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Start Over Author "Kraus, Stefan" Journal monthly notices of the royal astronomical society
9 results on '"Kraus, Stefan"'

1. Orbits and dynamical masses for the active Hyades multiple system HD 284163

Author

Torres, Guillermo, primary, Schaefer, Gail H, additional, Stefanik, Robert P, additional, Latham, David W, additional, Jones, Jeremy, additional, Lanthermann, Cyprien, additional, Monnier, John D, additional, Kraus, Stefan, additional, Anugu, Narsireddy, additional, ten Brummelaar, Theo, additional, Chhabra, Sorabh, additional, Codron, Isabelle, additional, Ennis, Jacob, additional, Gardner, Tyler, additional, Gutierrez, Mayra, additional, Ibrahim, Noura, additional, Labdon, Aaron, additional, Mortimer, Dan, additional, and Setterholm, Benjamin R, additional

Published
2023
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2. Orbits and dynamical masses for the active Hyades multiple system HD 284163.

Author

Torres, Guillermo, Schaefer, Gail H, Stefanik, Robert P, Latham, David W, Jones, Jeremy, Lanthermann, Cyprien, Monnier, John D, Kraus, Stefan, Anugu, Narsireddy, ten Brummelaar, Theo, Chhabra, Sorabh, Codron, Isabelle, Ennis, Jacob, Gardner, Tyler, Gutierrez, Mayra, Ibrahim, Noura, Labdon, Aaron, Mortimer, Dan, and Setterholm, Benjamin R

Subjects
ORBITS (Astronomy), LOW mass stars, STELLAR mass, PARALLAX, MASS measurement
Abstract

We report near-infrared long-baseline interferometric observations of the Hyades multiple system HD 284163, made with the Center for High Angular Resolution Astronomy array, as well as almost 43 yr of high-resolution spectroscopic monitoring at the Center for Astrophysics. Both types of observations resolve the 2.39 d inner binary, and also an outer companion in a 43.1 yr orbit. Our observations, combined with others from the literature, allow us to solve for the 3D inner and outer orbits, which are found to be at nearly right angles to each other. We determine the dynamical masses of the three stars (good to better than 1.4 per cent for the inner pair), as well as the orbital parallax. The secondary component (0.5245 ± 0.0047 M⊙) is now the lowest mass star with a dynamical mass measurement in the cluster. A comparison of these measurements with current stellar evolution models for the age and metallicity of the Hyades shows good agreement. All three stars display significant levels of chromospheric activity, consistent with the classification of HD 284163 as an RS CVn object. We present evidence that a more distant fourth star is physically associated, making this a hierarchical quadruple system. [ABSTRACT FROM AUTHOR]

Published
2024
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3. Scattering and sublimation: a multiscale view of µm-sized dust in the inclined disc of HD 145718

Author

Davies, Claire L., Rich, Evan A., Harries, Tim J., Monnier, John D., Laws, Anna S. E., Andrews, Sean M., Bae, Jaehan, Wilner, David J., Anugu, Narsireddy, Ennis, Jacob, Gardner, Tyler, Kraus, Stefan, Labdon, Aaron, Bouquin, Jean-Baptiste le, Lanthermann, Cyprien, Schaefer, Gail H., Setterholm, Benjamin R., and Brummelaar, Theo ten

Subjects
Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

We present multi-instrument observations of the disc around the Herbig~Ae star, HD~145718, employing geometric and Monte Carlo radiative transfer models to explore the disc orientation, the vertical and radial extent of the near infrared (NIR) scattering surface, and the properties of the dust in the disc surface and sublimation rim. The disc appears inclined at $67-71^{\circ}$, with position angle, PA\,$=-1.0-0.6^{\circ}$, consistent with previous estimates. The NIR scattering surface extends out to $\sim75\,$au and we infer an aspect ratio, $h_{\rm{scat}}(r)/r\sim0.24$ in $J$-band; $\sim0.22$ in $H$-band. Our GPI images and VLTI+CHARA NIR interferometry suggest that the disc surface layers are populated by grains $\gtrsim \lambda/2\pi$ in size, indicating these grains are aerodynamically supported against settling and/or the density of smaller grains is relatively low. We demonstrate that our geometric analysis provides a reasonable assessment of the height of the NIR scattering surface at the outer edge of the disc and, if the inclination can be independently constrained, has the potential to probe the flaring exponent of the scattering surface in similarly inclined ($i\gtrsim70^{\circ}$) discs. In re-evaluating HD~145718's stellar properties, we found that the object's dimming events - previously characterised as UX~Or and dipper variability - are consistent with dust occultation by grains larger, on average, than found in the ISM. This occulting dust likely originates close to the inferred dust sublimation radius at $0.17\,$au., Comment: 18 pages, 16 figures; Accepted for publication in MNRAS

Published
2022

4. The orbit and stellar masses of the archetype colliding-wind binary WR 140

Author

Thomas, Joshua D, primary, Richardson, Noel D, additional, Eldridge, J J, additional, Schaefer, Gail H, additional, Monnier, John D, additional, Sana, Hugues, additional, Moffat, Anthony F J, additional, Williams, Peredur, additional, Corcoran, Michael F, additional, Stevens, Ian R, additional, Weigelt, Gerd, additional, Zainol, Farrah D, additional, Anugu, Narsireddy, additional, Le Bouquin, Jean-Baptiste, additional, ten Brummelaar, Theo, additional, Campos, Fran, additional, Couperus, Andrew, additional, Davies, Claire L, additional, Ennis, Jacob, additional, Eversberg, Thomas, additional, Garde, Oliver, additional, Gardner, Tyler, additional, Fló, Joan Guarro, additional, Kraus, Stefan, additional, Labdon, Aaron, additional, Lanthermann, Cyprien, additional, Leadbeater, Robin, additional, Lester, T, additional, Maki, Courtney, additional, McBride, Brendan, additional, Ozuyar, Dogus, additional, Ribeiro, J, additional, Setterholm, Benjamin, additional, Stober, Berthold, additional, Wood, Mackenna, additional, and Zurmühl, Uwe, additional

Published
2021
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7. First NIR interferometrically resolved high-order Brackett and forbidden Fe lines of a B[e] star: V921 Sco.

Author

Kreplin, Alexander, Kraus, Stefan, Tambovtseva, Larisa, Grinin, Vladimir, and Hone, Edward

Subjects
*LOCAL thermodynamic equilibrium, *RADIATIVE transfer, *CIRCUMSTELLAR matter
Abstract

We present near-infrared interferometric AMBER observations of the B[e] binary V921 Sco at low (R ∼ 30) and medium spectral resolution (R ∼ 1500) in the K and H bands. Low spectral resolution AMBER data were used to estimate the position of the companion V921 Sco B and confirmed a clockwise movement on sky with respect to the primary of 33° between 2008 and 2012. Our observations resolve for the first time higher order Brackett lines (Br6–Br12). The modelling of the different line transitions revealed a decrease in the size of the line-emitting regions from Br3 to Br12. We are able to reproduce this decrease with a simple radiative transfer model of an equatorial disc in local thermodynamic equilibrium. In addition to the Brackett series, we also resolve permitted and forbidden Fe line emission. Our modelling shows that these lines originate from ∼2 au from the star, corresponding roughly to the measured dust sublimation region. This might indicate that the forbidden line emission arises from shock excitation at the base of a disc wind. [ABSTRACT FROM AUTHOR]

Published
2020
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9. Probing the wind-launching regions of the Herbig Be star HD 58647 with high spectral resolution interferometry

Author

Kurosawa, Ryuichi, primary, Kreplin, A., additional, Weigelt, G., additional, Natta, A., additional, Benisty, M., additional, Isella, Andrea, additional, Tatulli, Eric, additional, Massi, F., additional, Testi, Leonardo, additional, Kraus, Stefan, additional, Duvert, G., additional, Petrov, Romain G., additional, and Stee, Ph., additional

Published
2016
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