Posted on by Elizabeth Howell

‘Mega-Earth’ And Doomed Planets Top Today’s Exoplanet Finds

Artist's impression of "mega-Earth" Kepler 10c. Credit: David A. Aguilar (CfA)

Can you imagine a world that is 17 times as massive as Earth, but still rocky? Or two planets that are doomed to be swallowed up by their parent star in just a blink of astronomical time?

While these scenarios sound like science fiction, these are real-life finds released today (June 2) at the American Astronomical Association meeting in Boston.

Here’s a rundown of the finds about these planets in our ever-more-amazing universe.

‘Mega-Earth’ Kepler-10c

Spinning around its star every 45 days is Kepler-10c, which is about 2.3 times as large as Earth but a heavyweight, at 17 times more massive. The planet was discovered by the prolific NASA Kepler space telescope (which was sidelined after a reaction wheel failed last year, but now has been tasked with a new planet-hunting mandate.)

While initially astronomers thought Kepler-10c was a “mini-Neptune”, or a world that is similar to that planet in our solar system, its mass measured by the HARPS-North instrument on the Galileo National Telescope showed it was a rocky world. What’s more, astronomers believe the planet did not “let go” of any atmosphere over time, which implies the planet’s past is similar to what it was today.

Here’s the other neat thing: astronomers found that the system was 11 billion years old, at a time when the universe was young (it was formed 13.7 billion years ago) and the elements needed to make rocky planets were scarce. This implies that rocky planets could have formed earlier than previously thought.

“I was wrong that old stars do not have rocky planets, which has consequences about the Fermi Paradox,” the Harvard-Smithsonian Center for Astrophysics’s (CfA) Dimitar Sasselov said in a webcast press conference today (June 2).  The Fermi Paradox, simply put, refers to the question of why we can’t see civilizations since they are assumed to have spread quite a ways since the universe was formed.

Artist's impression of Kepler-56b being torn apart by its star about 130 million years from today. Its sibling planet, Kepler-56c, will last until 155 million years from now. Credit: David A. Aguilar (CfA)
Artist’s impression of Kepler-56b being torn apart by its star about 130 million years from today. Its sibling planet, Kepler-56c, will last until 155 million years from now. Credit: David A. Aguilar (CfA)

‘We’re doomed!’ Kepler-56b and Kepler-56c

If there was anybody in the vicinity of these two planets, you’d want to move out of the way fairly quickly — at least when talking about astronomical time. Both of these planets, whose orbits are within the equivalent distance of Mercury to the sun, are expected to be swallowed up by their star in 130 million years (for Kepler-56b) and 155 million years (Kepler-56c). It’s the first time two doomed planets have been found in a single system.

“Possibly the core of planet will be left behind and you [will] see this dead corpse floating behind in the universe,” said CfA’s Gongjie Li in the press conference.

There are two factors behind this: the size of the star will enlarge as it gets older (which is typical among stars) and the tidal forces between the planets and their star will also cause them to slow down in their orbits and rip apart. Interestingly enough, another gas giant planet called Kepler-56d will remain safe from most of the chaos since its orbit is equivalent to the asteroid belt in our own solar system.

“Looking at this system is like foreseeing our own solar system,” added Li, referring to the fact that in another five billion years or so our sun will enlarge and swallow Mercury and Venus at the least, boiling off all the oceans on our planet and killing anything left.

Artist's conception of an exoplanet orbiting a red dwarf star. Credit: David A. Aguilar (CfA)
Artist’s conception of an exoplanet orbiting a red dwarf star. Credit: David A. Aguilar (CfA)

Windy City: Why living near a red dwarf might be a bad idea

One fertile ground for exoplanet discoveries — particularly when looking for planets about Earth’s size in the habitable zone — is red dwarfs, because they are smaller and therefore have less light to obscure any rocky worlds orbiting nearby. A new study warns that they could be less friendly to life than previously believed.

CfA’s Ofer Cohen said that red dwarfs can have intense stellar winds, when looking at the model of a known red dwarf with three planets around it: KOI 1422.02, KOI 2626.01, KOI 584.01. Even a magnetic field the size of Earth would not be able to protect the planet from being stripped of its atmosphere assuming a certain intensity of stellar flares.

A member of the audience pointed out that the red dwarf star under study likely has stronger winds than 95% of all red dwarfs, however. Cohen acknowledged that, but added “the main effect is not the stellar activity, but these giants are close to the star.” All the same, this could require a more nuanced understanding of the habitable zone around these stars, he added.

Artist's impression of exoplanets. Credit: J. Jauch
Artist’s impression of exoplanets. Credit: J. Jauch

Heavy metal: Figuring out how much planets have

In astronomical terms, any elements heavier than hydrogen and helium are considered to be “metallic”. Past research found that metal-rich stars tend to have hot Jupiter exoplanets, while the smaller planets have a larger span of metal possibilities.

A team led by CfA’s Lars Buchhave surveyed more than 400 stars with 600 exoplanets, and found that planets smaller than 1.7 times the size of Earth are more likely to be rocky, while those than are 3.9 times the size of Earth or larger are likely gassy.

In between is a zone called “gas dwarfs”, which are planets 1.7 and 3.9 times the size of Earth that likely have hydrogen and helium atmospheres blanketing their surface.

Also intriguing: the researchers discovered that planets far away from their stars can get larger before picking up a lot of gas and becoming a “gas dwarf”, presumably because there isn’t as much gas material out there.

The team also discovered that stars with smaller, Earth-like worlds metallicities like our sun, while stars with “gas dwarfs” have more metals, and stars with gas giants have even more metals. But bear in mind these are for planets close to their host star, which are easiest for Kepler to find. Buchhave plans to do work for planets further away.

The papers for these findings are on arVix: Kepler 10b, habitable planets orbiting M-dwarfs, exoplanets around metal-rich stars.

Posted on by Elizabeth Howell

There Might Be 100 Million Planets In The Galaxy With Complex Life

Artist's impression of complex life on other worlds. Credit: PHL @ UPR Arecibo, NASA, Richard Wheeler @Zephyris

What a multitude of worlds! A new study suggests that the Milky Way could host 100 million planets with complex life, leaving no lack of choice for astronomers to look for organisms beyond Earth. The challenge is, however, that these worlds might be too far away from us to do much yet.

“On the one hand, it seems highly unlikely that we are alone,” stated Louis Irwin, lead author of the study and professor emeritus at the University of Texas at El Paso. “On the other hand, we are likely so far away from life at our level of complexity, that a meeting with such alien forms is extremely improbable for the foreseeable future.”

The figure came from studying a list of more than 1,000 exoplanets for metrics such as their density, temperature, chemistry, age and distance from the parent star. From this, Irwin’s team formulated a “biological complexity index” that ranges between 0 and 1.0. The index is rated on “the number and degree of characteristics assumed to be important for supporting multiple forms of multicellular life,” the research team stated.

Assuming that Europa (a moon of Jupiter believed to have an ocean below its ice) is a good candiate for life, the team estimated that 1% to 2% of exoplanets would have a BCI that is even higher than that. So to translate that into some estimates: 10 billion stars in the Milky Way, averaging one planet a star, which brings us to 100 million planets minimum.

Goldilocks Zone
Artists impression of Gliese 581g. Credit: Lynette Cook/NSF

So what does this metric mean? There’s of course no guarantee that complex life exists in any of these places — just that the conditions could be conducive to life. Also, the researchers added, don’t assume that any life in this category would be intelligent life, but more life that is more complex than a microbe. And the known planets with higher BCIs tend to be pretty far away from us. (One of the closest is the Gliese 581 system, which is 20 light-years away.)

Read more about the research in the journal Challenges. Recall that a few years ago, this group also wrote about an “Earth Similarity Index” rating exoplanets on how close they are to our own.

“Planets with the highest BCI values tend to be larger, warmer, and older than Earth,” added Irwin, “so any search for complex or intelligent life that is restricted just to Earth-like planets, or to life as we know it on Earth, will probably be too restrictive.”

Source: Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo

Posted on by Elizabeth Howell

How Much Can Titan’s Sunsets Teach Us About Alien Planets?

An illustration of a Titanic lake by Ron Miller. All rights reserved. Used with permission.

Titan — that smoggy, orangy moon circling Saturn — is of great interest to exobiologists because its chemistry could be good for life. It has a thick atmosphere of nitrogen and methane and likely has lakes filled with liquid hydrocarbons, and scientists believe there is enough light filtering down into the atmosphere to drive chemical reactions.

It turns out the moon could also be a good analog to help us understand the atmospheres of exoplanets far beyond our solar system. From looking at sunsets on the moon, scientists led by NASA believe that a thick atmosphere could influence how we perceive a planet from afar.

First, a bit of information about how scientists learn about planet atmospheres in the first place. When a distant planet passes in front of its parent star, the light from the star passes through the atmosphere and gets distorted.

The spectra that telescopes pick up can then tell scientists information about what the atmosphere is made of, what temperature it is, and how it is structured. (This science, it should be noted, is in its very early stages and works best on very large exoplanets that are relatively close to Earth, since the planets are so small and far away.)

“Previously, it was unclear exactly how hazes were affecting observations of transiting exoplanets,” stated Tyler Robinson, a postdoctoral research fellow at NASA’s Ames Research Center who led the research. “So we turned to Titan, a hazy world in our own solar system that has been extensively studied by Cassini.”

Titan's surface is almost completely hidden from view by its thick orange "smog" (NASA/JPL-Caltech/SSI. Composite by J. Major)
Titan’s surface is almost completely hidden from view by its thick orange “smog” (NASA/JPL-Caltech/SSI. Composite by J. Major)

To do this, Robinson’s team used data from the Cassini spacecraft during four solar occultations, or times when Titan passed in front of our own sun from the perspective of the spacecraft. They found out that the moon’s hazy atmosphere makes it difficult to figure out what is in its spectra.

“The observations might be able to glean information only from a planet’s upper atmosphere,” NASA stated. “On Titan, that corresponds to about 90 to 190 miles (150 to 300 kilometers) above the moon’s surface, high above the bulk of its dense and complex atmosphere.”

The haze is even more powerful in the shorter (bluer) wavelengths of light, which contradicts previous studies assuming that all wavelengths of light would have the same distortions. Models of exoplanet atmospheres usually have simplified spectra because hazes are complex to model, requiring a lot of computer power.

Researchers hope to take these observations of Titan and then use them to better inform how exoplanet models are created.

The research was published May 26 in the Proceedings of the National Academy of Science.

Source: NASA

Posted on by Jason Major

Will We Find Alien Life Within 20 Years? You Can Bet On It.

SETI's Allen Telescope Array monitor the stars for signs of intelligent life (SETI.org)

During a hearing last week before the U.S. House Science and Technology Committee SETI scientists Seth Shostak and Dan Werthimer asserted that solid evidence for extraterrestrial life in our galaxy — or, at the very least, solid evidence for a definitive lack of it — will come within the next two decades. It’s a bold claim for scientists to make on public record, but one that Shostak has made many times before (and he’s not particularly off-schedule either.) And with SETI’s Allen Telescope Array (ATA) continually scanning the sky for any signals that appear intentional, exoplanets being discovered en masse, and new technology on deck that can further investigate a select few of their (hopefully) Earth-like atmospheres, the chances that alien life — if it’s out there — will be found are getting better and better each year.

Would you put your bet on E.T. being out there? Actually, you can.

Thanks to the internet and the apparently incorrigible human need to compete you can actually place a wager on when alien life will be discovered, via an Irish online betting site.

Illustration of Kepler-186f, a recently-discovered, possibly Earthlike exoplanet that could be a host to life. (NASA Ames, SETI Institute, JPL-Caltech, T. Pyle)
Illustration of Kepler-186f, a recently-discovered, possibly Earthlike exoplanet that could be a host to life. (NASA Ames, SETI Institute, JPL-Caltech, T. Pyle)

Typically focused on the results of international sporting matches, PaddyPower.com has also included the announcement of extraterrestrial life in its novelty bet section, hinging on “the sitting President of the USA making a statement confirming without doubt the existence of alternative life beings from another planet.” The odds of such an announcement being made in the years 2015-2018 are currently listed at 100 to one. After that they drop significantly… probably because by then the JWST will be in operation and we will “have the technology.” Stranieri.com also has offered a chance for Italian players of chance to bet on the sitting president discussing life from other planets, with betting open until 2025 for long-term gamblers!

Of course, whether you personally would place a wager on such things is purely personal preference, and neither I nor Universe Today condones or supports gambling, for aliens or otherwise. (And the legalities of doing so and any and all results thereof are the sole responsibility of the reader.) But it is interesting that we now live in a time when wagering on the discovery of alien life sits just a click away from the results of the Kentucky Derby, French Open, or World Cup.

Now if you really want to support the science that will make such a discovery possible — maybe even within our own Solar System — you can “stand up for space” and write your representatives to tell them you want NASA’s planetary science budget to be funded, and rather than gamble your money you can make a donation to support SETI’s ongoing mission here (or even help out yourself via SETI@home.)

And even if all else fails, you could end up with a free coffee courtesy of Dr. Shostak…

Learn more about SETI and how the ATA works here, and read Dan Werthimer’s May 21 statement to the House Committee here.

Source/ht: FloridaToday Space and The Independent

“Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.”

– Arthur C. Clarke

Posted on by Elizabeth Howell

Kepler Space Telescope Gets A New Exoplanet-Hunting Mission

Artist's conception of the Kepler Space Telescope. Credit: NASA/JPL-Caltech

After several months with their telescope on the sidelines, the Kepler space telescope team has happy news to report: the exoplanet hunter is going to do a new mission that will compensate for the failure that stopped its original work.

Kepler’s exoplanet days were halted last year when the second of its four reaction wheels (pointing devices) failed, which meant the telescope could not gaze at its “field” of stars in the Cygnus constellation for signs of exoplanets transiting their stars.

Results of a NASA Senior Review today, however, showed that the telescope will receive the funding for the K2 mission, which allows for some exoplanet hunting, among other tasks. The telescope will essentially change positions several times a year to do its new mission, which is funded through 2016.

“The approval provides two years of funding for the K2 mission to continue exoplanet discovery, and introduces new scientific observation opportunities to observe notable star clusters, young and old stars, active galaxies and supernovae,” wrote Charlie Sobeck, the mission manager for Kepler, in a mission update today (May 16).

Artist’s rendering of the Earth-sized Kepler-186f (Credit: NASA Ames/SETI Institute/Caltech)
Artist’s rendering of the Earth-sized Kepler-186f (Credit: NASA Ames/SETI Institute/Caltech)

“The team is currently finishing up an end-to-end shakedown of this approach with a full-length campaign (Campaign 0), and is preparing for Campaign 1, the first K2 science observation run, scheduled to begin May 30.”

While Kepler itself was not being used for planet hunting, scientific discoveries continue because the telescope has a legacy of observations stretching between 2009 and 2013. One notable find: 715 exoplanets were announced in one swoop earlier this year using a new technique called “verification by multiplicity”, which is useful in multiple-planet systems.

Kepler also spotted the first known Earth-sized planet in a habitable zone outside of our solar system, which achieves the mission’s stated goal of finding extrasolar Earths.

Read more about NASA’s 2014 senior science review at this website.

Posted on by David Dickinson

Direct Image of an Exoplanet 155 Light Years Away

Credit

Chalk up another benchmark in the fascinating and growing menagerie of extra-solar planets.

This week, an international team of researchers from the Université de Montréal announced the discovery of an exoplanet around the star GU Piscium in the constellation of Pisces the Fishes 155 light years distant. Known as GU Psc b, this world is estimated to be 11 times the mass of Jupiter — placing it just under the lower mass limit for brown dwarf status — and orbits its host star 2,000x farther than the distance from Earth to the Sun once every 80,000 (!) years. In our own solar system, that would put GU Psc b out over twice the distance of the aphelion of 90377 Sedna.

The primary star, GU Psc A, is an M3 red dwarf weighing in at 35% the mass of our Sun and is just 100 million years old, give or take 30 million years. In fact, researchers targeted GU Psc after it was determined to be a member of the AB Doradus moving group of relatively young stars, which are prime candidates for exoplanet detection. Another recent notable discovery, the free-floating “rogue planet” CFBDSIR 2149-0403 is also thought to be a member of the AB Doradus moving group.

The fact that GU Psc B was captured by direct imaging at 155 light years distant is amazing. The international team that made the discovery was led by PhD student at the Department of Physics Université de Montréal  Marie-Ève Naud. The team was able to discern this curious planet by utilizing observations from the W.M. Keck observatory, the joint Canada-France-Hawaii Telescope, the Gemini Observatory and the Observatoire Mont-Mégantic in Québec.

Credit
An artist’s conception of the forlorn world of GU Psc b. Credit– Lucas Granito.

Universe Today recently caught up with researcher Marie-Ève Naud and her co-advisor Étienne Artigau about this exciting discovery.

What makes this discovery distinctive? Is this the most distant exoplanet ever imaged?

“Well, first, there are not a lot of exoplanets that were detected ‘directly’ so far. Most were found indirectly through the effect they have on their parent star. The few planets for which we have an actual image are interesting because we can analyze their light directly, and thus learn much more about them. It was also one of the “coolest” planets that have been directly imaged, showing methane absorption. And yes, it is certainly the most distant exoplanet to a main-sequence star that has been found so far.

This distance makes GU Psc b very interesting from a theoretical point of view, because it’s hard to imagine how it could have formed in the protoplanetary disk of its star. The current working definition of an exoplanet is based solely on mass (<13 Jupiter masses), so GU Psc b probably formed in a way that is more similar to how stars formed. It is definitely the kind of object that makes us think about what exactly is an exoplanet.”   

At a distance of 2000 A.U.s from its primary, how are astronomers certain that PU Psc b is related to its host and not a foreground or background object?

“As the host star, GU Psc is relatively nearby; it displays a significant apparent proper motion (note: around 100 milliarcseconds a year) relative to distant background stars and galaxies.

On images taken one year apart with WIRCam on the Canada-France-Hawaii Telescope, we observed that the companion displays the same big proper motion, i.e. they move together in the plane of the sky, while the rest of the stars in the field don’t. We also determined the distance of the both the planet and the host star, and they both agree. Also, they both display signs that they are very young.”

Were any groundbreaking techniques used for the discovery, and what does this mean for the future of exoplanet science?

“Quite the opposite… most planet hunting techniques using direct imaging involve state-of-the-art adaptive optics systems, but we used ‘standard’ imaging without any exotic techniques. Planet searches usually attempt to find planets in orbits similar to those of our own solar system giants, and finding these objects, indeed, requires groundbreaking techniques. In a sense, there is an anthropocentric bias in the searches for exoplanets, as people tend to look for systems that are similar to our own solar system. Very distant planets like GU Psc b have been under the radar, even though they are easier to find than their closer-in counterparts. To find this planet, we used very sensitive ‘standard’ imaging, but we chose carefully the wavelengths where planets display colors that are unlike most other astrophysical objects such as stars and galaxies.”    

The general field of PU Piscium A & B in the night sky... note that this currently puts it in the dawn sky, near Venus and Uranus! Credit: Starry Night.
The general field of GU Piscium A & B in the night sky… note that this currently puts it in the dawn sky, near Venus and Uranus! Credit: Starry Night.

GU Piscium shines at magnitude +13.6 northeast of the March equinoctial point in the constellation of Pisces. Although its exoplanet companion is too faint to be seen with a backyard telescope, its angular separation is a generous 42,” about the apparent span of Saturn, complete with rings. And it’s shaping up to be a red dwarf sort of week at Universe Today, with our recent list of red dwarf stars for backyard telescopes. And the current tally for extra-solar planets sits at 1,791… hey; didn’t we just pass 1,000 last year?

Congrats to Marie-Ève Naud and her team on this exciting new discovery… and here’s to many more to come!

Read the original paper, Discovery of a Wide Planetary-Mass Companion to the Young M3 Star GU Psc.

Posted on by David Dickinson

14 Red Dwarf Stars to View with Backyard Telescopes

An artist's conception of a red dwarf solar system. Credit: NASA/JPL-Caltech.

They’re nearby, they’re common and — at least in the latest exoplanet newsflashes hot off the cyber-press — they’re hot. We’re talking about red dwarf stars, those “salt of the galaxy” stars that litter the Milky Way. And while it’s true that there are more of “them” than there are of “us,” not a single one is bright enough to be seen with the naked eye from the skies of Earth.

A reader recently brought up an engaging discussion of what red dwarfs might be within reach of a backyard telescope, and thus this handy compilation was born.

Of course, red dwarfs are big news as possible hosts for life-bearing planets. Though the habitable zones around these stars would be very close in, these miserly stars will shine for trillions of years, giving evolution plenty of opportunity to do its thing. These stars are, however, tempestuous in nature, throwing out potentially planet sterilizing flares.

Red dwarf stars range from about 7.5% the mass of our Sun up to 50%. Our Sun is very nearly equivalent 1000 Jupiters in mass, thus the range of red dwarf stars runs right about from 75 to 500 Jupiter masses.

For this list, we considered red dwarf stars brighter than +10th magnitude, with the single exception of 40 Eridani C as noted.

The closest stars within 14 light years of our solar system. Credit: Wikimedia Commons, Public Domain graphic.
The closest stars within 14 light years of our solar system. Credit: Wikimedia Commons, Public Domain graphic.

I know what you’re thinking…  what about the closest? At magnitude +11, Proxima Centauri in the Alpha Centauri triple star system 4.7 light years distant didn’t quite make the cut. Barnard’s Star (see below) is the closest in this regard. Interestingly, the brown dwarf pair Luhman 16 was discovered just last year at 6.6 light years distant.

Also, do not confuse red dwarfs with massive carbon stars. In fact, red dwarfs actually appear to have more of an orange hue visually! Still, with the wealth of artist’s conceptions (see above) out there, we’re probably stuck with the idea of crimson looking red dwarf stars for some time to come.

 

Star Magnitude Constellation R.A. Dec
Groombridge 34 +8/11(v) Andromeda 00h 18’ +44 01’
40 Eridani C +11 Eridanus 04h 15’ -07 39’
AX Microscopii/Lacaille 8760 +6.7 Microscopium 21h 17’ -38 52’
Barnard’s Star +9.5 Ophiuchus 17h 58’ +04 42’
Kapteyn’s Star +8.9 Pictor 05h 12’ -45 01’
Lalande 21185 +7.5 Ursa Major 11h 03’ +35 58’
Lacaille 9352 +7.3 Piscis Austrinus 23h 06’ -35 51’
Struve 2398 +9.0 Draco 18h 43’ +59 37’
Luyten’s Star +9.9 Canis Minor 07h 27’ +05 14’
Gliese 687 +9.2 Draco 17h 36’ +68 20’
Gliese 674 +9.9 Ara 17h 29’ -46 54’
Gliese 412 +8.7 Ursa Major 11h 05’ +43 32’
AD Leonis +9.3 Leo 10h 20’ +19 52’
Gliese 832 +8.7 Grus 21h 34’ -49 01’

 

Notes on each:

Groombridge 34: Located less than a degree from the +6th magnitude star 26 Andromedae in the general region of the famous galaxy M31, Groombridge 34 was discovered back in 1860 and has a large proper motion of 2.9″ arc seconds per year.

Locating Groombridge 34. Created using Stellarium.
Locating Groombridge 34. Created using Stellarium.

40 Eridani C:  Our sole exception to the “10th magnitude or brighter” rule for this list, this multiple system is unique for containing a white dwarf, red dwarf and a main sequence K-type star all within range of a backyard telescope.  In sci-fi mythos, 40 Eridani is also the host star for the planet Richese in Dune and the controversial location for Vulcan of Star Trek fame.

Locating 40 Eridani. Created using Stellarium.
Locating 40 Eridani. Created using Stellarium.

AX Microscopii: Also known as Lacaille 8760, AX Microscopii is 12.9 light years distant and is the brightest red dwarf as seen from the Earth at just below naked eye visibility at magnitude +6.7.

A 20 year animation showing the proper motion of Barnard's Star. Credit: Steve Quirk, images in the Public Domain.
A 20 year animation showing the proper motion of Barnard’s Star. Credit: Steve Quirk, images in the Public Domain.

Barnard’s Star: the second closest star system to our solar system next to Alpha Centuari and the closest solitary red dwarf star at six light years distant, Barnard’s Star also exhibits the highest proper motion of any star at 10.3” arc seconds per year. The center of many controversial exoplanet claims in the 20th century, it’s kind of a cosmic irony that in this era of 1790 exoplanets and counting, planets have yet to be discovered around Barnard’s Star!

Kapteyn’s Star: Discovered by Jacobus Kapteyn in 1898, this red dwarf orbits the galaxy in a retrograde motion and is the closest halo star to us at 12.76 light years distant.

Lalande 21185: currently 8.3 light years away, Lalande 21185 will pass 4.65 light years from Earth and be visible to the naked eye in just under 20,000 years.

Lacaille 9352: 10.7 light years distant, this was the first red dwarf star to have its angular diameter measured by the VLT interferometer in 2001.

Struve 2398: A binary flare star system consisting of two +9th magnitude red dwarfs orbiting each other 56 astronomical units apart and 11.5 light years distant.

Luyten’s Star: 12.36 light years distant, this star is only 1.2 light years from the bright star Procyon, which would appear brighter than Venus for any planet orbiting Luyten’s Star.

Gliese 687: 15 light years distant, Gliese 687 is known to have a Neptune-mass planet in a 38 day orbit.

Gliese 674: Located 15 light years distant, ESO’s HARPS spectrograph detected a companion 12 times the mass of Jupiter that is either a high mass exoplanet or a low mass brown dwarf.

Gliese 412: 16 light years distant, this system also contains a +15th magnitude secondary companion 190 Astronomical Units from its primary.

AD Leonis: A variable flare star in the constellation Leo about 16 light years distant.

Gliese 832: Located 16 light years distant, this star is known to have a 0.6x Jupiter mass exoplanet in a 3,416 day orbit.

The closest stars to our solar system over the next 80,000 years. Credit: FrancescoA under a Creative Commons Attribution Share-Alike 3.0 Unported license.
The closest stars to our solar system over the next 80,000 years. Credit: FrancescoA under a Creative Commons Attribution Share-Alike 3.0 Unported license.

Consider this list a teaser, a telescopic appetizer for a curious class of often overlooked objects. Don’t see you fave on the list? Want to see more on individual objects, or similar lists of quasars, white dwarfs, etc in the range of backyard telescopes in the future? Let us know. And while it’s true that such stars may not have a splashy appearance in the eyepiece, part of the fun comes from knowing what you’re seeing. Some of these stars have a relatively high proper motion, and it would be an interesting challenge for a backyard astrophotographer to build an animation of this over a period of years. Hey, I’m just throwing that out project out there, we’ve got lots more in the files…

 

 

 

 

Posted on by Elizabeth Howell

Spin! Exoplanet’s Day Finishes Blazing Fast Compared To Earth

Artist's impression of Beta Pictoris b. Credit: ESO L. Calçada/N. Risinger (skysurvey.org)

Between the time you got to work this morning and the time you leave today — assuming an eight-hour work cycle — an entire day will have passed on Beta Pictoris b, according to new measurements of the exoplanet.

This daily cycle, mapped for the first time on a planet outside of the solar system, may reveal a link between how big a planet is and how fast it rotates, astronomers stated. That said, caution is needed because there are only a handful of planets where the rotation is known: the eight planets of our Solar System and Beta Pictoris b.

The planet’s day is shorter than any other planet in our Solar System, which at first blush makes sense because the planet is also larger than any other planet in our Solar System. Beta Pictoris b is estimated at 16 times larger and 3,000 times more massive than Earth. (For comparison, Jupiter is about 11 times larger and 318 times more massive than Earth.)

“It is not known why some planets spin fast and others more slowly,” stated says co-author Remco de Kok, “but this first measurement of an exoplanet’s rotation shows that the trend seen in the Solar System, where the more massive planets spin faster, also holds true for exoplanets. This must be some universal consequence of the way planets form.”

Planets in our Solar system size comparison. Largest to smallest are pictured left to right, top to bottom: Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury. Via Wikimedia Commons.
Planets in our Solar system size comparison.
Largest to smallest are pictured left to right, top to bottom: Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury. Via Wikimedia Commons.

Astronomers mapped the planet’s equatorial rotation using the CRIRES instrument on the Very Large Telescope. What helped was not only the planet’s large size, but also its proximity to Earth: it’s about 63 light-years away, which is relatively close to us.

As the planet ages (it’s only 20 million years old right now) it is expected to shrink and spin more quickly, assuming no other external forces. The Earth’s rotation is slowed by the moon, for example.

The study (“Fast spin of a young extrasolar planet” will soon be up on Nature’s website and was led by Leiden University’s Ignas Snellen.

Source: European Southern Observatory 

Posted on by Elizabeth Howell

What Steps Are Needed To Find More Earths?

Artist's rendering of Kepler-186f (Credit: NASA Ames/SETI Institute/Caltech)

It wasn’t so long ago that we found out there is an Earth-sized planet in a habitable zone of a star. But how many others are out there, and do we know if planets like this are truly habitable?

“Looking towards the future, what we really want to do eventually is transform our knowledge from planets in the habitable zone to [characterizing] planetary environments,” said Natalie Batalha, a co-investigator on NASA’s Kepler Space Telescope, in a webcast presentation today (April 28) .

This means that astronomers will be able to, from a distance, look at “biosignatures” of life in the atmosphere. What a biosignature would be is still being characterized, but it could be something like an unusually high proportion of oxygen — as long as abiotic processes are not accounted for, of course.

Batalha identified these parameters for finding other Earths in a presentation at the “Habitable Worlds Across Time and Space” conference presented by the Space Telescope Science Institute:

Detections of planets: other telescopes (left) vs. Kepler. Credit: Natalie Batalha / NASA (screenshot)
Detections of planets in the habitable zone: other telescopes (left) vs. the Kepler space telescope. Credit: Natalie Batalha / NASA (screenshot)

– The telescope must be sensitive to an Earth-sized planet in the habitable zone of a G, K or M-type star (which are stars that are like the sun);

– A uniform and reliable detection catalog with well-understood sizes, orbital periods and insolation fluxes (energy received from the sun);

– Knowledge of Kepler’s detection efficiency and the planetary catalog’s reliability;

– Well-documented and accessible data products for other community members to analyze.

What would also be helpful to planetary scientists is learning more about how a planet forms in the habitable region of its star.

Meet Kepler-22b, an exoplanet with an Earth-like radius in the habitable zone of its host star. Unfortunately its mass remains unknown. Image Credit: NASA
Meet Kepler-22b, an exoplanet with an Earth-like radius in the habitable zone of its host star. Unfortunately its mass remains unknown. Image Credit: NASA

In a presentation at the same conference, the University of Toronto’s Diana Valencia (an astrophysicist) pointed out there is no single predictor for how large a planet will get. It depends on how close a planetesimal disc is to its star, the rate of accretion in the area and dust opacity, among other factors.

She also gave a brief overview of processes that demonstrate how hard it is to predict habitability. Earth had at least two atmospheres in its past, presentation slides said, with the first atmosphere lost and the second built from volcanism and impacts. Valencia also pointed to complexities involving the Earth’s mantle and plate tectonics.

The University of Puerto Rico keeps a list of potentially habitable planets on its website, which as of this writing stands at 21.

The conference runs through May 1, and you can see the agenda here.

Posted on by Nancy Atkinson

Take a Fly-by Of All the Known Exoplanets

This bubble chart shows the relative sizes of all discovered planets. The color corresponds to the mean equilibrium temperature of the planet. Click to interact on the Open Exoplanet Catalogue website.

Here’s a fun trip through the galaxy, put together by PhD student Tom Hands at the University of Leicester: In the above video, you can fly to of all the known exoplanets (around single stars only), ordered roughly by semi-major axis of largest orbit. Hands said the video is designed to give the viewer an overview of the current distribution of exoplanets.

Hands used data from the Open Exoplanet Catalogue.