Sirius A

Lalande 21185 is a nearby red dwarf in Ursa Major, also cataloged as Gliese 411 and HD 95735. It is the brightest red dwarf in the northern celestial hemisphere, yet it is still too dim for unaided eyes and is better known through telescopes, surveys, and its nearby planetary system.

Object class

M-type red dwarf star

Composition

Hydrogen and helium

Mass

~0.39 solar masses

Temperature

~3,550 K surface

Sagittarius A* is the supermassive black hole at the center of the Milky Way. Event Horizon Telescope observations imaged the glowing material around it, resolving a radio ring about 64 million kilometers across around a black hole of roughly 4.3 million solar masses.

Object class

Supermassive black hole

Host

Milky Way

Mass

~4.3 million solar masses

Proxima Centauri is the nearest known star to the Sun, just over four light-years away. ESA describes it as a flare star prone to dramatic brightening, yet because it burns fuel so slowly it may remain on the main sequence for another four trillion years.

Object class

M-type red dwarf star

Mass

~0.12 solar masses

Host

Alpha Centauri system

Estimated age

~4.8 billion years

Composition

Hydrogen and helium

Temperature

~3,000 K surface