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The Orbit and Dynamical Mass of Polaris: Observations with the CHARA Array
Nancy Remage Evans, Gail Schaefer, Alexandre Gallenne +19
The 30 year orbit of the Cepheid Polaris has been followed with observations by the CHARA Array (Center for High Angular Resolution Astronomy) from 2016 through 2021. An additional…
Shocks and Photoionization of the Inner 650 AU Jet of the Interacting Binary Star R Aquarii from Multiwavelength Hubble Space Telescope Observations
Caroline D. Huang, Margarita Karovska, Warren Hack +3
Astrophysical jets are present in a range of environments, including young stellar objects, X-ray binaries, and active galactic nuclei, but their formation is still not fully under…
Hubble Space Telescope Snapshot Survey for Resolved Companions of Galactic Cepheids: Final Results
Nancy Remage Evans, H. Moritz Guenther, Howard E. Bond +13
Cepheids in multiple systems provide information on the outcome of the formation of massive stars. They can also lead to exotic end-stage objects. This study concludes our survey o…
A carbon-rich hot bubble in the planetary nebula NGC 5189
J. A. Toalá, R. Montez, M. Karovska
We present the discovery of extended X-ray emission from the planetary nebula (PN) NGC 5189 around the [WO1]-type WD 1330-657 with XMM-Newton. The X-ray-emitting gas fills the cavi…
Stars at High Spatial Resolution
Kenneth G. Carpenter, Gerard van Belle, Alexander Brown +19
We summarize some of the compelling new scientific opportunities for understanding stars and stellar systems that can be enabled by sub-milliarcsec (sub-mas) angular resolution, UV…
Cool, evolved stars: results, challenges, and promises for the next decade
Gioia Rau, Rodolfo Montez, Kenneth G. Carpenter +27
Cool, evolved stars are the main source of chemical enrichment of the interstellar medium (ISM), and understanding their mass loss and structure offers a unique opportunity to stud…
The Orbit of the Close Companion of Polaris: Hubble Space Telescope Imaging 2007 to 2014
Nancy Remage Evans, Margarita Karovska, Howard E. Bond +6
As part of a program to determine dynamical masses of Cepheids, we have imaged the nearest and brightest Cepheid, Polaris, with the Hubble Space Telescope Wide Field Planetary Came…
Mapping Excitation in the Inner Regions of the Planetary Nebula NGC 5189 using HST WFC3 Imaging
Ashkbiz Danehkar, Margarita Karovska, W. Peter Maksym +1
The planetary nebula (PN) NGC 5189 around a Wolf-Rayet [WO] central star demonstrates one of the most remarkable complex morphologies among PNe with many multi-scale structures, sh…
Three-dimensional hydrodynamical models of wind and outburst-related accretion in symbiotic systems
M. de Val-Borro, M. Karovska, D. D. Sasselov +1
Gravitationally focused wind accretion in binary systems consisting of an evolved star with a gaseous envelope and a compact accreting companion is a possible mechanism to explain…
Hubble Space Telescope: Snapshot Survey for Resolved Companions of Galactic Cepheids
Nancy Remage Evans, Howard E. Bond, Gail H. Schaefer +4
We have conducted an imaging survey with the Hubble Space Telescope Wide Field Camera~3 (WFC3) of 70 Galactic Cepheids, typically within 1~kpc, with the aim of finding resolved phy…
Resolved Companions of Cepheids: Testing the Candidates with X-Ray Observations
Nancy Remage Evans, Ignazio Pillitteri, Scott Wolk +7
We have made {\it XMM-Newton\/} observations of 14 Galactic Cepheids that have candidate resolved (5$\arcsec$) companion stars based on our earlier {\it HST\/} WFC3 imaging s…
Resolving the stellar activity of the Mira AB binary with ALMA
W. H. T. Vlemmings, S. Ramstedt, E. O'Gorman +4
We present the size, shape and flux densities at millimeter continuum wavelengths, based on ALMA science verification observations in Band 3 (~94.6 GHz) and Band 6 (~228.7 GHz), fr…
X-ray Detection of the Cluster Containing the Cepheid S Mus
Nancy Remage Evans, Ignazio Pillitteri, Scott J. Wolk +7
The galactic Cepheid S Muscae has recently been added to the important list of Cepheids linked to open clusters, in this case the sparse young cluster ASCC 69. Low-mass members of…
Binary Cepheids: Separations and Mass Ratios in Binaries
Nancy Remage Evans, Howard E. Bond, Gail H. Schaefer +3
Deriving the distribution of binary parameters for a particular class of stars over the full range of orbital separations usually requires the combination of results from many diff…
The Coronal Abundance Anomalies of M Dwarfs
Brian E. Wood, J. Martin Laming, Margarita Karovska
We analyze Chandra X-ray spectra of the M0 V+M0 V binary GJ 338. As quantified by X-ray surface flux, these are the most inactive M dwarfs ever observed with X-ray grating spectros…
Stellar Imager (SI): developing and testing a predictive dynamo model for the Sun by imaging other stars
Kenneth G. Carpenter, Carolus J. Schrijver, Margarita Karovska +39
The Stellar Imager mission concept is a space-based UV/Optical interferometer designed to resolve surface magnetic activity and subsurface structure and flows of a population of Su…
Numerical Simulations of Wind Accretion in Symbiotic Binaries
M. de Val-Borro, M. Karovska, D. Sasselov
We study the dynamical effects of gravitational focusing by a binary companion on winds from late-type stars. In particular, we investigate the mass transfer and formation of accre…
Mass Transport Processes and their Roles in the Formation, Structure, and Evolution of Stars and Stellar Systems
Kenneth G. Carpenter, Margarita Karovska, Carolus J. Schrijver +15
We summarize some of the compelling new scientific opportunities for understanding stars and stellar systems that can be enabled by sub-mas angular resolution, UV/Optical spectral…
Long-Period Variability in o Ceti
Matthew R. Templeton, Margarita Karovska
We carried out a new and sensitive search for long-period variability in the prototype of the Mira class of long-period pulsating variables, o Ceti (Mira A), the closest and bright…
Quantifying Stellar Mass Loss with High Angular Resolution Imaging
Stephen Ridgway, Jason Aufdenberg, Michelle Creech-Eakman +7
Mass is constantly being recycled in the universe. One of the most powerful recycling paths is via stellar mass-loss. All stars exhibit mass loss with rates ranging from ~10(-14) t…