Joint annual meeting of Swiss and Austrian Physical Societies 2017

Session

Astronomy and Astrophysics

25 Aug 2017, 11:15

Room 14 (CICG)

32. 【91】 Open questions in the formation of binary stellar systems containing black holes.

Anastasios Fragkos (University of Geneva)

25/08/2017, 11:15

Astronomy and Astrophysics

Talk

The recent detection of gravitational waves from coalescing binary black holes by LIGO allowed for the first time the direct observation of stellar-mass black holes. These gravitational wave detections, complemented by a 45-year-long history of indirect observations of black holes in X-ray binaries, can give us now a more complete picture of the formation and evolution of binary stellar...

339. 【92】 The spin of the second-born Black hole in coalescing double BH binaries

Mr Ying Qin (Geneva Observatory)

25/08/2017, 11:45

Astronomy and Astrophysics

Talk

For the “classical” isolated binary evolution, we ran an extensive grid of BH(Black hole)-He star binary evolution tracks, keeping track of the angular momentum evolution of the He star. For a He star with a compact object companion in a close orbit, tides can be efficient only when the orbital period is shorter than ~2 days. Based on the direct-collapse model (no angular momentum loss during...

34. 【93】 Fermi acceleration under control: η Carinae

Roland Walter (University of Geneva)

25/08/2017, 12:00

Astronomy and Astrophysics

Talk

The η Carinae binary system hosts one of the most massive stars, which features the highest known mass-loss rate. This dense wind encounters the much faster wind expelled by the stellar companion, dissipating mechanical energy in the shock, where particles can be accelerated up to relativistic energies and subsequently produce very high energy γ-rays. We aim at comparing the variability of the...

407. 【94】 The Evolution of Supermassive Population III Stars

Dr Lionel Haemmerlé (Uni Genève)

25/08/2017, 12:30

Astronomy and Astrophysics

Supermassive primordial stars forming in atomically-cooled halos at redshifts 15-20 are currently thought to be the progenitors of the earliest quasars in the Universe. In this picture, the star evolves under rapid accretion (0.1-1 M_sun/yr) until the general relativistic instability triggers its collapse to a black hole at masses of ~10⁵ M_sun. However, the...

408. 【95】 Observation of Exoplanetary Atmospheres with High-Resolution Transmission Spectroscopy

Aurélien Wyttenbach (Uni Genève)

25/08/2017, 12:45

Astronomy and Astrophysics

Under specific conditions, exoplanets and their atmospheres gradually unveiling themselves to our knowledge. Among the best characterized exoplanets, hot Jupiters still show a number of peculiarities that remained unexplained. Among them are the radius anomaly, the presence of clouds that darken atmospheres and the atmospheric evaporation due to different mechanisms. The transmission...

188. 【96】 Quantifying degradation of a cavity detector in a total solar irradiance instrument on a FengYun3 satellite

Dr Huiduan Li (Chuxiong Normal University, China)

25/08/2017, 13:15

Astronomy and Astrophysics

Talk

Accurate long-time data of Total Solar Irradiance (TSI) are fundamental to understand solar forcing of climate change. The TSI space radiometers suffered degradations of their cavity detectors due to strong solar exposure. The detector degradation has been a challenge to get accurate space measurements of TSI. Degradation of one routine channel in a TSI instrument onboard a Chinese FengYun-3...