What is Alpha centauri: Definition and 30 Discussions

Alpha Centauri is the closest star system and closest planetary system to Earth's Solar System at 4.37 light-years (1.34 parsecs) from the Sun. The name is Latinized from α Centauri, and abbreviated Alpha Cen or α Cen. It is a triple star system, consisting of three stars: α Centauri A (officially Rigil Kentaurus), α Centauri B (officially Toliman), and α Centauri C (officially Proxima Centauri).Alpha Centauri A and B are Sun-like stars (Class G and K), and together they form the binary star Alpha Centauri AB. To the naked eye, the two main components appear to be a single star with an apparent magnitude of −0.27, the brightest star in the southern constellation of Centaurus and the third-brightest in the night sky, outshone only by Sirius and Canopus.
Alpha Centauri A has 1.1 times the mass and 1.519 times the luminosity of the Sun, while Alpha Centauri B is smaller and cooler, at 0.907 times the Sun's mass and 0.445 times its luminosity. The pair orbit around a common centre with an orbital period of 79.91 years. Their elliptical orbit is eccentric, so that the distance between A and B varies from 35.6 AU (astronomical units), or about the distance between Pluto and the Sun, to 11.2 AU, or about the distance between Saturn and the Sun.
Alpha Centauri C, or Proxima Centauri, is a small and faint red dwarf (Class M). Though not visible to the naked eye, Proxima Centauri is the closest star to the Sun at a distance of 4.24 light-years (1.30 pc), slightly closer than Alpha Centauri AB. Currently, the distance between Proxima Centauri and Alpha Centauri AB is about 13,000 astronomical units (0.21 ly), equivalent to about 430 times the radius of Neptune's orbit.
Proxima Centauri has two planets: Proxima b, an Earth-sized exoplanet in the habitable zone discovered in 2016; and Proxima c, a super-Earth 1.5 AU away, which is possibly surrounded by a huge ring system, discovered in 2019. Alpha Centauri A may have a Neptune-sized habitable-zone planet, though it is not yet known to be planetary in nature and could be an artifact of the discovery mechanism. Alpha Centauri B has no known planets: planet Bb, purportedly discovered in 2012, was found to be an artifact, and a separate transiting planet has yet to be confirmed.

View More On Wikipedia.org
  1. S

    B Night Sky of Alpha Centauri: Sol as a Bright Star

    I finally got around to watching the movie "Avatar", which takes place in the Alpha Centauri system. I was thinking that a great little scene between the 2 main characters (i.e., the paraplegic Earthling and the Centauri woman) would have been looking up at the night sky and seeing Sol as a...
  2. W

    B Alpha Centauri Orbits to Scale?

    I sometimes get surprised by things that do not seem to exist in this world. For example, as far as I know, nobody has ever, during the entire history of photography, made a photographic time-lapse of lunar libration. There are plenty of computer renderings, but no photographic time-lapse...
  3. kolleamm

    B Mini spacecraft to Alpha Centauri

    The idea for the mission is that if we built a spacecraft small enough, we could push it with laser(s) to Alpha Centuri within a resonable amount of time, and once there it could send us back images of the star/planets. My question is, would a tiny spacecraft even able to transmit the data...
  4. A

    B The search for habitable exoplanets in Alpha Centauri

    In October 2012, astronomers announced the discovery of an exoplanet orbiting the star Alpha Centauri B. However, three years later, they concluded that it probably doesn’t exist. In 2013, astronomers also detected another possible exoplanet, but it hasn’t been confirmed yet. As of today, no...
  5. W

    I Duration of a round-trip to Alpha Centauri

    (No, this is not homework assignment. This is something I'm curious about.) Assume an astronaut were to travel from Earth to Alpha Centauri (about 4.37 light years distance) in a rocket. During the first half of the distance the rocket constantly accelerates at a comfortable 9.8 m/s2. At the...
  6. R

    I Is a trip to explore the Alpha Centuri system actually feasible?

    Can the journey be completed within the lifetime of a human adult? Assuming we have got around little problems like having an adequate form of propulsion, shielding from radiation, and avoiding deadly collisions with milligram sized dust particles. Let's say our engines can provide constant...
  7. F

    Writing: Input Wanted Some problem solving -- probe is traveling to Alpha centauri

    Hello, I am trying to write a scene- story is set a bit in the future in which theoretically, using nuclear as a fuel is a possibility in space travel. The problem I'm trying to solve right now is if a probe is traveling to Alpha centauri (4.37) light years from the sun and the probe...
  8. A

    I How do the Lorenz equations for time account for the movement of Alpha Centauri?

    They say that the light that reaches us from Alpha Centauri left that star 4 years ago but this assumes that both alpha centauri and the Earth are not moving relative to each other. In face Alpha Centauri s approaching us at about 10% of the speed of light. By the Lorenz equations for time...
  9. R

    B Math tools in a travel to Alpha Centauri?

    I want to know what mathematical tools I would use in the event that we have the right technology. So far I have only calculated the distance to Alpha Centauri using parallax. I need any other tool: hypothetical speeds of ships, trigonometry, vectors, trajectories, any tool that is necessary...
  10. DHF

    Need help figuring out a possible fusion engine

    Hello, I am in the process of writing space based sci fi novella, I made a few posts last year and earlier this year regarding different aspects of the ship and crew. If anyone is interested, I wanted to concentrate on the fusion engine of the ship itself and hopefully come up with a feasible...
  11. C

    And now for the latest news from Alpha Centauri

    A new analysis suggests that the orbit of the possible planet around Alpha Centauri B is oriented in such a way that the planet is only 1 to 3 times as massive as Earth. Link: Science.
  12. Y

    How long would it take to get to Alpha Centauri?

    So Alpha Centauri is about 4.37 lightyears from earth, but that's in Earth's frame of reference, if you could build a spaceship to go, say 9/10c relative to Earth how long would it take to get to alpha centauri, because then space-time would be warped and therefore it would no longer be 4.37...
  13. Drakkith

    Planet Found Orbiting Alpha Centauri

    From here: http://blogs.discovermagazine.com/badastronomy/2012/10/16/alpha-centauri-has-a-planet/
  14. Eirhead

    I have a spacecraft that can trave to Alpha Centauri in 1 week

    Am I going to absorb 4 years of light data from Alpha Centauri or is it just going massively blueshift?
  15. Q

    How long would it take for an interstellar spaceship to reach Alpha Centauri?

    I'm writing a science fiction story and have a basic understanding of theoretical propulsion systems (ramjets, ion drives, solar sails, etc.). But I'm also trying to make my story plausible. So, that means no faster-than-light travel, infinite energy sources, artificial gravity generators, etc...
  16. C

    Practical Interstellar Mission to Alpha Centauri?

    Can this be done feasibly (with current/near term emerging technologies and sub-trillion dollar budget)? Assuming that the human race survives the 21st century, I think we'll have the resources for a multi-decade unmanned flyby mission to Alpha Centauri even if technology shows little progress...
  17. W

    Hypothetical Planet in the Alpha Centauri System (Book research)

    I am writing a science fiction book that includes the idea of a planet orbiting within the habitable zone of Alpha Centauri A and I'm hoping this is a good place to get some questions answered. It's science fiction, so I'm perfectly fine with stretching the limits of possibility, here, just...
  18. P

    Exploring the Potential for Habitable Planets in the Alpha Centauri Star System

    I have been reading about the star system on wiki and noticed that one of the Alpha Centauri stars could in theory have a terrestrial planet in the goldilocks region. I also came to know that its orbit would only be stable for 250 million years. Given that these stars have been around for a few...
  19. L

    Reaching Alpha Centauri in 100 Years: Calculating Speed & Magnitude

    Suppose you wanted to reach Alpha Centauri in 100 years. a. How fast would you have to go, in km/hr3 b. How many times faster is the speed you found in (a) than the speeds ofour fastest current spacecraft (around 50,000 km/hr)?
  20. J

    Reaching Alpha Centauri in human lifetime

    Hello, I'm new on this forum and I hope I will blend in nicely. I happen to have a couple of questions on the Alpha Centauri star in the constellation of Centaurus. I know the distance between this star and our milk way is huge, but suppose one could travel at the speed of light X 25, would...
  21. A

    Could We Send a Probe to Alpha Centauri with Current Technology?

    I Have read a lot recently about Alpha centuri having a planet that's identical to earth. i qquote On January 15, 2010, a team of astronomers released the results of computer simulations indicating that kilometer-size planetesimals can form and accrete into rocky Earth-size planets around...
  22. U

    Should we send interstellar probe to Alpha Centauri?

    Should we send an interstellar (unmanned) probe to Alpha Centauri? Would it be much more expensive than a manned mission to Mars? According to Wikipedia, velocities as high as 0.10c are possible with hydrogen bombs. That means that ~40 years flight time to the nearest star would be possible...
  23. Ookke

    Win Alpha Centauri Lottery - Journey from Earth to Alpha Centauri

    A rocket is preparing for journey from Earth to Alpha Centauri. The Earth and Alpha Centauri systems are at rest with each other and have syncronized their clocks to time t=0. ________E__________________________________________________A (distance: 4 ly) ________R Rocket speed is known...
  24. D

    Calculating Time Dilation for Travel to Alpha Centauri

    Say I travel to Alpha Centauri (4.35 light-years from the Sun) AND back to Earth at 50 percent of speed of light. How much time would the clock on my spaceship and a clock on Earth record me to have taken?
  25. A

    Are There Habitable Planets Orbiting Alpha Centauri?

    An article about the likely magnitudes and feasibility of terrestrial sized rocky planets orbiting in the habitable zones in the Alpha Centauri system: (link removed)AA http://www.publishedauthors.net/aa_spaceagent/
  26. O

    Calculating Travel Time to Alpha Centauri

    Alright, so I'm new here and don't really know the ropes. This question could go either in Astronomy, or here; but here is better since what I need involves an equation. So first a little about me: I'm new to this forum, and suck at maths. That is all. So maybe some clever mathematician...
  27. R

    Cylindrical interior (first ark) starship to Alpha Centauri - by A. Ahad

    This gigantic thing here called the Centauri Princess, can it be built in the next few hundred years? http://www.astroscience.org/abdul-ahad/firstarktoalphacentauri.htm That would be the greatest engineering achievement in all human history...
  28. E

    Can we please look for 'New Earth' at Alpha Centauri?

    Abdul Ahad wrote: "A Tiny Ray of Hope in the Eternal Darkness... Successfully locating an Earth-like planet in the habitable zone around one of the two principal 'suns' of the Alpha Centauri system will surely rank as one of the greatest discoveries in the entire history of science. Such...
  29. M

    Could We Reach Alpha Centauri in Just 132 Years with an Orion Drive?

    Using a VASIMR rocket, 1320 years of voyage are needed Using an Orion drive, the duration of the voyage is 132 years