NGC 5506

NGC 5506
NGC 5506 by the Hubble Space Telescope
Observation data (J2000 epoch)
Constellation	Virgo
Right ascension	14h 13m 14.9s[1]
Declination	−03° 12′ 27″[1]
Redshift	0.006084 ± 0.000009 [1]
Heliocentric radial velocity	1,824 ± 3 km/s[1]
Distance	77 ± 15 Mly (23.6 ± 4.6 Mpc)[1]
Apparent magnitude (V)	11.9
Characteristics
Type	Sa pec sp [1]
Apparent size (V)	3.16′ × 0.75′[1]
Notable features	Seyfert galaxy
Other designations
UGCΑ 387, MRK 1376, MCG +00-36-028, PGC 50782[1]

NGC 5506 is a spiral galaxy located in the constellation Virgo. It is located at a distance of about 75 million light years from Earth, which, given its apparent dimensions, means that NGC 5506 is about 80,000 light years across.^[1] It was discovered by William Herschel on April 15, 1787.^[2] It is a Seyfert galaxy.^[1]

Characteristics

NGC 5506 is a spiral galaxy seen edge-on, with dust lanes visible south of the nucleus.^[3]

Active nucleus

The nucleus of NGC 5506 has been found to be active and it has been categorised as a narrow line type I Seyfert galaxy, and is the brightest such nucleus.^[4] The classification of the active nucleus had been an issue of debate, as it lacked broad emission lines in the visual wavelength. However, broader lines were observed in the infrared,^[5] indicating that the broad line region is obscured in visual light.^[4]

The most accepted theory for the energy source of active galactic nuclei is the presence of an accretion disk around a supermassive black hole. The mass of the black hole in the centre of NGC 5506 is estimated to be 8.8×10⁷ M_☉ based on stellar velocity dispersion and 5.1×10⁶ M_☉ based on the M_BH–σ⋆ relation and X-ray variability.^[6]

NGC 5506 is a bright X-ray source, detected by all X-ray space observatories, starting with Uhuru.^[7] The X-ray spectrum indicates that there is both a compton-thick and a compton-thin absorber. The compton-thick absorber is a dust torus around the supermassive black hole at a distance of around one parsec, while the compton thin absorbs the softer X-rays emitted by the nucleus.^[7] The soft emission by the nucleus extends to a distance of about 350 pc and is attributed to reflection of the nuclear emission by photoionized gas.^[7] The inclination of the accretion disk is estimated to be between 40° and 50°.^[8] The iron line is complex, indicating emission by neutral and ionised iron.^[9] A broad component of the Fe Kα fluorescent emission line was observed by XMM-Newton.^[10]

The galaxy also emits radiowaves. The galaxy exhibits a central source that accounts for 75% of the total emission and diffuse wing-like emission towards the north-west and east of the nucleus and a low-surface-brightness halo measuring 2.75 arcseconds in diameter that surrounds these features.^[11] The features have no clear axis of symmetry.^[12] The galaxy has been found to host an H₂O megamaser.^[13]

Nearby galaxies

NGC 5506 is the foremost galaxy in a galaxy group known as the NGC 5506 Group. Other members of the group include NGC 5507, while IC 978 lies a bit farther away.^[14] Garcia identified as members of group also the galaxies NGC 5496, and UGC 9057.^[15] NGC 5506 forms a pair with NGC 5507, which lies 4 arcminutes from it.^[16] The group is part of the Virgo III Groups, a very obvious chain of galaxy groups on the left side of the Virgo cluster, stretching across 40 million light years of space.^[17]

References

External links

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