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Newsletter 135 of Working Group on Massive Star

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Newsletter 135 of Working Group on Massive Star ISSN 1783-3426 THE MASSIVE STAR NEWSLETTER formerly known as the hot star newsletter * No. 135 2013 May-June Editors: Philippe Eenens (University of Guanajuato) [email protected] Raphael Hirschi (Keele University) http://www.astroscu.unam.mx/massive_stars CONTENTS OF THIS NEWSLETTER: News Next Massive Star Meeting A Spectroscopic Campaign on WR 134, WR135, and WR 137 European Ultraviolet Visible Observatory The Advanced Telescope for High Energy Astrophysics Abstracts of 12 accepted papers Evolution of blue supergiants and alpha Cygni variables; Puzzling CNO surface abundances Single-Star HII Regions as a Probe of Massive Star Spectral Turbulent Entrainment at the Boundaries of the Convective Cores of Main-sequence Stars The distance to the young open cluster Westerlund 2 X-ray properties of the young open clusters HM1 and IC2944/2948 Luminous and Variable Stars in M31 and M33. I. The Warm Hypergiants and Post-Red Supergiant Evolution Constraints on porosity and mass loss in O-star winds from modeling of X-ray On magnetic inhibition of photospheric macro turbulence generated in the iron-bump opacity zone of O- stars On the simultaneous evolution of massive protostars and their host cores Unexpected Ionization Structure in Eta Carinae's ``Weigelt Knots'' HD45314: a new gamma Cas analog among Oe stars Advanced burning stages and fate of 8-10 Mo stars Abstracts of 2 conference proceedings Strange mode instability for micro-variations in Luminous Blue Variables The Galactic O-Star Spectroscopic Catalog (GOSC) and Survey (GOSSS): first whole-sky results and further updates Abstracts of 1 other types of papers Eta Carinae Splinter session at 223rd AAS Meeting January 2014, Washington, DC, USA Jobs Post-doctoral or PhD position in stellar astrophysics Postdoctoral Research Fellow Numerical Modelling of Stellar Interiors Meetings Giants of Eclipse IAUS 302 - Full program and registration deadline News Next Massive Star Meeting Dear colleagues, After the fantastic meeting in Rhodes (thanks to Alceste Bonanos and Danny Lennon as organizers) we have to start preparing the next Massive Stars Meeting. We foresee that this meeting will probably take place in 2017. With this call the Organizing Committee of our Massive Stars Working Group invites any interested people to send an email before next October 15th communicating his/her interest in organizing the next meeting. The email shall be sent to me as chair of the OC (ahd-at-iac.es). We do not want that anyone spends too much time and effort with the proposals. A short email indicating the willingness to organize the meeting with some comments about the adequacy of the proposed place will be enough. The OC will consider all proposals and select one of the proposed places before end of the year, based on criteria like: - the meeting location (traditionally, our group prefers locations near a beach where a relaxed atmosphere favours personal contacts) - the availability of hotels with large conference rooms (at least 200 people) and meeting facilities at affordable prices - the support of a local astronomical community - the balance of locations hosting our meetings Best regards, Artemio Herrero Chair of the Organizing Committee of the IAU Massive Stars Working Group Back to contents A Spectroscopic Campaign on WR 134, WR 135, and WR 137 We are announcing that the large "Pro-Am" campaign to spectroscopically study the variability in 3 WR stars will start on May 17, continuing through September 17 of this year. We have received several telescope allocations, including a 4-month span at the IAC 0.8m (with only a few nights devoted to other projects) and a few allocations of a few weeks. A team of amateur spectroscopists will be observing both at the IAC as well as their small telscopes to study the CIRs and clumps in these stars to create a long, intense time-series. We welcome additional contributors if you have the availability and telescope time. Weblink: http://www.stsci.de/wr134/index.htm Email: [email protected] Back to contents European Ultraviolet Visible Observatory In response to the recent ESA call for science themes for large missions, the UV astrophysics community has submitted a white paper (http://www.nuva.eu/whitepaper/files/euvo_wp_220513_fin.pdf) to promote a mission for a visible-UV observatory. Several areas of astrophysics are interested in UV observations, in particular massive stars. EUVO will provide access to key diagnostics of stellar properties, stellar winds, and star-ISM interactions. The EUVO team invites you to become a supporter of this project : http://www.nuva.eu/whitepaper/supporters.php Weblink: http://www.nuva.eu/whitepaper/index.php Email: [email protected] Back to contents The Advanced Telescope for High Energy Astrophysics In response to the recent ESA call for science themes to define its future large missions, the X-ray astrophysics community has submitted a white paper (http://arxiv.org/abs/1306.2307) to promote the Advanced Telescope for High Energy Astrophysics (Athena+) mission. Athena+ provides the necessary performance (e.g. angular resolution, spectral resolution, survey grasp) to address a number of fundamental questions in modern astrophysics and revolutionize our understanding of the Hot and Energetic Universe. These capabilities will provide a powerful observatory to be used in all areas of astrophysics as illustrated by a series of supporting papers, including one on star formation and evolution (http://arxiv.org/abs/1306.2333). In the field of massive stars, Athena+ will not only allow us to study many more objects with an unprecedented spectral resolution, but will also pioneer the study of the dynamics of their X-ray emission via time-resolved high-resolution spectroscopy. In this way, Athena+ will be a unique tool to study small and large-scale structures in the winds of single massive stars, wind interactions in massive binary systems, and many other topics. The Athena+ Science Working Group invites you to become a supporter of this project. You can do so by signing up at http://fs6.formsite.com/ATHENA2028/form2/index.html Weblink: http://www.the-athena-x-ray-observatory.eu/ Email: [email protected] Back to contents PAPERS Abstracts of 12 accepted papers Evolution of blue supergiants and alpha Cygni variables; Puzzling CNO surface abundances Hideyuki Saio$^1$, Cyril Georgy$^2$, and Georges Meynet$^3$ 1 - Astronomical Institute, Tohoku University, 2 - Astrophysics, Lennard-Jones Laboratories, EPSAM, Keele, University, 3 - Geneva Observatory, University of Geneva A massive star can enter the blue supergiant region either evolving directly from the main-sequence, or evolving from a previous red supergiant stage. The fractions of the blue supergiants having different histories depend on the internal mixing and mass-loss during the red supergiant stage. We study the possibility to use diagnostics based on stellar pulsation to discriminate blue supergiants having different evolution histories. For this purpose we have studied the pulsation property of massive star models calculated with the Geneva stellar evolution code for initial masses ranging from 8 to 50 M_odot with a solar metallicity of Z=0.014. We have found that radial pulsations are excited in the blue-supergiant region only in the models that had been red-supergiants before. This would provide us with a useful mean to diagnose the history of evolution of each blue-supergiant. At a given effective temperature, much more nonradial pulsations are excited in the model after the red-supergiant stage than in the model evolving towards the red-supergiant. The properties of radial and nonradial pulsations in blue supergiants are discussed. Predicted periods are compared with period ranges observed in some alpha-Cygni variables in the Galaxy and NGC 300. We have found that blue supergiant models after the red- supergiant stage roughly agree with observed period ranges in most cases. However, we are left with the puzzle that the predicted surface N/C and N/O ratios seem to be too high compared with those of Deneb and Rigel. Reference: MNRAS in press Status: Manuscript has been accepted Weblink: http://arxiv.org/abs/1305.2474 Comments: Email: [email protected] Back to contents Single-Star HII Regions as a Probe of Massive Star Spectral Energy Distributions J. Zastrow(1), M.S. Oey(1), E.W. Pellegrini(2) (1) U. Michigan; (2) U. Toledo The shape of the OB-star spectral energy distribution is a critical component in many diagnostics of the ISM and galaxy properties. We use single-star HII regions from the LMC to quantitatively examine the ionizing SEDs from widely available CoStar, TLUSTY, and WM-basic atmosphere grids. We evaluate the stellar atmosphere models by matching the emission-line spectra that they predict from CLOUDY photoionization simulations with those observed from the nebulae. The atmosphere models are able to reproduce the observed optical nebular line ratios, except at the highest energy transitions > 40 eV, assuming that the gas distribution is non-uniform. Overall we find that simulations using WM-basic produce the best agreement with the observed line ratios. The rate of ionizing photons produced by the model SEDs is consistent with the rate derived from the Halpha luminosity for standard, log(g) = 4.0 models adopted from the atmosphere grids. However, there is a systematic offset between the rate of ionizing photons from different atmosphere models that is correlated with the relative hardness of the SEDs. In general WM-basic and TLUSTY atmosphere models predict similar effective temperatures, while CoStar predicts effective temperatures that are cooler by a few thousand degrees. We compare our effective temperatures, which depend on the nebular ionization balance, to conventional photospheric- based calibrations from the literature. We suggest that in the future, spectral type to effective temperature calibrations can be constructed from nebular data. Reference: ApJ, 769, 94 Status: Manuscript has been accepted Weblink: http://iopscience.iop.org/0004-637X/769/2/94/ Email: [email protected] Back to contents Turbulent Entrainment at the Boundaries of the Convective Cores of Main-sequence Stars E.I.
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