A new approach for detecting planets in the Alpha Centauri system

December 18, 2017, Yale University
Yale astronomers have taken a fresh look at the nearby Alpha Centauri star system. Credit: Michael S. Helfenbein.

Yale astronomers have taken a fresh look at the nearby Alpha Centauri star system and found new ways to narrow the search for habitable planets there.

According to a study led by Professor Debra Fischer and graduate student Lily Zhao, there may be small, Earth-like planets in Alpha Centauri that have been overlooked. Meanwhile, the study ruled out the existence of a number of larger planets in the system that had popped up in previous models.

"The universe has told us the most common types of planets are small planets, and our study shows these are exactly the ones that are most likely to be orbiting Alpha Centauri A and B," said Fischer, a leading expert on exoplanets who has devoted decades of research to the search for an Earth analog.

The new study appears in the Astronomical Journal. Co-authors are John Brewer and Matt Giguere of Yale and Bárbara Rojas-Ayala of Universidad Andrés Bello in Chile.

The Alpha Centauri system is located 1.3 parsecs (24.9 trillion miles) from Earth, making it our closest neighboring system. It has three stars: Centauri A, Centauri B, and Proxima Centauri. Last year, the discovery of an Earth-like planet orbiting Proxima Centauri set off a new wave of scientific and public interest in the system.

"Because Alpha Centauri is so close, it is our first stop outside our solar system," Fischer said. "There's almost certain to be small, around Alpha Centauri A and B."

The findings are based on data coming in from a new wave of more advanced spectrographic instruments at observatories located in Chile: CHIRON, a spectrograph built by Fischer's team; HARPS, built by a team from Geneva; and UVES, part of the Very Large Telescope Array. "The precision of our instruments hasn't been good enough, until now," Fischer said.

The researchers set up a grid system for the Alpha Centauri system and asked, based on the spectrographic analysis, "If there was a small, rocky planet in the habitable zone, would we have been able to detect it?" Often, the answer came back: "No."

Zhao, the study's first author, determined that for Alpha Centauri A, there might still be orbiting planets that are smaller than 50 Earth masses. For Alpha Centauri B there might be orbiting planets than are smaller than 8 Earth masses; for Proxima Centauri, there might be orbiting planets that are less than one-half of Earth's mass.

In addition, the study eliminated the possibility of a number of larger planets. Zhao said this takes away the possibility of Jupiter-sized planets causing asteroids that might hit or change the orbits of smaller, Earth-like planets.

"This is a very green study in that it recycles existing data to draw new conclusions," said Zhao. "By using the data in a different way, we are able to rule out large planets that could endanger small, habitable worlds and narrow down the search area for future investigations."This new information will help astronomers prioritize their efforts to detect additional in the system, the researchers said.

Likewise, the continuing effort by Fischer and others to improve spectrographic technology will help identify and understand the composition of exoplanets.

Explore further: Image: Hubble's best image of Alpha Centauri A and B

More information: Lily Zhao et al. Planet Detectability in the Alpha Centauri System, The Astronomical Journal (2017). DOI: 10.3847/1538-3881/aa9bea , iopscience.iop.org/article/10. … 847/1538-3881/aa9bea , On Arxiv: arxiv.org/abs/1711.06320

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Thorium Boy
1 / 5 (4) Dec 19, 2017
Want to get there in six years instead of 40,000? Project Orion. If the U.S. doesn't build it, someone else will.
Ensign_nemo
5 / 5 (4) Dec 19, 2017
An Orion-type spacecraft couldn't accelerate a ship to 70% of the speed of light and travel 4.37 light years in six years.

Orion was intended to be an interplanetary ship rather than an interstellar ship.

It might be feasible to accelerate an unmanned probe to a speed fast enough to get there in 50 years, which is about the design lifetime of our Voyager probes, but Orion isn't an ideal design for that.
Nik_2213
3 / 5 (1) Dec 19, 2017
The BIS' landmark 'Project Daedalus' laid out a road-map for a high speed stellar fly-by with a swarm of sub-probes. Sadly, the necessary pulsed-fusion tech failed to materialise...

Mind you, before the famous meeting where the 'Daedalus Final Report' was presented, we discussed post-rocketry options...
yaridanjo
1 / 5 (1) Dec 24, 2017
Here is a new way to detect planets from a given star system. Ask an E. T alien from that star system what their planets are like. For example,There are at least three sentient species in the Alpha Centauri Star system, the Cenos (Proxima b) Hand's (Alpha Centauri B?) and Greys (on satellites of a large planet in the Alpha Centauri Star system). Here is an Example how to do it:
http://yaridanjo..../PS.html
HANDS
UNIQUE DESCRIPTIONS OF TWO ET ALIEN CULTURES
Using this technique, a tidally locked planet in the Proxima star system was discovered in Aug. 2012. Astronomers verified this finding in August, 2012.
This technique suggests that there is a big planet in the Alpha Centauri system, something our astronomers are not anticipating.
http://www.barry....6.html#4
4. THE ALIEN CROP CIRCLE FORMATION MECHANISM
It's long past time for our astronomer to wake up to the probability of an ET alien presence in our solar system!
yaridanjo
1 / 5 (1) Dec 24, 2017
Here is another person that directly ask the 'Greys' where they were from.

http://yaridanjo....ien.html
THE HILL ALIENS
This is the first 'abduction' that the public became aware of.
This data came directly from the person who ask the question.

Correction to above post:
Using this technique, a tidally locked planet in the Proxima star system was discovered in Aug. 2012. Astronomers verified this finding in August, 2016.

Ensign_nemo
not rated yet Dec 28, 2017
Dec. 28 (UPI) -- Scientists at NASA's Jet Propulsion Laboratory are making preliminary plans for an interstellar mission, the agency's first. The team wants to send a probe to look for sings of life on the exoplanets surrounding Alpha Centauri, the closest star system to Earth.

According to New Scientist, which first revealed the news, the proposed launch is set for 2069 -- a celebration of the 100th anniversary of the Apollo 11 moon landing.

[snip]

Scientists are working on the kinds of technology that would allow a probe to travel at 10 percent of the speed of light. Researchers are considering laser-powered probes, as well as nuclear propulsion, sail power and thrust derived from collisions between antimatter and matter.

https://www.upi.c...14473538

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