0000000000360034
AUTHOR
Peter H. Hauschildt
showing 5 related works from this author
VLTI/AMBER observations of cold giant stars: atmospheric structures and fundamental parameters
2014
The main goal of this research is to determine the angular size and the atmospheric structures of cool giant stars and to compare them with hydrostatic stellar model atmospheres, to estimate the fundamental parameters, and to obtain a better understanding of the circumstellar environment. We conducted spectro-interferometric observations of epsilon Oct, beta Peg, NU Pav, and psi Peg in the near-infrared K band (2.13-2.47 microm), and gamma Hya (1.9-2.47 microm) with the VLTI/AMBER instrument at medium spectral resolution. To obtain the fundamental parameters, we compared our data with hydrostatic atmosphere models (PHOENIX). We estimated the Rosseland angular diameters of epsilon Oct, beta …
The atmospheric structure and fundamental parameters of Red Supergiants
2013
We present studies of the atmospheric structure and fundamental properties of the red supergiants (RSGs) VY CMa, AH Sco, UY Sct, and KW Sgr based on near-infrared K -band interferometry obtained with the VLTI/AMBER instrument with a spectral resolution of 1500. In our visibility data, we observe the presence of molecular layers of water and CO in extended atmospheres. For a uniform disk modeling, we observe size increases in the water band centered at 1.9 μ m and in the CO band at 2.3–2.5 μ m, with respect to the near-continuum bandpass (2.20–2.25 μ m). With our spectral resolution, we obtain diameters in the near-continuum, that are free from contamination by molecular layers. Using PHOENI…
A giant exoplanet orbiting a very-low-mass star challenges planet formation models
2019
Surveys have shown that super-Earth and Neptune-mass exoplanets are more frequent than gas giants around low-mass stars, as predicted by the core accretion theory of planet formation. We report the discovery of a giant planet around the very-low-mass star GJ 3512, as determined by optical and near-infrared radial-velocity observations. The planet has a minimum mass of 0.46 Jupiter masses, very high for such a small host star, and an eccentric 204-day orbit. Dynamical models show that the high eccentricity is most likely due to planet-planet interactions. We use simulations to demonstrate that the GJ 3512 planetary system challenges generally accepted formation theories, and that it puts con…
What causes the large extensions of red-supergiant atmospheres? Comparisons of interferometric observations with 1-D hydrostatic, 3-D convection, and…
2015
We present the atmospheric structure and the fundamental parameters of three red supergiants, increasing the sample of RSGs observed by near-infrared spectro-interferometry. Additionally, we test possible mechanisms that may explain the large observed atmospheric extensions of RSGs. We carried out spectro-interferometric observations of 3 RSGs in the near-infrared K-band with the VLTI/AMBER instrument at medium spectral resolution. To comprehend the extended atmospheres, we compared our observational results to predictions by available hydrostatic PHOENIX, available 3-D convection, and new 1-D self-excited pulsation models of RSGs. Our near-infrared flux spectra are well reproduced by the P…
Fundamental properties and atmospheric structure of the red supergiant VY CMa based on VLTI/AMBER spectro-interferometry
2012
We investigate the atmospheric structure and fundamental properties of the red supergiant VY CMa. We obtained near-infrared spectro-interferometric observations of VY CMa with spectral resolutions of 35 and 1500 using the AMBER instrument at the VLTI. The visibility data indicate the presence of molecular layers of water vapor and CO in the extended atmosphere with an asymmetric morphology. The uniform disk diameter in the water band around 2.0 mu is increased by \sim20% compared to the near-continuum bandpass at 2.20-2.25 mu and in the CO band at 2.3-2.5 mu it is increased by up to \sim50%. The closure phases indicate relatively small deviations from point symmetry close to the photospheri…