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IC 1101 is a class S0 supergiant (cD) lenticular galaxy at the center of the Abell 2029 galaxy cluster. It has an isophotal diameter at about 123.65 to 169.61 kiloparsecs (400,000 to 550,000 ly). It possesses a diffuse core which is the largest known core of any galaxy to date,[5] and also hosts a supermassive black hole that is one of the largest black holes known.[5] The galaxy is located at 354.0 megaparsecs (1,150 million light-years) from Earth. The galaxy was discovered on 19 June 1790, by the British astronomer William Herschel.[6]

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IC 1101
June 1995 image of IC 1101 taken by the Hubble Space Telescope
Observation data (J2000 epoch)
Constellation	Virgo
Right ascension	15h 10m 56.1s[1]
Declination	+05° 44′ 41″[1]
Redshift	0.078054±0.000027[1][2]
Helio radial velocity	22,419 km/s (13,931 mi/s)[1]
Distance	354.0 ± 24.8 Mpc (1,154.6 ± 80.9 million ly)h−1 0.67[1]
Group or cluster	Abell 2029
Apparent magnitude (V)	13.22[1]
Characteristics
Type	cD; S0-[1]
Size	123.65 to 169.61 kpc (403,300 to 553,200 ly) (D25 B-band and total K-band isophotes)[3][4][lower-alpha 1]
Apparent size (V)	1'.2 × 0'.6[1]
Other designations
UGC 9752,[1] PGC 54167,[1] A2029-BCG[1]

Characteristics

Morphology

The galaxy is classified as a supergiant elliptical (E) to lenticular (S0)[7] and is the brightest galaxy in A2029 (hence its other designation A2029-BCG; BCG meaning brightest cluster galaxy).[8][9] The galaxy's morphological type is debated due to it possibly being shaped like a flat disc but only visible from Earth at its broadest dimensions. A morphology of S0- (Hubble stage -2; see Hubble stage for details) has been given by the Third Reference Catalogue of Bright Galaxies (RC3) in 1991.[3]

Size

IC 1101 is considered a large galaxy characterized by an extensive, diffuse halo. Defining the size of a galaxy varies according to the method used in the astronomical literature. Photographic plates of blue light from the galaxy (sampling stars excluding the diffuse halo) yield an effective radius (the radius within which half the light is emitted) of 65 ± 12 kpc (212 ± 39 thousand ly) [10] based on an earlier distance measurement. The galaxy has a very large halo of much lower intensity "diffuse light" extending to a radius of 600 kpc (2 million ly).[11]^{[verification needed]} The authors of the study identifying the halo conclude that IC 1101 is "possibly one of the largest and most luminous galaxies in the universe",[11] though this figure was based on an earlier assumed distance of 262 megaparsecs (855 million light-years)

More recent measurements, using the 25.0 magnitude/arcsec² standard (commonly known as D₂₅, a method recommended by R.O. Redman in 1936)[12][lower-alpha 2] has been utilized by the RC3 in the B-band, with a measured major axis (log 2a+1) of 1.08 (equivalent to 72.10 arcseconds),[3] translating to a diameter of 123.65 kiloparsecs (403,000 ly).[1] Another calculation by the Two Micron All-Sky Survey using the "total" aperture at the K-band yield a much larger size of 169.61 kiloparsecs (553,000 ly).[4] Both measurements are based on the currently-accepted distance to IC 1101. This would make it one of the largest and most luminous galaxies known, though there are other galaxies with larger isophotal diameter measurements (such as NGC 623, Abell 1413 BCG, and ESO 306-17).

Distance

The distance to IC 1101 has also been uncertain, with different methods across different wavelengths producing varying results. An earlier distance calculation from 1980 using the galaxy's photometric property yield a distance of 262.0 Mpc (855 million ly) and a redshift of z = 0.077, based on a Hubble constant value H₀ of 60 km/s/Mpc.[13] The RC3 catalogue gave a nearly similar value of z=0.078, based on optical emission lines,[3] a value conformed to as recently as 2017 based on luminosity, stellar mass, and velocity dispersion functions,[2] all yielding distances of 354.0 megaparsecs (1.2 billion light-years) based on the modern value of the Hubble constant H₀ = 67.8 km/s/Mpc; the currently accepted values. Lower redshifts have been calculated for other wavelengths such as the photometric redshift measurement by the Two Micron All-Sky Survey (2MASS) in 2014, which gave a value of z = 0.045,[14] translating to a distance of 197.1 megaparsecs (643 million light-years). A measurement made in 2005 by the Arecibo Observatory using the 21-cm hydrogen emission line yields a redshift of z = 0.021,[15] and hence a distance of 97.67 ± 6.84 megaparsecs (318.6 ± 22.3 million light-years).

Like most large galaxies, IC 1101 is populated by a number of metal-rich stars, some of which are seven billion years older than the Sun, making it appear golden yellow in color. It has a bright radio source at the center, which is likely associated with an ultramassive black hole in the mass range of 40–100 billion M_☉ measured using core dynamical models,[5] or alternatively at 50-70 billion M_☉ using gas accretion rate and growth modelling.,[16] which would make IC 1101's black hole one of the most massive known to date. The authors also say that the galaxy is one of the most luminous and largest cD-galaxy.[16]

A 2017 paper suggests that IC 1101 has the largest core size of any galaxy, with a core radius of around 4.2 ± 0.1 kpc (13.70 ± 0.33 thousand ly), making its core larger than the one observed in A2261-BCG. The core is also roughly an order of magnitude larger than the cores of other large elliptical galaxies, such as NGC 4889 and NGC 1600.[5] However, when examining large and diffuse galactic cores, caution must be taken, as various estimates may differ between the computer models used. As an example, Holmberg 15A was originally claimed to have the largest galactic core of any galaxy but other studies proved otherwise.[17]

See also

• List of galaxies
• List of largest galaxies
• List of most massive black holes

Notes

References

External links

• Wilford, John Noble (26 October 1990). "Sighting of Largest Galaxy Hints Clues on the Clustering of Matter". The New York Times.
• Nemiroff, R.; Bonnell, J., eds. (12 March 2012). "The Scale of the Universe - Interactive". Astronomy Picture of the Day. NASA.
• IC 1101 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images

На других языках

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[de] IC 1101

IC 1101 ist die zentrale cD-Galaxie des Galaxienhaufens Abell 2029. Sie ist eine der größten bekannten Galaxien. IC 1101 liegt im Sternbild Virgo, unmittelbar an der Grenze zu Serpens, in einer Entfernung von etwa einer Milliarde Lichtjahre. Ihr Effektivradius wird mit 42 Bogensekunden angegeben, entsprechend etwa 50 kpc (150.000 Lichtjahren).[4] Sie ist von einem diffusen Halo umgeben, der sich bis zu etwa 300 Bogensekunden von der Galaxie verfolgen lässt, also einen Durchmesser von etwa 900 kpc hat.[5][6] Dieser Halo wird allerdings nicht der Galaxie selbst, sondern als so genanntes intra-cluster light dem Galaxienhaufen zugeordnet.

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- [en] IC 1101

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[es] IC 1101

IC 1101 es una galaxia elíptica supergigante en el centro del cúmulo de galaxias Abell 2029. Está a 1,05 mil millones de años luz de distancia, en la constelación de Virgo y está clasificada como una galaxia de clase cD. Fue descubierta el 19 de junio de 1790 por William Herschel.

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[ru] IC 1101

IC 1101 — сверхгигантская эллиптическая галактика в центре скопления галактик Abell 2029.

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