M85-HCC1

M85-HCC1 is an ultracompact dwarf galaxy with a star density 1,000,000 times that of the solar neighbourhood,[3][2] lying near the galaxy Messier 85. As of 2015, it is the densest galaxy known.[4]

M59-UCD3
Images of two ultracompact dwarf galaxies. M59-UCD3 is in the inset to the left, while M85-HCC1 is in the inset to the right.
Observation data (J2000 epoch)
Constellation	Virgo
Right ascension	12^h 25^m 22.842^s[1]
Declination	+18° 10′ 53.67″[1]
Helio radial velocity	658 ± 4[2]
Apparent magnitude (V)	18.80 ± 0.03[2]
Absolute magnitude (V)	−12.55 ± 0.07[2]
Characteristics
Mass	(1.2±0.1)×10^7[2] M☉
Half-light radius (physical)	1.85 ± 0.9 pc[2]
Other designations
2MASS J12252287+1810539, SDSS J122522.84+181053.6[1]

References

1. "2MASS J12252287+1810539". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 6 May 2018.
2. Michael A. Sandoval, Richard P. Vo, Aaron J. Romanowsky (2015). "Hiding in plain sight: record-breaking compact stellar systems in the Sloan Digital Sky Survey". Astrophysical Journal Letters. 808: L32. arXiv:1506.08828. Bibcode:2015ApJ...808L..32S. doi:10.1088/2041-8205/808/1/l32.CS1 maint: uses authors parameter (link)
3. "Hiding in plain sight: Undergraduates discover the densest galaxies known". physOrg. 27 July 2015. Retrieved 29 July 2015.
4. "Undergraduates discover the densest galaxies known". Space Daily. 29 July 2015.

See also

• M59-UCD3 (second-densest galaxy known, as of 2015)
• M60-UCD1 (another dense galaxy)