Astronomy Picture of the Day 7-15-02

NASA ^ | 7-15-02 | Robert Nemiroff and Jerry Bonnell

[petuniasevan]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2002 July 15

Proxima Centauri: The Closest Star
Credit & Copyright: David Malin, UK Schmidt Telescope, DSS, AAO

Explanation: What is the closest star to our Sun? It is Proxima Centauri, the nearest member of the Alpha Centauri triple star system. Light takes only 4.22 years to reach us from Proxima Centauri. This small red star, captured in the center of the above image, is so faint that it was only discovered in 1915 and is only visible through a telescope. Stars of all types from our Milky Way Galaxy are visible in the background. The brightest star in the Alpha Centauri system is quite similar to our Sun, has been known as long as recorded history, and is the fourth brightest star in the night sky. The Alpha Centauri system is primarily visible from Earth's Southern Hemisphere.

[petuniasevan]

Astronomy Fun Fact:

The third member of the system, Alpha Centauri C (Proxima Centauri), lies 13,000 AU from A and B,
or 400 times the distance between the Sun and Neptune. "Proxima" is from the Latin proximus "nearest".

Get on the APOD PING list!

[petuniasevan]

APOD PING!

[MeekOneGOP]

Thank you! Very nice.

[sistergoldenhair]

Nice one.

[RightWhale]

It's always been assumed that the next star system we actually reach will be Alpha Cen. Being part of a binary system, not counting Proxima, it wouldn't have planets of the kind we like. Alpha Cen A is a lot like our sun, otherwise.

[aimhigh]

How does Proxima compare to Jupitor in size?

[BossyRoofer]

Awsome! Are there any magnetic flux readings being done from Proxima?

[MozartLover]

bump

[Graewoulf]

Thanks for this scale reference. Are there known stars smaller than Proxima Centauri?

[petuniasevan]

Yes. Many white dwarfs are smaller; all neutron stars are much smaller. Those are stellar remnants, though. As for main-sequence M-class stars (red dwarves), the smallest one found so far is Gliese 623B. It's only 1/10 the sun's mass, and is 1/60000 as bright.

There is a class of objects between the smallest stars and the largest planets, called brown dwarves. They glow faintly in red and more brightly in the infrared, but do not sustain nuclear reactions in their cores.