Search Publications
Microlensing Events by Proxima Centauri in 2014 and 2016: Opportunities for Mass Determination and Possible Planet Detection
Anderson, Jay; Bond, Howard E.; Sahu, Kailash C. +1 more
We have found that Proxima Centauri, the star closest to our Sun, will pass close to a pair of faint background stars in the next few years. Using Hubble Space Telescope (HST) images obtained in 2012 October, we determine that the passage close to a mag 20 star will occur in 2014 October (impact parameter 1.''6), and to a mag 19.5 star in 2016 Feb…
Tracing Ram-pressure Stripping with Warm Molecular Hydrogen Emission
Rieke, George H.; Rieke, Marcia J.; Sivanandam, Suresh
We use the Spitzer Infrared Spectrograph to study four infalling cluster galaxies with signatures of ongoing ram-pressure stripping. H2 emission is detected in all four, and two show extraplanar H2 emission. The emission usually has a warm (T ~ 115-160 K) and a hot (T ~ 400-600 K) component that is approximately two orders of…
Navy Precision Optical Interferometer Measurements of 10 Stellar Oscillators
van Belle, Gerard T.; Zavala, R. T.; Schmitt, Henrique R. +3 more
Using the Navy Precision Optical Interferometer, we measured the angular diameters of 10 stars that have previously measured solar-like oscillations. Our sample covered a range of evolutionary stages but focused on evolved subgiant and giant stars. We combined our angular diameters with Hipparcos parallaxes to determine the stars' physical radii, …
RX J0848.6+4453: The Evolution of Galaxy Sizes and Stellar Populations in a z = 1.27 Cluster
Toft, Sune; Jørgensen, Inger; Chiboucas, Kristin +4 more
RX J0848.6+4453 (Lynx W) at redshift 1.27 is part of the Lynx Supercluster of galaxies. We present an analysis of the stellar populations and star formation history for a sample of 24 members of the cluster. Our study is based on deep optical spectroscopy obtained with Gemini North combined with imaging data from Hubble Space Telescope. Focusing o…
Abundances in the ejecta of core-collapse supernova remnants G350.1-0.3 and G349.7+0.2
Koyama, Katsuji; Uchida, Hiroyuki; Yasumi, Masato +5 more
We present Suzaku results of the two Galactic supernova remnants (SNRs) G350.1-0.3 and G349.7+0.2. We find Al and Ni Kα lines from both the SNRs for the first time, in addition to previously detected K-shell lines of Mg, Si, S, Ar, Ca, and Fe. The spectra are well described by two optically thin thermal plasmas: a low-temperature (low-kT) plasma i…
Herschel observations of debris discs orbiting planet-hosting subgiants
Wyatt, Mark C.; Johnson, John A.; Kennedy, Grant M. +2 more
Debris discs are commonly detected orbiting main-sequence stars, yet little is known regarding their fate as the star evolves to become a giant. Recent observations of radial velocity detected planets orbiting giant stars highlight this population and its importance for probing, for example, the population of planetary systems orbiting intermediat…
The long-period Galactic Cepheid RS Puppis. III. A geometric distance from HST polarimetric imaging of its light echoes
Szabados, L.; Kervella, P.; Anderson, R. I. +8 more
As one of the most luminous Cepheids in the Milky Way, the 41.5-day RS Puppis is an analog of the long-period Cepheids used to measure extragalactic distances. An accurate distance to this star would therefore help anchor the zero-point of the bright end of the period-luminosity relation. But, at a distance of about 2 kpc, RS Pup is too far away f…
Physical structure of the photodissociation regions in NGC 7023. Observations of gas and dust emission with Herschel
Abergel, A.; Teyssier, D.; Zavagno, A. +16 more
Context. The determination of the physical conditions in molecular clouds is a key step towards our understanding of their formation and evolution of associated star formation. We investigate the density, temperature, and column density of both dust and gas in the photodissociation regions (PDRs) located at the interface between the atomic and col…
Proton acceleration at two-dimensional dipolarization fronts in the magnetotail
Artemyev, A.; Zimbardo, G.; Greco, A.
Transient reconnection events in the planetary magnetotail give rise to fast plasma jets, whose leading edges are called dipolarization fronts. We perform a test particle simulation of ion acceleration in a 2-D model of dipolarization fronts. We study the dependence of acceleration on several parameters of the model. We obtain that the interaction…
Heavy metals in a light white dwarf: abundances of the metal-rich, extremely low-mass GALEX J1717+6757
Hermes, J. J.; Gänsicke, B. T.; Dhillon, V. S. +9 more
Using the Hubble Space Telescope, we detail the first abundance analysis enabled by far-ultraviolet spectroscopy of a low-mass (≃0.19 M⊙) white dwarf (WD), GALEX J1717+6757, which is in a 5.9-h binary with a fainter, more-massive companion. We see absorption from nine metals, including roughly solar abundances of Ca, Fe, Ti, and P. We d…