Search Publications
Direct Evidence of the Hybrid Nature of Extreme-ultraviolet Waves and the Reflection of the Fast-mode Wave
Chen, P. F.; Chandra, Ramesh; Devi, Pooja
We performed an analysis of the extreme-ultraviolet (EUV) wave event on 2022 March 31. The event originated from active region (AR) 12975 located at N13W52 in the field of view of the Atmospheric imaging Assembly (AIA) and exactly at the west limb viewed by the EUV Imager (EUVI) of the Solar Terrestrial Relations Observatory-Ahead (STEREO-A) satel…
Magnetic Fields Observed along the East–West Outflow of IRAS 16293-2422
Pattle, Kate; Sadavoy, Sarah; Looney, Leslie W. +6 more
Magnetic fields likely play an important role in the formation of young protostars. Multiscale and multiwavelength dust polarization observations can reveal the inferred magnetic field from scales of the cloud to core to protostar. We present continuum polarization observations of the young protostellar triple system IRAS 16293-2422 at 89 µm…
Rotation and Hα Emission in a Young SMC Cluster: A Spectroscopic View of NGC 330
Dupree, Andrea K.; Milone, Antonino P.; Dotter, Aaron +4 more
We present an analysis of high-resolution optical spectra recorded for 30 stars of the split extended main-sequence turnoff of the young (∼40 Myr) Small Magellanic Cloud globular cluster NGC 330. Spectra were obtained with the Michigan/Magellan Fiber System and Magellan Inamori Kyocera Echelle spectrographs located on the Magellan-Clay 6.5 m teles…
Tidal Disruption Event AT2020ocn: Early Time X-Ray Flares Caused by a Possible Disk Alignment Process
Jonker, P. G.; Zabludoff, A. I.; Pasham, D. R. +3 more
A tidal disruption event (TDE) may occur when a star is torn apart by the tidal force of a black hole (BH). Eventually, an accretion disk is thought to form out of stellar debris falling back toward the BH. If the star's orbital angular momentum vector prior to disruption is not aligned with the BH spin angular momentum vector, the disk will be ti…
Study of a Red Clump Giant, KIC 11087027, with High Rotation and Strong Infrared Excess—Evidence of Tidal Interaction for High Lithium Abundance
Zhao, Gang; Reddy, Bacham E.; Pandey, Jeewan C. +2 more
This Letter presents results from Kepler photometric light curves and a high-resolution spectroscopic study of a super-Li-rich giant KIC11087027. Using the light-curve analysis, we measured the star's rotational period P rot = 30.4 ± 0.1 days, which translates to rotational velocity V rot = 19.5 ± 1.7 km s‑1. The s…
Evidence of Third Dredge-up in Post-AGB Stars in Galactic Globular Clusters
Dixon, William V.
To better understand the mixing and mass loss experienced by low-mass stars as they ascend the asymptotic giant branch (AGB), I have gathered from the literature the abundances of CNO and s-process elements in post-AGB stars in Galactic globular clusters. These species are mixed to the surface during third dredge-up (3DU) events, so their abundanc…
Exploring the Diversity of Faint Satellites in the M81 Group
Bell, Eric F.; Monachesi, Antonela; Bailin, Jeremy +9 more
In the last decade, we have been able to probe further down the galaxy luminosity function than ever before and expand into the regime of ultra-faint dwarfs (UFDs), which are some of the best probes we have of small-scale cosmology and galaxy formation. Digital sky surveys have enabled the discovery and study of these incredibly low-mass, highly d…
On the Origin of Infrared Bands Attributed to Tryptophan in Spitzer Observations of IC 348
McGuire, Brett A.; Jørgensen, Jes K.; Schroetter, Ilane +12 more
Infrared emission features toward interstellar gas of the IC 348 star cluster in Perseus have been recently proposed to originate from the amino acid tryptophan. The assignment was based on laboratory infrared spectra of tryptophan pressed into pellets, a method which is known to cause large frequency shifts compared to the gas phase. We assess th…
Differential Rotation of CoRoT Stars and a Kepler Binary Star from Starspot Transit Mapping
Valio, Adriana; Araújo, Alexandre; Menezes, Fabian
While direct magnetic field measurements are rare for slowly rotating stars, spots observed during planetary transits provide a potential indicator of magnetic activity on stellar surfaces. Moreover, the rotation of the stellar surface can be probed by monitoring the spots' position with time in subsequent transits. This study investigates the dyn…
Metallicity Mapping of the Ionized Diffuse Gas at the Milky Way Disk–Halo Interface
Prochaska, J. Xavier; Strader, Jay; Putman, Mary E. +5 more
Metals in the diffuse, ionized gas at the boundary between the Milky Way's interstellar medium (ISM) and circumgalactic medium, known as the disk–halo interface (DHI), are valuable tracers of the feedback processes that drive the Galactic fountain. However, metallicity measurements in this region are challenging due to obscuration by the Milky Way…