Carbon-enhanced metal-poor stars in the SDSS–APOGEE data base

Kielty, Collin; Venn, Kim A.; Loewen, Nic; Shetrone, Matthew; Placco, Vinicius M.; Jahandar, Farbod; Mészáros, Szabolcs; Martell, Sarah L.

doi:10.1093/mnras/stx1594

Cited by 6 publications

(6 citation statements)

References 133 publications

(210 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The radial velocity uncertainties provided in DR2 are the result of the combination of multiple radial velocity measurements, and if stars vary in radial velocity over the course of the Gaia observations they will have higher radial velocity uncertainties than expected from the precision for stars of their magnitude and effective temperature. This approach is similar to what was done to investigate binarity in CEMP stars discovered in the APOGEE survey (Kielty et al 2017).…”

Section: Radial Velocity Outlook With Gaiamentioning

confidence: 86%

Binarity among CEMP-no stars: an indication of multiple formation pathways?

Arentsen

Starkenburg

Shetrone

et al. 2019

A&A

Self Cite

View full text Add to dashboard Cite

Carbon-enhanced metal-poor (CEMP) stars comprise a large percentage of stars at the lowest metallicities. The stars in the CEMP-no subcategory do not show any s-process enhancement and therefore cannot easily be explained by transfer of carbon and s-process elements from a binary AGB companion. We have performed radial velocity monitoring of a sample of 22 CEMP-no stars to further study the role binarity plays in this type of CEMP star. We find four new binary CEMP-no stars based on their radial velocity variations, thereby significantly enlarging the population of known binaries to a total of eleven. One of the new binary systems is HE 0107−5240, one of the most iron-poor stars known, supporting the binary transfer model for the origin of the abundance pattern of this star. In our sample we find a difference in binary fraction depending on the absolute carbon abundance, with a binary fraction of 47 +15 −14 % for stars with higher absolute carbon abundance and 18 +14 −9 % for stars with lower absolute carbon abundance. This potentially implies a relation between a high carbon abundance and the binarity of a metal-poor star. Although binarity does not equate to mass transfer, there is a possibility that a CEMP-no star in a binary system has been polluted and care has to be taken in the interpretation of their abundance patterns. We furthermore demonstrate the potential of Gaia to discover additional binary candidates.

show abstract

Section: Radial Velocity Outlook With Gaiamentioning

confidence: 86%

Binarity among CEMP-no stars: an indication of multiple formation pathways?

Arentsen

Starkenburg

Shetrone

et al. 2019

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…Stars in the nearby dwarf galaxies typically have lower abundances of αand odd-Z elements, attributed to their slower star formation histories and/or fewer number of high mass stars overall (Venn et al 2004;Tolstoy et al 2009;Nissen & Schuster 2010;McWilliam et al 2013;Frebel & Norris 2015;Hayes et al 2018), while significant variations in heavy r-process elements in some dwarf galaxies, and globular clusters, are discussed in terms of contributions from individual compact binary merger events, like GW170817 (e.g., Roederer 2011;Roederer et al 2018a;Ji et al 2016Ji et al , 2019. In addition, about a third of the [Fe/H] < −2.5 stars 1 in the Galactic halo show very high enhancements in carbon (the carbon-enhanced metal-poor stars, "CEMP"; Yong et al 2013;Aguado et al 2019a also see Kielty et al 2017;Mardini et al 2019), discussed as a signature of the earliest chemical enrichment in the Universe. However, at least one ultra metal-poor star is not carbonenhanced (SDSS J102915+172927, Caffau et al 2012), and the known metal-poor stars in the Galactic bulge do not show carbon-enhancements (Howes et al 2016;Lamb et al 2017).…”

Section: Introductionmentioning

confidence: 99%

The Pristine survey – IX. CFHT ESPaDOnS spectroscopic analysis of 115 bright metal-poor candidate stars

Venn

Kielty

Sestito

et al. 2019

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

A chemo-dynamical analysis of 115 metal-poor candidate stars selected from the narrow-band Pristine photometric survey is presented based on CFHT highresolution ESPaDOnS spectroscopy. We have discover 28 new bright (V < 15) stars with [Fe/H]< −2.5 and 5 with [Fe/H]< −3.0 for success rates of 40% (28/70) and 19% (5/27), respectively. A detailed model atmospheres analysis is carried out for the 28 new metal-poor stars. Stellar parameters were determined from SDSS photometric colours, Gaia DR2 parallaxes, MESA/MIST stellar isochrones, and the initial Pristine survey metallicities, following a Bayesian inference method. Chemical abundances are determined for 10 elements (Na, Mg, Ca, Sc, Ti, Cr, Fe, Ni, Y, Ba). Most stars show chemical abundance patterns that are similar to the normal metal-poor stars in the Galactic halo; however, we also report the discoveries of a new r-process rich star, a new CEMP-s candidate with [Y/Ba]>0, and a metal-poor star with very low [Mg/Fe]. The kinematics and orbits for all of the highly probable metal-poor candidates are determined by combining our precision radial velocities with Gaia DR2 proper motions. Some stars show unusual kinematics for their chemistries, including planar orbits, unbound orbits, and highly elliptical orbits that plunge deeply into the Galactic bulge (R peri < 0.5 kpc); also, eight stars have orbital energies and actions consistent with the Gaia-Enceladus accretion event. This paper contributes to our understanding of the complex chemo-dynamics of the metal-poor Galaxy, and increases the number of known bright metal-poor stars available for detailed nucleosynthetic studies.

show abstract

“…Many studies have indicated that metal-poor stars may show high carbon-to-iron ratios, and thus classified as carbon-enhanced metal-poor stars (Beers & Christlieb 2005;Aoki et al 2007;Hansen et al 2016a;Placco et al 2016;Kielty et al 2017;Roriz et al 2017;Cruz et al 2018;Caffau et al 2018). Furthermore, CEMP stars can be divided into four sub-classes, according to their neutron-capture elements nature.…”

Section: Introductionmentioning

confidence: 99%

Metal-poor Stars Observed with the Automated Planet Finder Telescope. I. Discovery of Five Carbon-enhanced Metal-poor Stars from LAMOST

Mardini¹,

Li²,

Placco³

et al. 2019

ApJ

View full text Add to dashboard Cite

We report on the discovery of five carbon-enhanced metal-poor (CEMP) stars in the metallicity range of −3.3 < [Fe/H] < −2.4. These stars were selected from the LAMOST DR3 low-resolution (R∼ 2,000) spectroscopic database as metal-poor candidates and followed-up with high-resolution spectroscopy (R∼110,000) with the LICK/APF. Stellar parameters and individual abundances for 25 chemical elements (from Li to Eu) are presented for the first time. These stars exhibit chemical abundance patterns that are similar to those reported in other literature studies of very and extremely metal-poor stars. One of our targets, J2114−0616, shows high enhancement in carbon ([C/Fe]=1.37), nitrogen ([N/Fe]= 1.88), barium ([Ba/Fe]=1.00), and europium ([Eu/Fe]=0.84). Such chemical abundance pattern suggests that J2114−0616 can be classified as CEMP-r/s star. In addition, the star J1054+0528 can be classified as a CEMP-rI star, with [Eu/Fe]=0.44 and [Ba/Fe]=−0.52. The other stars in our sample show no enhancements in neutron-capture elements and can be classified as CEMP-no stars. We also performed a kinematic and dynamical analysis of the sample stars based on Gaia DR2 data. The kinematic parameters, orbits, and binding energy of these stars, show that J2114−0616 is member of the outer halo population, while the remaining stars belong to the inner halo population but with an accreted origin. Collectively, these results add important constraints on the origin and evolution of CEMP stars as well as on their possible formation scenarios.

show abstract

Carbon-enhanced metal-poor stars in the SDSS–APOGEE data base

Cited by 6 publications

References 133 publications

Binarity among CEMP-no stars: an indication of multiple formation pathways?

Binarity among CEMP-no stars: an indication of multiple formation pathways?

The Pristine survey – IX. CFHT ESPaDOnS spectroscopic analysis of 115 bright metal-poor candidate stars

Metal-poor Stars Observed with the Automated Planet Finder Telescope. I. Discovery of Five Carbon-enhanced Metal-poor Stars from LAMOST

Contact Info

Product

Resources

About