Search Publications
An Unbiased CO Survey Toward the Northern Region of the Small Magellanic Cloud with the Atacama Compact Array. II. CO Cloud Catalog
Tokuda, Kazuki; Tachihara, Kengo; Kawamura, Akiko +16 more
The nature of molecular clouds and their statistical behavior in subsolar metallicity environments are not fully explored yet. We analyzed data from an unbiased CO (J = 2-1) survey at the spatial resolution of ~2 pc in the northern region of the Small Magellanic Cloud with the Atacama Compact Array to characterize the CO cloud properties. A cloud-…
New Metrics to Probe the Dynamical State of Galaxy Clusters
Natarajan, Priyamvada; Cappelluti, Nico; Cerini, Giulia
We present new diagnostic metrics to probe the dynamical state of galaxy clusters. These novel metrics rely on the computation of the power spectra of the matter and gas distributions and their cross-correlation derived from cluster observations. This analysis permits us to cross-correlate the fluctuations in the matter distribution, inferred from…
Iron-peak Element Abundances in Warm Very Metal-poor Stars
Roederer, Ian U.; Sneden, Christopher; Cowan, John J. +3 more
We have derived new detailed abundances of Mg, Ca, and the Fe-group elements Sc through Zn (Z = 21-30) for 37 main-sequence turnoff very metal-poor stars ([Fe/H] ≲-2.1). We analyzed Keck HIRES optical and near-UV high signal-to-noise spectra originally gathered for a Be abundance survey. Using typically ~400 Fe-group lines with accurate laboratory…
Supernova 2020wnt: An Atypical Superluminous Supernova with a Hidden Central Engine
Kilpatrick, Charles D.; Foley, Ryan J.; Jones, David O. +34 more
We present observations of a peculiar hydrogen- and helium-poor stripped-envelope (SE) supernova (SN) 2020wnt, primarily in the optical and near-infrared (near-IR). Its peak absolute bolometric magnitude of -20.9 mag (L bol, peak = (6.8 ± 0.3) × 1043 erg s-1) and a rise time of 69 days are reminiscent of hydrogen-p…
On the Nature of the Three-part Structure of Solar Coronal Mass Ejections
Chen, Yao; Xia, Lidong; Li, Leping +4 more
Coronal mass ejections (CMEs) result from eruptions of magnetic flux ropes (MFRs) and can possess a three-part structure in white-light coronagraphs, including a bright front, dark cavity, and bright core. In traditional opinion, the bright front forms due to the plasma pileup along the MFR border, the cavity represents the cross section of the MF…
Nuclear Activity in the Low-metallicity Dwarf Galaxy SDSS J0944-0038 : A Glimpse into the Primordial Universe
Nyland, Kristina; Canalizo, Gabriela; Satyapal, Shobita +11 more
Local low-metallicity dwarf galaxies are relics of the early universe and are thought to hold clues into the origins of supermassive black holes. While recent studies are uncovering a growing population of active galactic nuclei (AGNs) in dwarf galaxies, the vast majority reside in galaxies with solar or supersolar metallicities and stellar masses…
Using the Gaia Excess Uncertainty as a Proxy for Stellar Variability and Age
Barber, Madyson G.; Mann, Andrew W.
Stars are known to be more active when they are young, resulting in a strong correlation between age and photometric variability. The amplitude variation between stars of a given age is large, but the age-variability relation becomes strong over large groups of stars. We explore this relation using the excess photometric uncertainty in Gaia photom…
UOCS-IX. AstroSat/UVIT Study of the Open Cluster NGC 2818: Blue Stragglers, Yellow Stragglers, Planetary Nebula, and their Membership
Rao, N. Kameswara; Subramaniam, Annapurni; Rani, Sharmila +1 more
We present the first far-UV (FUV) imaging results of the intermediate-age Galactic open cluster NGC 2818 that has a planetary nebula (PN) within the field using images taken from the Ultra Violet Imaging Telescope (UVIT) aboard AstroSat. We identify cluster members by combining UVIT-detected sources with Gaia EDR3 data. We detect four bright and h…
What Do Halo CMEs Tell Us about Solar Cycle 25?
Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji +3 more
It is known that the weak state of the heliosphere due to diminished solar activity in cycle 24 backreacted on coronal mass ejections (CMEs) to make them appear wider for a given speed. One of the consequences of the weak state of the heliosphere is that more CMEs appear as halo CMEs (HCMEs), and halos are formed at shorter heliocentric distances.…
Cool, Luminous, and Highly Variable Stars in the Magellanic Clouds. II. Spectroscopic and Environmental Analysis of Thorne-Żytkow Object and Super-AGB Star Candidates
Drout, Maria R.; O'Grady, Anna J. G.; Kochanek, C. S. +9 more
In previous work, we identified a population of 38 cool and luminous variable stars in the Magellanic Clouds and examined 11 in detail in order to classify them as either Thorne-Żytkow objects (TŻOs; red supergiants with a neutron star cores) or super-asymptotic giant branch (sAGB) stars (the most massive stars that will not undergo core collapse)…