Search Publications
A Dust Trap in the Young Multiple System HD 34700
Wilner, David J.; Zhang, Qizhou; Rich, Evan A. +6 more
Millimeter observations of disks around young stars reveal substructures indicative of gas pressure traps that may aid grain growth and planet formation. We present Submillimeter Array observations of HD 34700: two Herbig Ae stars in a close binary system (Aa/Ab, ∼0.25 au), surrounded by a disk presenting a large cavity and spiral arms seen in sca…
Identification of Two Distinct Electron Populations in an Impulsive Solar Energetic Electron Event
Wang, L.; Zhao, L.; Li, G. +2 more
We examine the release times of energetic electrons in the 2001 April 25 event. An M2.7 flare occurred on 2001 April 25, from AR 09433, located at N18W09. The flare was observed in X-rays by GOES and the Yohkoh spacecraft. The Yohkoh observation also included hard X-ray (HXR) images for all four energy channels: L, M1, M2, and H. We use Yohkoh obs…
Comparing Observed Stellar Kinematics and Surface Densities in a Low-latitude Bulge Field to Galactic Population Synthesis Models
Anderson, Jay; Penny, Matthew T.; Bennett, David P. +3 more
We present an analysis of Galactic bulge stars from Hubble Space Telescope Wide Field Camera 3 observations of the Stanek window (l, b = [0.25, -2.15]) from two epochs approximately two years apart. This data set is adjacent to the provisional Wide-field Infrared Survey Telescope (WFIRST) microlensing field. Proper motions are measured for approxi…
What Determines Solar Flares Producing Interplanetary Type III Radio Bursts?
Liu, Y.; Cheng, X.; Ding, M. D. +4 more
Energetic electrons accelerated by solar flares often give rise to type III radio bursts at a broad wave band and even interplanetary type III bursts (IT3) if the wavelength extends to a decameter-kilometer. In this Letter, we investigate the probability of the flares that produce IT3, based on the sample of 2272 flares above M-class observed from…
Magnetic Connectivity between the Light Bridge and Penumbra in a Sunspot
Feng, Song; Nakariakov, Valery M.; Yuan, Ding +2 more
A light bridge is a prominent structure commonly observed within a sunspot. Its presence usually triggers a wealth of dynamics in a sunspot and has a lasting impact on sunspot evolution. However, the fundamental structure of light bridges is still not well understood. In this study, we used the high-resolution spectropolarimetry data obtained by t…
A Multiwavelength Study of PSR J1119-6127 after 2016 Outburst
Takata, J.; Wang, H. -H.; Dai, S. +4 more
The high magnetic field pulsar PSR J1119-6127, detected from radio to high-energy wavelengths, underwent a magnetar-like outburst beginning on 2016 July 27. In this paper, we study the postoutburst multiwavelength properties of this pulsar from the radio to GeV bands and discuss its similarity with the outburst of the magnetar XTE J1810-197. In ph…
Active-region Tilt Angles from White-light Images and Magnetograms: The Role of Magnetic Tongues
Démoulin, Pascal; Mandrini, Cristina H.; Poisson, Mariano +1 more
The presence of elongations in active-region (AR) polarities, called magnetic tongues, is mostly visible during their emergence phase. AR tilts have been measured thoroughly using long-term white-light (WL) databases, sometimes combined with magnetic-field information. Since the influence of magnetic tongues on WL tilt measurements has not been ta…
Distortion of Magnetic Fields in BHR 71
Kwon, Jungmi; Nagata, Tetsuya; Tamura, Motohide +9 more
The magnetic field structure of a star-forming Bok globule BHR 71 was determined based on near-infrared polarimetric observations of background stars. The magnetic field in BHR 71 was mapped from 25 stars. By using a simple 2D parabolic function, the plane-of-sky magnetic axis of the core was found to be θmag = 125° ± 11°. The plane-of-…
A Survey for C II Emission-line Stars in the Large Magellanic Cloud
Massey, Philip; Morrell, Nidia; Neugent, Kathryn F. +1 more
We present a narrowband imaging survey of the Large Magellanic Cloud (LMC), designed to isolate the C II λλ7231, 7236 emission lines in objects as faint as mλ7400 ∼ 18. The work is motivated by the recent serendipitous discovery in the LMC of the first confirmed extragalactic [WC11] star, whose spectrum is dominated by C II emission, an…
Time-domain Study of the Young Massive Cluster Westerlund 2 with the Hubble Space Telescope. I
Anderson, J.; Lennon, D. J.; Bastian, N. +8 more
Time-domain studies of pre-main-sequence (PMS) stars have long been used to investigate star properties during their early evolutionary phases and to trace the evolution of circumstellar environments. Historically these studies have been confined to the nearest, low-density, star-forming regions. We used the Wide Field Camera 3 on board the Hubble…