Constraining Nucleosynthesis in Two CEMP Progenitors Using Fluorine. (arXiv:2008.10136v2 [astro-ph.SR] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Mura_Guzman_A/0/1/0/all/0/1">A. Mura-Guzmán</a> (1,2), <a href="http://arxiv.org/find/astro-ph/1/au:+Yong_D/0/1/0/all/0/1">D. Yong</a> (1,2), <a href="http://arxiv.org/find/astro-ph/1/au:+Abate_C/0/1/0/all/0/1">C. Abate</a> (3), <a href="http://arxiv.org/find/astro-ph/1/au:+Karakas_A/0/1/0/all/0/1">A. Karakas</a> (4,2), <a href="http://arxiv.org/find/astro-ph/1/au:+Kobayashi_C/0/1/0/all/0/1">C. Kobayashi</a> (5,2), <a href="http://arxiv.org/find/astro-ph/1/au:+Oh_H/0/1/0/all/0/1">H. Oh</a> (6), <a href="http://arxiv.org/find/astro-ph/1/au:+Chun_S/0/1/0/all/0/1">S. Chun</a> (6), <a href="http://arxiv.org/find/astro-ph/1/au:+Mace_G/0/1/0/all/0/1">G. Mace</a> (7). ((1) Research School of Astronomy and Astrophysics, Australian National University, Australia, (2) ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), Australia, (3) Deep Blue Srl, Rome, Italy, (4) School of Physics and Astronomy, Monash University, Australia, (5) Centre for Astrophysics Research, University of Hertfordshire, UK, (6) Korea Astronomy and Space Science Institute, Republic of Korea, (7) Department of Astronomy and McDonald Observatory, University of Texas at Austin, USA.)
We present new fluorine abundance estimations in two carbon enhanced
metal-poor (CEMP) stars, HE 1429-0551 and HE 1305+0007. HE 1429-0551 is also
enriched in slow neutron-capture process (s-process) elements, a CEMP-s, and HE
1305+0007 is enhanced in both, slow and rapid neutron-capture process elements,
a CEMP-s/r. The F abundances estimates are derived from the vibration-rotation
transition of the HF molecule at 23358.6 A using high-resolution infrared
spectra obtained with the Immersion Grating Infrared Spectrometer (IGRINS) at
the 4m-class Lowell Discovery Telescope. Our results include a F abundance
measurement in HE 1429-0551 of A(F) = +3.93 ([F/Fe] = +1.90) at [Fe/H] = -2.53,
and a F upper limit in HE 1305+0007 of A(F) < +3.28 ([F/Fe] < +1.00) at [Fe/H]
= -2.28. Our new derived F abundance in HE 1429-0551 makes this object the most
metal-poor star where F has been detected. We carefully compare these results
with literature values and state-of-the-art CEMP-s model predictions including
detailed AGB nucleosynthesis and binary evolution. The modelled fluorine
abundance for HE 1429-0551 is within reasonable agreement with our observed
abundance, although is slightly higher than our observed value. For HE
1429-0551, our findings support the scenario via mass transfer by a primary
companion during its thermally-pulsing phase. Our estimated upper limit in HE
1305+0007, along with data from the literature, shows large discrepancies
compared with AGB models. The discrepancy is principally due to the
simultaneous s- and r-process element enhancements which the model struggles to
reproduce.
We present new fluorine abundance estimations in two carbon enhanced
metal-poor (CEMP) stars, HE 1429-0551 and HE 1305+0007. HE 1429-0551 is also
enriched in slow neutron-capture process (s-process) elements, a CEMP-s, and HE
1305+0007 is enhanced in both, slow and rapid neutron-capture process elements,
a CEMP-s/r. The F abundances estimates are derived from the vibration-rotation
transition of the HF molecule at 23358.6 A using high-resolution infrared
spectra obtained with the Immersion Grating Infrared Spectrometer (IGRINS) at
the 4m-class Lowell Discovery Telescope. Our results include a F abundance
measurement in HE 1429-0551 of A(F) = +3.93 ([F/Fe] = +1.90) at [Fe/H] = -2.53,
and a F upper limit in HE 1305+0007 of A(F) < +3.28 ([F/Fe] < +1.00) at [Fe/H]
= -2.28. Our new derived F abundance in HE 1429-0551 makes this object the most
metal-poor star where F has been detected. We carefully compare these results
with literature values and state-of-the-art CEMP-s model predictions including
detailed AGB nucleosynthesis and binary evolution. The modelled fluorine
abundance for HE 1429-0551 is within reasonable agreement with our observed
abundance, although is slightly higher than our observed value. For HE
1429-0551, our findings support the scenario via mass transfer by a primary
companion during its thermally-pulsing phase. Our estimated upper limit in HE
1305+0007, along with data from the literature, shows large discrepancies
compared with AGB models. The discrepancy is principally due to the
simultaneous s- and r-process element enhancements which the model struggles to
reproduce.
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