Barnard's Star
| DISTANCE 5.97 light years |
| MASS 0.144 |
| LUMINOSITY 0.00044 |
| RADIUS 0.196 |
| SURFACE TEMPERATURE 3134 K |
| AGE 11 to 12 billion years old |
Named after the American astronomer Edward Emerson Bernard who discovered it in 1916, and with an estimated age of 11 to 12 billion years, this very low-mass red dwarf 'flare-type' star of spectral type M5 is considered very old even by most red dwarf standards. As another peculiarity, Barnard's Star is moving, relative to our Sun, at about 140 kilometres per second, making it the fastest moving stellar object known to us. At this speed, it will make its closest approach to us at a distance of 3.85 light years in just under 10,000 years time.
Measurements of its path through space have been a source of excitement for astronomers at the Sproul Observatory, Pennsylvannia, USA, since the work began in the 1940s. According to Peter van de Kamp and his colleagues at the observatory, the data suggested the presence of two large planets in orbit due to a slight wobble in the star's motion through space. Further analysis using data from more modern observatories elsewhere has cast doubt on de Kamp's observations of possible dark companions, but has not totally ruled out the idea altogether.
Only a direct visit to the star will settle the planetary debate once and for all. But if the debate is more about whether extraterrestrial life exists, scientists might be disappointed. There are far better star systems to visit out there that will provide the answer in a more guaranteed way.
In fact, because of the reasonable prospect of finding planets, Barnard's Star was the target of possible future exploration by an unmanned spaceship known as Daedalus — a nuclear-powered machine devised on paper by the British Interplanetary Team in 1973. While Barnard's Star still remains of great interest to astronomers, when a spacecraft is finally built to travel to the stars (of the electromagnetic variety), it is likely that the search for planets and alien life will be directed to those stars closer to our Sun. Even if scientists are itching for an opportunity to see a red dwarf, they would do well to visit Proxima Centauri — the red dwarf closest to our Sun.
Luhman 16 (WISE 1049-5319)
| DISTANCE 6.5 light years |
| MASS A: 0.032 B: 0.027 |
| LUMINOSITY A: 0.0000219 B: 0.0000209 |
| RADIUS A: 0.87 B: 0.107 |
| TEMPERATURE A: 1,350 K B: 1,210 K |
WISE 1049-5319, also known as Luhman 16, is a brown-dwarf binary system in the southern constellation of Vela. Both objects emit so little light and looks so uninspiring in the night sky that for a long time astronomers were unaware that this binary system existed. Then, in March 2013, after using NASA's Wide-field Infrared Survey Explorer (WISE), astronomer Professor Kevin Luhman of Penn State University and his colleagues obtained enough data and careful analysis of multi-epoch astrometry data to convince him that we now have two brown dwarfs sitting close to our Sun. The dwarfs are said to orbit each other every 27.54 years in a moderately elliptical orbit with an eccentricity of 0.343. The average distance between the stars is approximately 3.557 astronomical units (AU).
For readers who may not be entirely familiar with what these objects are, a brown dwarf is not strictly speaking a star. It is more like a gaseous planet similar to Jupiter only much larger and hotter, but not quite big and hot enough to initiate a nuclear fusion reaction at its core to become a star. In the case of this brown dwarf system, these oversized planets do emit a reasonable amount of heat, but not quite enough visible light to stand out in the night sky to say, "Hey, look at me. I'm interesting!".
Our latest newcomer has created some interest among scientists. In particular, Kevin Luhman, a Pennsylvannia State University astronomer and a researcher in Penn State's Center for Exoplanets and Habitable Worlds, said:
"The distance to this brown dwarf pair is 6.5 light years — so close that Earth's television transmissions from 2006 are now arriving there.
It will be an excellent hunting ground for planets because it is very close to Earth, which makes it a lot easier to see any planets orbiting either of the brown dwarfs. It might one day be one of the first destinations for manned expeditions outside our solar system."
If Luhman is eluding to us of the possibility of life around this binary system and wants to send probes to find out, he might find it a little easier, quicker and more likely to find what he wants at Alpha Centauri and in a more advanced state than any scientist could ever have imagined. Even the map below, prepared by Janella Williams of Pennsylvannia State University, shows that it would be much easier to go to Alpha Centauri first before mucking around at a further distance just to get to this binary system (and possibly be disappointed by the lack of life there):
Maybe we shouldn't make things any harder than they have to be. If the search for alien life is meant to be the ultimate goal in visiting other star systems, you might as well just visit another sun-like star and be done with it. Again, we must emphsise the fact that Apha Centauri is the closest to our Sun and the place where the punters will put their money on in finding alien life.
But, then again, if there is a chance alien microbes might exist and grow on a neighbouring planet (or satellite) around either of these two brown dwarfs, you can be sure that NASA will be jumping for joy and doing all it can to send probes to this system. It was only in the 1970s that scientists were contemplating the idea of sending a nuclear-powered spaceship called Daedalus to Barnard's Star to perform a typical flyby mission just to tell us if there were exo-planets around this star. Now we are considering going for another second-rate star system to look for alien microbes. Seriously, how about looking for an advanced alien civilisation with a technology at a first-class star system like Alpha Centauri and stopping for a visit with the right technology? Much better surely!
At any rate, the discovery has at least given more hope to the scientific boffins at the NASA-funded WISE project to find more planets beyond our solar system.
You can read more about Luhman's discovery in his scientific paper. If you have trouble finding his paper, we suggest you try here.
WOLF 359
| DISTANCE 7.78 light years |
| MASS 0.11 |
| LUMINOSITY 0.00002 |
| RADIUS 0.144 |
| TEMPERATURE 2,749 K |
Wolf 359 is a red dwarf star (spectral type M8) in the constellation Leo near the ecliptic plane of our solar system. It is about 20 billion years old and emits bursts of light in the form of flares and even radio noise. It also seems to emit extra strong X-rays and gamma rays just to keep any alien life form on an unseen planet well underground for protection. The star also has a strong magnetic field.
So far, no official planets have been detected.
Lalande 21185
| DISTANCE 8.29 light years |
| MASS 0.46 |
| LUMINOSITY 0.0052 |
| RADIUS 0.39 |
| SURFACE TEMPERATURE 3,601 K |
| AGE 7.5 billion years |
Lalande 21185 (named after the French astronomer Jérôme Lalande who published its celestial coordinates in 1801) has a number of scientific names, including BD+36 2147, Gliese 411, and HD 95735. Whatever name we give it, scientists know with reasonable certainty that it is a red dwarf star in the constellation of Ursa Major. Although it is a variable 'flare-type' star that emits bursts of light, it appears to have a large dark companion of mass 20 relative to Jupiter, with an orbital period of 420 days and an orbital distance of about 10.5 million kilometres — it is probably a brown dwarf. Lalande 21185 (spectral type M2) is about 20 billion years old as if older than our universe. Hmm, that sounds a bit odd.
However, recent observations are indicating that up to three planets may be encircling the red dwarf. Two of these have been confirmed, but the third is a little elusive and needs more time to confirm its existence. Over the years, astronomers will learn more and make a more definitive announcement about the likelihood of this third planet being present.
Beyond these details, we know that the star is heading in our direction. In about 19,900 years, it will be at its closest point to the Sun, approximately 4.65 light-years away. Surely by then we will have the electromagnetic vehicles to venture into this star system without too much difficulty.