Search Publications
White Dwarf Photospheric Abundances in Cataclysmic Variables. IV. Deriving the [N/C] Ratio
Sion, Edward M.; Godon, Patrick
We present results from our ongoing far-ultraviolet archival analysis of cataclysmic variable white dwarf (WD) abundances for six more systems: four SU UMa dwarf novae (BW Scl, SW UMa, BC UMa, and VW Hyi) together with the dwarf nova RX And, and the novalike DW UMa. To derive a reliable nitrogen abundance, for the four SU UMa systems (with a WD te…
Identifying and Characterizing Infrared Excesses in the Spitzer Kepler Survey (SpiKeS)
Gorjian, Varoujan; Bryden, Geoffrey; Werner, Michael W. +2 more
We report our search for infrared excesses in the Spitzer/Infrared Array Camera survey of the Kepler field at 3.6 and 4.5 µm. The Spitzer Kepler Survey contains ∼190,000 targets, which we reduce to ∼117,000 targets after applying multiple filters to arrive at a high-quality sample for spectral energy distribution fitting. Of the ∼117,000, we…
Fe/O Variations Relative to Source Longitude and Heliospheric Current Sheet in Large Solar Energetic Particle Events
Moon, Yong-Jae; Jeong, Hyun-Jin; Park, Jinhye +1 more
The Fe/O enhancements exhibit significant variations in gradual solar energetic particle (SEP) events. Several causes have been suggested including transport effects in the interplanetary space and flare contribution. In this study, we investigate the relationship between the integrated Fe/O ratios of 27 gradual SEP events, locations of associated…
DIISC-IV. DIISCovery of Anomalously Low Metallicity H II Regions in NGC 99: Indirect Evidence of Gas Inflows
Heckman, Timothy; Momjian, Emmanuel; Jansen, Rolf A. +6 more
As a part of the Deciphering the Interplay between the Interstellar medium, Stars, and the Circumgalactic medium (DIISC) survey, we investigate indirect evidence of gas inflow into the disk of the galaxy NGC 99. We combine optical spectra from the Binospec spectrograph on the MMT telescope with optical imaging data from the Vatican Advanced Techno…
The Redshift of GRB 190829A/SN 2019oyw: A Case Study of GRB-SN Evolution
Fruchter, Andrew S.; Izzo, Luca; Tanvir, Nial +7 more
The nearby long gamma-ray burst (GRB) 190829A was observed using the Hubble Space Telescope/Wide Field Camera 3/infrared grisms about four weeks to 500 days after the burst. We find the spectral features of its associated supernova, SN 2019oyw, are redshifted by several thousand km s‑1 compared to the redshift of the large spiral galaxy…
Possible Supercritical Accretion on the Ultraluminous X-Ray Source in the Metal-poor Galaxy I Zw 18
Yoneyama, Tomokage; Matsumoto, Hironori; Noda, Hirofumi +2 more
We present an analysis of X-ray observations of the ultraluminous X-ray source (ULX) in I Zw 18 based on archival data taken with Chandra, XMM-Newton, and Suzaku. This ULX is considered to be an intermediate-mass black hole candidate simply because it is in the lowest-metallicity environment among ULXs, where the formation of heavy black holes is …
Orbits and Dynamical Masses for Six Binary Systems in the Hyades Cluster
Torres, Guillermo; Latham, David W.; Klement, Robert +8 more
We report long-baseline interferometric observations with the CHARA Array that resolve six previously known double-lined spectroscopic binary systems in the Hyades cluster, with orbital periods ranging from 3 to 358 days: HD 27483, HD 283882, HD 26874, HD 27149, HD 30676, and HD 28545. We combine those observations with new and existing radial-vel…
CME Arrival Time Prediction Based on Coronagraph Observations and Machine-learning Techniques
Shen, Fang; Yang, Yi; Li, Yucong +2 more
The timely and precise prediction of the arrival time of coronal mass ejections (CMEs) is crucial in mitigating their potential adverse effects. In this study, we present a novel prediction method utilizing a deep-learning framework coupled with physical characteristics of CMEs and background solar wind. Time series images from synchronized solar …
An Informed and Systematic Method to Identify Variable Mid-L Dwarfs
Karalidi, Theodora; Manjavacas, Elena; Faherty, Jacqueline K. +3 more
Most brown dwarfs show some level of photometric or spectral variability. However, finding the most variable dwarfs more suited for a thorough variability monitoring campaign remained a challenge until a few years ago with the design of spectral indices to find the most likely L and T dwarfs using their near-infrared (NIR) single-epoch spectrum. I…
The Second Case of a Major Merger Triggering a Starburst in a Green Pea Galaxy
Ghosh, T.; Malhotra, S.; Rhoads, J. +4 more
We have used the Karl G. Jansky Very Large Array (VLA) to map H I 21 cm emission from the Green Pea galaxy GP J1148+2546 at z ≈ 0.0451, only the second measurement of the H I spatial distribution of a Green Pea. The VLA H I 21 cm image, the DECaLS optical image, and Sloan Digital Sky Survey spectroscopy show that GP J1148+2546 has two neighbors, t…