PHL 293B

PHL 293B, also known as Kinman's dwarf, is a low-metallicity blue compact dwarf galaxy about 22.6 Mpc from the Earth in the constellation Aquarius.^[2]

PHL 293B
Hubble Space Telescope image of PHL 293B; the purported luminous blue variable is located near the core of the galaxy
Observation data (J2000 epoch)
Constellation	Aquarius
Right ascension	22h 30m 36.8s[1]
Declination	−00° 06′ 37″[1]
Redshift	0.0051[1]
Distance	74 Mly (22.6 Mpc)[2]
Apparent magnitude (V)	16.87[3]
Apparent magnitude (B)	17.35[3]
Characteristics
Type	Im?[1]
Other designations
Kinman's Dwarf, PGC 69018[3]

PHL 293B star

Observation data Epoch J1950      Equinox J1950
Constellation	Aquarius
Right ascension	22h 28.1m [4]
Declination	−0° 22′[4]
Characteristics
Evolutionary stage	Luminous blue variable?
Astrometry
Radial velocity (Rv)	(of galaxy) 1,606[5] km/s
Distance	22,600,000[2] pc
Details
Radius	1,348–1,463[6] R☉
Luminosity	2,500,000–3,500,000[6] L☉
Temperature	6,000–6,800[6] K
Other designations
SDSS J2230–0006,[7] SDSS J223036.79-000636.9, A2228-00[8]
Database references
SIMBAD	PHL 293B
	PHL 293 (Simbad mistakenly showing results for PHL 293B)

It had a very likely associated, notable, blue-light, long-lived star with constant outbursts or a large supernova observed to have faded and which then disappeared. Although this bright visible jet-producing object responsible for broad hydrogen emission lines with P Cygni profiles was widely considered to be a luminous blue variable ejecting matter, other studies posited the mentioned, competing, explanations for the bright light source within.

Observation history

PHL 293 was first listed as entry 293 in a catalogue of faint blue stars published by Guillermo Haro and Willem Jacob Luyten in 1962.^[9] In 1965, Thomas Kinman observed two faint possible companions to it, about 1′ away, which he dubbed A and B. HL 293B, sometimes called Kinman's Dwarf, was noted to be an extragalactic, nonstellar object, with a jet, approximately 22.6 Mpc away from Earth.^[2][8] The acronym PHL has since been applied to distinguish it from other HL catalogues; it is most commonly referred to by astronomers as PHL 293B.^[4] The galaxy was identified as a blue compact dwarf, a type of small irregular galaxy undergoing a strong burst of star formation.^[7]

The spectrum of PHL 293B is unusual both for its low metallicity and for broad hydrogen emission lines with P Cygni profiles. These are interpreted as being from a large luminous blue variable star in the galaxy. The star is believed to have been undergoing an outburst during previous observations,^[7] an interpretation is disputed by some publications.^{[citation needed]} An alternative explanation would be a long-lived type IIn supernova, similar to the transient event of SDSS1133.^[10] These emission features in the spectrum of the galaxy faded during 2019 and by the end of the year had disappeared (at least visibly), likely due to the disappearance of a bright star of the galaxy.^[6]

See also

• AG Carinae
• Markarian 177
• LBV 1806-20
• Eta Carinae