Vinicius M. Placco

  • Citations Per Year
Learn More
  • Reinout J. van Weeren, Felipe Andrade-Santos, +15 authors Kevin Fogarty
  • 2016
On the largest scales, the Universe consists of voids and filaments making up the cosmic web. Galaxy clusters are located at the knots in this web, at the intersection of filaments. Clusters grow through accretion from these large-scale filaments and by mergers with other clusters and groups. In a growing number of galaxy clusters, elongated Mpc-sized radio(More)
On 17 August 2017, Swope Supernova Survey 2017a (SSS17a) was discovered as the optical counterpart of the binary neutron star gravitational wave event GW170817. We report time-series spectroscopy of SSS17a from 11.75 hours until 8.5 days after merger. Over the first hour of observations the ejecta rapidly expanded and cooled. Applying blackbody fits to the(More)
We present a comprehensive abundance analysis of two newly-discovered carbon-enhanced metalpoor (CEMP) stars. HE 2138−3336 is a s-process-rich star with [Fe/H] = −2.79, and has the highest [Pb/Fe] abundance ratio measured thus far, if NLTE corrections are included ([Pb/Fe] = +3.84). HE 2258−6358, with [Fe/H] = −2.67, exhibits enrichments in both sand(More)
Context. An increasing fraction of carbon-enhanced metal-poor (CEMP) stars is found as their iron abundance, [Fe/H], decreases below [Fe/H] = −2.0. The CEMP-s stars have the highest absolute carbon abundances, [C/H], and are thought to owe their enrichment in carbon and the slow neutron-capture (s-process) elements to mass transfer from a former asymptotic(More)
We revisit the observed frequencies of carbon-enhanced metal-poor (CEMP) stars as a function of the metallicity in the Galaxy, using data from the literature with available high-resolution spectroscopy. Our analysis excludes stars exhibiting clear overabundances of neutron-capture elements and takes into account the expected depletion of surface carbon(More)
We present an elemental abundance analysis for four newly discovered ultra metal-poor stars from the Hamburg/ESO survey, with [Fe/H] −4. Based on high-resolution, high signal-to-noise spectra, we derive abundances for 17 elements in the range from Li to Ba. Three of the four stars exhibit moderate to large overabundances of carbon, but have no enhancements(More)
We present a Magellan/MIKE high-resolution (R∼35,000) spectrum of the ancient star SD 1313−0019, which has an iron abundance of Fe H 5.0 [ ] = / , paired with a carbon enhancement of C Fe 3.0 [ ] ~ / . The star was initially identified by Allende Prieto et al. in the BOSS survey. Its medium-resolution spectrum suggested a higher metallicity of Fe H 4.3 [(More)
We present a comprehensive abundance analysis of two newly-discovered carbon-enhanced metalpoor (CEMP) stars. HE 2138−3336 is a s-process-rich star with [Fe/H] = −2.79, and has the highest [Pb/Fe] abundance ratio measured thus far, if NLTE corrections are included ([Pb/Fe] = +3.84). HE 2258−6358, with [Fe/H] = −2.67, exhibits enrichments in both sand(More)
We present a detailed abundance analysis of 23 elements for a newly discovered carbon-enhanced metal-poor (CEMP) star, HE0414−0343, from the Chemical Abundances of Stars in the Halo Project. Its spectroscopic stellar parameters are Teff=4863 K, g log 1.25, = ξ=2.20 km s , and [Fe/H]=−2.24. Radial velocity measurements covering seven years indicate(More)
  • 1