Search Publications
Binary Red Supergiants. II. Discovering and Characterizing B-type Companions
Massey, Philip; Levesque, Emily M.; Morrell, Nidia I. +1 more
The percentage of massive main-sequence OB stars in binary systems is thought to be as high as 100%. However, very few Galactic binary red supergiants (RSGs) have been identified, despite the fact that these stars are the evolved descendants of OB stars. As shown in our recent paper, binary RSGs will likely have B-type companions, as dictated by s…
Dust Continuum Emission and the Upper Limit Fluxes of Submillimeter Water Lines of the Protoplanetary Disk around HD 163296 Observed by ALMA
Walsh, Catherine; Nomura, Hideko; Tsukagoshi, Takashi +6 more
In this paper, we analyze the upper limit fluxes of submillimeter ortho-H2 16O 321 GHz, para-H2 18O 322 GHz, and HDO 335 GHz lines from the protoplanetary disk around the Herbig Ae star HD 163296, using the Atacama Large Millimeter/Submillimeter Array. These water lines are considered to be the best cand…
Planck Far-infrared Detection of Hyper Suprime-Cam Protoclusters at z ∼ 4: Hidden AGN and Star Formation Activity
Ono, Yoshiaki; Goto, Tomotsugu; Kodama, Tadayuki +11 more
We perform a stacking analysis of Planck, AKARI, Infrared Astronomical Satellite, Wide-field Infrared Survey Explorer, and Herschel images of the largest number of (candidate) protoclusters at z ∼ 3.8 selected from the Hyper Suprime-Cam Subaru Strategic Program. Stacking the images of the 179 candidate protoclusters, the combined infrared (IR) emi…
The Matter Beyond the Ring: The Recent Evolution of SN 1987A Observed by the Hubble Space Telescope
Larsson, J.; Sollerman, J.; Lundqvist, P. +14 more
The nearby SN 1987A offers a spatially resolved view of the evolution of a young supernova (SN) remnant. Here we present recent Hubble Space Telescope imaging observations of SN 1987A, which we use to study the evolution of the ejecta, the circumstellar equatorial ring (ER), and the increasing emission from material outside the ER. We find that th…
Multipoint Study of Successive Coronal Mass Ejections Driving Moderate Disturbances at 1 au
Poedts, Stefaan; Scolini, Camilla; West, Matthew J. +10 more
We analyze in this work the propagation and geoeffectiveness of four successive coronal mass ejections (CMEs) that erupted from the Sun during 2013 May 21-23 and were detected in interplanetary space by the Wind and/or STEREO-A spacecraft. All these CMEs featured critical aspects for understanding so-called “problem space weather storms” at Earth.…
Metal-poor Stars Observed with the Automated Planet Finder Telescope. I. Discovery of Five Carbon-enhanced Metal-poor Stars from LAMOST
Zhao, Gang; Placco, Vinicius M.; Li, Haining +6 more
We report on the discovery of five carbon-enhanced metal-poor (CEMP) stars in the metallicity range of -3.3 < [Fe/H] < -2.4. These stars were selected from the LAMOST DR3 low-resolution (R ∼ 2000) spectroscopic database as metal-poor candidates and followed up with high-resolution spectroscopy (R ∼ 110,000) with the Lick/APF. Stellar paramet…
Spectral Evidence for Heating at Large Column Mass in Umbral Solar Flare Kernels. I. IRIS Near-UV Spectra of the X1 Solar Flare of 2014 October 25
Kowalski, Adam F.; De Pontieu, Bart; Kerr, Graham S. +5 more
The GOES X1 flare SOL2014-10-25T17:08:00 was a three-ribbon solar flare observed with the Interface Region Imaging Spectrograph (IRIS) in the near-UV (NUV) and far-UV. One of the flare ribbons crossed a sunspot umbra, producing a dramatic, ∼1000% increase in the NUV continuum radiation. We comprehensively analyze the UV spectral data of the umbral…
HAZMAT. V. The Ultraviolet and X-Ray Evolution of K Stars
Barman, Travis; Meadows, Victoria S.; Richey-Yowell, Tyler +3 more
Knowing the high-energy radiation environment of a star over a planet’s formation and evolutionary period is critical in determining if that planet is potentially habitable and if any biosignatures could be detected, as UV radiation can severely change or destroy a planet’s atmosphere. Current efforts for finding a potentially habitable planet are…
Keck OSIRIS AO LIRG Analysis (KOALA): Feedback in the Nuclei of Luminous Infrared Galaxies
Inami, Hanae; Murphy, Eric; Díaz-Santos, Tanio +21 more
The role of feedback in triggering or quenching star formation and hence driving galaxy evolution can be directly studied with high-resolution integral field observations. The manifestation of feedback in shocks is particularly important to examine in galaxy mergers, where violent interactions of gas take place in the interstellar medium during th…
ALMA Detection of Dark Chromospheric Holes in the Quiet Sun
Solanki, Sami K.; White, Stephen M.; Loukitcheva, Maria A.
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of a quiet-Sun region at a wavelength of 3 mm, obtained during the first solar ALMA cycle on 2017 April 27, and compare them with available chromospheric observations in the UV and visible as well as with photospheric magnetograms. ALMA images clearly reveal the presence o…