Of the more than 600,000 known asteroids in our Solar System, almost 10 000 are known as Near-Earth Objects (NEOs). These are asteroids or comets whose orbits bring them close to Earth’s, and which could potentially collide with us at some point in the future. As such, monitoring these objects is a vital part of NASA’s ongoing efforts in space. One such mission is NASA’s Near-Earth Object Wide-field Survey Explorer (NEOWISE), which has been active since December 2013.
And now, after two years of study, the information gathered by the mission is being released to the public. This included, most recently, NEOWISE’s second year of survey data, which accounted for 72 previously unknown objects that orbit near to our planet. Of these, eight were classified as potentially hazardous asteroids (PHAs), based on their size and how closely their orbits approach Earth.
The story of KIC 8462852 appears far from over. You’ll recall NASA’s Kepler mission had monitored the star for four years, observing two unusual incidents, in 2011 and 2013, when its light dimmed in dramatic, never-before-seen ways. Models to explain its erratic behavior were so lacking that some considered the possibility that alien megastructures built to capture sunlight around the host star (think Dyson Spheres) might be the cause.
Shattered comets and asteroids were also suggested as possible explanations — dust and ground-up rock would be at the right temperature to glow in the infrared — but Kepler could only observe in visible light where any debris would be invisible or swamped by the light of the star. So researchers looked through older observations made in 2010 by the Wide Field Infrared Survey Explorer (WISE) space telescope. Unfortunately, WISE observed the star before the strange variations were seen and therefore before any putative dust-busting collisions.
Not to be stymied, astronomers next checked out the data from NASA’s Spitzer Space Telescope, which like WISE, is optimized for infrared light. Spitzer just happened to observe KIC 8462852 much more recently in 2015.
“Spitzer has observed all of the hundreds of thousands of stars where Kepler hunted for planets, in the hope of finding infrared emission from circumstellar dust,” said Michael Werner, the Spitzer project scientist and the lead investigator of that particular Spitzer/Kepler observing program.
I’d love to report that Spitzer tracked down glowing dust but no, it also came up empty-handed. This makes the idea of an asteroidal smash-up very unlikely, but not one involving comets according to Massimo Marengo of Iowa State University (Ames) who led the new study. Marengo proposes that cold comets are responsible. Picture a family of comets traveling on a very long, eccentric orbit around the star with a very large comet at the head of the pack responsible for the big fading seen by Kepler in 2011. Later, in 2013, the rest of the comet family, a band of various-sized fragments lagging behind, would have passed in front of the star and again blocked its light. By 2015, the comets would have moved even farther away on their long orbital journey, leaving no detectable infrared excess.
“This is a very strange star,” said Marengo. “It reminds me of when we first discovered pulsars. They were emitting odd signals nobody had ever seen before, and the first one discovered was named LGM-1 after ‘Little Green Men.'”
Clearly, more long-term observations are needed. And frankly, I’m still puzzled why cold or less active comets might still not be detected by their glowing dust. But let’s assume for a moment the the comet idea is correct. If so, we should expect to see similar dips in KIC 8462852’s light as the comet swarm swings around again.
Beam us up, Scotty. There’s no signs of intelligent life out there. At least, no obvious signs, according to a recent survey performed by researchers at Penn State University. After reviewing data taken by the NASA Wide-field Infrared Survey Explorer (WISE) space telescope of over 100,000 galaxies, there appears to be little evidence that advanced, spacefaring civilizations exist in any of them.
First deployed in 2009, the WISE mission has been able to identify thousands of asteroids in our solar system and previously undiscovered star clusters in our galaxy. However, Jason T. Wright, an assistant professor of astronomy and astrophysics at the Center for Exoplanets and Habitable Worlds at Penn State University, conceived of and initiated a new field of research – using the infrared data to assist in the search for signs of extra-terrestrial civilizations.
And while their first look did not yield much in the way of results, it is an exciting new area of research and provides some very useful information on one of the greatest questions ever asked: are we alone in the universe?
“The idea behind our research is that, if an entire galaxy had been colonized by an advanced spacefaring civilization, the energy produced by that civilization’s technologies would be detectable in mid-infrared wavelengths,” said Wright, “exactly the radiation that the WISE satellite was designed to detect for other astronomical purposes.”
This logic is in keeping with the theories of Russian astronomer Nikolai Kardashev and theoretical physicist Freeman Dyson. In 1964, Kardashev proposed that a civilization’s level of technological advancement could be measured based on the amount of energy that civilization is able to utilize.
To characterize the level of extra-terrestrial development, Kardashev developed a three category system – Type I, II, and III civilizations – known as the “Kardashev Scale”. A Type I civilization uses all available resources on its home planet, while a Type II is able to harness all the energy of its star. Type III civilizations are those that are advanced enough to harness the energy of their entire galaxy.
Similarly, Dyson proposed in 1960 that advanced alien civilizations beyond Earth could be detected by the telltale evidence of their mid-infrared emissions. Believing that a sufficiently advanced civilization would be able to enclose their parent star, he believed it would be possible to search for extraterrestrials by looking for large objects radiating in the infrared range of the electromagnetic spectrum.
These thoughts were expressed in a short paper submitted to the journal Science, entitled “Search for Artificial Stellar Sources of Infrared Radiation“. In it, Dyson proposed that an advanced species would use artificial structures – now referred to as “Dyson Spheres” (though he used the term “shell” in his paper) – to intercept electromagnetic radiation with wavelengths from visible light downwards and radiating waste heat outwards as infrared radiation.
“Whether an advanced spacefaring civilization uses the large amounts of energy from its galaxy’s stars to power computers, space flight, communication, or something we can’t yet imagine, fundamental thermodynamics tells us that this energy must be radiated away as heat in the mid-infrared wavelengths,” said Wright. “This same basic physics causes your computer to radiate heat while it is turned on.”
However, it was not until space-based telescopes like WISE were deployed that it became possible to make sensitive measurements of this radiation. WISE is one of three infrared missions currently in space, the other two being NASA’s Spitzer Space Telescope and the Herschel Space Observatory – a European Space Agency mission with important NASA participation.
WISE is different from these missions in that it surveys the entire sky and is designed to cast a net wide enough to catch all sorts of previously unseen cosmic interests. And there are few things more interesting than the prospect of advanced alien civilizations!
To search for them, Roger Griffith – a postbaccalaureate researcher at Penn State and the lead author of the paper – and colleagues scoured the entries in the WISE satellites database looking for evidence of a galaxy that was emitting too much mid-infrared radiation. He and his team then individually examined and categorized 100,000 of the most promising galaxy images.
And while they didn’t find any obvious signs of a Type II civilization or Dyson Spheres in any of them, they did find around 50 candidates that showed unusually high levels of mid-infrared radiation. The next step will be to confirm whether or not these signs are due to natural astronomical processes, or could be an indication of a highly advanced civilization tapping their parent star for energy.
In any case, the team’s findings were quite interesting and broke new ground in what is sure to be an ongoing area of research. The only previous study, according to the G-HAT team, surveyed only about 100 galaxies, and was unable to examine them in the infrared to see how much heat they emitted. What’s more, the research may help shed some light on the burning questions about the very existence of intelligent, extra-terrestrial life in our universe.
“Our results mean that, out of the 100,000 galaxies that WISE could see in sufficient detail, none of them is widely populated by an alien civilization using most of the starlight in its galaxy for its own purposes,” said Wright. “That’s interesting because these galaxies are billions of years old, which should have been plenty of time for them to have been filled with alien civilizations, if they exist. Either they don’t exist, or they don’t yet use enough energy for us to recognize them.”
Alas, it seems we are no closer to resolving the Fermi Paradox. But for the first time, it seems that investigations into the matter are moving beyond theoretical arguments. And given time, and further refinements in our detection methods, who knows what we might find lurking out there? The universe is very, very big place, after all.
The research team’s first research paper about their Glimpsing Heat from Alien Technologies Survey (G-HAT) survey appeared in the Astrophysical Journal Supplement Series on April 15, 2015.
Nature once again shows us how hard it is to fit astronomical objects into categories. An examination of a so-far unique brown dwarf — an object that is a little too small to start nuclear fusion and be a star — shows that it could have been as hot as a star in the ancient past.
The object is one of a handful of brown dwarfs that are called “Y dwarfs”. This is the coolest kind of star or star-like object we know of. These objects have been observed at least as far back as 2008, although they were predicted by theory before.
A group of scientists observed the object, called WISE J0304-2705, with NASA’s space-based Wide-field Infrared Survey Explorer (WISE). Looking at the spectrum of light it had emitted, which shows the object’s composition, has scientists saying that what the brown dwarf is made of suggests it is rather old — billions of years old.
“Our measurements suggest that this Y dwarf may have a composition … or age characteristic of one of the galaxy’s older members,” stated David Pinfield at the University of Hertfordshire, who led the research.
“This would mean its temperature evolution could have been rather extreme – despite starting out at thousands of degrees, this exotic object is now barely hot enough to boil a cup of tea.”
While the object started out hot, its interior never was quite enough to fuse hydrogen. That led to the extreme cooling visible today.
Models suggest the object would have begun its life shining at 2,800 degrees Celsius (5,072 Fahrenheit), for a phase that would have lasted for 20 million years. In the next 100 million years, its temperature would have almost halved to 1,500 Celsius (2,730 Fahrenheit).
And it would have kept cooling, with a temperature of 1,000 Celsius (1,832 Fahrenheit) after a billion years, and after billions of more years, the temperature we see today — somewhere between 100 Celsius (212 Fahrenheit) and 150 Celsius (302 Fahrenheit).
The paper will be published shortly in the Monthly Notices of the Royal Astronomical Society. The research is available in preprint version on Arxiv. One limitation of the research is the small number of Y dwarfs discovered, only about 20, which means that more observations will be needed to see if other objects could have had this same evolution.
Brazilian astronomers have discovered some 300+ star clusters that were largely overlooked owing to sizable obscuration by dust. The astronomers, from the Universidade Federal do Rio Grande do Sul, used data obtained by NASA’s WISE (Wide-Field Infrared Survey Explorer) space telescope to detect the clusters.
“WISE is a powerful tool to probe … young clusters throughout the Galaxy”, remarked the group. The clusters discovered were previously overlooked because the constituent stars are deeply embedded in their parent molecular cloud, and are encompassed by dust. Stars and star clusters can emerge from such environments.
The group added that, “The present catalog of new clusters will certainly become a major source for future studies of star cluster formation.” Indeed, WISE is well-suited to identify new stars and their host clusters because infrared radiation is less sensitive to dust obscuration. The infrared part of the electromagnetic spectrum is sampled by WISE.
Historically, new star clusters were often identified while inspecting photographic plates imaged at (or near) visible wavelengths (i.e., the same wavelengths sampled by the eye). Young embedded clusters were consequently under-sampled since the amount of obscuration by dust is wavelength dependent. As indicated in the figure above, the infrared observations penetrate the dust by comparison to optical observations.
The latest generation of infrared survey telescopes (e.g., Spitzer and WISE) are thus excellent instruments for detecting clusters embedded in their parent cloud, or hidden from detection because of dust lying along the sight-line. The team notes that, “The Galaxy appears to contain 100000 open clusters, but only some 2000 have established astrophysical parameters.” It is hoped that continued investigations using WISE and Spitzer will help astronomers minimize that gap.
CORRECTION: This story corrects a previously stated misinterpretation of the NASA Senior Report that the WISE spacecraft itself was denied an extension.
NASA has denied funding to an idea to use NEOWISE image exposures for additional processing for science purposes, according to Amy Mainzer, the deputy project scientist for the Wide-field Infrared Survey Explorer (WISE) at NASA’s Jet Propulsion Laboratory. The project, called MaxWISE, was supposed to run for three years and to use NEOWISE data for other purposes.
“We were hoping it would be possible to combine data from the prime mission, with the NEO mission, to look at
things that vary on different timescales,” Mainzer said in an interview Friday (May 16) with Universe Today.
Its goals would have included measuring the motions and distances for stars and brown dwarfs near the sun, examining variable stars and setting up a “transient detection and alerts program” for certain astronomical phenomena.
In its review, the panel said it was “concerned that the proposed transient detection program would yield little science considering how much it cost”, and approved the program at half of the budgetary levels originally requested. NASA, however, wrote that it would decline the proposal altogether.
“The MaxWISE proposal was recommended for selection by the senior review. However, the only source of funding would be to displace funding from higher rated operating missions in the senior review. Due to constrained budget conditions, the MaxWISE proposal is declined,” NASA wrote in its response.
“It’s tremendously disappointing,” Mainzer said of the decision, adding it is a tough NASA budget environment overall. She is encouraging people to get in touch with their elected representatives if they want to see changes.
After its launch in 2009 and successful prime mission, WISE was put into hibernation in 2011 before being turned on again last summer to look for asteroids that could pose a threat to Earth, and possibly to participate in NASA’s asteroid mission by looking for a space rock that could be captured and explored.
NEOWISE is expected to run until about 2016 or 2017, depending on how active the Earth’s atmosphere becomes. Since the spacecraft is in a relatively low orbit of 311 miles (500 km), if the sun’s activity increases molecule interactions in the atmosphere and expands it, the spacecraft can be somewhat twisted out of its orbit. Also, more scattering can occur. Both would make it harder for the spacecraft to carry out its mission, Mainzer said.
In the meantime, amateur astronomers can follow along with one of NEOWISE’s recent discoveries: the spacecraft recently found a fairly large near-Earth asteroid, about 1.24 miles to 1.86 miles (2 to 3 km) in size. It’s called 2014 JH 57 and you can get more orbital parameters on it at this page after typing in “2014 JH57” (no quotes) into the search bar.
Our stellar neighborhood just got a little busier … and a little colder.
A brown dwarf that’s as frosty as the Earth’s North Pole has been discovered lurking incredibly close to our Solar System. Astronomer Keven Luhman from Pennsylvania State University used NASA’s Wide-field Infrared Survey Explorer (WISE) and the Spitzer Space Telescope to pinpoint the object’s temperature and distance. This is the coldest brown dwarf found so far, and it’s a mere 7.2 light-years away, making it the seventh closest star-like object to the Sun.
“It is very exciting to discover a new neighbor of our Solar System that is so close,” said Luhman in a press release.
Brown dwarfs emerge when clouds of gas and dust collapse. But unlike stars, they never grow dense enough or burn hot enough to ignite nuclear fusion in their cores. They live their lives less massive than stars, but more massive than gas giants. So they burn hot at first, then cool over time. And this newly discovered brown dwarf is as cold as ice. Literally.
WISE surveyed the entire sky twice in its short 14-month lifetime, looking at cooler objects, which radiate in infrared light (but often remain invisible in visible light). It saw cold asteroids, dust clouds, proto-planetary disks, distant galaxies and hundreds of brown dwarfs.
But one of these objects — dubbed WISE J085510.83-071442.5 — was moving rapidly, suggesting it was extremely close to the Solar System. All stars orbit around the Milky Way, with apparent motions seen on the timescale of hundreds of years. Stars close to the Sun, however, can be seen to make the slightest of movements on the timescale of just a few years. This object appeared to move in just a few months.
After first spotting this wacky object in the WISE data, Luhman analyzed additional images taken with the Spitzer Space Telescope and the Gemini South Pole Telescope in Chile. The combined detections taken from different positions around the Sun enabled the measurement of the objects parallax — the apparent position of the object against a background set of stars as seen along multiple lines of sight — allowing Luhman to determine the objects distance.
Spitzer’s additional observations helped pin down the objects chilly temperature, which can be determined based on how much light it gives off in different colors. Like a flame, the hottest part is blue, while the coldest part is red. Luhman found the brown dwarfs temperature to be between –54° and 9° Fahrenheit (–48° to –13° Celsius). Previous record-holders for the coldest brown dwarfs were about room temperature.
“It is remarkable that even after many decades of studying the sky, we still do not have a complete inventory of the Sun’s nearest neighbors,” said Michael Werner from NASA’s Jet Propulsion Laboratory. “This exciting new result demonstrates the power of exploring the universe using new tools, such as the infrared eyes of WISE and Spitzer.”
With a stretch of the imagination and advanced technology, it’s possible that other cooler objects, be them brown dwarfs of even rogue exoplanets, are yet closer to the Sun.
The paper will be published in the Astrophysics Journal and is available for download here.
It’s one of those rumors that just won’t quiet down — a large planet lurking at the solar system’s edge. Back in the 1840s, when Neptune was discovered, its orbit seemed to be a little “off” from what was expected.
Some astronomers of the time said that was caused by a planet further out. Although the Neptune perturbations are now ascribed to observational errors, the tale of Planet X continues, and has sometimes even been linked with doomsday. (See this past Universe Today story for the full tale.)
NASA’s latest survey puts even less credence in that theory. A scan of the sky showed nothing Saturn’s size or bigger at a distance of 10,000 Earth-sun distances, or astronomical units. Nothing bigger than Jupiter exists as far as 26,000 AU. (To put that in perspective, Pluto is 40 AU from the sun.)
“The outer solar system probably does not contain a large gas giant planet, or a small, companion star,” stated Kevin Luhman of the Center for Exoplanets and Habitable Worlds at Penn State University, author of a paper in the Astrophysical Journal describing the results.
Astronomers used information from NASA’s Wide-Field Infrared Survey Explorer, which did two full-sky scans in 2010 and 2011 to look at asteroids, stars and galaxies. NASA’s AllWISE program, released in November 2013, allows astronomers to find moving objects by comparing the two surveys.
A second study of the data found other objects further out in space — 3,525 stars and brown dwarfs (objects just below the threshold for fusion) within 500 light-years of the sun.
“We’re finding objects that were totally overlooked before,” stated Davy Kirkpatrick of NASA’s Infrared and Processing Analysis Center at the California Institute of Technology, who led the second paper.
Both papers will be published in the Astrophysical Journal.
NASA’s NEOWISE mission — formerly known as just WISE — has identified the first comet of its new near-Earth object hunting career… and, according to mission scientists, it’s a “weirdo.”
In its former life NASA’s WISE (Wide-field Infrared Survey Explorer) spacecraft scanned the entire sky in infrared wavelengths. It helped discover the galaxy’s coldest stars, the Universe’s brightest galaxies, and some of the darkest asteroids lurking in the main asteroid belt between Mars and Jupiter… as well as closer in to Earth’s neck of the woods.
After exhausting its supply of liquid coolant needed to shield itself from its own radiating heat, in 2011 WISE was put into a state of hibernation. It was awoken last year and rebranded NEOWISE, and set upon the task of locating unknown objects with orbits in the proximity of Earth’s.
To date several new asteroids have already been found by NEOWISE, and on February 14, 2014, it spotted its first comet.
“We are so pleased to have discovered this frozen visitor from the outermost reaches of our solar system,” said Amy Mainzer, NEOWISE principal investigator at JPL. “This comet is a weirdo — it is in a retrograde orbit, meaning that it orbits the sun in the opposite sense from Earth and the other planets.”
Designated “C/2014 C3 (NEOWISE),” the comet was 143 million miles (230 million km) away in the image above — a composite made from six infrared exposures. That’s 585 times the distance to the Moon, or about the average distance between the Earth and Mars.
The tail of the comet NEOWISE extends about 25,000 miles (40,000 km) to the right in the image.
Overall, C/2014 C3 (NEOWISE) was spotted six times before it moved out of range of the spacecraft’s view. The comet has a highly-eccentric 20-year orbit that takes it high above the plane of the Solar System and out past the orbit of Jupiter. Technically, with a perihelion distance greater than 1.3 AU, comet C/2014 C3 does not classify as a near-Earth object (and its orbit does not intersect Earth’s.) But it’s still good to know that NEOWISE is looking out for us.
While we’re unsure about the status of chocolates and flowers in locations far beyond Earth, there certainly is no lack of hearts for us to look at to enjoy Valentine’s Day. If you look at enough geologic features or gas clouds, statistically some of them will take on shapes that we recognize (such as faces).
Below, we’ve collected some hearts on Mars and other places in the universe. Have we missed any? Share other astronomy hearts in the comments!