Amateur Astronomer Chases Down Barnard’s Star – You Can Too!

It now covers 9 years (9 animation frames) from 2007 to 2015 (July). Nothing much has changed but for its location keeps moving north. For those looking to find it visually the arrowhead asterism to the south seen in the full frame image which is about a half degree wide and a third of a degree high. so fits a medium power telescope field of view. The galaxy near the bottom of the image is CGCG 056-003, a 15.6 magnitude galaxy some 360 million light-years distant and 85,000 light-years across. Credit: Rick Johnson

Tucked away in northern Ophiuchus and well-placed for observing from spring through fall is one of the most remarkable objects in the sky — Barnard’s Star.  A magnitude +9.5 red dwarf wouldn’t normally catch our attention were it not for the fact that it speeds across the sky faster than any other star known.

Incredibly, you can actually see its motion with a small telescope simply by dropping by once a year for 2-3 years and taking note of its position against the background stars. For one amateur astronomer, recording its wandering ways became a 9-year mission.

This map shows the sky facing southeast around 10:30 p.m. local time in early June. Barnard's Star is located 1° NW of the 4.8-magnitude star 66 Ophiuchi on the northern fringe of the loose open cluster Melotte 186. Source: Stellarium
This map shows the sky facing south-southwest around 9 o’clock local time in late September. Barnard’s Star is located 1° NW of the 4.8-magnitude star 66 Ophiuchi on the northern fringe of the loose open cluster Melotte 186. Use the more detailed map below to pinpoint the star’s location. Source: Stellarium

Located just 6 light years from Earth, making it the closest star beyond the Sun except for the Alpha Centauri system, Barnard’s Star dashes along at 10.3 arc seconds a year. OK, that doesn’t sound like much, but over the course of a human lifetime it moves a quarter of a degree or half a Full Moon, a distance large enough to be easily perceived with the naked eye.

Barnard's Star would be an undistinguished red dwarf in Ophiuchus were it not for its rapid motion across the sky. It measures 1.9 times Jupiter's diameter and lies only 6 light-years from Eart
Barnard’s Star is a very low mass red dwarf star 1.9 times Jupiter’s diameter only 6 light-years from Earth in the direction of the constellation Ophiuchus the Serpent Bearer. Credit: Wikipedia with additions by the author

This fleet-footed luminary was first spotted by the American astronomer E.E. Barnard in 1916. With a proper motion even greater than the triple star Alpha Centauri, we’ve since learned that the star’s speed is truly phenomenal; it zips along at 86 miles a second (139 km/sec) relative to the Sun. As the stellar dwarf moves north, it’s simultaneously headed in our direction.

Based on its high velocity and low “metal” content, Barnard’s Star is believed to be a member of the galactic bulge, a fastness of ancient stars formed early on in the Milky Way galaxy’s evolution. Metals in astronomy refer to elements heavier than hydrogen and helium, the fundamental building blocks of stars. That’s pretty much all that was around when the first generation of suns formed about 100 million years after the Big Bang.

Generally, the lower a star’s metal content, the more ancient it is as earlier generations only had the simplest elements on hand. More complex elements like lithium, carbon, oxygen and all the rest had to be cooked up the earliest stars’ interiors and then released in supernovae explosions where they later became incorporated in metal-rich stars like our Sun.

All this to say that Barnard’s Star is an interloper, a visitor from another realm of the galaxy here to take us on a journey across the years. It certainly got the attention of Lincoln, Nebraska amateur Rick Johnson, who first learned of the famous dwarf in 1957.

Close-up map showing Barnard's Star's northward march every 5 years from 2015 to 2030. Your guide star, 66 Ophiuchi, is at lower left. Stars are numbered with magnitudes and a 15? scale bar is at lower right. North is up. The line through the two 12th-magnitude stars will help you gauge Barnard's movement. Click for larger map.
Close-up map showing Barnard’s Star’s position every 5 years from 2015 to 2030. Your guide star, 66 Ophiuchi, also shown on the first map, is at lower left. Stars are numbered with magnitudes and a 15 arc minute scale bar is at lower right. North is up. The line through the two 12th-magnitude stars will help you gauge Barnard’s movement in the coming few years. Click for a larger map.

“One of the first things I imaged was Barnard’s Star on the off chance I could see its motion,” wrote Johnson, who used a cheap 400mm lens on a homemade tracking mount. “Taking it a couple months later didn’t show any obvious motion, though I thought I saw it move slightly.  So I took another image the following year and the motion was obvious.”

Many years later in 2005, Johnson moved to very dark skies, upgraded his equipment and purchased a good digital camera. Barnard’s Star continued to tug at his mind.

“Again one of my first thoughts was Barnard’s Star.  The idea of an animation however didn’t hit until later, so my exposure times were all over the map.  This made the first frames hard to match.” Later, he standardized the exposures and then assembled the individual images into a color animation.

This diagram illustrates the locations of the star systems closest to the sun. The year when the distance to each system was determined is listed after the system's name. NASA's Wide-field Infrared Survey Explorer, or WISE, found two of the four closest systems: the binary brown dwarf WISE 1049-5319 and the brown dwarf WISE J085510.83-071442.5. NASA's Spitzer Space Telescope helped pin down the location of the latter object. The closest system to the sun is a trio of stars that consists of Alpha Centauri, a close companion to it and Proxima Centauri. Credit: NASA / Penn State
This diagram illustrates the locations of the star systems closest to the Sun along with the dates of discovery. NASA’s Wide-field Infrared Survey Explorer, or WISE, found two of the four closest systems: the binary brown dwarf WISE 1049-5319 and the brown dwarf WISE J085510.83-071442.5. The closest system to the Sun is a trio of stars that consists of Alpha Centauri, a close companion to it and Proxima Centauri. Credit: NASA / Penn State

“Now the system is programed to take it each July,” he added. I’m automated, so its all automatic now.” Johnson said the Barnard video is his most popular of many he’s made over the years including short animations of the eye-catching Comet C/2006 M4 SWAN and Near-Earth asteroid 2005 YU55.

With Johnson’s wonderful animation in your mind’s eye, I encourage you to use the maps provided to track down the star yourself the next clear night. To find it, first locate 66 Ophiuchi (mag. 4.8) just above the little triangle of 4th magnitude stars a short distance east or left of Beta Ophiuchi. Then use the detailed map to star hop ~1° to the northwest to Barnard’s Star.

Barnard's Star is one of our galaxy's ancient ones with age of somewhere between 7 and 12 billion years
Barnard’s Star, a red dwarf low in metals,  is very ancient with an age between 7 and 12 billion years. Like people, older stars slow down and Barnard’s is no exception with a rotation rate of 150 days. Heading in the Sun’s direction, the star will come closest to our Solar System around the year 11,800 A.D. at a distance of just 3.75 light years. Credit: NASA

It’s easily visible in a 3-inch or larger telescope. Use as high a magnification as conditions will allow to make a sketch of the star’s current position, showing it in relation to nearby field stars. Or take a photograph. Next summer, when you return to the field, sketch it again. If you’ve taken the time to accurately note the star’s position, you might see motion in just a year. If not, be patient and return the following year.

Most stars are too far away for us to detect motion either with the naked eye or telescope in our lifetime. Barnard’s presents a rare opportunity to witness the grand cycling of stars around the galaxy otherwise denied our short lives. Chase it.

When Will We Find Another Earth?

When Will We Find Another Earth?

We hear about discoveries of exoplanets every day. So how long will it take us to find another planet like Earth?

Back in the olden days, astronomers could only guess if there were planets orbiting other stars.

These were the days when we had to wait at the bank to pay our bills, nobody carried computers in their pockets and those computers gave direct connections to everyone else’s pockets because pocket connectivity is highly important, school was uphill both ways, the number 6 was brand new, we recorded images on thin sheets of transparent plastic, 5 bees were worth a quarter and I had an onion tied to my belt, as was the style at the time.

With the discovery of a mega Jupiter-sized world orbiting the star 51 Pegasi in 1995, the floodgates opened up. In the years that followed, dozens more planets were discovered. Then hundreds, and now, we know about thousands orbiting other stars.

The bad news is we can’t get to any of them. The good news is most of these worlds suck. You don’t want any part of them. For starters their wifi is terrible.

Consider Kepler-70b. This world orbits its star 4 times in a 24 hour period. This means it’s super close, and a great place to really quickly win all the human torch cosplay competitions. The surface temperature is a completely unreasonable 7200 Kelvin, hotter than the surface temperature of the Sun.

There’s the planets orbiting pulsar PSR B1257+12, a millisecond pulsar in the constellation of Virgo. As they whip around their exotic host, they’re bathed in intense radiation. Which is generally considered bad for creatures who need functioning organs.

Perhaps HD 106906 b, orbiting its star 650 times more distantly than we orbit the Sun. You’d spend every second of your short life on that planet inventing new words for cold. And then you’d die. Cold.

Imagine a world that orbits a star like our Sun. A world made of about an Earth’s worth of rocky material that you could stand on, at just the right distance from its star that water can exist as a liquid.

This is what astronomers search for, the tri-wizard cup of extrasolar planetary research. Earth 2? Terra Nova? The Gaia part le deux.

Here’s the exciting part. Astronomers have found each of these characteristics in a planet, but never all together. They’ve found plenty of stars similar to our Sun, with planets orbiting them. In fact, the star HD 10180 is incredibly similar to the Sun, and astronomers have discovered 9 planets orbiting it so far. Which does have a familiar ring to it. No word so far on which ones are about to be demoted to dwarf planets.

Sizes and temperatures of Kepler discoveries compared to Earth and Jupiter
Sizes and temperatures of Kepler discoveries compared to Earth and Jupiter

They’ve found planets roughly the same mass as the Earth. Kepler-89, with 98% the mass of the Earth. So close! Sadly, it’s way too close to its parent hydrogen furnace to be habitable.

They’ve found planets in the habitable zone. Here on Earth, the global average temperature is -18 degrees C. Sounds cold, but the wintery nights in Antarctica absolutely wreck our GPA.

The closest analog discovered is Kepler-22b, with a global average temperature of -11C. So, it should feel downright balmy. Except, it’s about 2.4 times bigger than Earth and orbits a nasty red dwarf star.

Astronomers have even matched up two criteria at the same time. Earth-sized world orbiting around a Sun-like star, but it’s hellishly hot. Wrong flavor star but with the right temperature and size, it’s a veritable tic tac toe board of near wins.

So far, there hasn’t been a single extrasolar planet discovered that meets all three criteria. An Earth-sized world, orbiting a Sun-like star inside the habitable zone where liquid water could be present.

Astronomers were hoping that NASA’s Kepler spacecraft would have been the first to discover Earth 2.0. It had already turned up thousands of planets, including many of the ones I’ve already mentioned.

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

Sadly, just a few years into the mission, it lost too many reaction wheels, which allow the spacecraft to change direction. It wasn’t able to make enough observations to help confirm a true Earth 2.0. Kepler is still searching for planets, but with a reduced ability to point, it’s only looking at red dwarf stars.

Don’t worry, NASA’s Transiting Exoplanet Survey Satellite will launch in 2017, and will survey a region of the sky 400 times larger than Kepler did. It should turn up thousands of planets, Earth-sized and larger.

Once we actually find New Terra, things get really interesting. Astronomers will search those planets for life. I know it sounds almost impossible to see life from this distance, but astronomers know that if they can analyze the atmosphere of these worlds, they can detect life flourishing there.

They might even be able to detect the pollution from their alien cars and heavy industry, contributing to their CO2 levels, and learn we’re not so different after all. Even if they’re icky bug people.

At the time I’m recording this video, no analog Earth planet has been discovered so far. But it’s just a matter of time. In the next few decades astronomers are going to find that first Earth 2.0, and then dozens, then hundreds, and even figure out which ones have life on them.

It’s a great time to be alive. Place your bets. Predict the date astronomers announce that we’ll find Earth 2.0. Put your guess into the comments below.

What is the Smallest Star?

What is the Smallest Star?

We’ve talked about the biggest stars, but what about the smallest stars? What’s the smallest star you can see with your own eyes, and how small can they get?

Space and astronomy is always flaunting its size issues. Biggest star, hugest nebula, prettiest most talented massive galaxy, most infinite universe, and which comet came out on top in the bikini category. Blah blah blah.

In an effort to balance the scales a little we’re going look at the other end of the spectrum. Today we’re talking small stars. First, I’m going to get the Gary Coleman and Emmanuel Lewis joke out of the way, so we can start talking about adorable little teeny tiny fusion factories.

We get big stars when we’ve got many times the mass of the Sun’s worth of hydrogen in one spot. Unsurprisingly, to get smaller stars we’ll need less hydrogen, but there’s a line we can’t cross where there’s so little, that it won’t generate the temperature and pressure at its core to ignite solar fusion. Then it’s a blob, it’s a mess. It’s clean-up in aisle Andromeda. It’s who didn’t put the lid back on the jar marked H.

So how small can stars get? And what’s the smallest star we know about? In the traditional sense, a star is an object that has enough mass and pressure in its core that it can ignite fusion, crushing atoms of hydrogen into helium.

Fusion is exothermic, releasing energy. It’s this energy that counteracts the force of gravity pulling everything inward. That gives you the size of the star and keeps it from collapsing in on itself.

By some random coincidence and fluke of nature our Sun is exactly 1 solar mass. Actually, that’s not true at all, our shame is that we use our Sun as the measuring stick for other stars. This might be the root of this size business. We’re in an endless star measuring contest, with whose is the most massive and whose has the largest circumference?

So, as it turns out, you can still have fusion reactions within a star if you get all the way down to 7.5% of a solar mass. This is the version you know as a red dwarf. We haven’t had a chance to measure many red dwarf stars, but the nearest star, Proxima Centauri, has about 12.3% the mass of the Sun and measures only 200,000 kilometers across. In other words, the smallest possible red dwarf would only be about 50% larger than Jupiter.

There is an important distinction, this red dwarf star would have about EIGHTY times the mass of Jupiter. I know that sounds crazy, but when you pile on more hydrogen, it doesn’t make the star that much bigger. It only makes it denser as the gravity pulls the star together more and more.

At the time I’m recording this video, this is smallest known star at 9% the mass of the Sun, just a smidge over the smallest theoretical size.

X-Ray image of Proxima Centauri. Image credit: Chandra
X-Ray image of Proxima Centauri. Image credit: Chandra

Proxima Centauri is about 12% of a solar mass, and the closest star to Earth, after the Sun. But it’s much too dim to be seen without a telescope. In fact, no red dwarfs are visible with the unaided eye. The smallest star you can see is 61 Cygni, a binary pair with one star getting only 66% the size of the Sun. It’s only 11.4 light years away, and you can just barely see it in dark skies. After that it’s Spock’s home, Epsilon Eridani, with 74% the size of the Sun, then Alpha Centauri B with 87%, and then the Sun. So, here’s your new nerd party fact. The Sun is the 4th smallest star you can see with your own eyes. All the other stars you can see are much bigger than the Sun. They’re all gigantic terrifying monsters.

And in the end, our Sun is absolutely huge compared to the smallest stars out there. We here like to think of our Sun as perfectly adequate for our needs, it’s ours and all life on Earth is there because of it. It’s exactly the right size for us. So don’t you worry for one second about all those other big stars out there.

And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!

Foom! ‘Superflares’ Erupt From Tiny Red Dwarf Star, Surprising Scientists

Artist's impression of a flare erupting from binary star sytem DG CVn. Credit: NASA's Goddard Space Flight Center/S. Wiessinger

Don’t get too close to this little star! In April, a red dwarf star sent out a series of explosions that peaked at 10,000 times as powerful as the largest solar flare ever recorded.

The tiny star packs a powerful punch because its spin is so quick: it rotates in less than a day, or 30 times faster than the Sun does. Astronomers believe that in the distant past, when the Sun was young, it also was a fast turner — and could have produced “superflares”, as NASA terms the explosions, of its own.

“We used to think major flaring episodes from red dwarfs lasted no more than a day, but Swift detected at least seven powerful eruptions over a period of about two weeks,” stated Stephen Drake, an astrophysicist at NASA’s Goddard Space Flight Center in Maryland. “This was a very complex event.”

The surprising activity came from a red dwarf star in a binary system that together is known as DG Canum Venaticorum (DG CVn). Located just 60 light-years away, the two red dwarfs are each about one-third the size and mass of the Sun. Astronomers can’t say for sure which one sent out the eruption because the stars were so close to each other, at about three times the distance of Earth’s average distance to the sun.

The first flare (which sent out a burst of X-rays) caused an alert in NASA’s Swift Space Telescope’s burst alert telescope on April 23. It’s believed to be caused by the same process that creates flares on our Sun — magnetic field lines twisting and then releasing a burst of energy that sends out radiation.

Three hours later came another flare — scientists have seen similar events on the Sun after one active region sets off flares in another — and then came “successively weaker blasts” in the next 11 days, NASA said. Normal X-ray emissions stabilized about 20 days after the first flare. Swift is now monitoring this star for further activity.

Drake presented his results at the August meeting of the American Astronomical Society’s high energy astrophysics division, which was highlighted in a recent release from NASA.

Source: NASA

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…

 

 

 

 

Planets Plentiful Around Abundant Red Dwarf Stars, Study Says

Artist's impression of a planet orbiting a red dwarf star. Credit: University of Hertfordshire

Good news for planet-hunters: planets around red dwarf stars are more abundant than previously believed, according to new research. A new study — which detected eight new planets around these stars — says that “virtually” all red dwarfs have planets around them. Moreover, super-Earths (planets that are slightly larger than our own) are orbiting in the habitable zone of about 25% of red dwarfs nearby Earth.

“We are clearly probing a highly abundant population of low-mass planets, and can readily expect to find many more in the near future – even around the very closest stars to the Sun,” stated Mikko Tuomi, who is from the University of Hertfordshire’s centre for astrophysics research and lead author of the study.

The find is exciting for astronomers as red dwarf stars make up about 75% of the universe’s stars, the study authors stated.

The researchers looked at data from two planet-hunting surveys: HARPS (High Accuracy Radial Velocity Planet Searcher) and UVES (Ultraviolet and Visual Echelle Spectrograph), which are both at the European Southern Observatory in Chile. The two instruments measure the effect a planet has on its parent star, specifically by examining the gravitational “wobble” the planet’s orbit produces.

An artist's concept of a rocky world orbiting a red dwarf star. (Credit: NASA/D. Aguilar/Harvard-Smithsonian center for Astrophysics).
An artist’s concept of a rocky world orbiting a red dwarf star. (Credit: NASA/D. Aguilar/Harvard-Smithsonian center for Astrophysics).

Putting the information from both sets of data together, this amplified the planet “signals” and revealed eight planets around red dwarf stars, including three super-Earths in habitable zones. The researchers also applied a probability function to estimate how abundant planets are around this type of star.

The planets are between 15 and 80 light years away from Earth, and add to the 17 other planets found around low-mass dwarfs. Scientists also detected 10 weaker signals that could use more investigation, they said.

The study will be available shortly in the Monthly Notices of the Royal Astronomical Society and is available in preprint version at this link.

Source: University of Hertfordshire

‘Wobbly’ Alien Planet Has Weird Seasons And Orbits Two Stars

Diagram of Kepler-413b's unusual orbit around red and orange dwarf stars. Its orbit "wobbles" or precesses around the stars every 11 years. Credit: NASA, ESA, and A. Feild (STScI)

We’re lucky to live on a planet where it’s predictably warmer in the summer and colder in the winter in many regions, at least within a certain range. On Kepler-413b, it’s a world where you’d have to check the forecast more frequently, because its axis swings by a wild 30 degrees every 11 years. On Earth, by comparison, it takes 26,000 years to tilt by a somewhat lesser amount (23.5 degrees).

The exoplanet, which is 2,300 light-years away in the constellation Cygnus, orbits two dwarf stars — an orange one and a red one — every 66 days. While it would be fun to imagine a weather forecast on this planet, in reality it’s likely too hot for life (it’s close to its parent stars) and also huge, at 65 Earth-masses or a “super-Neptune.”

What’s even weirder is how hard it was to characterize the planet. Normally, astronomers spot these worlds either by watching them go across the face of their parent star(s), or by the gravitational wobbles they induce in those stars. The orbit, however, is tilted 2.5 degrees to the stars, which makes the transits far more unpredictable. It took several years of Kepler space telescope data to find a pattern.

“What we see in the Kepler data over 1,500 days is three transits in the first 180 days (one transit every 66 days), then we had 800 days with no transits at all,” stated Veselin Kostov, the principal investigator on the observation. “After that, we saw five more transits in a row,” added Kostov, who works both with the  the Space Telescope Science Institute and  Johns Hopkins University  in Baltimore, Md.

It will be an astounding six years until the next transit happens in 2020, partly because of that wobble and partly because the stars have small diameters and aren’t exactly “edge-on” to our view from Earth. As for why this planet is behaving the way it does, no one is sure. Maybe other planets are messing with the orbit, or a third star is doing the same thing.

The next major question, the astronomers added, is if there are other planets out there like this that we just can’t see because of the gap between transit periods.

You can read more about this finding in The Astrophysical Journal (a Jan. 29 publication that doesn’t appear to be on the website yet) or in preprint version on Arxiv.

Source: Space Telescope Science Institute

Is That Planet Habitable? Look To The Star First, New Study Cautions

Artist’s impression of the deep blue planet HD 189733b, based on observations from the Hubble Space Telescope. Credit: NASA/ESA.

Finding Earth 2.0, in the words of noted SETI researcher Jill Tarter, is something a lot of exoplanet searchers are hoping for one day. They’re trying not to narrow down their search to Sun-like stars, but also examine stars that are smaller, like red dwarfs.

A new study, however, cautions that the X-ray environment of these dwarfs may give us false positives. They looked at Earth-mass planets in the neighborhood of four stars, such as GJ 667 (which has three planets that could be habitable), and concluded it’s possible for oxygen to reside in these planets even in the absence of life.

The work builds on a published paper in the Astrophysical Journal that argues that GJ 876, studied by the Hubble Space Telescope, could allow a hypothetical planet to have plenty of oxygen in its atmosphere, even without the presence of life.

This artist's conception shows the newly discovered super-Earth GJ 1214b, which orbits a red dwarf star 40 light-years from our Earth. Credit: Credit: David A. Aguilar, CfA
This artist’s conception shows the newly discovered super-Earth GJ 1214b, which orbits a red dwarf star 40 light-years from our Earth. Credit: Credit: David A. Aguilar, CfA

The researchers themselves, however, caution that the results are preliminary and there is a lot more to study before coming to a definitive conclusion.

For example: “The effects of stellar flares on the atmosphere of the hypothetical Earth-like planet around GJ 876 have not been considered in this work,” stated Kevin France, who is with the University of Colorado at Boulder and also a co-author.

“At this point, we do not have a sufficient understanding of the amplitude and frequency of such flares on older, low-mass exoplanet host stars to make predictions about their impact on the production of biomarker signatures.”

The report was presented at the American Astronomical Society division for planetary sciences meeting in Denver today (Oct. 7). It was not immediately clear from a press release if the newer study has been submitted for peer review.

Source: AAS Division for Planetary Sciences

Weekly Space Hangout – July 19, 2013

Here’s our Weekly Space Hangout for July 19, 2013. Watch as a team of space and astronomy journalists discuss the big space stories of the week. We do this every Friday at 12:00 pm Pacific Time / 3:00 pm Eastern Time. You can join us live, or watch the archive here or on Google+.

Host: Fraser Cain

Participants: Sondy Springmann, Amy Shira Teitel, Jason Major, David Dickenson, Dr. Matthew Francis

And here are the stories that we covered.

Famed Pair of Stars Closer To Earth Than We Imagined

An artist's conception of the SS Cygni system, with a red dwarf star's material being pulled on to a nearby white dwarf. Credit: Bill Saxton, NRAO/AUI/NSF

If you’re a semi-serious amateur astronomer, chances are you’ve heard of a variable pair of stars called SS Cygni. When you watch the system for long enough, you’re rewarded with a brightness outburst that then fades away and then returns, regularly, over and over again.

Turns out this bright pair is even closer to us than we imagined — 370 light-years away, to be precise.

Before we get into how this was discovered, a bit of background on what SS Cygni is. As the name of the system implies, it’s in the constellation of Cygnus (the Swan). The pair consists of a cooling white dwarf star that is locked in a 6.6-hour orbit with a red dwarf.

The white dwarf’s gravity, which is much stronger than that of the red dwarf, is bleeding material from its neighbor. This interaction causes outbursts — on average, about once every 50 days.

Previously, the Hubble Space Telescope put the distance to these stars much further away, at 520 light-years. But that caused some head-scratching among astronomers.

Hubble Against Earth's Horizon (1997)
Hubble Against Earth’s Horizon (1997)

“That was a problem. At that distance, SS Cygni would have been the brightest dwarf nova in the sky, and should have had enough mass moving through its disk to remain stable without any outbursts,” stated James Miller-Jones, of the Curtin University node of the International Centre for Radio Astronomy Research in Perth, Australia.

Astronomers call SS Cygni a dwarf nova. When comparing it to similar systems, astronomers said the outbursts happen as matter changes its flow speed through the disc of material surrounding the white dwarf.

“At high rates of mass transfer from the red dwarf, the rotating disk remains stable, but when the rate is lower, the disk can become unstable and undergo an outburst,” stated the National Radio Astronomy Observatory. So what was happening?

A star's distance is measured by observing a slight shift in position that occurs, from Earth's perspective, on opposite sides of our planet's orbit. Credit: Bill Saxton, NRAO/AUI/NSF
A star’s distance is measured by observing a slight shift in position that occurs, from Earth’s perspective, on opposite sides of our planet’s orbit. Credit: Bill Saxton, NRAO/AUI/NSF

To again look at the distance of the star, astronomers used two sets of radio telescopes, the Very Large Baseline Array and the European VLBI Network. Each set has a bunch of telescopes working together as an interferometer, allowing for precise measurements of star distances.

Scientists then took measurements at opposite ends of the Earth’s orbit, using the planet itself as a tool. By measuring the star’s distance at opposite sides of the orbit, we can calculate its parallax or apparent movement in the sky from the perspective of Earth. It’s an old astronomical tool used to pin down distances, and still works.

“This is one of the best-studied systems of its type, but according to our understanding of how these things work, it should not have been having outbursts. The new distance measurement brings it into line with the standard explanation,” stated Miller-Jones.

And where did Hubble go wrong? Here’s the theory:

“The radio observations were made against a background of objects far beyond our own Milky Way Galaxy, while the Hubble observations used stars within our galaxy as reference points,” NRAO stated. “The more-distant objects provide a better, more stable, reference.”

The results were published in Science on May 24.

Source: National Radio Astronomy Observatory