You might get confused between Alpha Centauri and Proxima Centauri. Alpha Centauri is a star system that consists of 3 stars…and one of those stars is Proxima Centauri. They are our closest stellar neighbor, 4.37 light years away. In this post, we’ll dig into the differences between Alpha Centauri and Proxima Centauri.
Ready? Let’s dive in!
Alpha Centauri is a triple-star system
From the naked eye view, we see Alpha Centauri (Rigil Kentaurus) as a single star. It consists of 3 stars (Alpha Centauri A, Alpha Centauri B, and Alpha Centauri C) orbiting each other. FYI, Alpha Centauri C is also called Proxima Centauri. Below we present an overview of the characteristics of the stars in the Alpha Centauri system.
| Feature | Alpha Centauri A | Alpha Centauri B | Proxima Centauri |
| Type of Star | G-type Main-Sequence | K-type Main-Sequence | M-type Red Dwarf |
| Spectral Class | G2V | K1V | M5.5Ve |
| Mass | About 1.1 Solar Masses | About 0.9 Solar Masses | About 0.12 Solar Masses |
| Luminosity | 1.519 Solar Luminosities | 0.5 Solar Luminosities | 0.0017 Solar Luminosities |
| Surface Temperature | About 5,790 K | About 5,260 K | About 3,050 K |
| Diameter | About 1.227 Solar Diameters | About 0.865 Solar Diameters | About 0.141 Solar Diameters |
| Distance from Earth | 4.37 Light-Years | 4.37 Light-Years | 4.24 Light-Years |
| Orbital Period (around each other) | — | 79.91 Years (with Alpha Centauri A) | Not precisely defined (loosely gravitationally bound to Alpha Centauri AB) |
You must be wondering how these stars move between each other. Alpha Centauri A and B orbit each other closely around a common center of mass, and form a binary system. On the other hand, Proxima Centauri is much farther out and loosely bound with the Alpha Centauri AB pair.
What constellation is Alpha Centauri located in
Alpha Centauri is located in the Centauri constellation. It appears as one of the bright stars in our night sky as viewed from Earth. You can easily spot it next to the Crux constellation in the southern sky.
Alpha Centauri A is the brightest among the three with a magnitude around -0.01. On the other hand, Alpha Centauri B’s magnitude is +1.35 while Proxima Centauri is +11.05. The combined apparent magnitude of the Alpha Centauri AB binary system (when viewed as a single point of light) is about -0.27, making it the third brightest star in the night sky as viewed from Earth, after Sirius and Canopus.
Why do you need a telescope to see Proxima Centauri
We can’t see Proxima Centauri through the naked eye. It’s because it’s too dim and the magnitude is higher than the magnitude that can be perceived by human eyes (magnitude +6 and below). Moreover, it is a small red dwarf and can be outshined by bigger Alpha Centauri A and B stars. This makes it even more challenging to distinguish with the naked eye.
Alpha Centauri A is a G-type Main-Sequence star just like our Sun. Meanwhile, Alpha Centauri B K-type Main-Sequence star which is a bit smaller and cooler than our Sun. Scientists considered them as potential candidates for hosting habitable planets in their respective habitable zones. The stability and relatively long lifespans of these stars allow for the possibility of complex life to develop on orbiting planets. However, the exoplanet that would orbit this binary star is yet to be found.
Will we ever get to Alpha Centauri?
Absolutely “No”, sorry to disappoint you. Maybe future generations could get there when the spacecraft can fly comparatively close to the speed of light. Here’s the comparative distance between each star in the Alpha Centauri system from Earth:
- Alpha Centauri A : Approximately 4.37 light-years
- Alpha Centauri B : Approximately 4.37 light-years
- Proxima Centauri: Approximately 4.22 light-years (24.81 trillion miles)
Proxima Centauri is a bit closer to us and to reach it would take around 63,000 years of journey. Meanwhile, Alpha Centauri A and B, as a binary system, are at almost the same distance from Earth. As we said earlier, the distance is about 4.37 light years away. It’s equivalent to 25.69 trillion miles and would take 77,000 years to reach it.
Proxima Centauri system
Proxima Centauri star has been found to host a planetary system. One of its planets, Proxima b has been known as the “poster boy” for Earth-like exoplanet. But, scientists had some doubts about its potential to host life. This is due to Proxima Centauri’s notorious solar flares. It is a typical behavior of a red dwarf star.
In addition, Proxima b orbits so close to Proxima Centauri, very close that it completes an orbital cycle in just around 11 days! At best, we could assume that the planet has a magnetic field that would deflect most of these dangerous flares and retain its atmosphere.
Proxima b has siblings, one of them is Proxima c. This planet could be a super-Earth or mini-Neptune with a size 1.5 times bigger than Earth. It also has been reported there is another exoplanet in this system but yet to be confirmed (at the time this post is written).
Summary
Understanding the differences between Alpha Centauri and Proxima Centauri provides insight into the complexities of our nearest stellar neighborhood. Each star in this system presents distinct characteristics and opportunities for exploration and discovery. They will be a continual focus of astronomical research and interest.
Moreover, the discovery of planets like Proxima b around Proxima Centauri star has significant implications for the field of exoplanetary science. The fact that such an Earth-like planet exists around our nearest star underscores the possibility of countless other habitable worlds awaiting discovery.
Disclaimer:
While we strive to provide accurate and reliable information, please be aware that the content of this blog post is subject to a margin of error. The probability of absolute accuracy is not guaranteed.
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