Search Publications
Absolute Ages and Distances of 22 GCs Using Monte Carlo Main-sequence Fitting
Chaboyer, Brian; O'Malley, Erin M.; Gilligan, Christina
The recent Gaia Data Release 1 of stellar parallaxes provides ample opportunity to find metal-poor main-sequence stars with precise parallaxes. We select 21 such stars with parallax uncertainties better than σ π /π ≤ 0.10 and accurate abundance determinations suitable for testing metal-poor stellar evolution models and determining the …
Properties of the cosmological filament between two clusters: A possible detection of a large-scale accretion shock by Suzaku
Kaastra, J. S.; Mernier, F.; Ishisaki, Y. +7 more
We report on the results of a Suzaku observation of the plasma in the filament located between the two massive clusters of galaxies, Abell 399 and Abell 401. Abell 399 (z = 0.0724) and Abell 401 (z = 0.0737) are expected to be in the initial phase of a cluster merger. In the region between the two clusters, we find a clear enhancement in the tempe…
The Sirius System and Its Astrophysical Puzzles: Hubble Space Telescope and Ground-based Astrometry
Schaefer, Gail H.; Bond, Howard E.; Burleigh, Matthew R. +11 more
Sirius, the seventh-nearest stellar system, is a visual binary containing the metallic-line A1 V star Sirius A, the brightest star in the sky, orbited in a 50.13 year period by Sirius B, the brightest and nearest white dwarf (WD). Using images obtained over nearly two decades with the Hubble Space Telescope (HST), along with photographic observati…
Sulfur dioxide in the Venus atmosphere: I. Vertical distribution and variability
Vandaele, A. C.; Robert, S.; Montmessin, F. +18 more
Recent observations of sulfur containing species (SO2, SO, OCS, and H2SO4) in Venus' mesosphere have generated controversy and great interest in the scientific community. These observations revealed unexpected spatial patterns and spatial/temporal variability that have not been satisfactorily explained by models. S…
Diamagnetic region(s): structure of the unmagnetized plasma around Comet 67P/CG
Glassmeier, K. -H.; Nilsson, H.; Carr, C. +14 more
The ESA's comet chaser Rosetta has monitored the evolution of the ionized atmosphere of comet 67P/Churyumov-Gerasimenko (67P/CG) and its interaction with the solar wind, during more than 2 yr. Around perihelion, while the cometary outgassing rate was highest, Rosetta crossed hundreds of unmagnetized regions, but did not seem to have crossed a larg…
The PdBI Arcsecond Whirlpool Survey (PAWS): The Role of Spiral Arms in Cloud and Star Formation
Leroy, Adam K.; Meidt, Sharon E.; Hughes, Annie +9 more
The process that leads to the formation of the bright star-forming sites observed along prominent spiral arms remains elusive. We present results of a multi-wavelength study of a spiral arm segment in the nearby grand-design spiral galaxy M51 that belongs to a spiral density wave and exhibits nine gas spurs. The combined observations of the (ioniz…
Star Formation In Nearby Clouds (SFiNCs): X-Ray and Infrared Source Catalogs and Membership
Garmire, Gordon P.; Feigelson, Eric D.; Broos, Patrick S. +5 more
The Star Formation in Nearby Clouds (SFiNCs) project is aimed at providing a detailed study of the young stellar populations and of star cluster formation in the nearby 22 star-forming regions (SFRs) for comparison with our earlier MYStIX survey of richer, more distant clusters. As a foundation for the SFiNCs science studies, here, homogeneous dat…
The Solar Neighborhood. XXXIX. Parallax Results from the CTIOPI and NOFS Programs: 50 New Members of the 25 parsec White Dwarf Sample
Henry, Todd J.; Bergeron, P.; Lépine, Sébastien +9 more
We present 114 trigonometric parallaxes for 107 nearby white dwarf (WD) systems from both the Cerro Tololo Inter-American Observatory Parallax Investigation (CTIOPI) and the U. S. Naval Observatory Flagstaff Station (NOFS) parallax programs. Of these, 76 parallaxes for 69 systems were measured by the CTIOPI program and 38 parallaxes for as many sy…
HICOSMO - cosmology with a complete sample of galaxy clusters - I. Data analysis, sample selection and luminosity-mass scaling relation
Reiprich, T. H.; Schellenberger, G.
The X-ray regime, where the most massive visible component of galaxy clusters, the intracluster medium, is visible, offers directly measured quantities, like the luminosity, and derived quantities, like the total mass, to characterize these objects. The aim of this project is to analyse a complete sample of galaxy clusters in detail and constrain …
Evidence for a Time Lag in Solar Modulation of Galactic Cosmic Rays
Tomassetti, Nicola; Orcinha, Miguel; Barão, Fernando +1 more
The solar modulation effect of cosmic rays in the heliosphere is an energy-, time-, and particle-dependent phenomenon that arises from a combination of basic particle transport processes such as diffusion, convection, adiabatic cooling, and drift motion. Making use of a large collection of time-resolved cosmic-ray data from recent space missions, …