Post on 15-Jan-2016
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Photometric and Photometric and spectral observations of spectral observations of
the star the star EM CepEM CepD. Kjurkchieva & D. MarchevD. Kjurkchieva & D. Marchev
Photometric and Photometric and spectral observations of spectral observations of
the star the star EM CepEM CepD. Kjurkchieva & D. MarchevD. Kjurkchieva & D. Marchev
I. IntroductionI. Introduction
Disk-like starsDisk-like starsThe disks form
around stars at different evolu-tional stages
• T Tau stars• Cataclysmic stars• Symbiotic stars• X-Ray stars• Some semidetached
systems
The
TheThe accreation accreation Keplerian diskKeplerian disk produce two-two-peakedpeaked wide wide
emission linesemission lines(the inner fast rotating (the inner fast rotating
parts produces the parts produces the wings of their profiles)wings of their profiles)
TheThe accreation accreation Keplerian diskKeplerian disk produce two-two-peakedpeaked wide wide
emission linesemission lines(the inner fast rotating (the inner fast rotating
parts produces the parts produces the wings of their profiles)wings of their profiles)
II. Some preliminary resultsII. Some preliminary results
1. The cataclysmic star UX UMaUX UMa Our H spectra of (on the left) show
• the profile is one-peaked only around the eclipse phase;• the H profiles are two-peaked (V and R peak) at the rest phases;
• the H line is symmetric at the two quadratutes;
1. The cataclysmic star UX UMaUX UMa Our H spectra of (on the left) show
• the profile is one-peaked only around the eclipse phase;• the H profiles are two-peaked (V and R peak) at the rest phases;
• the H line is symmetric at the two quadratutes;
The conclusion: two-peaked wide H line of UX UMa is produced from
an accretion disk around the white dwarf. This disk is fed by matter from the secondary late compo-
nent filling-in its Roche lobe.
The conclusion: two-peaked wide H line of UX UMa is produced from
an accretion disk around the white dwarf. This disk is fed by matter from the secondary late compo-
nent filling-in its Roche lobe.
2. H2. H spectra of the spectra of the RS CVn star RS CVn star FK ComFK Com
Kjurkchieva D., Marchev D., 2005, A & A 434, 221, “H observations of the star FK Com”
• On the left top –
The spectra averaged in phase bins
• On the left bottom – The mean spectrum
The phase variability of the subtracted spectra gives information about the position of the sources of additional H emission and absorption
The phase variability of the subtracted spectra gives information about the position of the sources of additional H emission and absorption
It is seen a bulk of emission and a bulk of absorption which position is opposite at the two quadratures.
Spectra of FK Com around phases 0,25 and 0,5Spectra of FK Com around phases 0,25 and 0,5Spectra of FK Com around phases 0,75 and 0,5Spectra of FK Com around phases 0,75 and 0,5
The analysis of the phase variability of the subtracted spectra of FK Com (individual spectra minus the mean spectrum)
leads to the conclusion
The two sources of the additional emission
and absorption moves in anti-phase during
the whole cycle.
main star - source of the absorption reversalextended half-illuminated disk - source of the emission peaksSAE – source of additional emissionSAA - source of additional absorptionsecondary starsecondary star – source of the illumination of the disk
The modeling of our H spectra leads to a
binary binary configuration ofconfiguration of
FK ComFK Com consisting of
The modeling of our H spectra leads to a
binary binary configuration ofconfiguration of
FK ComFK Com consisting of
- almost equal intensities of the emission peaks above the continuum- almost equal widths of the absorption reversal, the two emission peaks- presence of additional emission features on the main V and R peak- almost the same position of the emission peaks
We noted the similarity of the H profile of FK ComFK Com and UX UMaUX UMa in
We noted the similarity of the H profile of FK ComFK Com and UX UMaUX UMa in
- the exchanging places of the two minima - the standstill at phase 0,83 an indication of alternation between the two states???
1. Two types of
light curves
1. Two types of
light curves
III. The B-star III. The B-star EM CepEM Cep
The irregular times of the minima (O-C=0,01d for a
couple of days) confirmation of secular linear decreasing of the
period
2. Our H spectra of EM Cep
on the left: spectra at Be-state in 2004 - H in emission
on the right: spectra at B-state in 2005 - H in absorption
Тhe full width and depth of the H profiles of EM Cep at Be and B state are almost the same.
on the left: The subtracted H profiles of EM Cep at B state (individual minus spectrum at phase 0.47) have central
additional emission (ADEM) and two side additional absorptions (ADABS)
on the left: The subtracted H profiles of EM Cep at B state (individual minus spectrum at phase 0.47) have central
additional emission (ADEM) and two side additional absorptions (ADABS)
bottom: The mirror image of the subtracted H profile at phase 0,24 is similar to real
H profile at Be state
bottom: The mirror image of the subtracted H profile at phase 0,24 is similar to real
H profile at Be state
The subtracted spectra of
EM Cep at Be state (individual minus spectrum
at phase 0.43) show central
additional emission
(ADEM) around the phases of quadratures
The H profiles of EM Cep at phases 0,75
and 0,47 coincidence
while the positions and the widths of the HeI
lines (6677 A) are different. What is the What is the
reason?reason?Is there some Is there some
contribution of contribution of secondary star?secondary star?
The H profiles of EM Cep at phases 0,75
and 0,47 coincidence
while the positions and the widths of the HeI
lines (6677 A) are different. What is the What is the
reason?reason?Is there some Is there some
contribution of contribution of secondary star?secondary star?
Conclusions from the radial velocity curves:Conclusions from the radial velocity curves:
The ADABS compensate ADEM at minima;The ADABS compensate ADEM at minima; The sources of ADABS are near the star surface;The sources of ADABS are near the star surface; The angle between the line-of-sight and star rotational axis is small.The angle between the line-of-sight and star rotational axis is small.
The radial velocity The radial velocity curves of the two curves of the two ADABS show the ADABS show the opposite motion opposite motion of their sources of their sources
with velocity with velocity equal to the star equal to the star
rotational velocity rotational velocity of of EM CepEM Cep
The radial velocity The radial velocity curves of the two curves of the two ADABS show the ADABS show the opposite motion opposite motion of their sources of their sources
with velocity with velocity equal to the star equal to the star
rotational velocity rotational velocity of of EM CepEM Cep
We noted the similarity of the H the similarity of the H profile of profile of EM CepEM Cep at Be state with that at Be state with that
of of FK ComFK Com in: in: a) positions and width of the emission peaks;
b) whole width of the H line
We found also a similarity of the H profile of FK Com FK Com andand EM Cep EM Cep
with
• the shape and phase variability of the H and H lines of the cataclysmic
SU UMa-type star HT CasHT Cas (Catalan 1995);
• the H line of the T Tau-type star AA TauAA Tau (Hartmann 1998) .
IV.IV. ConclusionConclusion
• The wide two-peaked H line of EM Cep at Be state means presence of extended disk;
• The alternation between the B and Be state may be caused by the change of the optical thickness of the disk;
• There are two sources of additional absorption on surface of EM Cep which radial velocities are opposite and their amplitudes are equal to the star rotation velocity;
• The phase variability of the brightness and spectra of EM Cep might be explained by the rotation of some inhomogeneous structure but presence of companion star is not excluded.
V. Open questionsV. Open questions
• Why the HWhy the H emission peaks in the spectra of emission peaks in the spectra of different types objects (Be stars, FK Com different types objects (Be stars, FK Com stars, cataclysmic stars, T Tau stars) have the stars, cataclysmic stars, T Tau stars) have the same velocities? same velocities?
• Why the full width of the HWhy the full width of the H line in the spectra line in the spectra of these different types objects are the same? of these different types objects are the same?
• Do these facts mean that there is some Do these facts mean that there is some unifiedunified mechanismmechanism of creating of similar gaseous of creating of similar gaseous structure with equal velocitiesstructure with equal velocities in different types different types of starsof stars?!??!?