The
Group of Stellar Spectroscopy
Staff Members
- Laimons Zacs, Dr.phys., leading researcher
- Oskars Alksnis, Mg.phys., scientific assistant
- Raivis Spelmanis, Bc.phys., programming engineer
- Aigars Atvars, Mg. student, programming engineer
Research Activities
- High Resolution Spectroscopy
- Astrophysics
- Chemical Composition of Stellar Atmospheres
- S-process Nucleosynthesis
- Circumstellar Matter
Recent Activities in pictures
- High resolution spectrum for very metal-poor (old) star HD196944 obtained
at European Southern Observatory. Given that the two stars
have about the same temperature it is evident from the FeI lines, that HD196944
has a much lower iron abundance than a comparison star HD211998. Despite this,
HD196944 has much stronger lines of s-process elements (Zacs, Nissen, &
Schuster 1998; http://ads.harvard.edu)
- The observed spectrum (thick line) obtained with the 6-meter telescope
(http://www.sao.ru) and the calculated one for carbon rich star BD+75º 348
with unknown evolutionary status. The abundances of neutron-capture elements
are up to 100 times enhanced on the average relative to solar values (Zacs,
Schmidt, & Schuster 2000; http://ads.harvard.edu).
Research
Projects
- L.Zacs (Head of Project). Preconditions for the formation of barium
stars. C&EE Programme of European Southern Observatory (1993-1994).
- L.Zacs (Head of Project). The evolutionary link among peculiar red
giants. Latvian Council of Science (1995-1996).
- L.Zacs (Head of Project). Complex investigations of protoplanetary
nebulae candidate. Latvian Council of Science (1997-2000).
- L.Zacs (Head of Project). A spectroscopic analysis of AGB objects.
Latvian Council of Science (2001-2004).
- NATO Collaborative linkage grant PST.CLG.979128 "Abundances in AGB stars:
clues to the chemical evolution of the Galaxy", Heads of Project: Dr. A.Jorissen
(Free University of Brussels) and Dr. L.Zacs (University of Latvia), 2002-2003.
- The research project "Taiwan-Baltic Open Cluster Study" financed by the Mutual
Fund of the National Science Council (Taiwan), the Ministry of Education and Science
of the Republic of Latvia, and the Ministry of Education and Science of the Republic
of Lithuania, Heads of Project: Prof. W.-P.Chen (National Central University),
Dr. L.Zacs (University of Latvia), Dr. G.Tautvaisiene (Vilnius University), 2002-2005.
- Scientific cooperation joint project "Abundances in AGB and post-AGB stars" in
the frame of collaboration between Latvian and Polish Academy of Sciences, Heads of project:
Dr. M.Schmidt (N.Copernicus Astronomical Center) and Dr. L.Zacs (University of Latvia), 2003-2005.
International Scientific
Cooperation
- A number of observational programs on the 6-meter optical telescope of
the Russian Academy of Sciences, Nizhnij Arkhiz, North Caucasus, 1987-1994
(Drs. Vladimir E. Panchuk, Valentina G.Klochkova, Ilfan F.Bikmaev, Gazinur
A.Galazutdinov, Faig A.Musaev).
- Institute of Physics and Astronomy (Prof. Poul E. Nissen), University
of Aarhus, Denmark.
- The observational program at the European Southern Observatory
(CAT+CES), Chile (remote control from Headquarters at Garching near Munich,
Germany).
- Institut dÒAstronomie et dÒAstrophysique (Dr. Henri M.J.Boffin),
Brussels, Belgium.
- N.Copernicus Astronomical Center (Drs. Ryszard Szczerba and Mirek
Schmidt), Torun, Poland.
- Kazan State University (Drs. Ludmila I.Mashonkina, Ilfan F. Bikmaev),
Tatarstan, Russia
- Observatorio Astronomico Nacional (Dr. William J. Schuster), UNAM,
Mexico
- National Central University (Prof. W.-P.Chen), Taiwan
- Free University of Brussels (Dr. A.Jorissen), Belgium
- Vilnius University (Dr. J.Sperauskas), Lithuania
Recent/Representative
Publications
- L.Zacs. A spectroscopic analysis of barium stars. - Astronomy and Astrophysics, Springer
Verlag, 1994, vol. 283, pp.937-954.
- O.Alksnis, L.Zacs. The violet opacity in the red peculiar stars. II.
Spectral analysis of the cool carbon stars WZ Cas and V Cyg. - Astrophysics and Space Science, Kluwer
Academic Publishers, 1994, vol. 215, pp.73-82.
- H.M.J Boffin, L.Zacs. Examination of the wind accretion scenario for
barium stars. -Astronomy and
Astrophysics, Springer Verlag, 1994, vol.291, pp.811-814.
- L.Zacs, V.G.Klochkova, V.E.Panchuk. The chemical composition of
post-AGB star, proto-planetary nebulae candidate IRAS 22272+5435 = SAO 34504. -
Monthly Notices of the Royal Astronomical
Society, Blackwell Science, 1995, vol.275, pp.764-772.
- L.I.Mashonkina, L.Zacs. On the problem of selective enhancement of
barium in the atmospheres of Ba II stars. - Astrophysics
and Space Science, Kluwer Academic Publishers, 1996, vol.236, pp.185-199.
- L.Zacs, V.G.Klochkova, V.E.Panchuk, R.Spelmanis. The chemical
composition of the protoplanetary nebula candidate HD 179821. - Monthly Notices of the Royal Astronomical
Society, Blackwell Science, 1996, vol.282, pp.1171-1180.
- L.Zacs, F.A.Musaev, I.F.Bikmaev, O.Alksnis. An abundance analysis of
single-lined spectroscopic binaries with barium stars like orbital elements. I.
Analysis and results. -Astronomy and
Astrophysics Supplement Series, EDP Sciences, 1997, vol.122, pp.31-42.
- L.Zacs. Detection of C2 and C3 absorption in two
post-AGB objects IRAS22272+5435 and CIT6. - Astrophysics
and Space Science, Kluwer Academic Publishers, 1997, vol. 251, pp.289-292.
- L.Zacs, P.E.Nissen, W.J.Schuster. The chemical composition of HD196944:
a carbon and s-process rich, very metal-poor star. - Astronomy and Astrophysics, Springer Verlag, 1998, vol. 337,
pp.216-222.
- L.Zacs, O.Alksnis, F.A.Musaev, I.F.Bikmaev, G.A.Galazutdinov. An
abundance analysis of the single-lined spectroscopic binaries with barium stars
like orbital elements. II. The spectroscopic data. - Astronomy and Astrophysics Supplement Series, EDP Sciences, 1999,
vol.136, pp.453-454.
- L.Zacs, M.R.Schmidt, R.Szczerba. A search for diffuse absorption bands
in the spectra of two PPN candidate stars: HD179821 and SAO34504. - Monthly Notices of the Royal Astronomical
Society, Blackwell Science, 1999, vol.306, pp.903-912.
- L.Zacs, M.R.Schmidt, W.J.Schuster. A carbon rich star BD+75 348: a
binary? Ö Astronomy and Astrophysics,
Springer Verlag, 2000, vol.358, pp.1022-1026.
- L.Zacs. The chemical composition and orbital parameters of barium
stars.- In The Carbon Star Phenomenon, IAU Symp. 177, ed. R.F.Wing, Kluwer Academic Publishers,
2000, pp.277-284.
- L.Zacs, R.Spelmanis. The violet opacity in the red peculiar stars. III.
Spectral analysis of the SC star GP Ori. - Astrophysics
and Space Science, Kluwer Academic Publishers, 2001, vol.275, 239-247
- L.Zacs, R.Spelmanis, F.Musaev. A search for diffuse absorption bands in
carbon-rich stars.- Barium and related stars. - Monthly Notices of the Royal Astronomical Society,
Blackwell Science, 2003, vol.339, pp.460-466.