The mass and helium discrepancy in massive young stars

Herrero, A.; Kudritzki, R. P.; Vílchez, J. M.; Kunze, D.; Butler, K.; Haser, S. M.

doi:10.1007/3-540-55256-1_269

Cited by 86 publications

(152 citation statements)

References 3 publications

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“…Herrero et al 1992). Whilst most main sequence stars showed normal He abundances, He/H≈0.1 by number, as expected, rapid rotators were surprisingly found to have enriched He at their surfaces, suggesting that rotational mixing has brought products of core nucleosynthesis to the surface while the star is still on the main sequence.…”

Section: Compositionsupporting

confidence: 56%

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Fundamental parameters of massive stars

Crowther

2004

EAS Publications Series

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Section: Compositionsupporting

confidence: 56%

“…Optical He i-ii lines generally provide temperature diagnostics for O stars (e.g. Herrero et al 1992) while Si ii-iv lines are used for B stars (e.g. McErlean et al, 1999).…”

Section: Line Techniquesmentioning

confidence: 99%

Fundamental parameters of massive stars

Crowther

2004

EAS Publications Series

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“…On the other hand, fixing the radius of the primary to the value in Table 2, leads to overestimating the distance compared to the literature value. Such discrepancies between different methods of parameter estimations have been reported before (e.g., Herrero et al 1992).…”

Section: (λ)mentioning

confidence: 65%

Detection of frequency spacings in the young O-type binary HD 46149 from CoRoT photometry

Degroote¹,

Briquet²,

Auvergne

et al. 2010

A&A

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Aims. Using the CoRoT space based photometry of the O-type binary HD 46149, stellar atmospheric effects related to rotation can be separated from pulsations, because they leave distinct signatures in the light curve. This offers the possibility of characterising and exploiting any pulsations seismologically. Methods. Combining high-quality space based photometry, multi-wavelength photometry, spectroscopy and constraints imposed by binarity and cluster membership, the detected pulsations in HD 46149 are analyzed and compared with those for a grid of stellar evolutionary models in a proof-of-concept approach.Results. We present evidence of solar-like oscillations in a massive O-type star, and show that the observed frequency range and spacings are compatible with theoretical predictions. Thus, we unlock and confirm the strong potential of this seismically unexplored region in the HR diagram.

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“…The disagreement between evolutionary and spectroscopic masses of OB stars is a long-standing problem, already reported by Herrero et al (1992). The difference was partly reconciled when a more detailed description of the OB star atmospheres was used to derive the spectroscopic masses Repolust et al 2004) or when other factors such as He abundance were taken into account (see the review by ).…”

Section: Mass Discrepancy In Ic 1613?mentioning

confidence: 97%

The young stellar population of IC 1613

García

Herrero

Castro

et al. 2010

A&A

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Context. To understand the structure and evolution of massive stars, systematic surveys of the Local Group galaxies have been undertaken, to find these objects in environments of different chemical abundances. We focus on the metal-poor irregular galaxy IC 1613 to analyze the stellar and wind structure of its low-metallicity massive stars. We ultimately aim to study the metallicitydependent driving mechanism of the winds of blue massive stars and use metal-poor massive stars of the Local Volume as a proxy for the stars in the early Universe. Aims. In a previous paper we produced a list of OB associations in IC 1613. Their properties are not only a powerful aid towards finding the most interesting candidate massive stars, but also reveal the structure and recent star formation history of the galaxy. We characterize these OB associations and study their connection with the galactic global properties. Methods. The reddening-free Q parameter is a powerful tool in the photometric analysis of young populations of massive stars, since it exhibits a smaller degree of degeneracy with OB spectral types than the B − V color. The color-magnitude diagram (Q vs. V) of the OB associations in IC 1613 is studied to determine their age and mass, and confirm the population of young massive stars. Results. We identified more than 10 stars with M ≥ 50 M . Spectral classification available for some of them confirm their massive nature, yet we find the common discrepancy with the spectroscopically derived masses. There is a general increasing trend of the mass of the most massive member with the number of members of each association, but not with the stellar density. The average diameter of the associations of this catalog is 40 pc, half the historically considered typical size of OB associations. Size increases with the association population. The distribution of the groups strongly correlates with that of neutral and ionized hydrogen. We find the largest dispersion of association ages in the bubble region of the galaxy where hydrogen is abundant, implying that recent star formation has proceeded over a longer period of time than in the rest of the galaxy, and is still ongoing. Very young associations are found at the west of the galaxy far from the bubble region, traditionally considered the sole locus of star formation, but still rich in neutral hydrogen. Conclusions. The contrast in the stellar properties derived from photometry and spectroscopy (when the latter is available) shows that the Q pseudo-color is very useful for estimating the parameters of OB stars when only photometric observations exist. This work helped define an extensive pool of candidate OB stars for subsequent spectroscopic analyses designed to study the structure and winds of metal-poor massive stars.

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The mass and helium discrepancy in massive young stars

Cited by 86 publications

References 3 publications

Fundamental parameters of massive stars

Fundamental parameters of massive stars

Detection of frequency spacings in the young O-type binary HD 46149 from CoRoT photometry

The young stellar population of IC 1613

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