Dita Ayu Pertiwi

XI SCIENCE 2

Alpha Centauri

Definition

Alpha Centauri (α Centauri, α Cen; also knownas Rigel Kent )is the brightest star in the southernconstellationof Centaurus and is currently inside the G-cloud. Although itappears to the unaided eye as a single object, Alpha Centauriis actually a binary star system(designated Alpha CentauriAB or α Cen AB) whose combined visual magnitude of −0.27makes it the third-brightest star in the night sky after the−1.46 magnitude Sirius and the −0.72 magnitude Canopus.

The two main components are Alpha Centauri A and AlphaCentauri B. A third star, known as Proxima Centauri, or AlphaCentauri C (α Cen C), is probably gravitationally associatedwith Alpha Centauri AB. Proxima is at the slightly smallerdistance of 1.29 parsecs or 4.24 light years from the Sun,making it the closest star to the Sun, even though it is notvisible to the naked eye. The separation of Proxima from Alpha Centauri AB is about 0.06 parsecs 0.2 light years or13,000 astronomical units (AU); equivalent to 400 times thesize of Neptune's orbit.

Alpha Centauri Ais the principal member, or primary, of the binary systembeing slightly larger and more luminous than the Sun. It is asolar-like main-sequence star with a similar yellowish color

Alpha Centauri Bis the companion star, or secondary, of the binary system, andis slightly smaller and less luminous than the Sun. AlphaCentauri B is about 90% the mass of the Sun and 14% smallerin radius

Alpha Centauri Calso known as Proxima Centauri, is of spectral class M5 Ve[ orM5 VIe, suggesting this is either a small main-sequence star(Type V) or subdwarf (VI) with emission lines Its B−V colorindex is +1.90 and its mass is about 0.123 M☉, 129 Jupiter

masses.

How to see itUnluckily for us in the Northern Hemisphere, Alpha Centauriis located very far to the south on the sky’s dome. Most NorthAmericans never see it. The cut-off latitude is about 29degrees north, and anyone north of that is out of luck. In theU.S. the line passes near Houston and Orlando, but even fromthe Florida Keys, the star never rises more than a few degreesabove the southern horizon.

For northern observers, there really are no good pointer starsto Alpha Centauri. When the bright star Arcturus is highoverhead, Alpha Centauri might low in your southern sky,assuming you are south of 29 degrees N. latitude.

Arcturus is the brightest star in the constellation Boötes and the northerncelestial hemisphere. With a visual magnitude of −0.04, it is

the fourth brightest star in the nightt sky, after −1.46 magnitude Sirius, −0.86 magnitude Canopus, and −0.27 magnitude Alpha Centauri. It is a relatively close star at only 36.7 light-years from Earth, and, together

with Vega and Sirius, one of the most luminous stars in the Sun's neighborhood.

History and Myth

pandora

polyphemus

Who Don’t Know ?Remember..

Conclusion

1. Alpha Centauri is cool !2. Alpha Centauri is the brightest star in the

southernconstellation of Centaurus3. The Mythologist Of Alpha Centauri is Come

Fom Greek and Rome4. Proxima Centauri is The Nearest star from our

Sun

Thanks For The Attention