Four new exoplanets to start off the new year!

Jan 06, 2012 By Paul Scott Anderson, Universe Today
Artist's conception of a "hot Jupiter" orbiting close to its star. Credit: NASA/JPL-Caltech/T. Pyle (SSC)

It’s only a few days into 2012 and already some new exoplanet discoveries have been announced. As 2011 ended, there were a total of 716 confirmed exoplanets and 2,326 planetary candidates, found by both orbiting space telescopes like Kepler and ground-based observatories. The pace of new discoveries has accelerated enormously in the past few years. Now there are four more confirmed exoplanets to add to the list.

The four planets, HAT-P-34b, HAT-P-35b, HAT-P-36b, HAT-P-37b all have very tight orbits around their (four different) stars, taking only 5.5, 3.6, 1.3 and 2.8 days to complete an orbit. Compare that to , which takes 87.969 days and 365 days of course for Earth.

They were found by astronomers with the Harvard-Smithsonian Center for Astrophysics which operates a network of ground-based telescopes known as the HATNet project. The first exoplanet discovery by HATNet, the planet HAT-P-1b, was in 2006.

They are all “hot jupiter” type planets, gas giants which orbit very close to their stars and so are much hotter than Earth, like Mercury in our own solar system. Mercury though, of course, is a small rocky world, but in some alien solar systems, gas giants have been found orbiting just as close to their stars, or even closer, than Mercury does here. HAT-P-34b however, may have an “outer component” and is in a very elongated orbit. The other three are more typical hot Jupiters. They were discovered using the transit method, when a planet is aligned in its so that it passes in front of its star, from our viewpoint.

So what does this mean? If exoplanet discoveries continue to grow exponentially as expected, then 2012 should be a good year, not only for yet more new planets being found, but also for our understanding of these alien worlds and how such a wide variety of solar systems came to be. We’ve come a long way from 1992 and the first exoplanet discoveries and things promise to only get more exciting in the future.

Explore further: Image: Galactic wheel of life shines in infrared

More information: The abstract and paper are here.

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GSwift7
3.5 / 5 (11) Jan 06, 2012
I wonder if we will ever find planets in the Alpha Centauri system? I also wonder if we might discover that stars without planets are rare?

As the number of discoveries goes up, we may start to see trends that tell us where planets are more or less likely, if such trends exist.
Xbw
1.7 / 5 (10) Jan 06, 2012
Star Trek told me that there was a planet in Alpha Centauri. I think Zephram Cochran is hiding out there too.
nkalanaga
4.2 / 5 (5) Jan 06, 2012
I wouldn't be surprised to find planets at Alpha Centauri, as computer simulations have shown that orbits in, and just beyond, the habitable zone would be stable, and that rocky planets could have formed there.

Finding a habitable planet there, with current technology, would require either much better technology or fantastic good luck. Radial velocity studies have shown no Jupiter-mass planets in the A or B systems, but we couldn't detect Earth that way. Transits are unlikely given the system's tilt relative to our line-of-sight. And we don't have a telescope good enough to see Earth, even at AC's close distance.
that_guy
3.3 / 5 (6) Jan 06, 2012
At first they thought that planetary systems around binary and trinary (like alpha centauri) star systems were unlikely. Now that they've confirmed at least one case, they still think it might be rare.

However, the main issue is that due to the complex orbital mechanics, it is (1) hard to detect planets in such systems, (2) disfavors the close planets that are easier to detect, as a perterbance can send them into their parent star, and (3) favors planets that are either (Much) farther out, or positions in lagrangian type points where their gravitational effect is masked by the effect other stars or objects.(making them hard to detect or confirm)

Multi-star planetary systems are one of the most intriging questions/concepts of the cosmological frontier :).
GSwift7
2 / 5 (4) Jan 06, 2012
Radial velocity studies have shown no Jupiter-mass planets in the A or B systems, but we couldn't detect Earth that way


Exactly what I was thinking. Since there isn't a jupiter there, it might make an Earth more likely.

That_Guy: The AC system main and secondary stars orbit at about the distance from Sol to Saturn. There is plenty of room for planets in the orbits of our first four around either AC A or B, in the habitable zone. There's also the possibility of an orbit around the center of mass of both A and B combined, but it would have to be an ice ball world. AC A is so similar to our sun that if you placed Earth there in an orbit a little farther out, you might not notice the difference (except for the dim second sun which might be faintly visible in the daytime and would only be visible at night as our Sol is visible from Saturn.) Also, some simulations indicate that distant binaries might be even more likely to form planets than single systems.
GSwift7
1 / 5 (2) Jan 06, 2012
A likely place to look for planets around AC A would be in the same plane as the orbit of AC B, or in the plane of AC A around B, or both. If you think of AC B as an extra large planet, like a Jupiter that got big enough to go nuclear, then why not have a full system of planets orbiting AC A, just like we orbit Sol despite our gas giant Saturn, which is much closer to Sol than AC B is to A. When you look at it that way, do you see my point?
Deathclock
1 / 5 (4) Jan 06, 2012
I also wonder if we might discover that stars without planets are rare?


I'm sure this is the case. I wouldn't be surprised if "dark matter" was simply the planets, moons, and other non-luminous bodies that we can't detect at a distance.
hopefulbl
not rated yet Jan 06, 2012
what about Proxima....may ba small but far enough from other two
that_guy
5 / 5 (1) Jan 06, 2012
@Gswift - I don't think you got my point.

My point was that regardless of whether planets are common or not in multi-star systems, it poses some definite constraints which are ill defined at best, in addition to challenges to detection.

A planet orbiting in a multi-star system is either too far to easily detect, in a stable orbit in a similar or exact resonance as another star (IE, a signal with an identical wavelength)

OR, in your vision, in an orbit that would look much more chaotic than the mechanics of our solar system. The orbital resonances achieved would be a magnitude of order more complex than in our system. While it has been proven possible, it means that your simple wobbling waltz we see in a single star system looks like an interpretive new age dance in a multi star system. A full signal for a planet would look like the combined signal of two or three smaller planets.

That makes it difficult to detect
nkalanaga
not rated yet Jan 07, 2012
Generally speaking, in a binary with moderate eccentricity, a planet is stable if its distance from one of the stars is less than about 1/3 the binary separation, or around both if it's greater than 3 times the separation. Eccentricity does matter, and the more eccentric the binary's orbit, the closer planets must be to their star. In AC's case, the critical distance seems to be about 2.5 AUs, which is far enough out for a planet similar to Mars to be stable.

As for Proxima, it doesn't seem to have anything bigger than Neptune in orbits out to several AU. The habitable is very small around little red dwarfs, so any Earth-like planet would be very close, tidally locked, and subject to large flares. Some simulations indicate that such a world could still hold an atmosphere, and thus be "habitable", but it probably wouldn't be "Earth-like". Earth plants wouldn't like the red light.
MarkyMark
5 / 5 (3) Jan 07, 2012
I also wonder if we might discover that stars without planets are rare?


I'm sure this is the case. I wouldn't be surprised if "dark matter" was simply the planets, moons, and other non-luminous bodies that we can't detect at a distance.

I dont thnk you have really grasped the basics of the Dark Matter theory as the estimated ammount of it compared to normal matter is a bit much for it to be non luminouse bodies we cant see.
GSwift7
1 / 5 (2) Jan 09, 2012
to That_Guy:

OR, in your vision, in an orbit that would look much more chaotic than the mechanics of our solar system


as nkalanaga said, there is plenty of room for planets with normal orbits around either AC A or B. There could be planets almost exactly like Mercury, Venus, Earth and maybe Mars all orbiting AC A, in the plane of the orbit of AC B around A, and they could have perfectly normal orbits. Probably not Mars though.

As for Proxima Centauri, that's just a red dwarf. There's not really much of a habitable zone around a red dwarf, especially Proxima. Proxima is very small and dim. It's about the same size as Jupiter, so the habitable zone would need to be pretty close. However, Proxima has an unusual magnetic field that generates occasional bursts of x-ray as powerful as our Sol. So you would need to be out far enough to be clear of the x-rays, which places you out in the cold and dark.
that_guy
not rated yet Jan 09, 2012
Once again gswift, we don't know exactly how all the constraints change with multi-star systems.

And once again, I'm not debating that actual frequency of these planets.

Once again, one constraint that is definitely viable is that planets in certain areas will be susceptible to gravitational influence similar to jupiter's influence on the asteroid belt - but on a larger scale.

And lastly, the rest of what you say basically supports the concerns I'm bringing forward.

Stop trying to be 'right' because (1) its ridiculous - there is not enough info yet to reliably back up most claims and more importantly, (2) I'm not even arguing against you, idiot.

There are only one or two actual differences in our views, and for the most part, we're talking about two completely different sides of the issue.
GSwift7
1.3 / 5 (4) Jan 10, 2012
lol.

The physics that dictate where a stable orbit is possible are quite simple. I'm talking about facts, not unknowns.

I am not 'trying' to be right, I am right. Your statement that an orbit like Earth's around AC A or B would be eratic or unstable is wrong. I'm not arguing with you, I'm correcting you.
Deathclock
1 / 5 (2) Jan 10, 2012
Never wear your arrogance on your sleeve.

Never assert that you are correct when you can demonstrate it.