Search Publications
Unexpected Short-period Variability in Dwarf Carbon Stars from the Zwicky Transient Facility
Roulston, Benjamin R.; Green, Paul J.; Hermes, J. J. +1 more
Dwarf carbon (dC) stars, main-sequence stars showing carbon molecular bands, are enriched by mass transfer from a previous asymptotic-giant-branch (AGB) companion, which has since evolved to a white dwarf. While previous studies have found radial-velocity variations for large samples of dCs, there are still relatively few dC orbital periods in the…
The Formation and Lifetime of Outflows in a Solar Active Region
Polito, Vanessa; Warren, Harry P.; Barczynski, Krzysztof +4 more
Active regions are thought to be one contributor to the slow solar wind. Upflows in EUV coronal spectral lines are routinely observed at their boundaries, and provide the most direct way for upflowing material to escape into the heliosphere. The mechanisms that form and drive these upflows, however, remain to be fully characterized. It is unclear …
The Dragonfly Wide Field Survey. II. Accurate Total Luminosities and Colors of Nearby Massive Galaxies and Implications for the Galaxy Stellar-mass Function
van Dokkum, Pieter; Conroy, Charlie; Abraham, Roberto +8 more
Stellar-mass estimates of massive galaxies are susceptible to systematic errors in their photometry, due to their extended light profiles. In this study, we use data from the Dragonfly Wide Field Survey to accurately measure the total luminosities and colors of nearby massive galaxies. The low surface brightness limits of the survey (µg…
Statistical Survey of Reservoir Phenomenon in Energetic Proton Events Observed by Multiple Spacecraft
Wang, Yang; Lyu, Dan; Xiao, Boxi +3 more
In this work, reservoir phenomenon in the decay phase of gradual solar energetic particle (SEP) events are investigated with two Helios and the IMP 8 spacecraft from 1976 January to 1980 March and two STEREO and the SOHO spacecraft from 2010 January to 2014 September. Using these data, 62 reservoir events of solar energetic protons were identified…
Identifying Candidate Optical Variables Using Gaia Data Release 2
Strader, Jay; Andrew, Shion; Swihart, Samuel J.
Gaia is undertaking a deep synoptic survey of the Galaxy, but photometry from individual epochs has, as of yet, only been released for a minimal number of sources. We show that it is possible to identify variable stars in Gaia Data Release 2 by selecting stars with unexpectedly large photometric uncertainties given their brightness and number of o…
Star Formation in a Strongly Magnetized Cloud
Caselli, Paola; Arce, Héctor G.; Tan, Jonathan C. +6 more
We study star formation in the Center Ridge 1 (CR1) clump in the Vela C giant molecular cloud, selected as a high column density region that shows the lowest level of dust continuum polarization-angle dispersion, likely indicating that the magnetic field is relatively strong. We observe the source with the Atacama Large Millimeter/submillimeter Ar…
Probing the Disk-Corona Systems and Broad-line Regions of Changing-look Quasars with X-Ray and Optical Observations
Green, Paul J.; Anderson, Scott F.; Eracleous, Michael +8 more
"Changing-look" quasars are a new class of highly variable active galactic nuclei that have changed their spectral type over surprisingly short timescales of just a few years. The origin of this phenomenon is debated, but is likely to reflect some change in the accretion flow. To investigate the disk-corona systems in these objects, we measure opt…
The Star Formation History of a Post-starburst Galaxy Determined from Its Cluster Population
Chandar, Rupali; French, K. Decker; Mok, Angus +2 more
The recent star formation histories (SFHs) of post-starburst galaxies have been determined almost exclusively from detailed modeling of their composite starlight. This has provided important but limited information on the number, strength, and duration of bursts of star formation. In this work, we present a direct and independent measure of the re…
Local Analogs to High-redshift Galaxies. I. Characterization of Dust Emission and Star Formation History
Wiklind, Tommy; Eufrasio, Rafael T.; Motiño Flores, Skarleth M.
Star-forming dwarf galaxies have properties similar to those expected in high-redshift galaxies. Hence, these local galaxies may provide insights into the evolution of the first galaxies and the physical processes at work. We present a sample of 11 potential local analogs to high-z (LAHz) galaxies. The sample consists of blue compact dwarf galaxie…
Multiwavelength Quasi-periodic Pulsations in a Stellar Superflare
Nakariakov, Valery M.; Kolotkov, Dmitrii Y.; Holt, Robin +1 more
We present the first multiwavelength simultaneous detection of quasi-periodic pulsations (QPPs) in a superflare (more than a thousand times stronger than known solar flares) on a cool star, in soft X-rays (SXRs, with XMM-Newton) and white light (WL, with Kepler). It allowed for the first ever analysis of oscillatory processes in a stellar flare si…