59 research outputs found
Neutron-capture element deficiency of the Hercules dwarf spheroidal galaxy
We present an assessment of the barium abundance ratios for red giant member
stars in the faint Hercules dwarf spheroidal (dSph) galaxy. Our results are
drawn from intermediate-resolution FLAMES/GIRAFFE spectra around the Ba II
6141.71 AA absorption line at low signal-to-noise ratios. For three brighter
stars we were able to gain estimates from direct equivalent-width measurements,
while for the remaining eight stars only upper limits could be obtained. These
results are investigated in a statistical manner and indicate very low Ba
abundances of log epsilon (Ba) < 0.7 dex (3 sigma). We discuss various possible
systematic biasses, first and foremost, a blend with the Fe I 6141.73 AA-line,
but most of those would only lead to even lower abundances. A better match with
metal-poor halo and dSph stars can only be reached by including a large
uncertainty in the continuum placement. This contrasts with the high
dispersions in iron and calcium (in excess of 1 dex) in this galaxy. While the
latter spreads are typical of the very low luminosity, dark-matter dominated
dSphs, a high level of depletion in heavy elements suggests that chemical
enrichment in Hercules was governed by very massive stars, coupled with a very
low star formation efficiency. While very low abundances of some heavy elements
are also found in individual stars of other dwarf galaxies, this is the first
time that a very low Ba abundance is found within an entire dSph over a broad
metallicity range.Comment: 10 pages, 6 figures, accepted for publication in Astronomy &
Astrophysic
Petition for a Writ of Certiorari
Petition for a Writ of Certiorari submitted by Public Patent Foundation and ACLU attorney
Supplemental Brief for Appellees
Supplemental brief for appellees, written by appellees in support of plaintiffs-appellees in AMP v. Myriad Genetics (No. 2010-1406)
Plaintiffs-Appellees' Petition for Panel Rehearing
Petitioners-appelles' petition for panel rehearing, submitted after the CAFC's July 29, 2011 ruling
Brief for Petitioners
Petitioners Brief written by ACLU and Public Patent Foundation in support of petitioners in AMP v. Myriad Genetics (Supreme Court Case Docket No. 12-398)
Petition for a Writ of Certiorari
Petition for a Writ of Certiorari submitted by petitioners Public Patent Foundation and American Civil Liberties Union (No. 11-725
Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars: IV. Two bulge populations
Based on high-resolution (R ≈ 42 000 to 48 000) and high signal-to-noise (S/N ≈ 50 to 150) spectra obtained with UVES/VLT, we present detailed elemental abundances (O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Zn, Y, and Ba) and stellar ages for 12 new mic
Brief for the Appellees
Brief written by appellees (Public Patent Foundation and American Civil Liberties Union) supporting affirmance in AMP v. Myriad Genetics (No. 2010-1406)
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