Search Publications
The Parallax of the Red Hypergiant VX Sgr with Accurate Tropospheric Delay Calibration
Menten, Karl M.; Reid, Mark J.; Zhang, Bo +3 more
We report astrometric results of VLBI phase-referencing observations of 22 GHz H2O masers emission toward the red hypergiant VX Sgr, one of most massive and luminous red hypergiant stars in our Galaxy, using the Very Long Baseline Array. A background source, J1820-2528, projected 4.°4 from the target VX Sgr, was used as the phase refere…
Comet C/2011 W3 (Lovejoy) between 2 and 10 Solar Radii: Physical Parameters of the Comet and the Corona
Giordano, Silvio; Raymond, J. C.; Downs, Cooper +3 more
Comet C/2011 W3 (Lovejoy) is the first sungrazing comet in many years to survive perihelion passage. We report ultraviolet observations with the Ultraviolet Coronagraph Spectrometer (UVCS) spectrometer aboard the Solar and Heliospheric Observatory satellite at five heights as the comet approached the Sun. The brightest line, Lyα, shows dramatic va…
JVLA 1.5 GHz Continuum Observation of CLASH Clusters. I. Radio Properties of the BCGs
Donahue, Megan; Rosati, Piero; Aravena, Manuel +6 more
We present high-resolution (∼1″), 1.5 GHz continuum observations of the brightest cluster galaxies (BCGs) of 13 CLASH (Cluster Lensing And Supernova survey with Hubble) clusters at 0.18< z< 0.69 with the Karl G. Jansky Very Large Array (JVLA). Radio emission is clearly detected and characterized for 11 BCGs, while for two of them we obtain o…
Constraining Solar Position and Velocity with a nearby Hypervelocity Star
Hattori, Kohei; Castro, Norberto; Valluri, Monica
Gravitational three-body interaction among binary stars and the supermassive black hole at the center of the Milky Way occasionally ejects a hypervelocity star (HVS) with a velocity of ∼ 1000 {km} {{{s}}}-1. Due to the ejection location, such an HVS initially has negligible azimuthal angular momentum {L}z≃ 0 {kpc} {km} {{{s}}…
Don’t Blink: Constraining the Circumstellar Environment of the Interacting Type Ia Supernova 2015cp
Smith, M.; Filippenko, A. V.; Nugent, P. E. +12 more
Despite their cosmological utility, the progenitors of Type Ia supernovae (SNe Ia) are still unknown, with many efforts focused on whether accretion from a nondegenerate companion can grow a carbon-oxygen white dwarf to near the Chandrasekhar mass. The association of SNe Ia resembling SN 1991T (“91T-like”) with circumstellar interaction may be evi…
The Spread of Metals into the Low-redshift Intergalactic Medium
Danforth, Charles W.; Stocke, John T.; Keeney, Brian A. +1 more
We investigate the association between galaxies and metal-enriched and metal-deficient absorbers in the local universe (z < 0.16) using a large compilation of far-ultraviolet spectra of bright active galactic nuclei targets observed with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope. In this homogeneous sample of 18 O VI det…
A Cavity of Large Grains in the Disk around the Group II Herbig Ae/Be Star HD 142666
Rubinstein, A. E.; Calvet, N.; Zhang, K. +3 more
Herbig Ae/Be (HAeBe) stars have been classified into Group I or Group II, and were initially thought to be flared and flat disks, respectively. Several Group I sources have been shown to have large gaps, suggesting ongoing planet formation, while no large gaps have been found in the disks of Group II sources. We analyzed the disk around the Group …
Reconciling Optical and Radio Observations of the Binary Millisecond Pulsar PSR J1640+2224
Deller, Adam T.; Kaplan, David L.; Istrate, Alina G. +3 more
Previous optical and radio observations of the binary millisecond pulsar PSR J1640+2224 have come to inconsistent conclusions about the identity of its companion, with some observations suggesting that the companion is a low-mass helium-core (He-core) white dwarf (WD), while others indicate that it is most likely a high-mass carbon-oxygen (CO) WD.…
Actions Are Weak Stellar Age Indicators in the Milky Way Disk
Bedell, Megan; Ness, Melissa K.; Beane, Angus
The orbital properties of stars in the Milky Way disk are signatures of their formation, but they are also expected to change over time due to the dynamical evolution of the Galaxy. Stellar orbits can be quantified by the three dynamical actions, J r , L z , and J z , which provide measures of the orbital eccent…
Herschel Spectroscopy of the Taffy Galaxies (UGC 12914/12915 = VV 254): Enhanced [C II] Emission in the Collisionally Formed Bridge
Boulanger, F.; Falgarone, E.; Helou, G. +17 more
Using the PACS and SPIRE spectrometers on board Herschel, we obtained observations of the Taffy galaxies (UGC 12914/12915) and bridge. The Taffy system is believed to be the result of a face-on collision between two gas-rich galaxies, in which the stellar disks passed through each other, but the gas was dispersed into a massive H I and molecular b…