Yury V Pakhomov

Dr. Yury V Pakhomov

orcid

Research Focus & Metrics

Academic Career Length

41Years (1986-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
30 April 2015 in Physica Scripta
Verified
Journal Article
Closed access
TRT Ryabchikova
T Ryabchikova
NPN Piskunov
N Piskunov
RKR L Kurucz
R L Kurucz
HSH C Stempels
H C Stempels
UHU Heiter
U Heiter
PBP S Barklem
P S Barklem

19 December 2016 in The Astrophysical Journal
Verified
Journal Article
Closed access
PDF file
Gang ZhaoGang Zhao
Gang Zhao
LMLyudmila I. Mashonkina
Lyudmila I. Mashonkina
HYH. L. Yan
H. L. Yan
SAS. Alexeeva
S. Alexeeva
CKChiaki Kobayashi
Chiaki Kobayashi
MZM. Zhai
M. Zhai
For the first time, we present an extensive study of stars with individual non-LTE (NLTE) abundances for 17 chemical elements from Li to Eu in a sample of stars uniformly distributed over the −2.62 ≤ [Fe/H] ≤ +0.24 metallicity range that is suitable for the Galactic chemical evolution research. The star sample has been kinematically selected to trace the Galactic thin and thick disks and halo. We find new results and improve earlier ones as follows: (i) the element-to-iron ratios for Mg, Si, Ca, and Ti form a metal-poor (MP) plateau at a similar height of 0.3 dex, and the knee occurs at common [Fe/H] ≃ −0.8. The knee at the same metallicity is observed for [O/Fe], and the MP plateau is formed at [O/Fe] = 0.61. (ii) The upward trend of [C/O] with decreasing metallicity exists at [Fe/H] < −1.2, supporting the earlier finding of Akerman et al. (iii) An underabundance of Na relative to Mg in the [Fe/H] < −1 stars is nearly constant, with the mean [Na/ Mg] ≃ −0.5. (iv) The K/Sc, Ca/Sc, and Ti/Sc ratios form well-defined trends, suggesting a common site of the K–Ti production. (v) Sr follows the Fe abundance down to [Fe/H] ≃ −2.5, while Zr is enhanced in MP stars. (vi) The comparisons of our results with some widely used Galactic evolution models are given. The use of the NLTE element abundances gives increased credit to the interpretation of the data in the context of the chemical evolution of the Galaxy.

17 March 2016 in Journal of Physics B: Atomic, Molecular and Optical Physics
Verified
Journal Article
Open access
MDM L Dubernet
M L Dubernet
BABOBBY ANTONY
BOBBY ANTONY
YBY A Ba
Y A Ba
YBYu L Babikov
Yu L Babikov
KBK Bartschat
K Bartschat
CZC M Zwölf
C M Zwölf

29 July 2015 in The Astrophysical Journal
Verified
Journal Article
Closed access
PDF file
TSTatyana Sitnova
Tatyana Sitnova
GZG. Zhao
G. Zhao
LML. Mashonkina
L. Mashonkina
YCY. Chen
Y. Chen
FLFan Liu
Fan Liu
HZH.-W. Zhang
H.-W. Zhang

11 December 2017 in Astronomy & Astrophysics
Verified
Journal Article
Open access
PDF file
LMLyudmila I. Mashonkina
Lyudmila I. Mashonkina
PJP. Jablonka
P. Jablonka
TST. Sitnova
T. Sitnova
YPYury V Pakhomov
Yury V Pakhomov
PNP. North
P. North
We present the non-local thermodynamic equilibrium (NLTE) abundances of up to 10 chemical species in a sample of 59 very metal-poor (VMP, −4 ≤ [Fe/H] ≾−2) stars in seven dwarf spheroidal galaxies (dSphs) and in the Milky Way (MW) halo. Our results are based on high-resolution spectroscopic datasets and homogeneous and accurate atmospheric parameters determined in Paper I. We show that once the NLTE effects are properly taken into account, all massive galaxies in our sample, that is, the MW halo and the classical dSphs Sculptor, Ursa Minor, Sextans, and Fornax, reveal a similar plateau at [α/Fe] ≃ 0.3 for each of the α-process elements: Mg, Ca, and Ti. We put on a firm ground the evidence for a decline in α/Fe with increasing metallicity in the Boötes I ultra-faint dwarf galaxy (UFD), that is most probably due to the ejecta of type Ia supernovae. For Na/Fe, Na/Mg, and Al/Mg, the MW halo and all dSphs reveal indistinguishable trends with metallicity, suggesting that the processes of Na and Al synthesis are identical in all systems, independent of their mass. The dichotomy in the [Sr/Ba] versus [Ba/H] diagram is observed in the classical dSphs, similarly to the MW halo, calling for two different nucleosynthesis channels for Sr. We show that Sr in the massive galaxies is well correlated with Mg suggesting a strong link to massive stars and that its origin is essentially independent of Ba, for most of the [Ba/H] range. Our three UFDs, that is Boötes I, UMa II, and Leo IV, are depleted in Sr and Ba relative to Fe and Mg, with very similar ratios of [Sr/Mg] ≃−1.3 and [Ba/Mg] ≃−1 on the entire range of their Mg abundances. The subsolar Sr/Ba ratios of Boötes I and UMa II indicate a common r-process origin of their neutron-capture elements. Sculptor remains the classical dSph, in which the evidence for inhomogeneous mixing in the early evolution stage, at [Fe/H] <−2, is the strongest.

28 December 2019 in Astronomy Reports
Verified
Journal Article
Closed access
PDF file
YPYury V Pakhomov
Yury V Pakhomov
TRT. A. Ryabchikova
T. A. Ryabchikova
NPN. E. Piskunov
N. E. Piskunov
The Vienna Atomic Line Database (VALD) has been supplemented with new data and new functionality—the possibility of taking into account the effect of hyperfine splitting (HFS) of atomic levels in the...