A Second Planet May Have been Found Orbiting Proxima Centauri! And it's a Super Earth. – Universe Today
Astronomers have discovered another candidate exoplanet orbiting our neighbor, Proxima Centauri. A paper announcing these results was just published in the journal Science Advances. If confirmed, it will be the second exoplanet orbiting the star.
It was big news in 2016 when astronomers discovered a planet orbiting Proxima Centauri (PC,) the nearest star to our Sun. That planet, named Proxima b, is potentially habitable, and at the time there was speculation that we could send a robotic explorer there in only a few decades. The discovery of a second planet, even though it’s likely too far away from its star for liquid water, is intensifying interest in the PC system.
The discoverers of this new planet, Proxima c, say that follow-up observations are needed to confirm it as a planet. Changes in the stellar activity of Proxima Centauri indicated the presence of another planet. But they also say that the data they have can’t be explained in terms of any stellar activity itself. Due to its proximity, and also its angular separation from the star, it is a prime candidate for follow-up observations—and even imaging—with next generation telescopes.
Proxima c’s mass is about half that of Neptune and its orbit is about 1.5 times that of Earth. Its temperature is about -200 C, if it has no atmosphere. Proxima Centauri has undergone intense astronomical scrutiny in the last few years, and that has ruled out the presence of any Jupiter-sized planets between 0.8 and 5+ astronomical units from the star. But finding Proxima c is still surprising, because its presence challenges our models of how super-Earths form and evolve.
The lead author of this study is Mario Damasso from the INAF Astrophysical Observatory of Turin, Italy. The study is titled “A low-mass planet candidate orbiting Proxima Centauri at a distance of 1.5 AU.” It was published on January 15th, 2020.
Hugh Jones, a Professor of Astrophysics at Hertfordshire University, was also involved in the study. In an article in “The Conversation,” Jones pointed out how difficult it can be to separate data showing the presence of a planet, from data showing stellar activity at the host star. “Just like our sun, Proxima has spots caused by regions of intense magnetic activity which are moving in and out of view, changing in intensity on a variety of timescales. These features need to be considered when searching for any planetary signals.”
Even though stellar activity doesn’t match the data, the discoverers are being cautious until follow-up observations can either confirm or deny the presence of Proxima c, and definitively rule out stellar activity.
The discovery of this new candidate exoplanet is contained in this new paper, but the history goes back a few years.
Multiple teams of scientists have scoured Proxima Centauri for exoplanets. Much of their work depended on radial velocity data, notably from the ESO’s HARPS (High Accuracy Radial velocity Planet Searcher.) Study by study, astronomers have excluded the presence of certain mass-range planets within certain AU ranges from PC.
A 1999 study excluded the presence of any planets beyond 1700 AUs of PC, because PC itself orbits Alpha Centauri AB. A 2019 study set an upper limit of 0.3 Jupiter masses for any planet within 10 AU of PC. That same study excluded the presence of planets between 10 and 50 AU in the mass range 0.3 to 8 masses of Jupiter. Other studies put on more constraints.
But astronomers also know that red dwarfs host more small planets than other types of stars. So they kept looking.
Can We Really Send A Spacecraft There?
The Breakthrough Starshot Initiative (BSI) thinks they can send a tiny spacecraft to Proxima Centauri.
When the Centauri b exoplanet was discovered in 2016, the BSI got to work. They think they can send a nano-spacecraft with cameras to within one AU of the planet and return images much more detailed than we can hope to achieve with any telescope. They say they should be able to return images showing continents and oceans. On their website, BSI says “To achieve comparable resolution with a space telescope in Earth’s orbit, the telescope would have to be 300km in diameter.”
But even though PC is “close” in astronomical terms, it’s still an immense distance away. At 4.2 light years away, it would still take decades to get there, travelling at 20% the speed of light (about 216,000,000 kilometers per hour.) Currently, the fastest spacecraft is NASA’s Parker Solar Probe, which will reach a top speed of only 692,000 km/h.
But whether we can get a spacecraft there or not is only part of the story. Due to its proximity, the Proxima Centauri system is an observable laboratory for understanding other solar systems. And its presence and proximity might spur further technological development needed to study it and other systems in more detail.
As Hugh Jones said in his article at The Conversation, “Ultimately, the discovery of multiple signals from the very closest star shows that planets are more common than stars. Proxima represents an excellent location for understanding the closest exoplanets and developing new technologies to better understand the universe we live in.”
Proxima c’s existence is problematic, or at least significant, for our planet formation models. Among super-Earth planets around low-mass stars detected by radial velocity, Proxima c would have both the longest period and the lowest mass. It would also be the furthest distance from its parent star than the frost line in the original protoplanetary disk. The frost line was probably at 0.15 AU.
The authors say that it’s unlikely that Proxima c was kicked out from its initial position closer to the star due to some instability, “because its orbit is consistent with a circular one and because of the absence of more massive planets on shorter orbital distance.”
In their paper, they say, “The formation of a super-Earth well beyond the snowline challenges formation models according to which the snowline is a sweet spot for the accretion of super-Earths, due to the accumulation of icy solids at that location.”
Proxima Centauri is a red dwarf star, or M dwarf. It’s about 4.2 light years away from the Sun, making it our closest neighbour. It’s the third star in a trinary system, with the Alpha Centauri AB binary star. Proxima Centauri is about 13,000 AU from Alpha Centauri AB, and was discovered in 1915.
How to watch the Axiom-2 mission depart from the ISS on Tuesday – Digital Trends
This Tuesday, the crew of the second-ever all-private mission to the International Space Station will be returning to Earth. The Axiom 2 or Ax-2 mission launched last week and saw private astronauts Peggy Whitson, John Shoffner, Ali Alqarni, and Rayyanah Barnawi traveling to the ISS on a SpaceX Crew Dragon launched from the Kennedy Space Center in Florida.
Now, the crew of four will be traveling back to Earth in the same Crew Dragon, and NASA will be livestreaming the departure of the spacecraft from the station. A separate stream will also be available showing the Crew Dragon splashing down off the coast of Florida. We’ve got the details on how to watch both below.
How to watch the mission departure
Coverage of the departure of the Crew Dragon from the ISS will begin at 9 a.m. ET (6 a.m. PT) on Tuesday, May 30. NASA will show a short introduction before the closing of the hatch of the station’s Harmony module at 9:10 a.m. ET (6:10 a.m. PT). There will then be a short break in coverage, which will resume at 10:45 a.m. ET (7:45 a.m. PT) to show the undocking of the Dragon at 11:05 a.m. ET (8:05 a.m. PT), with coverage ending 30 minutes after undocking.
You can watch the livestream of the hatch closing and the undocking on NASA’s YouTube channel, or by using the video embedded near the top of this page.
The crew will then travel back to Earth throughout Tuesday and into Wednesday, May 31. When the Crew Dragon is approaching Earth for splashdown, you’ll be able to tune into a livestream from Axiom Space. That will be available on Axiom’s website, but the company has not yet confirmed the exact time that coverage is expected to begin on Wednesday. You can find the latest updates on Axiom Twitter.
What to expect from the mission departure
The Ax-2 crew will have spent 10 days in space before heading home, and they will be bringing around 300 pounds of cargo back with them. The mission is notable for including the first two astronauts from Saudi Arabia, Ali Alqarni and Rayyanah Barnawi, as well as famous American astronaut Peggy Whitson who has spent more days in space than any other American or any other woman.
Axiom Space launched its first private mission to the ISS in April last year, with a third mission planned for November this year and a fourth planned for 2024.
NASA's New Horizons Spacecraft Captures ''Heart-Shaped'' Glacier On Pluto's Surface – NDTV
Space agency NASA routinely captures stunning images of our universe, leaving space lovers mesmerized. On Sunday, NASA shared a stunning image on Instagram taken by its New Horizons spacecraft showing a heart-shaped glacier on Pluto’s surface. The heart-shaped region is known unofficially as Tombaugh Regio and is made of nitrogen and methane.
The image was captioned as ”Absence makes the heart grow fonder. Our New Horizons spacecraft captured this heart-shaped glacier. It lies on Pluto’s surface, which also features mountains, cliffs, valleys, craters, and plains, thought to be made of methane and nitrogen ice ”
See the image here:
It described the image as ”Pluto’s surface is marked with cracks and craters in shades of brown. The partially visible heart appears in the lower right of the small world, which is surrounded by black space.”
New Horizons launched in January 2006 and reached Pluto in July 2015, flying within 7,800 miles of its surface, and becoming the first probe to fly by Pluto and its moons. The far-traveling spacecraft also visited a distant Kuiper Belt object Ultima Thule (2014 MU69) in January 2019.
Instagram users loved the picture and shared a variety of comments. One user wrote, ”Wouahh what a great capture, thanks to New Horizon spacecraft.” Another commented, ”For me, Pluto will always be a planet.”
A third said, ”Why is Pluto, not a plane? it literally has a heart!” A fourth added, ”Being afar doesn’t mean you aren’t part of the family.”
Pluto was once considered the ninth planet in the solar system, however, it was demoted in 2006 and reclassified as a dwarf planet. The International Astronomical Union (IAU) downgraded the status of Pluto to that of a dwarf planet because it did not meet the three criteria the IAU uses to define a full-sized planet.
Pluto is slightly over 1,400 miles (2250 km) wide or about half the breadth of the United States or two-thirds the width of the Moon. With its average temperature of -387F (-232C) – Pluto’s surface is coated in ice made of water, methane, and nitrogen and is believed to have a rocky core and possibly a deep ocean.
This Week @NASA: Private Astronaut Mission, Autonomous Snake-Like Robot Explorer, TROPICS Launch – SciTechDaily
The second all-private astronaut mission to the space station …
Completing the set of tiny severe weather trackers …
And a robotic explorer – with a twist …
A few of the stories to tell you about – This Week at <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>NASA!
Second Private Astronaut Mission to the Space Station
On May 21, a <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>SpaceX Dragon spacecraft launched from NASA’s Kennedy Space Center on Axiom Mission 2, the second all private astronaut mission to the International Space Station.
The four-person crew, commanded by former NASA astronaut Peggy Whitson, is scheduled to spend several days conducting research, outreach, and commercial activities on the space station.
Final Pair of Storm-Observing CubeSats Launched
The final two CubeSats for NASA’s TROPICS mission launched from Rocket Lab’s Launch Complex 1 in New Zealand on May 26. The small satellites will join two other identical spacecraft that launched to orbit earlier this month.
All four will fly, as a constellation, in a unique low Earth orbit that will allow them to observe tropical cyclones, including hurricanes and typhoons, more often than what is possible with
current weather satellites.
Autonomous Snake-Like Robotic Explorer
A team at NASA’s Jet Propulsion Laboratory is creating and testing a snake-like robot called EELS, short for Exobiology Extant Life Surveyor. The self-propelled, autonomous robot is
being developed to go where other robots can’t go.
Although it was inspired by a desire to look for signs of life in the sub-surface ocean on <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>Saturn’s icy moon, Enceladus, EELS is not currently part of any NASA mission.
Artemis Rocket Engine Test Series Continues
On May 23, NASA’s Stennis Space Center conducted a hot fire test of an RS-25 rocket engine. It was the eighth hot fire of the current 12-test series to certify production of new RS-25s.
Four of the engines will help power NASA’s Space Launch System rocket on future Artemis missions to the Moon.
That’s what’s up this week @NASA.
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