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Direct evidence of the fossil origin of large-scale magnetic fields of chemically
peculiar stars obtained
A spectropolarimetric survey of all chemically peculiar (CP) stars identified
in the Orion OB1 association of young stars has been performed with the 6-m BTA
telescope. The sample includes 56 CP stars aged 1-15 Myr having a common origin
within the association. 31 stars have magnetic fields stronger than 500 G
including 14 stars, whose fields have been found for the first time in our survey.
The analysis of the obtained data shows a decrease in the fraction of CP stars in
general and in the fraction of magnetic CP stars in particular with age, relative
to normal stars of the same type but without significant chemical anomalies. It was
found for the first time that no magnetic field is detected in objects younger than
1 Myr; later the structure of the star is rearranged and the magnetic field becomes
visible reaching a maximum at times of the order of 2-3 Myr and then drops by
a factor of 3 at times of the order of 10 Myr. The result obtained is a direct
and statistically reliable confirmation of the fossil origin of the magnetic
fields of stars of early spectral types.
Authors:
Semenko E.A. (National Astronomical Research Institute of Thailand), Romanyuk I.I.,
Yakunin I.A., Kudryavtsev D.O., Moiseeva A.V. (SAO RAS)
Published:
Semenko E., Romanyuk I., Yakunin I., Kudryavtsev D., Moiseeva A. Spectropolarimetry of magnetic
Chemically Peculiar stars in the Orion OB1 association, Monthly Notices of the
Royal Astronomical Society, 2022, Volume 515, Issue 1, pp. 998-1011
Discovery of new LBVs in the Local Volume galaxy NGC 1156
Luminous Blue Variables (LBVs) are a rare type of massive stars with high luminosity
and strong photometric and spectroscopic variability. Clarification of the nature
and evolutionary status of LBVs requires a significant expansion of the sample
of known and studied stars of this type. In the galaxy NGC1156, we discovered
two massive stars with emission spectra which, according to the results of
spectroscopy and photometric monitoring at the 6-m SAO RAS telescope (BTA)
and the 2.5-m telescope of the Caucasian Mountain Observatory of SAI MSU,
are classified as LBVs. During the observation program at the BTA aimed at
searching for LBVs in the Local Volume, our research team discovered and
confirmed the status of 5 LBVs, while in total about 20 stars of this type
are known at such distances. Modeling the spectral energy distributions and
spectra of two detected LBVs made it possible to determine their bolometric
luminosities (8×105 and 1.6×106 of solar luminosities with the 10% accuracy),
photosphere temperatures (<7000 K for the fainter and 7900±400 K for the
brighter star). Both stars have extremely large radii for LBVs, 650-680 solar radii.
Authors:
Solovyeva Yu. N., Vinokurov A.S., Tikhonov N.A., Kostenkov A.E., Sarkisyan A.N.,
Dedov E.O., Moiseev A.V., Oparin D.V. (SAO RAS) in cooperation with Atapin K.E.
(SAO RAS, SAI MSU), Fabrika S.N. (SAO RAS, KFU), Valeev A.F. (SAO RAS, CrAO RAS)
Published:
1. Solovyeva, A. Kostenkov, E. Dedov, A. Vinokurov, Wind parameters of the new LBV in NGC1156, The Multifaceted
Universe: Theory and Observations - 2022, 23-27 May 2022, SAO RAS, Nizhny Arkhyz, Russia; published December 14, 2022.
Online at https://pos.sissa.it/cgi-bin/reader/conf.cgi?confid=425, id.49
2. Y. Solovyeva, A. Vinokurov, N. Tikhonov, A. Kostenkov, K. Atapin, A. Sarkisyan, A. Moiseev, S. Fabrika, D. Oparin,
A. Valeev, Search for LBVs in the Local Volume galaxies: study of two stars in NGC 1156,
Monthly Notices of the Royal Astronomical Society, 2023, Volume 518, Issue 3, pp.4345-4356, DOI: 10.1093/mnras/stac3408
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