| NGC 4565 | |
|---|---|
 NGC 4565 | |
| Observation data (J2000epoch) | |
| Constellation | Coma Berenices |
| Right ascension | 12h 36m 20.7710s[1] |
| Declination | +25° 59′ 15.678″[1] |
| Redshift | 0.004276[1] |
| Heliocentric radial velocity | 1282 ± 1km/s[1] |
| Distance | 38.16 ± 2.27 Mly (11.700 ± 0.697 Mpc)[2] 53 ± 4Mly (16.2 ± 1.3Mpc)[3] |
| Apparent magnitude (V) | 10.42[1] |
| Characteristics | |
| Type | SA(s)b?[1] |
| Size | ~175,850ly [53.94kpc] (estimated)[1] |
| Apparent size (V) | 15.90′ × 1.85′[1] |
| Other designations | |
| Caldwell 38, HOLM 426A,IRAS 12338+2615,UGC 7772,MCG +04-30-006,PGC 42038,CGCG 129-010[1] | |
NGC 4565 (also known as theNeedle Galaxy orCaldwell 38) is an edge-onspiral galaxy about 30 to 50 millionlight-years away in theconstellationComa Berenices.[2] It lies close to theNorth Galactic Pole and has avisual magnitude of approximately 10. It is known as the Needle Galaxy for its narrow profile, and is a prominent example of an edge-on spiral galaxy.[4][5] It was discovered by German-British astronomerWilliam Herschel on 6 April 1785.[6]
NGC 4565 is a giant spiral galaxy more luminous than theAndromeda Galaxy.[7] Much speculation exists in literature as to the nature of the central bulge. In the absence of clear-cut dynamical data on the motions of stars in the bulge, the photometric data alone cannot adjudge among various options put forth. However, its exponential shape suggested that it is abarred spiral galaxy.[8] Studies with the help of theSpitzer Space Telescope not only confirmed the presence of a central bar but also showed apseudobulge within it as well as an inner ring.[9]
This edge-on galaxy exhibits a slightly warped and extended disk under deep optical surveys, likely due to ongoing interactions with neighboring satellite galaxies or other galaxies in the Coma I group. GALEX images show the slight warp at the edge of the disc more clearly than other surveys.
Using theLOw-Frequency ARray (LOFAR), astronomers of theUniversity of Hamburg discovered a diffuseradio halo around NGC 4565. During the observations, a warp was detected in the radio continuum of NGC 4565 that is reminiscent of aneutral hydrogen line (HI) warp and identifying a slight flaring of the galaxy's radio halo. It is assumed that this flaring is caused by the warp as the vertical intensity profiles are asymmetric, which is in agreement with the warp. According to the study, a minimum age for the warp was estimated at approximately 130 million years. This is the spectral age of the galaxy'scosmic ray electrons, during which they are transported into the warp. This indicates that NGC 4565 may be in the aftermath of a period with more intensestar formation.
NGC 4565, along withNGC 4562,IC 3543, andIC 3546, are listed together asHolm 426 inErik Holmberg'sA Study of Double and Multiple Galaxies Together with Inquiries into some General Metagalactic Problems, published in 1937.[10]
NGC 4565 has at least twosatellite galaxies, one of which isinteracting with it.[11] It has a population of roughly 240globular clusters, more than theMilky Way.[7]
NGC 4565 is one of the brightest[12] member galaxies of theComa I Group.[13][12]
![The Needle Galaxy NGC 4565 taken in France by amateur astrophotographer Anthony MICHEL[14]](/mt/?noimg=&dark=on&url=http%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aNGC_4565.png)
Media related toNGC 4565 at Wikimedia Commons
