Tag: exoplanets

NASA’s New Planet Hunter Has Already Spotted Two Candidates For Earth-Like Alien Worlds

 

NASA’s Transiting Exoplanet Survey Satellite (TESS) has only been on the job less than two months, and already it’s ponying up the planet goods.

The exoplanet-hunting space telescope has found two candidate planets, and there are plenty more on the horizon.

The two candidate planets are called Pi Mensae c, orbiting bright yellow dwarf star Pi Mensae, just under 60 light-years from Earth; and LHS 3844 b, orbiting red dwarf star LHS 3844, just under 49 light-years away.

TESS took its first test observations on July 25 (and managed to get some pretty great snaps of a passing comet), and its first official science observations began on August 7.

However, it was observing a large swathe of sky from the moment it opened its eyes – four optical cameras – and both discoveries are based on data from July 25 to August 22.

So far, they are only candidate planets, yet to be validated by the final review process. If they pass that test, they’ll go down in history as TESS’s first two discoveries. Here’s what we know so far about them.

Both planets appear to be Earth-like and rocky, but neither is habitable according to our guidelines – both are too close to their stars for liquid water.

Pi Mensae c, the first planet announced, is a super-Earth, clocking in at just over twice the size of Earth. It’s really close to Pi Mensae – it orbits the star in just 6.27 days.




A preliminary analysis indicates that the planet has a rocky iron core, and also contains a substantial proportion of lighter materials such as water, methane, hydrogen and helium – although we’ll need a more detailed survey to confirm that.

It also has a sibling – it’s not the first object to be found orbiting Pi Mensae. That honour goes to Pi Mensae b, an enormous planet with 10 times the mass of Jupiter discovered in 2001.

It’s much farther out than Pi Mensae c, on an orbit of 2,083 days. LHS 3844 b is a little bit smaller, classified as a “hot Earth“.

It’s just over 1.3 times the size of Earth, and on an incredibly tight orbit of just 11 hours. Since the two are so close together, it’s highly likely the planet is blasted with too much stellar radiation to retain an atmosphere.

TESS does need a bit of time to collect enough data for identifying an exoplanet.

Like its predecessor Kepler, it uses what is known as the transit method for detection – scanning and photographing a region of the sky multiple times, looking for changes in the brightness of stars in its field of view.

When a star dims repeatedly and regularly, that is a good indication that a planet is passing between it and TESS.

By using the amount the light dims, and Doppler spectroscopy – that is, changes in the star’s light as it moves ever-so-slightly backwards and forwards due to the gravitational tug on the planet – astronomers can infer details about the planet, such as its size and mass.

 

Using this method, Kepler has discovered 2,652 confirmed planets to date between its first and second missions, located between 300 to 3,000 light-years away.

Kepler is still operational, but barely; it’s only a matter of time until it completely runs out of fuel.

TESS’s search is happening a lot closer, with targets between 30 and 300 light-years away – stars brighter than those observed by Kepler.

Thus, the exoplanets it identifies will be strong candidates to observe using spectroscopy, the analysis of light.

When a planet passes in front of a star, it has an effect on the light from the star, changing it based on the composition of its atmosphere (if it has one).

Ground-based observatories and the James Webb Space Telescope (once it launches in 2021) will have to make those follow-up observations.

Both papers are available on preprint resource arXiv. Pi Mensa c can be found here, and LHS 3844 b can be found here.

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Astronomers Just Found a Planet Where Star Trek’s Vulcan Was Predicted to Exist

So far, astronomers have identified thousands of exoplanets out there beyond the reaches of the Solar System, but only a rare few are the stuff of legend.

Such is the case with an Earth-like exoplanet, found orbiting a star called 40 Eridani A – Star Trek creator Gene Roddenberry’s preferred location for Vulcan, the home planet of Mr Spock.

Located around 16 light-years from Earth in the southern constellation of Eridanus, 40 Eridani A is part of a triple-star system.

Although it was never mentioned in the original TV series of Star Trek, it had been put forward as a proposed location for the planet by related literature.

In 1991, Roddenberry and three astronomers from the Harvard-Smithsonian Center for Astrophysics wrote a letter to Sky & Telescope magazine laying out their choice for Vulcan’s location, and why.

Based on the history of life on Earth, life on any planet around Epsilon Eridani would not have had time to evolve beyond the level of bacteria.




“On the other hand, an intelligent civilisation could have evolved over the aeons on a planet circling 40 Eridani. So the latter is the more likely Vulcan sun.

Epsilon Eridani does have one planet – an uninhabitable gas giant. Now astronomers on the University of Florida-led Dharma Planet Survey have found something that seems a bit more habitable orbiting 40 Eridani A.

More precisely, it’s an object known as a super-Earth – a rocky planet around twice the size of Earth, orbiting 40 Eridani A just inside the system’s habitable zone – not too hot and not too cold. It completes one orbit every 42 (Earth) days.

So life on the planet isn’t unfeasible.

The aim of the Dharma Planet Survey, using the 50-inch Dharma Endowment Foundation Telescope (DEFT) on Mount Lemmon in Arizona, is a dedicated survey to find low-mass planets orbiting bright, nearby stars.

It uses the radial velocity method – detecting the very slight wobble in a star’s position due to the gravitational pull of an exoplanet.

The candidate exoplanet, named HD 26965b (but we’ll probably call it Vulcan, obviously), is the first super-Earth found in the survey.

And if you’re in the southern hemisphere, you can even go outside and look for it.

“Now anyone can see 40 Eridani on a clear night and be proud to point out Spock’s home.”

The research has been published in the Monthly Notices of the Royal Astronomical Society.

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Atomic Iron And Titanium In The Atmosphere Of The Exoplanet KELT-9b

To constrain the formation history of an exoplanet, we need to know its chemical composition.

With an equilibrium temperature of about 4,050 kelvin, the exoplanet KELT-9b (also known as HD 195689b) is an archetype of the class of ultrahot Jupiters that straddle the transition between stars and gas-giant exoplanets and are therefore useful for studying atmospheric chemistry.

At these high temperatures, iron and several other transition metals are not sequestered in molecules or cloud particles and exist solely in their atomic forms




However, despite being the most abundant transition metal in nature, iron has not hitherto been detected directly in an exoplanet because it is highly refractory.

The high temperatures of KELT-9b imply that its atmosphere is a tightly constrained chemical system that is expected to be nearly in chemical equilibrium and cloud-free, and it has been predicted that spectral lines of iron should be detectable in the visible range of wavelengths.

Here we report observations of neutral and singly ionized atomic iron (Fe and Fe+) and singly ionized atomic titanium (Ti+) in the atmosphere of KELT-9b.

We identify these species using cross-correlation analysis of high-resolution spectra obtained as the exoplanet passed in front of its host star.

Similar detections of metals in other ultrahot Jupiters will provide constraints for planetary formation theories.

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NASA’s Planet-Hunting TESS Telescope Launches Today Aboard A SpaceX Rocket

Some of the most exciting space news of the past few years has been about Earth-like exoplanets that could one day (or perhaps already do) support life. TESS, a space telescope set to launch today aboard a SpaceX Falcon 9 rocket.

It will scan the sky for exoplanets faster and better than any existing platforms, expanding our knowledge of the universe and perhaps finding a friendly neighborhood to move to.

The Transit Exoplanet Survey Satellite has been in the works for years and in a way could be considered a sort of direct successor to the Kepler, the incredibly fruitful mission that has located thousands of exoplanets over nearly a decade.

But if Kepler was a telephoto aimed at dim targets far in the distance, TESS is an ultra-wide-angle lens that will watch nearly the entire visible sky.

They both work on the same principle, which is really quite simple: when a planet (or anything else) passes between us and a star (a “transit”), the brightness of that star temporarily dims.

By tracking how much dimmer and for how long over multiple transits, scientists can determine the size, speed, and other characteristics of the body that passed by.




It may seem like looking for a needle in a haystack, watching the sky hoping a planet will pass by at just the right moment.

But when you think about the sheer number of stars in the sky — and by the way, planets outnumber them — it’s not so crazy.

As evidence of this fact, in 2016 Kepler confirmed the presence of 1,284 new planets just in the tiny patch of sky it was looking at.

TESS will watch for the same thing with a much, much broader perspective.

Its camera array has four 16.4-megapixel imaging units, each covering a square of sky 24 degrees across, making for a tall “segment” of the sky like a long Tetris block.

The satellite will spend full 13.7-day orbits observing a segment, then move on to the next one.

There are 13 such segments in the sky’s Northern hemisphere and 13 in the southern; by the time TESS has focused on them all, it will have checked 85 percent of the visible sky.

It will be focusing on the brightest stars in our neighborhood: less than 300 light-years away and 30 to 100 times as bright as the ones Kepler was looking at.

The more light, the more data, and often the less noise — researchers will be able to tell more about stars that are observed, and if necessary dedicate other ground or space resources towards observing them.

Of course, with such close and continuous scrutiny of hundreds of thousands of stars, other interesting behaviors may be observed and passed on to the right mission or observatory.

Stars flaring or going supernova, bursts of interesting radiation, and other events could very well occur.

In fact, an overlapping area of observation above each of Earth’s poles will be seen for a whole year straight, increasing the likelihood of catching some rare phenomenon.

SpaceX is the launch partner, and the Falcon 9 rocket on which it will ride into orbit has already been test fired. TESS is packaged up and ready to go, as you see at right.

Currently the launch is planned for a 30-second window at 6:32 Florida time; if for some reason they miss that window, they’ll have to wait until the moon comes round again — a March 20 launch was already canceled.

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TRAPPIST-1 Planets Probably Rich In Water

Planets around the faint red star TRAPPIST-1, just 40 light-years from Earth, were first detected by the TRAPPIST-South telescope at ESO’s La Silla Observatory in 2016.

In the following year further observations from ground-based telescopes, including ESO’s Very Large Telescope and NASA’s Spitzer Space Telescope, revealed that there were no fewer than seven planets in the system, each roughly the same size as the Earth.

They are named TRAPPIST-1b,c,d,e,f,g and h, with increasing distance from the central star.

Further observations have now been made, both from telescopes on the ground, including the nearly-complete SPECULOOS facility at ESO’s Paranal Observatory, and from NASA’s Spitzer Space Telescope and the Kepler Space Telescope.

A team of scientists led by Simon Grimm at the University of Bern in Switzerland have now applied very complex computer modelling methods to all the available data and have determined the planets’ densities with much better precision than was possible before.




Simon Grimm explains how the masses are found: “The TRAPPIST-1 planets are so close together that they interfere with each other gravitationally, so the times when they pass in front of the star shift slightly.

“These shifts depend on the planets’ masses, their distances and other orbital parameters. With a computer model, we simulate the planets’ orbits until the calculated transits agree with the observed values, and hence derive the planetary masses.”

Team member Eric Agol comments on the significance: “A goal of exoplanet studies for some time has been to probe the composition of planets that are Earth-like in size and temperature.

“The discovery of TRAPPIST-1 and the capabilities of ESO’s facilities in Chile and the NASA Spitzer Space Telescope in orbit have made this possible — giving us our first glimpse of what Earth-sized exoplanets are made of!

The measurements of the densities, when combined with models of the planets’ compositions, strongly suggest that the seven TRAPPIST-1 planets are not barren rocky worlds.

They seem to contain significant amounts of volatile material, probably water, amounting to up to 5% the planet’s mass in some cases — a huge amount; by comparison the Earth has only about 0.02% water by mass!

TRAPPIST-1b and c, the innermost planets, are likely to have rocky cores and be surrounded by atmospheres much thicker than Earth’s.

TRAPPIST-1d, meanwhile, is the lightest of the planets at about 30 percent the mass of Earth. Scientists are uncertain whether it has a large atmosphere, an ocean or an ice layer.

Scientists were surprised that TRAPPIST-1e is the only planet in the system slightly denser than Earth, suggesting that it may have a denser iron core and that it does not necessarily have a thick atmosphere, ocean or ice layer.

It is mysterious that TRAPPIST-1e appears to be so much rockier in its composition than the rest of the planets.

In terms of size, density and the amount of radiation it receives from its star, this is the planet that is most similar to Earth.

TRAPPIST-1f, g and h are far enough from the host star that water could be frozen into ice across their surfaces.

If they have thin atmospheres, they would be unlikely to contain the heavy molecules that we find on Earth, such as carbon dioxide.

Astronomers are also working hard to search for further planets around faint red stars like TRAPPIST-1. As team member Michaël Gillon explains: “This result highlights the huge interest of exploring nearby ultracool dwarf stars — like TRAPPIST-1 — for transiting terrestrial planets.

“This is exactly the goal of SPECULOOS, our new exoplanet search that is about to start operations at ESO’s Paranal Observatory in Chile.

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Google Discovers New Planet Which Proves Solar System Is Not Unique

The Kepler-90 star system has eight planets, like our own

Google has previously discovered lost tribes, missing ships and even a forgotten forest. But now it has also found two entire planets.

The technology giant used one its algorithms to sift through thousands of signals sent back to Earth by Nasa’s Kepler space telescope.

One of the new planets was found hiding in the Kepler-90 star system, which is around 2,200 light years away from Earth.

The discovery is important because it takes the number of planets in the star system up to eight, the same as our own Solar System. It is the first time that any system has been found to have as many planets ours.

Andrew Vanderburg, astronomer and Nasa Sagan Postdoctoral Fellow at The University of Texas, Austin, said: “The Kepler-90 star system is like a mini version of our solar system.

You have small planets inside and big planets outside, but everything is scrunched in much closer.

“There is a lot of unexplored real estate in Kepler-90 system and it would almost be surprising if there were not more planets in the system.”




The planet Kepler-90i, is a small rocky planet, which orbits so close to its star that the surface temperature is a ‘scorchingly hot’ 800F (426C). It orbits its own sun once every 14 days.

The Google team applied a neural network to scan weak signals discovered by the Kepler exoplanet-hunting telescope which had been missed by humans.

Kepler has already discovered more than 2,500 exoplanets and 1,000 more which are suspected.

The telescope spent four years scanning 150,000 stars looking for dips in their brightness which might suggest an orbiting planet was passing in front.

Although the observation mission ended in 2013, the spacecraft recorded so much data during its four year mission that scientists expect will be crunching the data for many years to come.

The new planet Kepler-90i is about 30 per cent larger than Earth and very hot.

Christopher Shallue, senior software engineer at Google AI in Mountain View, California, who made the discovery, said the algorithm was so simple that it only took two hours to train to spot exoplanets.

Test of the neural network correctly identified true planets and false positives 96 percent of the time. They have promised to release all of the code so that amateurs can train computers to hunt for their own exoplanets.

Machine learning will become increasingly important for keeping pace with all this data and will help us make more discoveries than ever before,” said Mr Shallue.

This is really exciting discovery and a successful proof of concept in using neural networks to find planets even in challenging situations where signals are very weak.

We plan to search all 150,000 stars, we hope using our technique we will be able to find lots of planets including planets like Earth.”

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Venus May Once Have Been Habitable, According To NASA

Venus – a hellish planet with an atmosphere of carbon dioxide, almost no water and temperatures of more than 460 degrees Celsius – may once have been habitable, according to Nasa scientists.

Researchers used climate models to calculate that Venus might have had a shallow ocean of liquid water and temperatures that could have allowed life to exist for up to two billion years of its early history.

The atmosphere is 90 times as thick as the air on Earth and scientists had thought this was largely caused by the difference between the two planets’ rate of spin.

A day on Venus lasts 117 Earth days because it spins on its axis at a much slower rate. But recent research showed that Venus could have had an atmosphere similar to the Earth’s today.




The first signs that Venus once had an ocean were discovered by NASA’s Pioneer mission in the 1980s.

Venus is closer to the sun than Earth and receives far more sunlight.

This caused the ocean to evaporate, water-vapour molecules were broken apart into hydrogen and oxygen by ultraviolet radiation and the hydrogen escaped to space.

With no water left on the surface, carbon dioxide built up in the atmosphere and led to a runaway greenhouse gas effect that created present searing heat.

A map of Venus’s surface based on imagery collected by Magellan, Pioneer Venus, and Venera 13 and 14 .

Michael Way, a researcher at Nasa’s Goddard Institute for Space Studies (GISS) in New York, said: “Many of the same tools we use to model climate change on Earth can be adapted to study climates on other planets, both past and present.

Colleague Anthony Del Genio added: “In the GISS model’s simulation, Venus’ slow spin exposes its dayside to the sun for almost two months at a time.

In a statement, Nasa said it was thought that Venus may have had more land than Earth. One of the factors they had to take into consideration was the ancient sun was up to 30 per cent dimmer.

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Any Aliens On Exoplanet Proxima B Likely Wiped Out Last Year

The chances that the nearest planet beyond our solar system might be habitable and perhaps even host quirky, telepathic aliens have dimmed significantly thanks to one day last year when the star Proxima Centauri shone exceptionally bright.

Astronomers observed a huge solar flare from the star just four light-years away that increased its brightness a thousandfold for about 10 seconds and probably showered nearby planet Proxima b with energetic particles.

The findings were published Monday in The Astrophysical Journal Letters.

March 24, 2017, was no ordinary day for Proxima Cen,” said Meredith MacGregor, an astronomer at the Carnegie Institution for Science, in a statement.




It’s likely that Proxima b was blasted by high-energy radiation during this flare.

That’s bad news for the prospects of life there. Any intelligent beings would have basically experienced the horrible ending of the 2009 Nicolas Cage science fiction flick “Knowing.”

It was already known the dwarf star was prone to outbursts of smaller, X-ray flares.

But if Proxima b has also been on the receiving end of major flares like the one MacGregor and her colleagues caught with Chile’s Atacama Large Millimeter/submillimeter Array (ALMA), it’s not going to be worth planning a vacation there any century soon.

Over the billions of years since Proxima b formed, flares like this one could have evaporated any atmosphere or ocean and sterilized the surface,” she said.

There is hope for the future habitability of Proxima b, though. Eventually, Proxima Centauri will calm down and begin to cool into a white dwarf that might be far more hospitable.

Unfortunately, that’s unlikely to happen for at least another 4 trillion years, or roughly 300 times the current age of the universe.

Stubborn old star.

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Google’s AI Found An Overlooked Exoplanet

NASA has discovered an eighth planet around a distant star, which means we’re no longer the largest solar system we know of.

The discovery was made thanks to some artificial intelligence help from Google, which found the planet by scouring previously overlooked “weak” signals in data captured by the Kepler Space Telescope.

The newly found planet is located in the solar system around Kepler-90, a star about 2,500 light-years away from Earth that was previously discovered in 2014.

The Kepler Space Telescope has been searching the galactic sky for exoplanets, or planets outside our own Solar System, since it launched in 2009.

In order to sift through all the data that it’s captured since that launch, scientists usually look at the strongest signals first.




And that process has worked well enough so far. NASA has confirmed 2,525 exoplanets in that time, a number that has changed our understanding of how common it is to find planets around the stars that make up our galaxy.

Recently, though, artificial intelligence has become a more prominent tool in astronomy.

Scientists, including ones who work on the Kepler data, have increasingly turned to machine learning to help sort through typically lower-priority data to see what they might have missed.

In the process, they found an overlooked planet that’s now named Kepler-90i.

But while we now know that Kepler-90 has the same number of orbiting planets as our Sun, the solar system is a poor candidate in the search for extraterrestrial life or at least, life as we know it.

Kepler-90 is about 20 percent bigger and 5 percent warmer than our Sun. And its eight planets dance around the star in much closer orbits than the ones in our own Solar System.

In fact, their orbits are so comparatively small that seven of Kepler-90’s eight planets would fit in between the Earth and the Sun.

The discovery of Kepler-90i, came after NASA let Google train its machine learning algorithms on 15,000 signals from potential planets in the Kepler database.

The scientists then took the trained system and set it to work on data from 670 stars that were already known to have multiple planets, as they considered those to be the most likely hiding places.

The newly discovered planet in Kepler-90, along with one other found in the Kepler-80 solar system announced today, are the first NASA was able to confirm from these new results from Google’s AI.

The inclusion of machine learning in this process shouldn’t scare humans whose livelihood revolves around discovering and studying exoplanets, according to Chris Shallue, a senior Google AI software engineer who worked on the project.

What we’ve developed here is a tool to help astronomers have more impact,” Shallue said on a conference call about the news.

It’s a way to increase the productivity of astronomers. It certainly won’t replace them at all.

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Detecting Magnetic Fields On Brown Dwarfs And Exoplanets

Mysterious objects called brown dwarfs are sometimes called “failed stars.

They are too small to fuse hydrogen in their cores, the way most stars do, but also too large to be classified as planets.

But a new study in the journal Nature suggests they succeed in creating powerful auroral displays, similar to the kind seen around the magnetic poles on Earth.

This is a whole new manifestation of magnetic activity for that kind of object,” said Leon Harding, a technologist at NASA’s Jet Propulsion Laboratory, Pasadena, California, and co-author on the study.

On Earth, auroras are created when charged particles from the solar wind enter our planet’s magnetosphere, a region where Earth’s magnetic field accelerates and sends them toward the poles.

There, they collide with atoms of gas in the atmosphere, resulting in a brilliant display of colors in the sky.




As the electrons spiral down toward the atmosphere, they produce radio emissions, and then when they hit the atmosphere, they excite hydrogen in a process that occurs at Earth and other planets,” said Gregg Hallinan, assistant professor of astronomy at the California Institute of Technology in Pasadena, who led the team.

We now know that this kind of auroral behavior is extending all the way from planets up to brown dwarfs.

Brown dwarfs are generally cool, dim objects, but their auroras are about a million times more powerful than auroras on Earth, and if we could somehow see them, they’d be about a million times brighter, Hallinan said.

Additionally, while green is the dominant color of earthly auroras, a vivid red color would stand out in a brown dwarf’s aurora because of the higher hydrogen content of the object’s atmosphere.

The foundation for this discovery began in the early 2000s, when astronomers began finding radio emissions from brown dwarfs.

This was surprising because brown dwarfs do not generate large flares and charged-particle emissions the way the sun and other kinds of stars do. The cause of these radio emissions was a big question.

Harding, working as part of Hallinan’s group while pursuing his doctoral studies, found that there was also periodic variability in the optical wavelength of light coming from brown dwarfs that pulse at radio frequencies.

He published these findings in the Astrophysical Journal.

Harding built an instrument called an optical high-speed photometer, which looks for changes in the light intensity of celestial objects, to examine this phenomenon.

In this new study, researchers examined brown dwarf LSRJ1835+3259, located about 20 light-years from Earth.

Scientists studied it using some of the world’s most powerful telescopes the National Radio Astronomy Observatory’s Very Large Array, Socorro, New Mexico, and the W.M. Keck Observatory’s telescopes in Hawaii in addition to the Hale Telescope at the Palomar Observatory in California.

Given that there’s no stellar wind to create an aurora on a brown dwarf, researchers are unsure what is generating it on LSRJ1835+3259.

An orbiting planet moving through the magnetosphere of the brown dwarf could be generating a current, but scientists will have to map the aurora to figure out its source.

The discovery reported in the July 30, 2015 issue of Nature could help scientists better understand how brown dwarfs generate magnetic fields.

Additionally, brown dwarfs will help scientists study exoplanets, planets outside our solar system, as the atmosphere of cool brown dwarfs is similar to what astronomers expect to find at many exoplanets.

It’s challenging to study the atmosphere of an exoplanet because there’s often a much brighter star nearby, whose light muddles observations. But we can look at the atmosphere of a brown dwarf without this difficulty,” Hallinan said.

Hallinan also hopes to measure the magnetic field of exoplanets using the newly built Owens Valley Long Wavelength Array, funded by Caltech, JPL, NASA and the National Science Foundation.

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