Astrophysics and Astronomy Commons^™

Establishing Α Oph As A Prototype Rotator: Precision Orbit With New Keck, Chara, And Rv Observations, Tyler Gardner, John D. Monnier, Francis C. Fekel, Michael H. Williamson, Fabien Baron, Sasha Hinkley, Michael Ireland, Adam L. Kraus, Stefan Kraus, Rachael M. Roettenbacher, Gail Schaefer, Judit Sturmann, Laszlo Sturmann, Theo A. Ten Brummelaar

Information Systems and Engineering Management Research Publications

Alpha Ophiuchi (Rasalhague) is a nearby rapidly rotating A5IV star that has been imaged by infrared interferometry. α Oph is also part of a known binary system, with a companion semimajor axis of ∼430 mas and a high eccentricity of 0.92. The binary companion provides the unique opportunity to measure the dynamical mass to compare with the results of rapid rotator evolution models. The lack of data near periastron passage limited the precision of mass measurements in previous work. We add new interferometric data from the MIRC combiner at the CHARA Array as well as new Keck adaptive optics imaging …

Observations With The Differential Speckle Survey Instrument. X. Preliminary Orbits Of K-Dwarf Binaries And Other Stars, Elliott P. Horch, Kyle G. Broderick, Dana I. Casetti-Dinescu, Todd J. Henry, Francis C. Fekel, Matthew W. Muterspaugh, Daryl W. Willmarth, Jennifer G. Winters, Gerard T. Van Belle, Catherine A. Clark, Mark E. Everett

Information Systems and Engineering Management Research Publications

This paper details speckle observations of binary stars taken at the Lowell Discovery Telescope, the WIYN telescope, and the Gemini telescopes between 2016 January and 2019 September. The observations taken at Gemini and Lowell were done with the Differential Speckle Survey Instrument (DSSI), and those done at WIYN were taken with the successor instrument to DSSI at that site, the NN-EXPLORE Exoplanet Star and Speckle Imager (NESSI). In total, we present 378 observations of 178 systems, and we show that the uncertainty in the measurement precision for the combined data set is ∼2 mas in separation, ∼1°–2° in position angle …

Interferometric Imaging Of Λ Andromedae: Evidence Of Starspots And Rotation, J. Robert Parks, Russel J. White, Frédérique Baron, John D. Monnier, Brian Kloppenborg, Gregory W. Henry, Gail Schaefer, Xiao Che, Ettore Pedretti, Nathalie Thureau, Ming Zhao, Theo Ten Brummelaar, Harold Mcalister, Stephen T. Ridgway, Nils Turner, Judit Sturmann, Laszlo Sturmann

Information Systems and Engineering Management Research Publications

Presented are the first interferometric images of cool starspots on the chromospherically active giant λ Andromedae. Using the Michigan Infra-Red Combiner coupled to the Center for High Angular Resolution Astronomy Array, 26 interferometric observations were made between 2008 August 17 and 2011 September 24. The photometric time series acquired at Fairborn Observatory spanning 2008 September 20 to 2011 January 20 is also presented. The angular diameter and power-law limb-darkening coefficient of this star are 2.759 ± 0.050 mas and 0.229 ± 0.111, respectively. Starspot properties are obtained from both modeled and SQUEEZE reconstructed images. The images from 2010 through 2011 …

Observing The Changing Surface Structures Of The Active K Giant Σ Geminorum With Song★, Heidi Korhonen, Rachael M. Roettenbacher, Shenghong Gu, Frank Grundahl, Mads Fredslund Andersen, Gregory W. Henry, Jens Jessen-Hansen, Victoria L. Antoci, P. L. Pallé

Information Systems and Engineering Management Research Publications

Aims. We aim to study the spot evolution and differential rotation in the magnetically active cool K-type giant star σ Gem from broadband photometry and continuous spectroscopic observations that span 150 nights.

Methods. We use high-resolution, high signal-to-noise ratio spectra obtained with the Hertzsprung SONG telescope to reconstruct surface (photospheric) temperature maps with Doppler imaging techniques. The 303 observations span 150 nights and allow for a detailed analysis of the spot evolution and surface differential rotation. The Doppler imaging results are compared to simultaneous broadband photometry from the Tennessee State University T3 0.4 m Automated Photometric Telescope. The activity from …