Tabby's Star...

Another explanation for the dimming is that KIC 8462852 is surrounded by a swarm of dusty comets.

Topics: Astrophysics, Dyson Sphere, Exoplanets, Kardashev Scale, Kepler Telescope, SETI

Astronomers and alien life enthusiasts alike are buzzing over the sudden dimming of an otherwise unremarkable star 1300 light-years away in the constellation Cygnus. KIC 8462852 or “Tabby’s star” has dimmed like this several times before, prompting some researchers to suggest that the megastructures of an advanced alien civilization might be blocking its light. And now—based on new data from numerous telescopes—it’s doing it again.

“This is the first clear dip we have seen since [2013], and the first we have ever caught in real time,” says Jason Wright, an astronomer at Pennsylvania State University in State College. If they can rope in more telescopes, astronomers hope to gather enough data to finally figure out what’s going on. “This could be the first of several dips about to come,” says astronomer David Kipping of Columbia University. “Many observers will be closely watching.”

KIC 8462852 was first noticed to be dipping in brightness at seemingly random intervals between 2011 and 2013 by NASA’s Kepler telescope. Kepler, launched to observe the stellar dimmings caused when an exoplanet passes in front of its star, revealed that the dimming of Tabby’s star was much more erratic than a typical planetary transit. It was also more extreme, with its brightness sometimes dropping by as much as 20%. This was not the passage of a small circular planet, but of something much larger and more irregular.

Science Mag: Star that spurred alien megastructure theories dims again
Daniel Clery

#P4TC related links

Needle In A Haystack...October 19, 2015
Occam's Razor...February 8, 2016

Occam's Razor...

Credit: NASA/JPL-Caltech

Topics: Astrophysics, Dyson Sphere, Exoplanets, Kardashev Scale, Kepler Telescope, SETI

It's looking less likely that a swarm of comets or an "alien megastructure" can explain a faraway star's strange dimming.

The star (nicknamed "Tabby's Star," after its discoverer, Tabetha Boyajian) made major headlines last October when Jason Wright, an astronomer at Pennsylvania State University, suggested that it could be surrounded by some type of alien megastructure. A more likely idea — one that's far less exciting — is that the star is orbited by a swarm of comets. But scientists can't be sure either way.

The first signs of the star's oddity came from NASA's planet-hunting Kepler space telescope, which continually monitored the star (as well as 100,000 others) between 2009 and 2013. Astronomers, citizen scientists and computers could then search for regular dips in a star's light — a sign that an exoplanet has passed in front of that star. The largest planets might block 1 percent of a star's light, but Tabby's star dropped by as much as 20 percent in brightness. That, in and of itself, would be weird. But the periodic dimmings didn't occur at regular time intervals, either — they were sporadic. The signature couldn't be caused by a planet, scientists said.

Scientific American:
Comets May Not Explain "Alien Megastructure" Star's Strange Flickering after All
Shannon Hall, Space.com
#P4TC: Needle In A Haystack...

Needle In A Haystack...

Image Source: Discovery News (link below)

Topics: Astrophysics, Dyson Sphere, Exoplanets, Kardashev Scale, Kepler Telescope, SETI

There's kind of a rush when you read articles like this, at least initially. Then, you start asking yourself critical thinking questions to "peel away the onion" so to speak. In essence, they've seen some fluctuations in luminosity from a star the Kepler Telescope is observing 1,500 light years away (not exactly across the street). Also humbling we, as the human species on Earth circa 515 CE were essentially savages; beneath any potential advanced aliens' notice.

To quote the Discovery article:

"Follow-up studies focus on two interesting transit events at KIC 8462852, one that was detected between days 788 and 795 of the Kepler mission and between days 1510 to 1570. The researchers have tagged these events as D800 and D1500 respectively. The D800 event appears to have been a single transit causing a star brightness drop-off of 15 percent, whereas D1500 was a burst of several transits, possibly indicating a clump of different objects, forcing a brightness dip of up to 22 percent. To cause such dips in brightness, these transiting objects must be huge.

"The researchers worked through every known possibility, but each solution presented a new problem. For example, they investigated the possibility of some kind of circumstellar disk of dust. However, after looking for the infrared signal associated with these disks, no such signal could be seen. Also, the star is a mature F-type star, approximately 1.5 times the size of our sun. Circumstellar disks are usually found around young stars.

"The researchers also investigate the possibility of a huge planetary collision; could the debris from this smashup be creating this strange signal? The likelihood of us seeing a planetary collision is extremely low. There is no evidence in data taken by NASA’s Wide-field Infrared Survey Explorer (WISE) that a collision happened, creating a very tiny window of opportunity between WISE’s mission end and the beginning of Kepler’s mission (of a few years) for an astronomically unlikely cosmic event like this to occur.

"The only natural explanation favored by the researchers seems to focus on an intervening clump of exocomets."

All of that is fairly reasonable. If you explore the many links in the article, you'll get to the actual Physics arXiv paper in one of its conclusions states "the break-up of a exocomet provides the most compelling explanation."

Then...well, here you go:

"This research paper focuses only on natural and known possible causes of the mystery transit events around KIC 8462852. A second paper is currently being drafted to investigate a completely different transit scenario that focuses around the possibility of a mega-engineering project created by an advanced alien civilization.

"This may sound like science fiction, but our galaxy has existed for over 13 billion years, it’s not such a stretch of the imagination to think that an alien civilization may be out there and evolved to the point where they can build megastructures around stars."

From The Atlantic: Jason Wright, an astronomer from Penn State University, is set to publish an alternative interpretation of the light pattern. SETI researchers have long suggested that we might be able to detect distant extraterrestrial civilizations, by looking for enormous technological artifacts orbiting other stars. Wright and his co-authors say the unusual star’s light pattern is consistent with a “swarm of megastructures,” perhaps stellar-light collectors, technology designed to catch energy from the star.

“When [Boyajian] showed me the data, I was fascinated by how crazy it looked,” Wright told me. “Aliens should always be the very last hypothesis you consider, but this looked like something you would expect an alien civilization to build.”

The only mega - or very large - structure I can think of is a Dyson Sphere, postulated by Freeman Dyson in 1960 (now infamous for other things). An extremely old and advanced extraterrestrial civilization - a Type III on the Kardashev Scale (well beyond Kirk and Picard) could conceivably build a series of solar collectors around their own host star (or, in the case of the link I provide from earlier this year, a white dwarf star). Such a civilization should be well beyond our current geopolitical morass, fossil fuel addiction, tribalism and xenophobia of each other. Or, maybe not. We only assume functional alien societies are too advanced to be autocratic and authoritarian; that democratic republics are the natural order of things, when in our civilized time span, it's only a recent political invention. I hope our assumptions are correct, of course and more importantly: that we're not tasty.

Star Trek kind of had their own "rule" to answer the question posited by the Fermi Paradox ("where are they?") by the Prime Directive, meaning that no space faring warp-capable species would dare interfere with the development of a pre-warp society. This absurdly presumes faux aliens as rude as the Klingons and Romulans were both "down" with this as well. It was a Roddenberry stretch, but it's held the franchise together.

The reality might be, looking at some of our television transmissions - the now blurred lines of politics and reality TV; Internet postings and carbon signature writ/planet large, they might still find us primitive, boring...and terrifying. Waiting for the second paper...

Discovery News: Has NASA’s Kepler Mission Discovered an Alien Megastructure?
Dr. Ian O'Neill

Earth 2.0...

The artistic concept shows NASA's planet-hunting Kepler spacecraft operating in a new mission profile called K2. Using publicly available data, astronomers may have confirmed K2's first discovery of star with more than one planet. Image Credit: NASA Ames/JPL-Caltech/T Pyle

Topics: Astronomy, Astrophysics, Climate Change, Exoplanets, Kepler Telescope, Planetary Science, Space Exploration

There's an announcement coming out today at 12 noon EST. True to form, IFLS and Hopes and Fears have given their usual breathless hyperbole. I don't know if it's "another Earth," or even if it matters. Since our fastest propulsion gets us to Pluto in ~ nine years, we currently don't have a spare hyper/warp drive to get us there in current human lifespans, though Monday's post is a good step in the interplanetary direction. Climate change is a slow-mo existential train wreck, and despite warnings by the Pentagon no less, we can't seem to get our leaders to act on: I fear we're already out of options. I don't plan to be here in fifty years when Greenland's ice sheet disappears, and Florida's coasts are under water. Neither of our presidential candidates, some of whom and their constituents are apparently willing to debate the Pope, but not science publicly.  I'd rather, take care of the planet we're on as the expense would bankrupt the global economy; such an enterprise (pun intended) would take generations, not weeks.

NASA will host a news teleconference at 9 a.m. PDT (noon EDT) Thursday, July 23, to announce new discoveries made by its planet-hunting mission, the Kepler Space Telescope.

The first exoplanet orbiting another star like our sun was discovered in 1995. Exoplanets, especially small Earth-size worlds, belonged within the realm of science fiction just 21 years ago. Today, and thousands of discoveries later, astronomers are on the cusp of finding something people have dreamed about for thousands of years -- another Earth.

The teleconference audio and visuals will be streamed live at:

http://www.nasa.gov/newsaudio

JPL: NASA Hosts Media Telecon About Latest Kepler Discoveries

K2...

The artistic concept shows NASA's planet-hunting Kepler spacecraft operating in a new mission profile called K2. Using publicly available data, astronomers have confirmed K2's first exoplanet discovery proving Kepler can still find planets.

Image Credit: NASA Ames/JPL-Caltech/T Pyle

NASA's planet-hunting Kepler spacecraft makes a comeback with the discovery of the first exoplanet found using its new mission -- K2.

The discovery was made when astronomers and engineers devised an ingenious way to repurpose Kepler for the K2 mission and continue its search of the cosmos for other worlds.

Lead researcher Andrew Vanderburg, a graduate student at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, studied publicly available data collected by the spacecraft during a test of K2 in February 2014. The discovery was confirmed with measurements taken by the HARPS-North spectrograph of the Telescopio Nazionale Galileo in the Canary Islands, which captured the wobble of the star caused by the planet’s gravitational tug as it orbits.

The newly confirmed planet, HIP 116454b, is 2.5 times the diameter of Earth and follows a close, nine-day orbit around a star that is smaller and cooler than our sun, making the planet too hot for life as we know it. HIP 116454b and its star are 180 light-years from Earth, toward the constellation Pisces.

NASA: NASA’s Kepler Reborn, Makes First Exoplanet Find of New Mission

Alien Worlds...

Looking For Our Twin...

MOFFETT FIELD, Calif. -- NASA's Kepler mission has discovered two new planetary systems that include three super-Earth-size planets in the "habitable zone," the range of distance from a star where the surface temperature of an orbiting planet might be suitable for liquid water.

The Kepler-62 system has five planets; 62b, 62c, 62d, 62e and 62f. The Kepler-69 system has two planets; 69b and 69c. Kepler-62e, 62f and 69c are the super-Earth-sized planets.

Two of the newly discovered planets orbit a star smaller and cooler than the sun. Kepler-62f is only 40 percent larger than Earth, making it the exoplanet closest to the size of our planet known in the habitable zone of another star. Kepler-62f is likely to have a rocky composition. Kepler-62e, orbits on the inner edge of the habitable zone and is roughly 60 percent larger than Earth.

The third planet, Kepler-69c, is 70 percent larger than the size of Earth, and orbits in the habitable zone of a star similar to our sun. Astronomers are uncertain about the composition of Kepler-69c, but its orbit of 242 days around a sun-like star resembles that of our neighboring planet Venus.

Scientists do not know whether life could exist on the newfound planets, but their discovery signals we are another step closer to finding a world similar to Earth around a star like our sun.

NASA: NASA's Kepler Discovers Its Smallest 'Habitable Zone' Planets to Date

About a Third...




Kepler Field of View
Physics arXiv

 
...and hopefully, no Klingons!

Physics arXiv: The Kepler orbiting observatory is specifically designed to find Earth-like planets around nearby stars.

Earlier this year, the Kepler team released the mission's first 136 days of data and it has turned out to be a veritable jackpot. In that time Kepler looked at some 150,000 target stars and found evidence for 1,235 potential exoplanets. That's quite a haul.

Since then, most of the work on this database has been to identify the characteristics of all these exoplanets. But such a large dataset also allows for statistical analyses too, from which various projections can be made.

Today, Wesley Traub at the California Institute of Technology in Pasadena, reveals the results of just such a study. Traub has looked only at the stars that are most similar to the Sun, namely those with the classification F, G or K and worked out often various types of planets occur.

The results are straightforward to state. Traub says that mid-size planets are just as likely to be found around faint stars and bright ones. By contrast, far fewer small planets show up around faint stars. That's almost certainly because small planets are more difficult for Kepler to see.

It's also easier for Kepler to see planets that are closer to their stars because it looks for the tiny changes in brightness that these transits cause. That's why almost a third of all Kepler's detections orbit their star in less than 42 days. For the most part, these planets orbit too closely to be in the habitable zone.

What interests most astronomers is how many exoplanets orbit at a greater distance, inside the habitable zone. Most of these planets are too far away from their stars to have been picked up by Kepler yet. But Traub says his data analysis provides a way to work out how many their ought to be.

That's because he's found a power law that describes how the number of stars with a given orbital period. So all he has to do is assume a longer orbital period equivalent to being in the habitable zone to work out how many planets there ought to be at this distance.

Here's the answer: "About one-third of FGK stars are predicted to have at least one terrestrial, habitable-zone planet," he says.

So by this measure, there are plenty of other Earths out there.

Link: Terrestrial, Habitable-Zone Exoplanet Frequency from Kepler
NASA: Kepler Homepage