240213 - C5 "Hidden" galaxy
|
click image to enlarge
|
ASTRO:
type=Intermediate Spiral Galaxy const=Camelopardalis mag=9.1 dist=9 M ly size=75,000 ly IMAGE: location=EB Driveway BrtlCls=4 moon=22% WxCr exposure=CMOS OSC: 103x120s (3.4h) EQUIPMENT: camera=ZWO ASI2600MC-Pro optics=ES102 w 1.73x 24mmEP in Proj mode, FL=1238mm, f/12.1 filters=Optolong L-Pro LPS mount=Celestron AVX guiding=Orion 60x240mm, ZWO ASi224MC SOFTWARE: acquisition=Stellarium, APT, PHD2 processing=PixInsight, RCAstro, PhotoshopCC, APF-R, Lumenzia, LrC |
|
Caldwell 5 (or C5 for short; but also known as IC 342) is an intermediate spiral galaxy in the constellation Camelopardalis, and is located relatively close to our home galaxy, the Milky Way. Despite its size and actual brightness, C5's location behind dusty areas in the Milky Way's galactic equator makes it difficult to observe, leading to the nickname "The Hidden Galaxy", though it can readily be detected even with binoculars. Its golden-brown color comes from its being heavily obscured by dust. If the galaxy were not obscured, it would be visible by the naked (unaided) eye, and likely would be much more colorful. The dust makes it difficult to determine its precise distance; but modern estimates range from about 7 million light-years (M ly) to about 11 M ly.
The galaxy was discovered by British Amateur Astronomer, William Frederick Denning in 1892. It is one of the brightest in the C5/Maffei Group of galaxies, one of the closest galaxy groups to our home Local Group. Renowned Scientific Astronomer Edwin Hubble first thought it to be a part of our home Local Group, but it was later determined not to be a member.
In 1935, American scientist and head of the Harvard College Observatory, Harlow Shapley found that the apparent size of C5 was wider than the full moon, and by angular size the third-largest spiral galaxy then known - smaller only than Andromeda Galaxy (M31) and Triangulum Galaxy (M33). More modern estimates of C5's size approximate its diameter to be 75,000 light-years, making it less than 1/2 the size of the Milky Way. The star-field seen in this image, along with the incumbent dust, exists inside the Milky Way. It is because of our location within the Milky Way that we view C5 through a 'sea of dust and stars', all of which are inside the Milky Way, and existing at distances between appx 10 ly (close) to 100,000 ly (far) away from us. But C5 exists much further away than that. At a distance of appx 9,000,000 ly, the space between the outer reaches of our Milky Way and leading edge of The Hidden Galaxy is a large expanse of outer space called the intergalactic medium that is mostly void of visible objects like stars, nebulae or dust clouds.
C5's core is a specific type of galactic region called an H-II nucleus - an area of mostly atomic hydrogen that has become ionized. Such regions exist as a kind of energetic incubator where thousands of young stars can form over a short time (by astronomical standards) of a couple million years. Once born, each young extremely hot blue star emits intense ultraviolet light, intensifying the ionizing effect in the surrounding hydrogen.
Unlike galaxies with large central bulges like that of Andromeda Galaxy, The Hidden Galaxy has relatively few dwarf satellite galaxies. In 2020, the galaxy KKH 32 was identified as the first known satellite of C5; and it is a dwarf spheroidal galaxy. KKH 32 is located about 10.2 million light-years away from Earth and has a diameter of about 4,300 light-years.
This sparkling, face-on view of the galaxy is particularly prominent, despite its "hidden" aspect described above, thanks to the technology of a dedicated astronomical camera. C5's intertwined tendrils of dust in spectacular arms wrapping around a brilliant core of hot gas and stars can be readily captured with this modern amateur equipment.
The galaxy was discovered by British Amateur Astronomer, William Frederick Denning in 1892. It is one of the brightest in the C5/Maffei Group of galaxies, one of the closest galaxy groups to our home Local Group. Renowned Scientific Astronomer Edwin Hubble first thought it to be a part of our home Local Group, but it was later determined not to be a member.
In 1935, American scientist and head of the Harvard College Observatory, Harlow Shapley found that the apparent size of C5 was wider than the full moon, and by angular size the third-largest spiral galaxy then known - smaller only than Andromeda Galaxy (M31) and Triangulum Galaxy (M33). More modern estimates of C5's size approximate its diameter to be 75,000 light-years, making it less than 1/2 the size of the Milky Way. The star-field seen in this image, along with the incumbent dust, exists inside the Milky Way. It is because of our location within the Milky Way that we view C5 through a 'sea of dust and stars', all of which are inside the Milky Way, and existing at distances between appx 10 ly (close) to 100,000 ly (far) away from us. But C5 exists much further away than that. At a distance of appx 9,000,000 ly, the space between the outer reaches of our Milky Way and leading edge of The Hidden Galaxy is a large expanse of outer space called the intergalactic medium that is mostly void of visible objects like stars, nebulae or dust clouds.
C5's core is a specific type of galactic region called an H-II nucleus - an area of mostly atomic hydrogen that has become ionized. Such regions exist as a kind of energetic incubator where thousands of young stars can form over a short time (by astronomical standards) of a couple million years. Once born, each young extremely hot blue star emits intense ultraviolet light, intensifying the ionizing effect in the surrounding hydrogen.
Unlike galaxies with large central bulges like that of Andromeda Galaxy, The Hidden Galaxy has relatively few dwarf satellite galaxies. In 2020, the galaxy KKH 32 was identified as the first known satellite of C5; and it is a dwarf spheroidal galaxy. KKH 32 is located about 10.2 million light-years away from Earth and has a diameter of about 4,300 light-years.
This sparkling, face-on view of the galaxy is particularly prominent, despite its "hidden" aspect described above, thanks to the technology of a dedicated astronomical camera. C5's intertwined tendrils of dust in spectacular arms wrapping around a brilliant core of hot gas and stars can be readily captured with this modern amateur equipment.