Mercury-manganese star

{{short description|Type of star with a prominent spectral line due to absorption from ionized mercury}}

A mercury-manganese star (also HgMn star) is a type of chemically peculiar star with a prominent spectral line at 398.4 nm, due to absorption from ionized mercury.[http://www.daviddarling.info/encyclopedia/M/mercury-manganese_star.html Mercury-manganese star] {{Webarchive|url=https://web.archive.org/web/20140219222738/http://www.daviddarling.info/encyclopedia/M/mercury-manganese_star.html |date=2014-02-19 }}. The Internet Encyclopedia of Science, David Darling. Accessed on line August 14, 2008. These stars are of spectral type B8, B9, or A0, corresponding to surface temperatures between about 10,000 and 15,000 K, with two distinctive characteristics:

An atmospheric excess of elements like phosphorus, manganese, gallium, strontium, yttrium, zirconium, platinum and mercury.
A lack of a strong dipole magnetic field.

Their rotation is relatively slow, and as a consequence their atmosphere is relatively calm. It is thought, but has not been proven, that some types of atoms sink under the force of gravity, while others are lifted towards the exterior of the star by radiation pressure, making a heterogeneous atmosphere.{{cite journal|last=Michaud|first=Georges|title=Diffusion Processes in Peculiar A Stars|journal=Astrophysical Journal|date=May 1970|volume=160|pages=641–658|bibcode = 1970ApJ...160..641M |doi = 10.1086/150459 |doi-access=free}}

List

The following table includes the brightest stars in this group.

class=wikitable style="text-align: center;" ! width=150px\|Name!!width=240px\|Bayer or Flamsteed designation!!width=120px\|Spectral typeNames, spectral types and apparent magnitudes taken from SIMBAD, except as noted.!!Apparent visual magnitude
Alpheratz	α Andromedae	bgcolor="#ddffff"\| B8IVmnp	2.06
Gienah Corvi	γ Corvi A	bgcolor="#ddffff"\| B8III	2.59
Maia	20 Tauri	bgcolor="#ddffff"\| B8III	3.87
	χ Lupi	bgcolor="#eeffff"\| B9IV	3.96
Muliphein[http://www.astro.uiuc.edu/~kaler/sow/muliphein.html Muliphein] {{webarchive\|url=https://web.archive.org/web/20080517032814/http://www.astro.uiuc.edu/~kaler/sow/muliphein.html \|date=2008-05-17 }}, Stars, Jim Kaler. Accessed on line August 14, 2008.	γ Canis Majoris	bgcolor="#ddffff"\| B8II	4.10
	φ Herculis	bgcolor="#eeffff"\| B9mnp	4.23
	π¹ Bootis	bgcolor="#eeffff"\| B9p	4.91
	HIP 79098{{citation\|bibcode=2013MNRAS.429..119P\|title=A photometric study of chemically peculiar stars with the STEREO satellites - II. Non-magnetic chemically peculiar stars\|last1=Paunzen\|first1=E.\|last2=Wraight\|first2=K. T.\|last3=Fossati\|first3=L.\|last4=Netopil\|first4=M.\|last5=White\|first5=G. J.\|last6=Bewsher\|first6=D.\|journal=Monthly Notices of the Royal Astronomical Society\|year=2013\|volume=429\|issue=1\|page=119\|doi=10.1093/mnras/sts318\|doi-access=free \|arxiv=1211.1535}}	bgcolor="#eeffff"\| B9IVn	5.88
	ι Coronae Borealis	bgcolor="#f4ffff"\| A0p	4.98
	κ Cancri A	bgcolor="#ddffff"\| B8IIImnp	5.24
	14 Sagittae{{citation \| title=Elemental Abundance Analyses with Coadded DAO Spectrograms - Part Five - the Mercury-Manganese Stars Phi-Herculis 28-HERCULIS and HR:7664 \| last1=Adelman \| first1=S. J. \| postscript=. \| journal=Monthly Notices of the Royal Astronomical Society \| volume=235 \| issue=3 \| page=763 \| date=December 1988 \| doi=10.1093/mnras/235.3.763 \| bibcode=1988MNRAS.235..763A \| doi-access=free }}	bgcolor="#eeffff"\| B9p	5.89
Dabih Minor[http://www.astro.uiuc.edu/~kaler/sow/dabih.html Dabih] {{webarchive\|url=https://web.archive.org/web/20060824132239/http://www.astro.uiuc.edu/~kaler/sow/dabih.html \|date=2006-08-24 }}, Stars, Jim Kaler. Accessed on line August 14, 2008.	β Capricorni B	bgcolor="#eeffff"\| B9.5III/IV	6.10
	HD 30963	bgcolor="#eeffff"\| B9 III	7.23
Nath	β Tauri \|bgcolor="#ccffff"\| B7III	1.65
\|λ¹ Sculptoris A{{Cite journal \|last1=Monier \|first1=Richard \|last2=Niemczura \|first2=Ewa \|date=2022-05-17 \|title=A newly discovered southern HgMn star: HD 4065A \|journal=Research Notes of the AAS \|language=en \|volume=6 \|issue=5 \|pages=99 \|doi=10.3847/2515-5172/ac6f62 \|bibcode=2022RNAAS...6...99M \|s2cid=248883987 \|issn=2515-5172\|doi-access=free }} \|bgcolor="#eeffff"\| B9.5V \|6.61
\| 53 Aurigae A \|bgcolor="#eeffff"\| B9 Mn	5.74

References

Category:Star types

Category:Mercury (element)

Category:Manganese