Planet Found Orbiting Alpha Centauri!

cepheid

On the contrary, I think observational techniques are ever evolving, as the instrumentation that enables them improves. It's really important to innovate and think of new ways of observing the universe! Observations in previously unobserved frequency bands. Interferometry (even in the optical). Integral field spectroscopy to get spatially resolved spectral information (also with Fourier transform spectroscopy). Things like coronography and differential imaging techniques (that they used for direct imaging of planets). FFT telescopes (sort of) like CHIME. Adaptive Optics, including advanced varieties like multi-conjugate adaptive optics and robotic AO. The nascent field of gravitational wave astronomy (which hasn't seen anything yet).

Dude, the radial velocity method has been around since forever (okay, so has interferometry). It's just the same techniques that used to be applied to binary stars that are now being applied to planets. Transits are starting to seem kind of old hat too. So now you can do really really *really* precise photometry instead of just really really precise photometry. I'm not saying that sort of incremental progress isn't important. I'm just saying that it is boring. EDIT: and I'm also saying that some work in this field could stand to be more astrophysically motivated and smacks of stamp collecting. Like you said, to each his own. I'm not even saying that it's intrinsically boring, but it becomes boring when you are constantly beaten over the head with it. Like I've said, I've just attended a few too many planet talks in too short a span of time and am planeted out. I am sorry if I ruffled a few feathers. I will drop it.

Drakkith

Understandable. I'm sure if I had been beaten over the head with the same kind of technique over and over it would become boring too.

mfb

It is hard to sell that to the public. "Planet with mass of earth discovered at the nearest star system" is easier to understand.

Concerning life: We do not know where life can evolve yet - we just have one example: We know that it can evolve on earth-like planets. Naturally, our theories are biased and propose earth as perfect place for life.

Philosophaie

Alpha Centauri is a Binary Star with Alpha Centauri B and a Companion Star Alpha Centauri C.

Alpha Centauri A is solar-like yellow main sequence star.

Alpha Centauri B is smaller solar-like yellow main sequence star.

Alpha Centauri C is a small main sequence star (Type V) or sub-dwarf (VI) with emission lines.

All three combine to be the brightest and the closest of all the stars at 4.366 light years or 4.131E+13 km away.

A planet rotating around a Binary Star will be very unstable, at the very least, and would probably not be first on my list to be a habitable planet.

cepheid

I wasn't *talking* about selling any of that to the public. I was addressing Drakkith's question (post #17) about whether observational astronomy mainly consists of doing the same types of observations repeatedly, with only slight refinements or improvements each time. I was just trying to point out that in fact observational techniques have changed dramatically in the past few decades, with many innovations arising. I know I said I would drop this, but please don't make arguments against points I never made in the first place.

mfb

Well, I viewed your post in the context of that:

@Philosophaie:
It is not sure that Proxima Centauri ("Alpha Centauri C") is gravitationally bound. Sirius, Canopus and Arcturus are brighter (and our sun, too, of course).

There are several known exoplanets around binary stars, and simulations show that they are quite stable.
Depends on the orbit, as always.

cepheid

That wasn't the right context, but since I didn't quote the part of Drakkith's post that I was responding to, it's understandable that there would be some confusion as to what my point was.

It's supposed to be my job to keep things on topic, but instead I am guilty of veering off topic myself. Regarding planets in binary or multiple systems: what are the stable orbital configurations?

I imagine that if you had a close binary, the planet could perhaps orbit around the centre of mass of the system, only much farther out, so that it would essentially be in orbit around both stars.

On the other hand, given stars with a very wide separation, and a planet very close in to one of them, as seems to be the case with Alpha Cen B, then I imagine that the planet would orbit around its parent star, and then the planet + star would orbit around the centre or mass of the system.

Am I at least somewhat close the the mark?

mfb

That two options are the "conventional" stable orbits.

And then there is Kepler 16b.

There are even weirder solutions (which might or might not be stable at the timescale of 10^9 years), but I would not expect to see them frequently ;)
Figure-8
Orbits in binary systems

cepheid

These applets are pretty neat! I would not have expected such solutions. I like the Figure 8 ones that end up looking like spirographs.

EBENEZR

I guess it would become tedious to someone exposed to the reality of observation techniques time and time again, but I think it's exciting for the sake of being a discovery relatively close.

sshai45

But is it possible to simultaneously take into account the differing interests of the general public and also not misrepresent the science, etc.? To not misrepresent "what questions are of interest" while also not missing the general public's interest (i.e. what do you do since the two differ and contrast)?

stargazer3

Dropping by to point out that there is a calculated 10% probabitity that the planet detectable via transit method with transit depth about 10^-4. If we're that lucky, we'll find more about the structure of the planet for sure.

AlaskanGlitch

The interesting thing is that since the amount of separation at their closest approach is around 10 AU, there could be a solar system around each star, as long as the planets were not more than 5 AU distant from their own star. This would also seem to eliminate any possibility of a gas giant in either solar system.

Furthermore, both stars are close enough where their solar winds would impact right around the "snow line" which should create gas, dust, and ice particulates. We have observed this in other binary systems, such as R Scuti and WR-104.

With a higher mellicity than Sol, the odds are high that more than one rocky planet will be found around both Alpha Centauri A & B. The optimal distance around Alpha Centauri B would be about 65 million miles since it is 10% smaller, 50% dimmer, and about 10% cooler than Sol. Whereas the optimal distance around Alpha Centauri A would be about 128 million miles since it is 10% bigger, 50% brighter, and about 2% hotter than Sol.

If there are any planets (besides the one found) around either Alpha Centauri A and/or B, every 80 years they would be pelted with meteors and comets, as the stars make their closest approach. Alpha Centauri A would be visible during the day around any planet in the Alpha Centauri B solar system.

mfb

With a distance of 1/2 of the star separation, you don't get stable orbits around a single star. I think I read something about of 1/7 of the star separation for stable (and nearly circular) orbits.

Gas giant with close orbits should be possible due to orbital mechanics, but I think they would have been visible in the radial velocity measurements (did not check the numbers).

sophiecentaur

Man. You really can't be too surprised about that! Science and the Media is the serious. on-going scandal of our times.