Search Publications
Massive Stars in the SDSS-IV-APOGEE Survey: Wolf-Rayet Stars of the WN Type
Minniti, Dante; Hernández, Jesús; Roman-Lopes, Alexandre +3 more
In this paper, we describe the results obtained in our study of Galactic Wolf-Rayet stars of the WN type, using the APOGEE2 spectrographs. The APOGEE2 WN star near-infrared spectra presented here were selected through a careful examination of the APOGEE2 DR16 sample, being compound of at least one exemplar of each Wolf-Rayet star from WN4 to WN11 …
Flare Expansion to a Magnetic Rope Accompanied by Rare Radio Bursts
Dudík, Jaroslav; Kašparová, Jana; Zemanová, Alena +1 more
We present multispectral analysis (radio, Hα, ultraviolet (UV)/extreme ultraviolet (EUV), and hard X-ray) of a confined flare from 2015 March 12. This flare started within the active region NOAA 12 297 and then it expanded into a large preexisting magnetic rope embedded with a cold filament. The expansion started with several brightenings located …
Redshift Determinations from a Self-consistent Grid-based Lens Model for the Hubble Frontiers Field Cluster RXC J2248.7-4431 (AS1063)
Broadhurst, Tom; Coe, Dan; Lim, Jeremy +3 more
We present an iterative method to construct a freeform lens model that self-consistently reproduces the sky positions, geometrically inferred redshifts, and relative brightnesses of all multiply lensed images toward a galaxy cluster. This method is applied to the cluster RXC J2248.7-4431 (z = 0.348) from the Hubble Frontier Fields program, toward …
Using Stereoscopic Observations of Cometary Plasma Tails to Infer Solar Wind Speed
Wang, Yuming; Liu, Rui; Li, Xiaolei +2 more
Detection of the solar wind speed near the Sun is significant in understanding the heating and acceleration of the solar wind. Cometary plasma tails have long been used as natural probes for solar wind speed; previous solar wind speed estimates via plasma tails, however, were based on comet images from a single viewpoint, and the projection effect…
Interplanetary Magnetic Flux Rope Observed at Ground Level by HAWC
Alvarez, C.; Kieda, D.; Nieves-Chinchilla, T. +59 more
We report the ground-level detection of a Galactic cosmic-ray (GCR) flux enhancement lasting ∼17 hr and associated with the passage of a magnetic flux rope (MFR) over the Earth. The MFR was associated with a slow coronal mass ejection (CME) caused by the eruption of a filament on 2016 October 9. Due to the quiet conditions during the eruption and …
Follow-up Ground-based Observations of the Dwarf Nova KZ Gem
Thorstensen, John R.; Szkody, Paula; Dai, Zhibin +1 more
We present spectroscopy of stars in the immediate vicinity of the dwarf nova (DN) KZ Gem to confirm its identification, which is ambiguous in the literature. Analysis of 73 radial velocities spanning from 2014 to 2019 provides a high-precision orbital period of 0.2224628(2) days (∼5.34 hr) and shows KZ Gem to be a double-lined DN. Time series phot…
The Composition, Excitation, and Physical State of Atomic Gas in the Debris Disk Surrounding 51 Oph
Jenkins, Edward B.; Gry, Cécile
We measured 304 absorption features in the ultraviolet and visible spectra of the star 51 Oph, which is known to have a debris disk with a high inclination. We analyzed the relative populations of atoms in excited fine-structure and metastable levels that are maintained by optical pumping and collisional excitation by electrons, and we found that …
Two New Rapidly Rotating ON Stars Found with LAMOST
Howarth, Ian D.; Li, Guang-Wei
The ON stars are a rare subtype of O stars of uncertain origin. We report two new, rapidly rotating ON stars found in data acquired with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope. LS I +61 28 is an ON8.5 Vn dwarf with a projected equatorial rotational velocity of {V}{{e}}\sin I≃ 298 {km} {{{s}}}-1, while H…
Environmental Impact on Star-forming Galaxies in a z ∼ 0.9 Cluster during the Course of Galaxy Accretion
Suzuki, Tomoko L.; Koyama, Yusei; Kodama, Tadayuki +18 more
Galaxies change their properties as they assemble into clusters. In order to understand the physics behind that, we need to go back in time and observe directly what is occurring in galaxies as they fall into a cluster. We have conducted a narrowband and J-band imaging survey on a cluster CL1604-D at z = 0.923 using a new infrared instrument SWIMS…
Multiwavelength Imaging and Spectral Analysis of Jet-like Phenomena in a Solar Active Region Using IRIS and AIA
Morgan, Huw; Humphries, Llŷr Dafydd; Verwichte, Erwin +1 more
High-resolution observations of dynamic phenomena give insights into the properties and processes that govern the low solar atmosphere. We present an analysis of jet-like phenomena emanating from a penumbral footpoint in active region (AR) 12192 using imaging and spectral observations from the Interface Region Imaging Spectrograph (IRIS) and the A…