| NGC 5701 | |
|---|---|
 NGC 5701 by theMount Lemmon Observatory | |
| Observation data (J2000epoch) | |
| Constellation | Virgo |
| Right ascension | 14h 39m 11.0737s[1] |
| Declination | +05° 21′ 48.722″[1] |
| Redshift | 0.005020 ± 0.000002[1] |
| Heliocentric radial velocity | 1,505 ± 1km/s[1] |
| Distance | 50 ± 17Mly (15.4 ± 5.1Mpc)[1] |
| Group orcluster | Virgo III Groups |
| Apparent magnitude (V) | 10.9[2] |
| Characteristics | |
| Type | (R)SB(rs)0/a[1] |
| Size | ~66,000 ly (20.1 kpc) (estimated)[1] |
| Apparent size (V) | 4.3′ × 4.1′[1] |
| Other designations | |
| UGC 9436, CGCG 047-127,MCG +01-37-042,PGC 52365[1] | |
NGC 5701 is abarred lenticular galaxy with aring located in the constellationVirgo. It lies at a distance of about 50 millionlight years from Earth based on redshift-independent methods, which, given its apparent dimensions, means that NGC 5701 is about 65,000 light years across.[1] Based onredshift the galaxy lies at a distance of 85 million light years.[1] It was discovered byWilliam Herschel on April 29, 1786.[3]
The galaxy is categorised as a barred lenticular galaxy. The bar is faint and diffuse,[4] and almost completely dust-free.[5] At its ends it has elevated brightness, forming ansae.[6] It surrounds a large, bright and slightly ellipticalbulge with a bright nucleus. The bar lies inside a disk which mostly lacks features, with the exception of some knots or possible companion galaxies.[4] The bar is strong and dominates the disk, while the bulge component could overlap with the disk, making the galaxy appear to lack a disk.[7] The lack of disk however could be the result of a model that lacks the bar as different models indicate the presence of the disk.[8] An inner ring is detectable at the end of the bar.[7]
The stellar population in the barlens is mostly old, as 70–85% of the stellar mass is older than 10 billion years.[9] The intermediate age stars are more common at the outer edges of the barlens.[10] The bar doesn't show to induse star formation. At the centre themetallicity is solar and becomes subsolar towards the edges, and is higher than that of the bulge of theMilky Way.[9] Gas and stellar velocity fields are slightly offset with each other as indicated by theposition angles of theirmajor axes.[11] Theisophotes indicate that the bar is also misaligned with the stellar velocity field.[10]
The nucleus of the galaxy has been found to beactive and based on its emission lines has been identified as a transitional object between anHII region and aLINER.[12] The most accepted theory for the energy source of active galactic nuclei is the presence of anaccretion disk around asupermassive black hole. The mass of the black hole in the centre of NGC 5701 is estimated to be 107.9 (80 million)M☉ based on the absolute bulge magnitude.[13]
A faint nuclear spiral is visible in images by theHubble Space Telescope extending to about 10 arcseconds. As the galaxy is seen nearly face-on it is difficult to detect if an inner disk is present.[5] The nuclear spiral is associated with young stars, whose presence however is negligible as far as the total stellar mass of the bulge is concerned.[10]
The galaxy has an outerpseudo-ring which is more visible in blue light.[14] The ring is created by two arms which emerge from the end of the disk, but they start to branch into smaller arms, creating a ring of multiple fragmented arms.[6] ManyHII regions emittingH-alpha are visible in it, indicating it is a location of active star formation.[15] The ring is detached from the disk and gives the galaxy an appearance similar toHoag's Object. It is possible that the bar prevents the gas infalling to the central region of the galaxy.[16] The ring is elongated perpendicularly to the bar.[5]
The optical disk is surrounded by ahydrogen envelope which extends to over 10 arcminutes from the nucleus, about two and half times more than the optical edge of the galaxy. TheHI emission is about twice as strong at the west of the galaxy than the east but its western edge is sharper. The asymmetry could be the result of a pastinteraction with another galaxy.[17] Observations by theArecibo Observatory revealed an HI cloud about 15 arcminutes northwest of the centre[18] but it wasn't detected in observations by theVery Large Array.[17]
NGC 5701 is according to A. M. Garcia a member of theNGC 5746 Group, also known as LGG 386.[19] No companion galaxies are visible inhydrogen line or optical observations. UGC 9385, another member of the group, lies about 56 arcminutes to the west.[17] The group is a member of theVirgo III Groups, a long chain of galaxies extending for about 40 million light years from theVirgo Cluster.[20]
