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Astronomers Find Sun's Twin
mroch writes "Space.com is reporting that astronomers may have found a solar twin -- a star almost exactly like our own Sun. Interesting tidbits from the article include: "The star, 18 Scorpii, sits about 47.5 light-years away in the constellation Scorpio, and has long-been suspected of being Sun-like. [...] The star burns slightly hotter than the Sun, at 5,789 degrees Kelvin compared to 5,777 degrees. It appears to rotate slightly faster than the Sun, taking 23 days to complete a rotation rather than the Sun's 25." It boggles my mind to think that we can measure temperature that exactly from 279,000,000,000,000 miles away, and that they are complaining over a 12-degree difference."
Distance actually does not matter with respect to the method used to measure the temperature, as long as you have enough light, and there is no disturbing medium in between. Both conditions seems to be met.
They can determine the temperature by the wavelengths of light given off by the star.
And those dozen degrees are in Kelvin. These aren't your ordinary units of measurement we're talking about.
I have been pwned because my
IIRC, the temperature is measured by the colour of the sun. That doesn't change the further away you get, so its just as accurate over long distances as short. However, there is the problem of dopler shift if the stars are moving away/toward each other.
"When I grow up, I want to be a weirdo"
What do we know about that star and its surroundings? Is it likely to have inhabitable planets or is it bathed by lethal radiation from neighboring novas?
How long before we can actually check these stars for Earth-like planets? Last I heard, we now had the ability to detect planets slightly smaller than Jupiter. Will we find, or even see, an inhabitable planet within a few decades?
"... and that they are complaining over a 12-degree difference."
Who's complaining?
Observation != complaint.
for my 2 pence, this twin bit is just bunkum
They are 0.3 billion years different in age (presumably USian billions)
Which is almost 10% of their total age, that's like your human twin being born when you are 8 years old but you both weigh the same!
It is a bad analogy.
There are places where the networks are not touching,and there are places where they are-Boeing's Lori Gunter
From The U.S. Metric Association
The kelvin (K) temperature scale is an extension of the degree Celsius scale down to absolute zero, a hypothetical temperature characterized by a complete absence of heat energy. Temperatures on this scale are called kelvins, NOT degrees kelvin, kelvin is not capitalized, and the symbol (capital K) stands alone with no degree symbol. [In 1967 the new official name and symbol for "kelvin" were set by the 13th General Conference on Weights and Measures (CGPM).]
I like David Nash's list of 50 nearby sunlike stars within 50 light years.
18 Scorpii is on there, as is the infamous Tau Ceti. 18 Scorpii was one of the four closest matches.
Binary geeks can count to 1,023 on their fingers
does anyone here know what advances would be necessary to send probes & recover data about nearby star systems? Ion drives seem to be moving in the right direction, to use a phrase, but would they be sufficient in longevity & speed to make a multi-light year journey? And what sort of remote communication would be possible at such distances?
A corollory to this is, does anyone know what (if any) systems the Voyager spacecraft are going to encounter, and when?
Actually, that distance would be more like 2.7862056^14 miles.
186,000 miles/second x 60 seconds/minute x 60 minutes/hour x 24 hours/day x 365 days/year x 47.5 years.
There are no stupid questions, only stupid people asking questions.
You know, these arbitrary names come after greek words. They used these words to refer to small things, so scientists, centuries after them, use these words to refer to powers of ten.
If you are measuring in inches, you have to memorize arbitrary numbers, because there are 5280 inches in one mile, and 12 inches in a feet, which makes calculations cumbersome and prone to error.
Metric system is intuitive, because every unit is a power of ten of a meter. This is the only thing arbitrary.
Face it. Metric system r00lZ! Any other system sucks!!
Astronomers look at the spectrum of the star--the relative intensities of each wavelength of light produced by the star's heat. Assuming the star is a black-body radiator (which isn't totally true, but pretty darn close), using first principles you can solve for the temperature of such and object as a function of the peak wavelength of light radiated. See "Thermal Physics" by C. Kittel and H. Kroemer for a better discussion.
Also, single wavelength filters (like your green sheet of plastic) aren't a natural byproduct of nature, and wouldn't be found between here and the aformentioned star. What would would find, however, is interstellar dust, or clouds of hydrogen, helium, lithium, and other light elements. When the light passes through these clouds, certain frequencies of light are absorbed, and certian frequencies are flouresced, but these frequencies are predictable, and the overall shape (and especially the peak) of the spectrum is not changed beyond recognition. "Introduction to Quantum Mechanics" by D. Griffiths and "Introduction to Astronomy and Astrophysics" by Zeilik and Gregory should help you out with spectra and spectral lines.
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No.
"Left" and "right" have their origins in the seating arrangements of a pre-Revolution French parliament. Nobles sat on the right, commoners (or rather, their representatives, who weren't quite so common) sat on the left. Thus, generally, being on the right was to support the privileged class; being on the left was to support the common people and more equality.
In their modern forms, the right supports (and usually hopes to join) the "privileged nobles" of the capitialist class, those to whom the state has granted control of the means of production; the left seeks a more equitable arrangement, supporting the rights and interests of the "common" laborers.
Properly, "right" and "left" refer to economic arrangements. Using them to talk about the orthogonal political dimensions of legislated morality and foreign policy results in great confusion.
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You cannot wash away blood with blood
What do we know about that star and its surroundings? Is it likely to have inhabitable planets...
As cool as it is to find a star that's a twin to ours, it's incredibly unlikely that we'll find a planet even remotely similar to Earth.
For one thing, the article notes that 18 Sco is 4.2 billion years old, while Sol is 4.5 billion years old. If everything else were exactly equal, it would be like stepping back 300 million years back in time. A quick Google finds that one of the more complex forms of life found 300e6 years ago on this planet was the Velvet Worm -- not a species known for its technology.
But even that is unlikely, given the Earth's unusual formation. This planet has an unusual mix of minerals on its crust, plus plate tectonics to keep them mixed, and an iron core that's magnetic enough to keep out the sun's ionizing radiation. Plus, a moon big enough to stir up the oceans, and a tilt to generate asymmetrical solar heating... and all that apparently due to a one-in-a-million collision between a proto-Earth and a Mars-sized planet not long after Sol formed.
I can't find the quote, but someone calculated the odds of finding another sentient species as tiny. It's not that it doesn't develop elsewhere in the galaxy... there are billions of chances, so surely more than one came up all 7s. It's just that the distances are so vast, and the chances of favorable development so small, that entire civilizations (or species) could rise and fall by the time their transmissions reach another civilization's satellite dishes.
But still, at less than 50 light years, it would only take a few hundred years to get there and back. Are the generation ships ready yet?
Stressed? Me? Of course not. Stress is what a rubber band feels before it breaks, silly.
What if something in between the star and Earth is changing the wavelength of the light? I can shine a light-bulb through a green sheet of plastic, and change it
Wrong. Your filter can reduce the brightness at various wavelengths, but you CANNOT(*) change the wavelength. You can forget about brightnesses and calculate the temperature by measuring frequency behaviours.
(*) Footote: Yes, there are a handful of materials that can double or halve the wavelength of light, but there is no way in hell an enormous windowpane of some obscure mineral is sitting between us and another star - and if there were then we would blatantly see frequency doubling or halving.
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