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Ages of young star clusters, massive blue stragglers, and the upper mass limit of stars: Analyzing age-dependent stellar mass functions

Abstract

Massive stars rapidly change their masses through strong stellar winds and mass transfer in binary systems. The latter aspect is important for populations of massive stars as more than 70% of all O stars are expected to interact with a binary companion during their lifetime. We show that such mass changes leave characteristic signatures in stellar mass functions of young star clusters that can be used to infer their ages and to identify products of binary evolution. We model the observed present-day mass functions of the young Galactic Arches and Quintuplet star clusters using our rapid binary evolution code. We find that the shaping of the mass function by stellar wind mass loss allows us to determine the cluster ages as 3.5 ± 0.7 Myr and 4.8 ± 1.1 Myr, respectively. Exploiting the effects of binary mass exchange on the cluster mass function, we find that the most massive stars in both clusters are rejuvenated products of binary mass transfer, i.e., the massive counterpart of classical blue straggler stars. This resolves the problem of an apparent age spread among the most luminous stars exceeding the expected duration of star formation in these clusters. We perform Monte Carlo simulations to probe  More>>
Authors:
Schneider, F. R. N.; Izzard, R. G.; Langer, N.; Stolte, A.; Hußmann, B.; [1]  De Mink, S. E.; [2]  De Koter, A.; Sana, H.; [3]  Gvaramadze, V. V.; [4]  Liermann, A., E-mail: fschneid@astro.uni-bonn.de [5] 
  1. Argelander-Institut für Astronomie der Universität Bonn, Auf dem Hügel 71, D-53121 Bonn (Germany)
  2. Observatories of the Carnegie Institution for Science, 813 Santa Barbara St, Pasadena, CA 91101 (United States)
  3. Astronomical Institute \"Anton Pannekoek\", Amsterdam University, Science Park 904, 1098 XH, Amsterdam (Netherlands)
  4. Sternberg Astronomical Institute, Lomonosov Moscow State University, Universitetskij Pr. 13, Moscow 119992 (Russian Federation)
  5. Max Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)
Publication Date:
Jan 10, 2014
Product Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 780; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AGE DEPENDENCE; COMPUTERIZED SIMULATION; EVOLUTION; INSTABILITY; LIFETIME; LUMINOSITY; MASS TRANSFER; MONTE CARLO METHOD; SAMPLING; STAR CLUSTERS; STARS; STELLAR WINDS; STOCHASTIC PROCESSES
OSTI ID:
22348271
Country of Origin:
United States
Language:
English
Other Identifying Numbers:
Journal ID: ISSN 0004-637X; CODEN: ASJOAB; TRN: US15I3915054606
Availability:
Available from http://dx.doi.org/10.1088/0004-637X/780/2/117
Submitting Site:
USN
Size:
[16 page(s)]
Announcement Date:
Jun 30, 2015

Citation Formats

Schneider, F. R. N., Izzard, R. G., Langer, N., Stolte, A., Hußmann, B., De Mink, S. E., De Koter, A., Sana, H., Gvaramadze, V. V., and Liermann, A., E-mail: fschneid@astro.uni-bonn.de. Ages of young star clusters, massive blue stragglers, and the upper mass limit of stars: Analyzing age-dependent stellar mass functions. United States: N. p., 2014. Web. doi:10.1088/0004-637X/780/2/117.
Schneider, F. R. N., Izzard, R. G., Langer, N., Stolte, A., Hußmann, B., De Mink, S. E., De Koter, A., Sana, H., Gvaramadze, V. V., & Liermann, A., E-mail: fschneid@astro.uni-bonn.de. Ages of young star clusters, massive blue stragglers, and the upper mass limit of stars: Analyzing age-dependent stellar mass functions. United States. https://doi.org/10.1088/0004-637X/780/2/117
Schneider, F. R. N., Izzard, R. G., Langer, N., Stolte, A., Hußmann, B., De Mink, S. E., De Koter, A., Sana, H., Gvaramadze, V. V., and Liermann, A., E-mail: fschneid@astro.uni-bonn.de. 2014. "Ages of young star clusters, massive blue stragglers, and the upper mass limit of stars: Analyzing age-dependent stellar mass functions." United States. https://doi.org/10.1088/0004-637X/780/2/117.
@misc{etde_22348271,
title = {Ages of young star clusters, massive blue stragglers, and the upper mass limit of stars: Analyzing age-dependent stellar mass functions}
author = {Schneider, F. R. N., Izzard, R. G., Langer, N., Stolte, A., Hußmann, B., De Mink, S. E., De Koter, A., Sana, H., Gvaramadze, V. V., and Liermann, A., E-mail: fschneid@astro.uni-bonn.de}
abstractNote = {Massive stars rapidly change their masses through strong stellar winds and mass transfer in binary systems. The latter aspect is important for populations of massive stars as more than 70% of all O stars are expected to interact with a binary companion during their lifetime. We show that such mass changes leave characteristic signatures in stellar mass functions of young star clusters that can be used to infer their ages and to identify products of binary evolution. We model the observed present-day mass functions of the young Galactic Arches and Quintuplet star clusters using our rapid binary evolution code. We find that the shaping of the mass function by stellar wind mass loss allows us to determine the cluster ages as 3.5 ± 0.7 Myr and 4.8 ± 1.1 Myr, respectively. Exploiting the effects of binary mass exchange on the cluster mass function, we find that the most massive stars in both clusters are rejuvenated products of binary mass transfer, i.e., the massive counterpart of classical blue straggler stars. This resolves the problem of an apparent age spread among the most luminous stars exceeding the expected duration of star formation in these clusters. We perform Monte Carlo simulations to probe stochastic sampling, which support the idea of the most massive stars being rejuvenated binary products. We find that the most massive star is expected to be a binary product after 1.0 ± 0.7 Myr in Arches and after 1.7 ± 1.0 Myr in Quintuplet. Today, the most massive 9 ± 3 stars in Arches and 8 ± 3 in Quintuplet are expected to be such objects. Our findings have strong implications for the stellar upper mass limit and solve the discrepancy between the claimed 150 M {sub ☉} limit and observations of four stars with initial masses of 165-320 M {sub ☉} in R136 and of supernova 2007bi, which is thought to be a pair-instability supernova from an initial 250 M {sub ☉} star. Using the stellar population of R136, we revise the upper mass limit to values in the range 200-500 M {sub ☉}.}
doi = {10.1088/0004-637X/780/2/117}
journal = []
issue = {2}
volume = {780}
journal type = {AC}
place = {United States}
year = {2014}
month = {Jan}
}