Download OVERVIEW ABSTRACT HST/COS chemical abundance analysis of

HST/COS chemical abundance analysis of the
Hyper Metal-Poor (HMP) star HE1327-2326
Rana Ezzeddine , Anna Frebel , Ian Roederer
1,2
2,1
3,1
1 JINA-CEE, Michigan State University, East Lansing, MI, 48823, USA.
2 MIT Kavli Institute for Astrophysics, Cambridge, MA, 02139, USA.
3 Department of Astronomy, University of Michigan, 1085 S. University Avenue,, Ann Arbor, MI 48109, USA
ABSTRACT
We present new Near-UltraViolet
(NUV) elemental abundance
analysis, for the hyper metal-poor
star HE1327-2326 ([Fe/H] = -5.2)
using COS/HST data. We detect
for the first time 4 Fe II lines, in
addition to Zn I and Ni II
absorption lines. Fitting the
abundances to SNe yield models,
lead to Pop III progenitor mass of
28 Msolar and SNe explosion
energy of 0.3 Bethe (B).
Metals
12-13 billion years
Low-mass stars
still found in the
Galactic Halo today!
First Stars
Star Forming
gas Cloud
OVERVIEW
✦ Hyper Metal-Poor (HMP) stars are the local equivalents to the high-redshift Universe. In their
atmospheres, they carry imprints of the nucleosynthetic signatures of their progenitors Pop III (“First”)
stars [1]. They retain the chemical composition of the interstellar medium at the time and place of their
birth.
✦ We compare the UV + Optical abundance signatures of the Hyper Metal-Poor star
(HMP: [Fe/H] < -5.00 [2]) HE1327-2326 [3] to early low-mass stellar supernovae yields to provide
empirical constraints on the properties of its progenitor “First” stars, including their masses and
explosion energies.
✦ The best fit model shows that
HE1327-2326 has a Pop III
progenitor mass of 28 Msolar and
SNe exploding energy of 0.3 B
(1B=1044 J).
✦ Detecting new Zn and Fe lines in
UV spectrum of HE1327-2326
result in a larger Pop III progenitor
mass (higher by 6.5 Msolar) than
previous result [5].
HE1327-2326
He
0
28 M , 0.3 B, log(fmix ) =
H
Logarithm of Abundance Relative to Sun
RESULTS
✦ We derive for the first time Fe II
and Zn I abundances in
HE1327-2316 and compare the full
abundances pattern from Z=1-30 of
available measurements and upper
limits to theoretical model
predictions for non-rotating single
massive Pop III stars in the range
10–100 Solar masses [4] .
-2
1.2
N
Li
B
C
O
-4
Be
Ne
Mg
Cl
Na
F
Al
K
Si
V
Sc
Mn
S
-6
P
Co
Ar
Ca
Ti
Cr
Zn
Fe
Ni
-8
Cu
© www.StarFit.org
5
10
15
Element Charge Number
20
25
30
References and Acknowledgements
[1] Bromm (2013)
[2] Beers & Christlieb (2005)
[3] Frebel et al. (2005,2008)
[4] starfit.org : Heger & Woosley (2010)
[5] Placco et al. (2015)
This work was supported by the National Science Foundation under Grant No. PHY-1430152 (JINA
Center for the Evolution of the Elements).