Messier 109 (also known asNGC 3992 or theVacuum Cleaner Galaxy) is abarred spiral galaxy exhibiting a weak inner ring structure around the central bar approximately67.2 ± 23 millionlight-years[4] away in thenorthernconstellationUrsa Major. M109 can be seen south-east of the starPhecda (γ UMa, Gamma Ursa Majoris).
Messier 109 was discovered byPierre Méchain in 1781. Two years laterCharles Messier catalogued the object, as an appendedobject to his publication.
Between the 1920s through the 1950s, it was considered that Messier objects over 103 were not official, but later the additions, further referred target objects from Méchain, became more widely accepted.David H. Levy mentions the modern 110 object catalog while SirPatrick Moore places the limit at 104 objects but has M105 to 109 listed as addenda. By the late 1970s all 110 objects are commonly used among astronomers and remain so.
This galaxy is the most distant object in the Messier Catalog, followed byM91.
M109 has threesatellite galaxies (UGC 6923,UGC 6940 andUGC 6969) and possibly more. Detailedhydrogen line observations have been obtained from M109 and its satellites. M109'sH I (H one) distribution is regular with a low-level radial extension outside the stellar disc, while in the bar is a central H I hole in the gas distribution. Possibly the gas has been transported inwards by the bar, and because of the emptiness of the hole no large accretion events can have happened in the recent past.[5]
Onesupernova has been observed in M109:SN1956A (TypeIa, mag. 12.3) was discovered by Howard S. Gates on 8 March 1956, using the 18-inch Schmidt telescope at thePalomar Observatory. It was located 67" east and 9" south of the center of the galaxy.[10][11]
.jpg)
