ADDED MORE DATA

NGC 4449, also known as Caldwell 21, is an irregularMagellanic typegalaxy in the constellationCanes Venatici, being located about 13 million light-years away. It is part of the M94 Group or Canes Venatici I Group that is relatively close to the Local Group hosting our Milky Way galaxy.This galaxy is similar in nature to the Milky Way's satellite galaxy, the Large Magellanic Cloud (LMC),=10.5px  though is not as bright nor as large. NGC 4449 has a general bar shape, also characteristic of the LMC, with scattered young blue star clusters.Unlike the Large Magellanic Cloud, however, NGC 4449 is considered a starburst galaxy due to its high rate of star formation (twice the one of the LMC)=10.5px and includes several massive and young star clusters,=10.5px  one of them in the galaxy's center.Photos of the galaxy show the pinkish glow of atomic hydrogen gas, the telltale tracer of massive star forming regions.NGC 4449 is surrounded by a large envelope of neutral hydrogen that extends over an area of 75 arc minutes (14 times larger than the optical diameter of the galaxy). The envelope shows distortions and irregularities likely caused by interactions with nearby galaxies.Interactions with nearby galaxies are thought to have influenced star formation in NGC 4449 and, in fact, in 2012 two small galaxies have been discovered interacting with this galaxy: a very low surface brightness disrupted dwarf spheroidal with the same stellar mass as NGC 4449's halo but with a ratio of dark matter to stellar matter between 5 and 10 times that of NGC 4449=10.5px  and a highly flattened globular cluster with two tails of young stars that may be the nucleus of a gas-rich galaxy.=10.5px  Both satellites have apparently been disrupted by NGC 4449 and are now being absorbed by it.At least one ultra luminous X-ray source (ULX) is known in NGC 4449, called NGC 4449 X7. There are three candidates that have been identified as optical counterparts to NGC 4449 X7 (i.e. they may be associated with the ULX). They are all early (B-type to F-type) supergiant that are estimated to be about 40 to 50 million years old and about 8 times the mass of the Sun.
NGC 4449, resembling early star-forming galaxies, observed with Webb's MIRI and NIRCam instruments for detailed study. In May 2024, the James Webb Space Telescope captured a detailed image of NGC 4449=10.5px , highlighting widespread starburst activity. This infrared image revealed intricate structures of gas, dust, and newly forming stars=10.5px.  further enriching our understanding of star formation processes influenced by interactions with nearby galaxies. This discovery emphasizes NGC 4449's role as a key site for studying galaxy evolution and stellar birth.

NGC 4449 was discovered by the German-born British astronomer William Herschel on April 27, 1788.
NGC 4449 has been forming stars for several billion years, but it is currently experiencing a period of star formation at a much higher rate than in the past,” the Webb astronomers said. "Such unusually explosive and intense star formation activity is called a starburst and for that reason NGC 4449 is known as a starburst galaxy. In fact, at the current rate of star formation, the gas supply that feeds the production of stars would only last for another billion years or so. Starbursts usually occur in the central regions of galaxies, but NGC 4449 displays more widespread star formation activity, and the very youngest stars are observed both in the nucleus and in streams surrounding the galaxy. ”It’s likely that the current widespread starburst was triggered by interaction or merging with a smaller companion. ”Indeed, we think NGC 4449’s star formation has been influenced by interactions with several of its neighbors NGC4449 resembles primordial star-forming galaxies which grew by merging with and accreting smaller stellar systems,” they added. "The bright blue spots reveal countless individual stars, while the bright yellow regions that weave throughout the galaxy indicate concentrations of active stellar nurseries, where new stars are forming. ”
The orange-red areas indicate the distribution of a type of carbon-based compounds known as polycyclic aromatic hydrocarbons (or PAHs) — the MIRI F770W filter is particularly suited to imaging these important molecules. ”The bright red spots correspond to regions rich in hydrogen that have been ionized by the radiation from the newly formed stars. ”The diffuse gradient of blue light around the central region shows the distribution of older stars. ”The compact light-blue regions within the red ionized gas, mostly concentrated in the galaxy’s outer region, show the distribution of young star clusters.”Right Ascension12 : 28.2 (h:m)Declination+44 : 06 (deg:m)Distance13,700 (kly)Visual brightness9.4 (mag)Apparent dimension5.1 arc min)Right Ascension12 : 28.2 (h:m)Declination+44 : 06 (deg:m)Distance13,700 (kly)Visual brightness9.4 (mag)Apparent dimension5.1 arc min)