On Feb. 7, 2019, Ylva Götberg successfully defended her thesis on the properties and impact of stripped stars. She is continuing her research as a Alvin E. Nashman Postdoctoral Fellow in Theoretical Astrophysics at Carnegie Observatories in Pasadena, CA. Find more about her work at her new website.
Anticipating new gravitational wave detections of heavy binary black holes, Pablo Marchant (CIERA) together with Bincosmos group members Mathieu Renzo and Rob Farmer’s explore the effects of pulsations experienced by the most massive stars. Find a preview here.
“Pulsational pair-instability supernovae in very close binaries” by Pablo Marchant, Mathieu Renzo,Robert Farmer, Kaliroe M. W. Pappas, Ronald E. Taam, Selma de Mink, and Vassiliki Kalogera.
Mathieu Renzo’s investigation of what is probably the most massive runaway star currently known. Using Gaia and Hubble Space Telescope data he tries to determine the origin of this extreme star, which has likely been ejected by the very young star cluster R136. The cluster is famous for harboring several of these monster stars as shown in earlier work. Now published in MNRAS.
Ylva Götberg’s second paper on the spectra of the stripped stars stripped is now accepted, featuring “obese subdwarfs”, “underweight Wolf-Rayet stars” and everything in between, including a demonstration of why astronomers are effectively colorblind, making these stars nearly invisible to us when they have a companion.
Y. Götberg, S. E. de Mink, J. H. Groh, T. Kupfer, P. A. Crowther, E. Zapartas, M. Renzo (2018) “Spectral models for binary products: Unifying Subdwarfs and Wolf-Rayet stars as a sequence of stripped-envelope stars”, accepted for publication in Astronomy and Astrophysics, preprint available here https://arxiv.org/abs/1802.03018.
Abel investigated the binary system ϕ Persei, using new data by Douglas Gies and collaborators. The system contains one star, a subdwarf, with about the same mass as the Sun, but it is 10 times hotter and nearly 10,000 times brighter. It contains a second star, a Be star, that is nearly 10 times as massive as the Sun, which is spinning very rapidly. It is thought that the hot star is the remaining core of a star that has lost its envelope, transferring part of it to the companion which is now spinning very fast.
A. Schootemeijer, Y. Gotberg, S. E. de Mink, D. R. Gies, E. Zapartas, Clues about the scarcity of stripped-envelope stars from the evolutionary state of the sdO+Be binary system phi Persei, accepted for publication in A&A, 2018 https://arxiv.org/abs/1803.02379 Continue reading
Published in Science 05 Jan 2018, “The number of stars that form at each mass is known as the initial mass function (IMF). For most masses, the IMF follows a power-law distribution, first determined by Edwin Salpeter in 1955. Fabian Schneider et al. used observations of the nearby star-forming region 30 Doradus (also known as the Tarantula Nebula) and combined these with stellar modeling to determine its IMF. They found more stars above 30 solar masses than predicted by the Salpeter distribution. Because the most massive stars also have the biggest influence on their surroundings—for instance, through ultraviolet radiation, stellar winds, supernova explosions, and production of heavy elements—this excess will have wide-ranging implications. ” Editor summary in journal science.