Physical parameters and wind properties of galactic early B supergiants

By P. Crowther, D. Lennon, N. Walborn. 2005

226 citations recorded by the source corpus.

We present optical studies of the physical and wind properties, plus CNO chemical abundances, of 25 O9.5–B3 Galactic supergiants. We employ non-LTE, line blanketed, extended model atmospheres, which provide a modest downward revision in the effective temperature scale of early B supergiants of up to 1-2 kK relative to previous non-blanketed results. The so-called “bistability jump” at B1 ($T_{\rm eff} \sim 21$ kK) from Lamers et al. is rather a more gradual trend (with large scatter) from $v_{\infty}/v_{\rm esc}\sim3.4$ for B0–0.5 supergiants above 24 kK to $v_{\infty}/v_{\rm esc}\sim 2.5$ for B0.7–1 supergiants with 20 kK  ≤ T eff ≤  24 kK, and $v_{\infty}/v_{\rm esc}\sim 1.9$ for B1.5–3 supergiants below 20 kK. This, in part, explains the break in observed UV spectral characteristics between B0.5 and B0.7 subtypes as discussed by Walborn et al. We compare derived (homogeneous) wind densities with recent results for Magellanic Cloud B supergiants and generally confirm theoretical expectations for stronger winds amongst Galactic supergiants. However, winds are substantially weaker than predictions from current radiatively driven wind theory, especially at mid-B subtypes, a problem which is exacerbated if winds are already clumped in the H α  line forming region. In general, CNO elemental abundances reveal strongly processed material at the surface of Galactic B supergiants, with mean N/C and N/O abundances 10 and 5 times higher than the Solar value, respectively, with HD 2905 (BC0.7 Ia) indicating the lowest degree of processing in our sample, and HD 152236 (B1.5 Ia + ) the highest.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/a1b95c715b05d6846e9c00edc0654b3a6b970929

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In Astronomy and Astrophysics

1. N. Langer
2. N. Smith
3. S. Smartt
4. Stan Woosley
5. Selma de Mink
6. C. Conroy
7. P. Crowther
8. J. Vink

Citations in the corpus

• CORE-COLLAPSE SUPERNOVAE FROM 9 TO 120 SOLAR MASSES BASED ON NEUTRINO-POWERED EXPLOSIONS (2015, background): “…star was a Type B3-I blue supergiant, Sk −69° 202 (Walborn et al. 1987), with an effective temperature of14,000–17,000 K (Humphreys & McElroy 1984; Crowther et al. 2006; Smith 2007), a luminosity of ´3 6 1038– erg s−1 (Humphreys & McElroy 1984; Arnett et al. 1989), and thus a radius of ´2 4…”
• A Grid of NLTE Line-blanketed Model Atmospheres of Early B-Type Stars (2006, background): “Recent spectroscopic studies reveal that early B supergiants show strongly processed material at their surface (e. g., Dufton et al. 2005; Crowther et al. 2006).”
• The empirical metallicity dependence of the mass-loss rate of O- and early B-type stars (2007, methodology): “In the last decade the development of realistic stellar atmosphere models has allowed accurate determination of the wind parameters of a sizeable sample of early-type Galactic stars (e.g. Puls et al. 1996; Herrero et al. 2002; Repolust et al. 2004; Crowther et al. 2006).”
• MESA ISOCHRONES AND STELLAR TRACKS (MIST). I. SOLAR-SCALED MODELS (2016, background): “The symbols correspond to O- and B-type galactic dwarfs and supergiants (Takeda & Takada-Hidai 2000; Villamariz et al. 2002; Villamariz & Herrero 2005; Crowther et al. 2006; Morel et al. 2008; Searle et al. 2008; Przybilla et al. 2010).”
• The VLT-FLAMES survey of massive stars: constraints on stellar evolution from the chemical compositions of rapidly rotating Galactic and Magellanic Cloud B-type stars (2009, result): “…derived temperature scales for Galactic and Magellanic Cloud stars, which imply that stars at lower metallicity have higher effective temperatures for a given spectral type, in broad agreement with previous studies (Martins et al. 2002, 2005; Crowther et al. 2002, 2006; Massey et al. 2004, 2005).”
• 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, result): “…(1993) for NGC 330 and NGC 346. temperature scale in the literature for early B-type supergiants, temperatures were taken from the Galactic results (Crowther et al. 2006), which were found to be in good agreement with those from analysis of individual stars in the SMC (Trundle et al. 2004; Trundle…”
• Mass loss from hot massive stars (2008, background): “…“low temperature region” (i.e., all mid/late B-type stars), where the predicted mass-lo rates are larger than those found from NLTE analyses based on unified atmospheres (Vink et al 2000, Trundle and Lennon 2005, Crowther et al 2006, Lefever et al 2007, Benaglia et al 2007, Markova and Puls 2008).”
• The VLT-FLAMES survey of massive stars: evolution of surface N abundances and effective temperature scales in the Galaxy and Magellanic Clouds (2007, background): “17 line blanketing and non-LTE effects in the model atmospheres (Martins et al. 2002; Crowther et al. 2002, 2006; Massey et al. 2004, 2005).”
• A census of the Wolf–Rayet content in Westerlund 1 from near-infrared imaging and spectroscopy (2006, methodology): “We follow the approach of from Schild & Maeder (1984) and Massey et al. (2001), updated to account for the revised spectral type–Teff calibration of Martins et al. (2005) for O stars, Crowther et al. (2006) for B supergiants, plus the high mass-loss Meynet et al. (1994) solar metallicity isochrones.”