[/caption]
If you take a lot of digital pictures, you’re probably familiar with the frustration of keeping track of dozens of files, and always running out of hard drive space to store them. Well, the scientists and engineers on NASA’s Wide-field Infrared Survey Explorer (WISE) mission have no pity for you. Their spacecraft just finished photographing the entire sky in exquisite detail: a total of 1.3 million photos.
“The eyes of WISE have not blinked since launch,” said William Irace, the mission’s project manager at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Both our telescope and spacecraft have performed flawlessly and have imaged every corner of our universe, just as we planned.”
WISE surveys the sky in strips as it orbits the earth. It takes six months of constant observing to map the entire sky. By pointing at every part of the sky, astronomical surveys deliver excellent data covering both well-known objects and those that have never been seen before.
“WISE is filling in the blanks on the infrared properties of everything in the universe from nearby asteroids to distant quasars,” said Peter Eisenhardt of JPL, project scientist for WISE. “But the most exciting discoveries may well be objects we haven’t yet imagined exist.”
One example of a well-known object seen in new light by WISE is the Pleiades cluster: a group of young blue stars shrouded by dust that the cluster is currently passing through. In WISE’s false-color infrared vision, the hot stars look blue but the cooler dust clouds give off longer wavelengths of infrared light, causing them to glow in shades of yellow and green.
The WISE survey is particularly significant because such a wide range of objects in the universe are visible in infrared light. Giant molecular clouds glow in infrared light, as do brown dwarfs – objects that are bigger than planets but smaller than true stars. WISE can also see ultra-bright, extremely distant galaxies whose visible light has been stretched into the infrared by the expansion of the universe during its multi-billion-year journey.
The recently completed WISE survey also observed 100,000 asteroids in our solar system, many of which had never been seen before. 90 of the newly discovered asteroids are near-earth objects, whose orbits cross our own, making them potentially dangerous but also potential targets for future mission.
You might think that 1.3 million pictures would be plenty, but WISE will keep mapping the sky for another three months, covering half of the sky again and allowing astronomers to search for changes. The mission will end when the spacecraft’s solid hydrogen coolant finally runs out and the infrared detectors warm up (they don’t work as well when they are warm enough to emit the same wavelengths of infrared light that they are meant to detect).
But even as the telescope warms up, the astronomers on the WISE team will just be getting warmed up too. With nearly two million images, they will be busy making new discoveries for years to come.
The chances of a Nemesis existing are little to none, given periodic mass extinctions on Earth, as per a couple of scientists.
I wonder if any brown dwarfs will be found closer than the Alpha Centauri system (or within 10 l.y.)? THAT would shake things up.
@ Jon Hanford,
Some people in the scientific community have postulated that a Nemesis (Death) Star orbits the Sun at a distance of about 50,000 to 100,000 AU (about 1-2 light-years) beyond the Oort cloud, which certainly “would shake things up”!
@ Navneeth,
Yeah, I saw the research paper, the other day, by those two scientists: Nemesis_Reconsidered.
Oh, that again, 2nd round I believe. Well, I don’t believe in any of that, for the following top-down reasons:
1) There is no periodicity in the data, either modern or the original Raup-Sepkoski, as shown by simple autocorrelation:
“Quantitatively, extinction rates in the Fossil Record 2 family data (3) and Sepkoski’s family and genus data (1, 2) are not correlated with themselves at any time lag (49), which is a necessary condition for periodicity to hold. That said, analyses of origination rates in all three datasets (49, 50) suggest short-term autocorrelation. However, the current dataset shows no autocorrelation in either kind of rate (Fig. S1), and a standard spectral analysis (Fig. S2) also suggests purely random variation through the time series (i.e., white noise).” [Alroy, PNAS, 2008.]
I’m not aware of any criticism to this result. In fact, Melott and Bambach cites Alroy for its data, but doesn’t reply to its basic observations what I can see. Logically they would then admit that their method introduces a periodicity artifact.
2) This is an old contentious area with no consensus. Melott and Bambach admits this:
“Raup and Sepkoski (1984), hereafter RS, published a study of marine fossil families, describing in it a 26 My periodicity in local maxima of extinction; Sepkoski (1989) confirmed and refined it to 26.2 My with a study of genera; Lieberman & Melott (2007) found hints of it with spectral analysis. This result cannot be said to have been settled by consensus among paleontologists.”
3) I have looked at Raup and Sepkoski 1986 paper, which I assume contains much the same analysis as the 1984. It is terrible.
Among other things they introduce Fourier-techniques as used by Melott and Bambach, but does not test against null data by other filters than their own peak detector _which admit any sampled data local maxima in the noise_. Noise in, noise out.
4) Melott and Bambach seems superficially to massage their data similarly:
“We found that a signal at 27 Myr appeared in both data sets separately, but the suppression of random error in the combined set as well as a comparison with mass extinction timings (Part 4.2), clarified things greatly.”
5) It is pertinent to look at earlier work. arxiv records show that Melott nearly exclusively looks for patterns in data.
This is of course a permissible research strategy, but to be a viable one Melott should rigorously test his results. See however the 1) and 2) withdrawal from that.
As a layman I can say this, with the same strength (i.e. none): I can’t see any difference between this area and “cold fusion” pathological science.
In any case, no periodicity means no Nemesis as envisioned.
Possibly poisoning the well now: if the above is a correct analysis it clarifies the oddity that Bambach IIRC visits a Sepkoski and Ruse conference. Michael Ruse is a “crypto” (well) creationist “philosopher of biology”, which often equivocates on evolutionary facts. Muddling one area may indicate muddling others.
Thanks for the extra information, Torbjörn!
I think the Nemesis hypothesis has fallen into the back and is probably not viable. I doubt that WISE will find any nearby brown dwarf.
What WISE might do with respect to brown dwarf stars is to maybe give some statistics for their occurrence in our local region so as to maybe give more accurate accounting of non-illuminated matter. One candidate for dark matter were MACHOs (MAssive Cold Heavy Objects), of which brown dwarfs were thought to be a major contributor.
An astronomer, Weiman, if I recall the name, in 1992-3 looked at the winking of stars in the Magellanic Clouds, where the winking was due to a passage of a dark object such as a brown dwarf. A few were found, but using statistics it was found to be nowhere near enough to account for dark matter.
LC
IVAN3MAN_AT_LARGE, you are welcome! The benefits of being a layman, can haz no clout but big opinions. 😮
Also, d’oh, the vagaries to take from memory: It was not a Ruse and Sepkoski conference but a book (in press). And if Ruse is equivocating on evolution, Sepkoski may not be. [Which I know because I had to check him and his web pages up, J. Sepkoski is long dead. This is a D. Sepkoski, historian of science.]
I was actually hoping to see WISE nail the coffin shut wrt Nemesis. Why were previous all-sky IR surveys (IRAS, 2MASS) inadequate to reveal this object? Near aphelion? Low resolution? Lack of sensitivity/depth? I guess it’s too good a story to be bothered by facts. 🙂
It’s amazing how all these 2012 fanatics jump on the Nemesis theory and claim it’s proof of “Niburu”. They always keep pulling out that old 1980’s photo from IRAS about some IR source they couldn’t properly define back then in every single arguement.
I actually would love it if we found a Brown Dwarf in the outer reaches of our Solar System. (although getting there for probes would take very very long.)
But it seems highly unlikely.
If this image is clicked and opened in its full size, some of the bright stars have black dot in their center. Is this WISE anomaly? Or just an image processing problem?
Well if the Nemesis would be true then we should detect a wobble in the red-shift since Sun-Nemesis would have an additional barycentre.
These 2012 people are funny people. I checked the Nibiru that went all the way towards Nemesis and back to the Sun and immediately discovered that this is impossible. At first the Nibiru orbit would be very aperiodical and second it would miss Nemesis the next time it got there since Nemesis would have moved. LOL
Ishan, the “black dots” are artifacts probably related to pixel saturation of the detector.
IIRC, a team of researchers at JPL came up with a new name for Nemesis, which they acknowledged has an ‘image’ problem (more like a ‘no image’ problem :D) . Tyche is the monniker they chose. Still….new name, same problem!
Mass extinctions have happened 20 times in the last 540 million years, or every 27 million +/- 2 years. ~16 million years it is predicted to happen again. Intensity rates are highly variable, the most recent extinction was less then 10% while the worst was 90% marine life lost during the Permian-Triassic period when event happened 252.6 million years ago. The ordovician extinction was not part of the nemesis theory rather had a supernova cause. Every 250 million years the sun completes a revolution around the galaxy. Maybe stars like our sun encounter cosmic ray bombardment from supernova explosions as they orbit the galaxy because of its magnetic field about every 27 million years?
Thanks, Jon 🙂
I believe it is logical to assume that the mass extinction record on earth proved 99% predictable over the last 500 million years or longer is due to the milky way galaxy colliding and merging with another smaller galaxy, likely a satellite galaxy one of which is actually nearby now beginning to collide. galactic collisions increase star formation and supernova rates, causing cosmic ray flurries perhaps GRB alignment blasts. The Andromeda galaxy merger ahead will likely cause a mass extinction of life on practically all habitable life supporting planets throughout the galaxy. A collision with a smaller dwarf satellite galaxy in the Magellanic Clouds would have caused mostly mild extinctions in the geologic record.