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Hidden massive eclipsing binaries in red supergiant systems: The hierarchical triple system KQ Puppis and other candidates
D. Jadlovský, L. Molnár, A. Ercolino +26
The majority of massive stars are part of binary systems that may interact during their evolution. However, not many RSGs are known binaries, and only a few have constrained orbita…
Refining the Stellar Parameters of Ceti: a Pole-on Solar Analog
Maria Korolik, Rachael M. Roettenbacher, Debra A. Fischer +16
To accurately characterize the planets a star may be hosting, stellar parameters must first be well-determined. Ceti is a nearby solar analog and often a target for exoplanet s…
HD 166620: Portrait of a Star Entering a Grand Magnetic Minimum
Jacob K. Luhn, Jason T. Wright, Gregory W. Henry +2
HD 166620 was recently identified as a Maunder Minimum candidate based on nearly 50 years of Ca II H & K activity data from Mount Wilson and Keck-HIRES (Baum et al. 2022). These da…
Sun-like Stars Shed Light on Solar Climate Forcing
P. G. Judge, R. Egeland, G. W. Henry
Recently published, precise stellar photometry of 72 Sun-like stars obtained at the Fairborn Observatory between 1993 and 2017 is used to set limits on the solar forcing of Earth's…
The Large Scale Behaviour in the Disk of Scorpii from 2000-2018
M. W. Suffak, C. E. Jones, C. Tycner +4
We model the circumstellar disk of Sco using the 3-dimensional Monte Carlo radiative transfer code HDUST in order to quantify the large scale changes in the disk through the ye…
Towards comprehension of the variability of the magnetic chemically peculiar star CU Virginis (HD 124224)
Zdeněk Mikulášek, Jiří Krtička, Andrzej Pigulski +2
The upper main sequence stars CU Virginis is the most enigmatic object among magnetic chemically peculiar (mCP) stars. It is an unusually fast rotator showing strictly periodic lig…
What is New with Landstreet Star HD 37776 (V901 Ori)?
Zdeněk Mikulášek, Jiří Krtička, Matthew E. Shultz +6
HD\,37776 (V901\,Ori, B2\,Vp), also known as Landstreet's Star, is possibly the most remarkable magnetic chemically peculiar (mCP) star known. Zeeman Doppler Imaging revealed this…
Pulsations, eruptions, and evolution of four yellow hypergiants
A. M. van Genderen, A. Lobel, H. Nieuwenhuijzen +5
We aim to explore the variable photometric and stellar properties of four yellow hypergiants (YHGs), HR8752, HR 5171A, Cas, and HD 179821, and their pulsations of hundreds of d…
Topological changes in the magnetic field of LQ Hya during an activity minimum
Jyri J. Lehtinen, Maarit J. Käpylä, Thomas Hackman +6
Previous studies have related surface temperature maps, obtained with the Doppler imaging (DI) technique, of LQ Hya with long-term photometry. We compare surface magnetic field map…
Contemporaneous Imaging Comparisons of the Spotted Giant Geminorum Using Interferometric, Spectroscopic, and Photometric Data
Rachael M. Roettenbacher, John D. Monnier, Heidi Korhonen +8
Nearby, active stars with relatively rapid rotation and large starspot structures offer the opportunity to compare interferometric, spectroscopic, and photometric imaging technique…
Evolution of Long Term Variability in Solar Analogs
Ricky Egeland, Willie Soon, Sallie Baliunas +2
Earth is the only planet known to harbor life, therefore we may speculate on how the nature of the Sun-Earth interaction is relevant to life on Earth, and how the behavior of other…
On the nature of rotational period variability of magnetic stars
Zdenek Mikulasek, Jiri Krticka, Jan Janik +5
The magnetic chemically peculiar (mCP) stars of the upper main sequence exhibit periodic light, magnetic, radio, and spectroscopic variations that can be adequately explained by a…
General Model for Light curves of Chromospherically Active Binary Stars
L. Jetsu, G. W. Henry, J. Lehtinen
The starspots on the surface of many chromospherically active binary stars concentrate on long--lived active longitudes separated by 180 degrees. The activity shifts between these…
Dynamo Sensitivity in Solar Analogs with 50 Years of Ca II H & K Activity
Ricky Egeland, Willie Soon, Sallie Baliunas +3
The Sun has a steady 11-year cycle in magnetic activity most well-known by the rising and falling in the occurrence of dark sunspots on the solar disk in visible bandpasses. The 11…
A combined spectroscopic and photometric stellar activity study of Epsilon Eridani
Matthew J. Giguere, Debra A. Fischer, Cyril X. Y. Zhang +3
We present simultaneous ground-based radial velocity (RV) measurements and space-based photometric measurements of the young and active K dwarf Epsilon Eridani. These measurements…
Time series analysis of long-term photometry of BM Canum Venaticorum
L. Siltala, L. Jetsu, T. Hackman +10
Studying RS CVn binaries is challenging, because in addition to spot activity, other effects such as mass transfer between the components and gravitational distortion of their sphe…
Activity trends in young solar-type stars
Jyri Lehtinen, Lauri Jetsu, Thomas Hackman +2
We study a sample of 21 young and active solar-type stars with spectral types ranging from late F to mid K and characterize the behaviour of their activity. We apply the continuous…
Sun-Like Magnetic Cycles in the Rapidly-Rotating Young Solar Analog HD 30495
Ricky Egeland, Travis S. Metcalfe, Jeffrey C. Hall +1
A growing body of evidence suggests that multiple dynamo mechanisms can drive magnetic variability on different timescales, not only in the Sun but also in other stars. Many solar…
Detecting the Companions and Ellipsoidal Variations of RS CVn Primaries: II. omicron Draconis, a Candidate for Recent Low-Mass Companion Ingestion
Rachael M. Roettenbacher, John D. Monnier, Francis C. Fekel +14
To measure the stellar and orbital properties of the metal-poor RS CVn binary o Draconis (o Dra), we directly detect the companion using interferometric observations obtained with…
Detecting the Companions and Ellipsoidal Variations of RS CVn Primaries: I. sigma Geminorum
Rachael M. Roettenbacher, John D. Monnier, Gregory W. Henry +17
To measure the properties of both components of the RS CVn binary sigma Geminorum (sigma Gem), we directly detect the faint companion, measure the orbit, obtain model-independent m…
Stellar Activity and its Implications for Exoplanet Detection on GJ 176
Paul Robertson, Michael Endl, Gregory W. Henry +3
We present an in-depth analysis of stellar activity and its effects on radial velocity (RV) for the M2 dwarf GJ 176 based on spectra taken over 10 years from the High Resolution Sp…
Multiperiodicity, modulations and flip-flops in variable star light curves III. Carrier fit analysis of LQ Hya photometry for 1982-2014
Nigul Olspert, Maarit J. Käpylä, Jaan Pelt +4
We study LQ Hya photometry for 1982-2014 with the carrier fit (CF) -method and compare our results to earlier photometric analysis and recent Doppler imaging maps. We first utilize…
HST hot-Jupiter transmission spectral survey: Haze in the atmosphere of WASP-6b
N. Nikolov, D. K. Sing, A. S. Burrows +14
We report Hubble Space Telescope (HST) optical to near-infrared transmission spectroscopy of the hot Jupiter WASP-6b, measured with the Space Telescope Imaging Spectrograph (STIS)…
Using Photometry to Probe the Circumstellar Environment of delta Scorpii
C. E. Jones, Paul Wiegert, C. Tycner +4
We acquired Johnson BV photometry of the binary Be disk system delta~Scorpii during its 2009, 2010, 2011, and 2012 observing seasons and used it to probe the innermost regions of t…