from the Complete Sample (2005, methodology): “Walborn et al. (2002) attempted to reduce the O3 degeneracy problem by using the N IV λ 4058 and N III λ4634, 42 emission lines to extend the spectral classification to spectral type O2 (“N IV >>> N III”) with the introduction of an intermediate type (O3.”
• The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 M⊙ stellar mass limit (2010, result): “Overall, these results suggest a paradigm shift in our understanding of early O dwarfs, which have hitherto been considered to represent ZAMS stars for the highest mass stars (Walborn et al. 2002).”
• Quantitative Spectroscopy of O Stars at Low Metallicity: O Dwarfs in NGC 346 (2003, background): “Walborn et al. (2002) showed that the different ionization stages of nitrogen can be used as a temperature indicator, but the nitrogen lines are hardly seen in the visible spectrum of MPG 324 and therefore cannot be used for this purpose.”
• The relation between the most-massive star and its parental star cluster mass (2009, background): “While, traditionally they would be of spectral type O3 some classify them as spectral type O2 or even earlier (Walborn et al. 2002) while others prefere a Wolf-Rayet star classification (for example WN6h, Crowther 2007).”
• THE HIGH ANGULAR RESOLUTION MULTIPLICITY OF MASSIVE STARS (2008, result): “Our measurements agree with the first results on the pair from Walborn et al. (2002), who determined O-type classifications for both components.”
• The VLT-FLAMES survey of massive stars: observations centered on the Magellanic Cloud clusters NGC 330, NGC 346, NGC 2004, and the N11 region (2006, background): “These O3 stars were considered by Walborn et al. (2002) in their Article published by EDP Sciences and available at http://www.edpsciences.org/aa or http://dx.doi.org/10.1051/0004-6361:20064988 624 C. J. Evans et al.: FLAMES survey of massive stars: LMC and SMC clusters extension of the MK…”
• THE GALACTIC O-STAR SPECTROSCOPIC SURVEY. I. CLASSIFICATION SYSTEM AND BRIGHT NORTHERN STARS IN THE BLUE-VIOLET AT R ∼ 2500 (2011, result): “It can be seen that in some of the hottest Ofc spectra, Si iv λ4654 and C iv λ4658 become comparable to the C iii (see also Walborn et al. 2002).”
• The R136 star cluster dissected with Hubble Space Telescope/STIS. I. Far-ultraviolet spectroscopic census and the origin of He II λ1640 in young star clusters (2016, methodology): “…UV-derived wind velocities for Galactic O stars from Prinja et al. (1990) – based on the same methodology as used here – updated for O2–4 stars following Walborn et al. (2002a), and adopting the Martins, Schaerer & Hillier (2005) Galactic observational temperature calibration adapted for LMC O…”
• A Galactic O Star Catalog (2003, background): “The earliest spectral types were re-investigated with high-quality digital data by Walborn et al. (2002), resulting in the subdivision of the former O3 type into three, including the new types O2 and O3.”
• Revised Stellar Temperatures for Magellanic Cloud O Supergiants from Far Ultraviolet Spectroscopic Explorer and Very Large Telescope UV-Visual Echelle Spectrograph Spectroscopy (2002, methodology): “Among Magellanic Cloud O stars, the sole result involving carbon and nitrogen was by Haser et al. (1998), who obtained N=C 5 for the SMC O2 giant NGC 346 No. 3 (Walborn et al. 2002b).”
• O stars with weak winds: the Galactic case (2005, unknown): “5((f+)) Walborn et al. 2002).”
• Stellar and wind properties of LMC WC4 stars A metallicity dependence for Wolf-Rayet mass-loss rates ? (2002, methodology): “This ratio now forms the basis for classification of early O stars (Walborn et al. 2002a).”
• The Initial Mass Function of the Massive Star-forming Region NGC 3603 from Near-Infrared Adaptive Optics Observations (2007, unknown): “Walborn et al. (2002) reported that they identified two O2-3.”
• Toward Understanding Massive Star Formation (2007, background): “We refer to Walborn et al. (2002) for further discussion of the most massive stars known (O2V stars).”