Search Publications
Spatially Resolved X-Ray Study of Supernova Remnant G306.3-0.9 with Unusually High Calcium Abundance
Toonen, Silvia; Nomoto, Ken'ichi; Vink, Jacco +6 more
G306.3-0.9 is an asymmetric Galactic supernova remnant (SNR), whose progenitor has been thought to be a Type Ia supernova (SN), but its high Ca abundance appears inconsistent with the Type Ia origin. Hoping to uncover the reason for its asymmetry and the origin of this SNR, we performed a spatially resolved X-ray spectroscopic analysis of XMM-Newt…
Search for Hα Emitters at z 7.8: A Constraint on the Hα-based Star Formation Rate Density
Asada, Yoshihisa; Ohta, Kouji
We search for Hα emitters at z ~ 7.8 in four gravitationally lensed fields observed in the Hubble Frontier Fields program. We use the Lyman break method to select galaxies at the target redshift and perform photometry in the Spitzer/IRAC 5.8 µm band to detect Hα emission from the candidate galaxies. We find no significant detections of count…
Polarization Observations of a Split-band Type II Radio Burst from the Solar Corona
Ramesh, R.; Kathiravan, C.
Using temporal observations of circular polarized harmonic plasma emission from a split-band type II solar radio burst at 80 MHz, we separately estimated the coronal magnetic field strengths (B) associated with the lower (L) and upper (U) frequency bands of the burst. The corresponding Stokes I and V data were obtained with the polarimeter operati…
Distances to Local Group Galaxies via Population II, Stellar Distance Indicators. I. The Sculptor Dwarf Spheroidal
Madore, Barry F.; Freedman, Wendy L.; Cerny, William +5 more
We determine the distance to the Sculptor Dwarf Spheroidal via three Population II stellar distance indicators: (a) the Tip of the Red Giant Branch (TRGB), (b) RR Lyrae variables (RRLs), and (c) the ridgeline of the blue horizontal branch (HB). High signal-to-noise, wide-field VI imaging that covers an area $48^{\prime} \,\times \,48^{\prime} $ an…
Star Cluster Formation and Evolution in M101: An Investigation with the Legacy Extragalactic UV Survey
Sabbi, E.; Dale, D. A.; Calzetti, D. +13 more
We present Hubble Space Telescope WFC3/UVIS (F275W, F336W) and ACS/WFC optical (F435W, F555W, and F814W) observations of the nearby grand-design spiral galaxy M101 as part of the Legacy Extragalactic UV Survey (LEGUS). Compact sources detected in at least four bands were classified by both human experts and the convolutional neural network STARCNE…
New Clues to the Evolution of Dwarf Carbon Stars From Their Variability and X-Ray Emission
Roulston, Benjamin R.; Green, Paul J.; Anderson, Scott F. +6 more
As main-sequence stars with C > O, dwarf carbon (dC) stars are never born alone but inherit carbon-enriched material from a former asymptotic giant branch (AGB) companion. In contrast to M dwarfs in post-mass-transfer binaries, C2 and/or CN molecular bands allow dCs to be identified with modest-resolution optical spectroscopy, even a…
A New Cold Stream near the Southern Galactic Pole
Zhao, Gang; Zhao, Jing-Kun; Yang, Yong +2 more
We report the discovery of a cold stream near the southern Galactic pole (dubbed as SGP-S) detected in Gaia Early Data Release 3. The stream is at a heliocentric distance of ~9.5 kpc and spans nearly 58° by 0.°6 on sky. The color-magnitude diagram of SGP-S indicates an old and metal-poor (age ~12 Gyr, [M/H] ~ -2.0 dex) stellar population. The stre…
Two-point Separation Functions for Modeling Wide Binary Systems in Nearby Dwarf Galaxies
Peñarrubia, Jorge; Koposov, Sergey E.; Walker, Matthew G. +1 more
We use a geometric method to derive (two-dimensional) separation functions among pairs of objects within populations of specified position function ${dN}/d{\boldsymbol{R}}$ . We present analytic solutions for separation functions corresponding to a uniform surface density within a circular field, a Plummer sphere (viewed in projection), and the mi…
Massive Molecular Gas Reservoir in a Luminous Submillimeter Galaxy during Cosmic Noon
Cooray, A.; Marchetti, L.; Nayyeri, H. +11 more
We present multiband observations of an extremely dusty star-forming lensed galaxy (HERS1) at z = 2.553. High-resolution maps of HST/WFC3, SMA, and ALMA show a partial Einstein ring with a radius of ~3″. The deeper HST observations also show the presence of a lensing arc feature associated with a second lens source, identified to be at the same re…
Multi-passband Observations of a Solar Flare over the He I 10830 Å line
Polito, Vanessa; Xu, Yan; Cao, Wenda +5 more
This study presents a C3.0 flare observed by the Big Bear Solar Observatory/Goode Solar Telescope (GST) and Interface Region Imaging Spectrograph (IRIS) on 2018 May 28 around 17:10 UT. The Near-Infrared Imaging Spectropolarimeter of GST was set to spectral imaging mode to scan five spectral positions at ±0.8, ±0.4 Å and line center of He I 10830 Å…