Messier 84 - Elliptical Galaxy
Messier 84 (M84) was discovered by Charles Messier on the 18th of March in 1781 while he was surveying faint deep-sky objects in the constellation Virgo. This specific region is now commonly known as Markarian’s Chain. It is also catalogued as NGC 4374.
Elliptical Galaxy
An elliptical galaxy is a galaxy type that has a smooth, rounded appearance rather than the distinct spiral arms seen in other galaxies such as Messier 66 (M66). The shape of this galaxy type ranges from spherical to stretched and slightly oval-shaped. Elliptical galaxies are home to mostly older stars, containing a very small number of young blue stars.
These galaxies are typically found in clusters of galaxies, and many astronomers believe that most elliptical galaxies likely formed from the collision and mergers of spiral galaxies. Likewise with Messier 84, it is believed to have formed through mergers with other galaxies over billions of years, likely disrupting any original spiral structures.
More epecifically, M84 is listed as an Elliptical Galaxy (E1). Astonomers classify elliptical galaxies from E0 through to E7 based on how ‘structured’ they appear:
E0 = almost perfectly round
E1 = Slightly elongated
E2 = Mildy oval
E3 = Clearly ovel-shaped
E4 = Moderately elongated
E5 = Strongly elongated
E6 = Very elongated
E7 = Extremly elongated
This number is determined by a formula used based on the galaxy’s apparent shape:
Eₙ = 10(1 − b/a)
A = the length of the galaxy’s longest dimension
B = the length of the galaxy’s shortest dimension
Location
M84 is located 60 million light-years away from Earth, in the constellation Virgo and is a member of a large cluster of galaxies known as Markarian’s Chain. M84 is about 125,000 light-years in diameter, making it just slightly larger than the Milky Way (100,000-120,000 light-years). This galaxy has an apparent magnitude of approximately 10.1
In the Southern Hemisphere, this galaxy is best viewed in April.
The Supermassive Black Hole and Radio Galaxy
Like most galaxies, M84 contains a supermassive black hole, estimated to be about 1.5 billion times the mass of the Sun. For a quick comparison, the black hole at the centre of our Milky Way is about 4 million solar masses. Making M84’s supermassive black hole 375 times more massive than the one at the centre of the Milky Way.
Furthermore, despite the seemingly calm galaxy, M84 emits powerful radio wave jets that are launched near its black hole. These jets are not bright in visible light; however, they do shine through a process called synchrotron radiation. This occurs when charged particles spiral around magnetic field lines at extremely high speeds. In order to detect these jets, astronomers use radio telescopes.
Full image of Markarian’s Chain
Equipment
Telescope: ASKAR120 APO
Mount: HEQ5-Pro
Camera: ZWO ASI2600MM PRO
Filters: Antlia L, R G B, HA V-pro Series
Filter Wheel: ZWO EFW
Focuser: ZWO EAF
Computer: ZWO ASI AIR Pro
Guide Scope: ZWO 120MINI
Guide Camera: ZWO 120MM
Dew Heater: SV-BONY Dew Heater
Capture Details
Light Frames:
RED: 180 seconds x 200 frames
GREEN: 180 seconds x 200 frames
BLUE: 180 seconds x 200 frames
LUM: 180 seconds x 733 frames
Total: 66.65 hours
