By: Germán Martínez Hidalgo
Art t ass No. 1053
August showed an astronomical news was already described as one of the most spectacular of 2016, together with the discovery of gravitational waves. We talk about Pr or Xima b , potentially habitable exoplanet closest to our solar system.
The news is very interesting; but it is necessary to know more about the discovery, and above all, understand what you mean what of “potentially habitable”.
DISTANCE
Our sun belongs to the Milky Way, our galaxy. In it there are between 200 to 400 billion stars; Sun being one of them. All the stars are at different distances. Such distances are measured in light-years; that is, the distance light travels in a year. If your speed is 300,000 km / s, the number of kilometers traveled by light in a year is 9,460,730,472,581 km (9 000 460 billion, 730 million, 472 000 581), equivalent to 63.240 -ua- Astronomical Units. An astronomical unit is the distance between the Sun and Earth, 150 million km.
In our Solar System, the Sun’s light takes to reach Earth about 8 minutes-Luz. That is, if the Sun (something impossible and so) will go out, we would find eight minutes later. The planets are in average Sun:
Mercury 0.387 AU, Venus 0.723 AU, Earth 1 AU, Mars 1.52 AU, Jupiter 5.2 AU, Saturn 9.52 AU, Uranus 19.21 UA, Neptune 30.1 UA and Pluto 39.74 UA.
the farthest probe sent by NASA’s Pioneer 10, is at 116.7 UA travels to 11.98 km / s or 2.5 AU / year
Knowing this, understand the distances shown here.
RIGIL Kentaurus
The star closest to our Solar, our neighboring star Sun system is called Rigil Kentaurus or Alpha Centauri . It is the brightest star in the constellation Centaurus; It is seen in southern horizon Puebla during the months of April, May, June and July, the latter being the best month. However from the city of Puebla Alpha Centauri does not lift more than 10 degrees above the horizon, is very low, and with buildings and polluted horizon, makes it impossible to find. From other cities south of the Status , with less light pollution and clean horizons may appreciate it.
In 1752 the French astronomer Nicolas Louis de la Caille ( 1713-1762) when making routine observations, discovers that Rigil Kentaurus is actually a star binary , ie, are two stars instead of one. In the distance we only see one, when in fact they are two. The stars are named Alpha Centauri A and Alfa Cetauri B .
Alfa Centouri A is bigger and brighter our Sun; in particular, it has 1.1 times the mass of the Sun, 1.2 the radius of the Sun, and a luminosity of 1.5 times the Sun’s.
While Alpha Centauri B is smaller and fainter; It has 0.9 times the mass of the Sun, 0.8 times the radius of the Sun, and only 0.5 times the solar luminosity.
Both stars are separated by 15,000 ± 700 AU and take time to walk around each other 79 years.
In 1915 the British astronomer Robert Innes (1861-1933) making observations from South Africa finds that Rigil Kentaurus is not a star binary , but a triple star system; There are three stars instead of two.
A new star is known as Alpha Centauri C or Pr or Xima Centauri .
it should be mentioned that there are astronomers doubt that Pr or Xima Centauri belongs to the star system Alpha Centauri .
PR or XIMA CENTAURI
it is the third star in the system is very small, is an unstable red dwarf, only 12% of the mass of the sun, or 129 times the mass of Jupiter; its luminosity is 15% of the sun.
Of the three stars, Pr or Xima Centauri is -for now – closest to our solar system, only 4,246 light-years or 268,521.61 UA or 40,169,436,733,350 km
exoplanets IN RIGIL Kentaurus
. 2012 the discovery of a exoplanet around alpha Centauri B was announced. The term exoplanet refers to planets orbiting stars other than the sun. The new exoplanet alpha Centouri Bb became the exoplanet closest to us. He immediately knew the distance to the star was very large, in the coldest area outside the Goldilocks
According to the story.; when Goldilocks enters the house of the three bears and try their soups, one is very hot, one warm and the other cold. Around stars are the same temperature; very close to the star is very hot, then comes a temperate zone and finally a cold area. Depending on how we understand the processes that gave rise to life on Earth, finding a planet in the temperate zone increases the chances that, if water is in liquid state, and having oxygen atmosphere, there may be processes that give rise to life ..
Alpha Centauri Bb it was discovered by M é all Radial velocity or M é all of Espectrometr t a Doppler. This method It consists of measuring the displacement of spectral lines of a star because of his wobbling. In other words; Imagine a star, turning on itself as a perfect spin, no wobbling; similar to basketball players spin the ball on one of his fingers. If an exoplanet orbits of these stars, it is expected that the star itself present a very small wobble, because of the mutual gravitational attractions. This method searches this minimum deviation; and he discovered several exoplanets
But the method is not perfect, and often the interpreted data is a ghost signal, measurement errors.; not astronomers, but because of the enormous distances and radiation of the stars, especially unstable. Was so soon alpha Centouri Bb disappeared like exoplanet.
Putting in place of the Sun, the triple star system alpha Centauri on Moscow
PR or XIMA b
Between 2004 and 2014 the Spanish astronomer Guillem Anglada Escudé and his team,
in the first three months of 2016 turned to use these telescopes to confirm data; so information from the ghost signals are reduced and strengthens it discovered is real. Since Pr or Xima is an unstable red dwarf, with much radiation that contaminates a feedback.
As such, last August the discovery of an exoplanet detected around the star Pr or Xima Centauri was announced, called Pr or Xima b . Moreover, what is striking is that in the Goldilocks Zone, the temperate zone of the star Pr or Xima ; and not only that, the calculations indicate that the rock type and similar to Earth in size.
Of the 2,326 exoplanets discovered by the Kepler telescope, only 21 are similar in size to Earth.
in addition, information study leaves open the possibility of more exoplanets around Pr or Xima .
So much emotion can make us forget certain facts. Let’s see.
The new exoplanet can not be seen by now, the detection method is an indirect method, which betrays its presence. It is estimated that Pr or Xima b has 1.27 times the mass of Earth, is located 7.5 million km from its star, and broken in 11.2 days; that is, its 11.2 days last year. Despite being so close to the star (Earth is 150 million km from the Sun), the exoplanet is in the temperate zone, as Pr or Xima is a small, cool star. Pr or Xima is a red dwarf, as we said, has a UV radiation (UV), X-ray and infrared strong that bathes the planet; at 30 times more ultraviolet radiation than the Earth receives from the Sun, and 250 more X-rays is estimated that the average temperature in Pr or Xima b it is -39º; . Although greenhouse gases could change this
To learn more about Pr or Xima b must observe a planetary transit; that is, that the planet passes in front of its star and can observe. Thus, it would be detected if the planet has an atmosphere, and if there is, find out what elements compose
You also need to know:. The tilt of its axis of rotation, internal activity, if you have a magnetic field protect it from radiation. Changes in these factors become a Pr or Xima b in hell itself or the expected ideal world.
these data, we realize that the “potentially habitable” is a term more full of hope than certainty.
The good news is that Pr or Xima b is a rocky planet similar in size to Earth. This means that should a similar to Earth’s gravity and therefore know the biological processes that could occur (if and only if atmospheric conditions are met). Since, the larger more serious; and severity hundreds or thousands of times greater prevent many biological processes. It also strengthens the possibility of a hypothetical journey within centuries or millennia.
The tremendous closeness to its star leads us to believe that Pr or Xima b must suffer very strong tidal effects, it is likely that its axis is not tilted and not broken; so there would be no night and day, but on one side would always day and night on the other; causing extreme temperatures are on each side. Star Pr or Xima always would be in the same position in the sky, there would sunrises or sunsets.
having the essential components for life-oxygen, nitrogen, hydrogen, etc- the best places to inhabit such a world are the boundaries between day and night, where you can find warm temperatures.
If a world of water, would be a world like an eye; where everything would be frozen, except an ocean under the starlight
But, a red dwarf star is not a crash stable, presents X-ray flares that destroy everything.; so it is important that Pr or Xima b has a very strong magnetic field, to consider it potentially habitable, otherwise it will be a sterile world . A star and also produces a lot of infrared radiation, if it had a protective magnetic field, photosynthesis is easier than on Earth.
TRAVEL A PR or XIMA
In 2015 the physicist and entrepreneur Russian Yuri Milner associated with the cosmologist famous Stephen Hawking presented the project Breakthrough Starshot ; send him pretend robot swarms of small ships bound for Pr or Xima Centauri . Solar sails will propel through and reach between 15% and 20% of the speed of light; would reach the star Pr or Xima Centauri in 20 or 30 years. This is very interesting because, with current technology the Voyager 1 would take 75,000 years. The project would launch in 2036. We’re talking 2056 or 2066 that could have information in situ from Pr or Xima . The investment required is on the 10,000 million dollars. Mark Zuckerberg, founder of Facebook has joined the project
Much for now is speculation.; the story goes in the sense of having taken the first step to discover exoplanet similar in size to Earth, the rock type, the nearest star. New observations will tell us if Pr or Xima b is the closest expected exoplanet so desire.
german @ astropuebla. org
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