Mercury Manganese Star
Mercury-manganese stars or HgMn stars are blue-white stars with special features in the spectrum of their emitted light. They are closely related to the Ap stars ; Both star classes belong to the chemical peculiar stars , the CP stars.
The HgMn stars show strong abundances of Hg , Mn (naming), P , Ga , Br , Sr , Y , Zr , Rh , Pd , Xe , Pr , Yb , W , Re , Os , Pt and Au as well as pronounced low frequencies of Hey , Al , Zn , Ni and Co . The spectral type of the HgMn stars is a late B. Some elements show strongly different isotope ratios , but these are very individual for each star.
The mercury-manganese stars rotate very slowly for their early spectral class, with an average speed v ∙ sin i of up to 30 kilometers per second, corrected for the projected orbital inclination . The frequency of HgMn stars drops sharply with increasing rotation speed .
More than two thirds of all mercury-manganese stars belong to the spectroscopic binary stars with orbital periods of between three and twenty days.
Even with the mercury-manganese stars, the elements are not evenly distributed on the star's surface . The mercury is probably concentrated at the equator . Other elements such as Ti , Cr , Fe , Mn, Sr, Y, and Pt, on the other hand, are more like the Ap stars than spots somewhere on the hemispheres of the stars. This is mostly associated with a magnetic field on the surface of the stars. The mercury-manganese stars have extremely weak magnetic fields with flux densities of a few millitesla at most , while the magnetic flux density of the Ap stars reaches a few hundred millitesla.
Representative
The following table shows a selection of representatives of this star class according to their apparent brightness:
| Surname | Bayer or Flamsteed name | Spectral type | apparent brightness |
|---|---|---|---|
| Elnath | β Tauri | B7 IIIp | 1.6 mag |
| Alpheratz | α Andromedae | B8 IV-V | 2.0 mag |
| Gienah Corvi | γ Corvi | B8 III | 2.6 likes |
| μ Leporis | B9 IV | 3.3 mag | |
| Maia | 20 tauri | B8 III | 3.9 likes |
| χ Lupi | B9 IV | 4.0 likes | |
| Muliphein | γ Canis majoris | B8 II | 4.1 mag |
| φ Herculis | B9 V | 4.2 likes | |
| π 1 bootis | B9 IIIp | 4.5 mag | |
| υ Herculis | B9 III | 4.7 likes | |
| ET Ursae Majoris A | A0 sp | 4.9 likes | |
| ι Coronae Borealis | B9 IIIp | 5.0 likes | |
| κ Cancri | B8 IIIp | 5.2 likes | |
| 112 Herculis A | B9 II-IIIp | 5.4 likes | |
| ν Cancri | A0 III | 5.5 mag | |
| 53 Tauri | B9 V | 5.5 mag | |
| κ 2 Volantis | B9 / A0 IV | 5.6 likes | |
| 28 Herculis | B9.5 III | 5.6 likes | |
| 14 Sagittae | B9 mnp | 5.6 likes | |
| 21 pegasi | B9.5V | 5.8 likes | |
| Dabih Minor | β 2 capricorni | B9 / A0 III-IV | 6.1 mag |
See also
Individual evidence
- ↑ O. Kochukhov, V. Makaganiuk, N. Piskunov, SV Jeffers, CM Johns-Krull, CU Keller, M. Rodenhuis, F. Snik, HC Stempels, JA Valenti: Are there tangled magnetic fields on HgMn stars? In: Astronomy & Astrophysics. Vol. 554, A61, 2013, doi: 10.1051 / 0004-6361 / 201321467 , pp. 1–12, bibcode : 2013A & A ... 554A..61K .
- ^ S. Hubrig, JF Gonzalez, I. Ilyin, H. Korhonen, M. Schoeller, I. Savanov, R. Arlt, F. Castelli, G. Lo Curto, M. Briquet, TH Dall: Magnetic fields of HgMn stars. In: Astronomy & Astrophysics. Vol. 547, A90, 2012, doi: 10.1051 / 0004-6361 / 201219778 , pp. 1–24, bibcode : 2012A & A ... 547A..90H .
- ↑ K. Yüce, SJ Adelmann: Elemental Abundance Analyzes with DAO Spectrograms. XXXIV. A Three-Dimensional Graphical Examination of the Elemental Abundances of the Mercury-Manganese and Metallic-Line Stars. In: Publications of the Astronomical Society of the Pacific. Vol. 126, 2014, doi: 10.1086 / 676335 , pp. 345–358 bibcode : 2014PASP..126..345Y .
- ↑ a b c Information on name, spectral type and brightness from SIMBAD .