Discovery of HE 1523-0901, a strongly r-process-enhanced metal-poor star with detected uranium

Anna Frebel; Norbert Christlieb; John E. Norris; Christopher Thom; Timothy C. Beers; Jaehyon Rhee

doi:10.1086/518122

Discovery of HE 1523-0901, a strongly r-process-enhanced metal-poor star with detected uranium

Anna Frebel^*, Norbert Christlieb, John E. Norris, Christopher Thom, Timothy C. Beers, Jaehyon Rhee

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

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Abstract

We present age estimates for the newly discovered, very r-process-enhanced metal-poor star HE 1523-0901 ([Fe/H] = -2.95) based on the radioactive decay of Th and U. The bright (V = 11.1) giant was found among a sample of bright metal-poor stars selected from the Hamburg/ESO Survey. From an abundance analysis of a high-resolution (R = 75,000) VLT/UVES spectrum, we find HE 1523-0901 to be strongly overabundant in r-process elements ([r/Fe] = 1.8). The abundances of heavy neutron-capture elements (Z>56) measured in HE 1523-0901 match the scaled solar r-process pattern extremely well. We detect the strongest optical U line at 3859.57 Å. For the first time, we are able to employ several different chronometers, such as the U/Th, U/Ir, Th/ Eu, and Th/Os ratios to measure the age of a star. The weighted average age of HE 1523-0901 is 13.2 Gyr. Several sources of uncertainties are assessed in detail.

Original language	English
Pages (from-to)	L117-L120
Journal	Astrophysical Journal
Volume	660
Issue number	2 II
DOIs	https://doi.org/10.1086/518122
Publication status	Published - 10 May 2007

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@article{e09fb73cae354c2ebf2fa75f008287ec,

title = "Discovery of HE 1523-0901, a strongly r-process-enhanced metal-poor star with detected uranium",

abstract = "We present age estimates for the newly discovered, very r-process-enhanced metal-poor star HE 1523-0901 ([Fe/H] = -2.95) based on the radioactive decay of Th and U. The bright (V = 11.1) giant was found among a sample of bright metal-poor stars selected from the Hamburg/ESO Survey. From an abundance analysis of a high-resolution (R = 75,000) VLT/UVES spectrum, we find HE 1523-0901 to be strongly overabundant in r-process elements ([r/Fe] = 1.8). The abundances of heavy neutron-capture elements (Z>56) measured in HE 1523-0901 match the scaled solar r-process pattern extremely well. We detect the strongest optical U line at 3859.57 {\AA}. For the first time, we are able to employ several different chronometers, such as the U/Th, U/Ir, Th/ Eu, and Th/Os ratios to measure the age of a star. The weighted average age of HE 1523-0901 is 13.2 Gyr. Several sources of uncertainties are assessed in detail.",

keywords = "Early universe, Galaxy: halo, Nuclear reactions, nucleosynthesis, abundances, Stars: abundances, Stars: individual (HE 1523-0901)",

author = "Anna Frebel and Norbert Christlieb and Norris, {John E.} and Christopher Thom and Beers, {Timothy C.} and Jaehyon Rhee",

year = "2007",

month = may,

day = "10",

doi = "10.1086/518122",

language = "English",

volume = "660",

pages = "L117--L120",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "2 II",

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TY - JOUR

T1 - Discovery of HE 1523-0901, a strongly r-process-enhanced metal-poor star with detected uranium

AU - Frebel, Anna

AU - Christlieb, Norbert

AU - Norris, John E.

AU - Thom, Christopher

AU - Beers, Timothy C.

AU - Rhee, Jaehyon

PY - 2007/5/10

Y1 - 2007/5/10

N2 - We present age estimates for the newly discovered, very r-process-enhanced metal-poor star HE 1523-0901 ([Fe/H] = -2.95) based on the radioactive decay of Th and U. The bright (V = 11.1) giant was found among a sample of bright metal-poor stars selected from the Hamburg/ESO Survey. From an abundance analysis of a high-resolution (R = 75,000) VLT/UVES spectrum, we find HE 1523-0901 to be strongly overabundant in r-process elements ([r/Fe] = 1.8). The abundances of heavy neutron-capture elements (Z>56) measured in HE 1523-0901 match the scaled solar r-process pattern extremely well. We detect the strongest optical U line at 3859.57 Å. For the first time, we are able to employ several different chronometers, such as the U/Th, U/Ir, Th/ Eu, and Th/Os ratios to measure the age of a star. The weighted average age of HE 1523-0901 is 13.2 Gyr. Several sources of uncertainties are assessed in detail.

AB - We present age estimates for the newly discovered, very r-process-enhanced metal-poor star HE 1523-0901 ([Fe/H] = -2.95) based on the radioactive decay of Th and U. The bright (V = 11.1) giant was found among a sample of bright metal-poor stars selected from the Hamburg/ESO Survey. From an abundance analysis of a high-resolution (R = 75,000) VLT/UVES spectrum, we find HE 1523-0901 to be strongly overabundant in r-process elements ([r/Fe] = 1.8). The abundances of heavy neutron-capture elements (Z>56) measured in HE 1523-0901 match the scaled solar r-process pattern extremely well. We detect the strongest optical U line at 3859.57 Å. For the first time, we are able to employ several different chronometers, such as the U/Th, U/Ir, Th/ Eu, and Th/Os ratios to measure the age of a star. The weighted average age of HE 1523-0901 is 13.2 Gyr. Several sources of uncertainties are assessed in detail.

KW - Early universe

KW - Galaxy: halo

KW - Nuclear reactions, nucleosynthesis, abundances

KW - Stars: abundances

KW - Stars: individual (HE 1523-0901)

UR - http://www.scopus.com/inward/record.url?scp=34249864533&partnerID=8YFLogxK

U2 - 10.1086/518122

DO - 10.1086/518122

M3 - Article

SN - 0004-637X

VL - 660

SP - L117-L120

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2 II

ER -

Discovery of HE 1523-0901, a strongly r-process-enhanced metal-poor star with detected uranium

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