Search Publications
Plasma Interactions with the Space Environment in the Acceleration Region: Indications of CME-trailing Reconnection Regions
Vilas, Faith; Heiles, Carl; Kepley, Amanda A. +6 more
Coronal mass ejections (CMEs) are sources of major geomagnetic disturbances. On 2013 May 10, a CME crossed the signal path between the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft and Earth. Using the MESSENGER signal, characteristics of the density, velocity, and magnetic field properties of the crossing pl…
An Extreme-ultraviolet Wave Generating Upward Secondary Waves in a Streamer-like Solar Structure
Chen, Yao; Feng, Shiwei; Zheng, Ruisheng +2 more
Extreme-ultraviolet (EUV) waves, spectacular horizontally propagating disturbances in the low solar corona, always trigger horizontal secondary waves (SWs) when they encounter the ambient coronal structure. We present the first example of upward SWs in a streamer-like structure after the passing of an EUV wave. This event occurred on 2017 June 1. …
Optical Observations of the Young Type Ic Supernova SN 2014L in M99
Zhang, Yu; Wang, Lifan; Wheeler, J. Craig +22 more
We present optical spectroscopic and photometric observations of the nearby type Ic supernova (SN Ic) SN 2014L. This SN was discovered by the Tsinghua-NAOC Transient Survey (TNTS) in the nearby type-Sc spiral galaxy M99 (NGC 4254). Fitting to the early-time light curve indicates that SN 2014L was detected at only a few hours after the shock breako…
Toward the Measurement of the Mass of Isolated Neutron Stars: Prediction of Future Astrometric Microlensing Events by Pulsars
Ofek, Eran O.
The mass of single neutron stars (NSs) can be measured using astrometric microlensing events. In such events, the center-of-light motion of a star lensed by an NS will deviate from the expected nonlensed motion and this deviation can be used to measure the mass of the NS. I search for future conjunctions between pulsars, with measured proper motio…
Observations of Upward Propagating Waves in the Transition Region and Corona above Sunspots
Fu, Hui; Li, Bo; Xia, Lidong +2 more
We present observations of persistent oscillations of some bright features in the upper-chromosphere/transition region above sunspots taken by IRIS SJ 1400 Å and upward propagating quasi-periodic disturbances along coronal loops rooted in the same region taken by the AIA 171 Å passband. The oscillations of the features are cyclic oscillatory motio…
EPIC 203868608: A Low-mass Quadruple Star System in the Upper Scorpius OB Association
Albrecht, Simon; Hillenbrand, Lynne A.; Mawet, Dimitri +3 more
Young multiple star systems provide excellent testing grounds for theories of star formation and evolution. EPIC 203868608 was previously studied as a triple star system in the Upper Scorpius OB association, but the followup Keck NIRC2/HIRES/NIRSPAO observations reported here reveal its quadruple nature. We find that the system consists of a doubl…
Size-Luminosity Scaling Relations of Local and Distant Star-forming Regions
Do, Tuan; Armus, Lee; Larkin, James E. +8 more
We investigate star-forming scaling relations using Bayesian inference on a comprehensive data sample of low- (z < 0.1) and high-redshift (1 < z < 5) star-forming regions. This full data set spans a wide range of host galaxy stellar mass (M * ∼ 106-1011 {M}⊙ ) and clump star formation rates (SFR…
Discovery of an Active Intermediate-mass Black Hole Candidate in the Barred Bulgeless Galaxy NGC 3319
Shu, Xinwen; Zhou, Hongyan; Jiang, Ning +7 more
We report the discovery of an active intermediate-mass black hole (IMBH) candidate in the center of nearby barred bulgeless galaxy NGC 3319. The point X-ray source revealed by archival Chandra and XMM-Newton observations is spatially coincident with the optical and UV galactic nuclei from Hubble Space Telescope observations. The spectral energy di…
Measuring the Local ISM along the Sight Lines of the Two Voyager Spacecraft with HST/STIS
Redfield, Seth; Wood, Brian E.; Linsky, Jeffrey L. +1 more
In 2012 August, Voyager 1 crossed the heliopause, becoming the first human-made object to exit the solar system. This milestone signifies the beginning of an important new era for local interstellar medium (LISM) exploration. We present measurements of the structure and composition of the LISM in the immediate path of the Voyager spacecraft by usi…
Large-amplitude Rapid X-Ray Variability in the Narrow-line Seyfert 1 Galaxy PG 1404+226
Dewangan, G. C.; Mallick, L.
We present the first results from a detailed analysis of a new, long (∼100 ks) XMM-Newton observation of the narrow-line Seyfert 1 galaxy PG 1404+226, which showed a large-amplitude, rapid X-ray variability by a factor of ∼7 in ∼10 ks with an exponential rise and a sharp fall in the count rate. We investigate the origin of the soft X-ray excess em…