Everything you do will help us

Image

I’m Jill Tarter, the Director of the Center for SETI Research.  Since we launched at TED last Wednesday, I’ve been reading what you’ve been writing.  There have been a bunch of comments on SETILive about not knowing what to do or what to mark or whether you are getting it right. We’ll work on making the tutorial more accessible and more informative as you’ve suggested, and over time we will implement some better marking tools as you’ve requested – but the ‘getting it right’ part is a bit more dicey.  That’s because we really don’t know yet exactly what ‘right’ is.

As Lou Nigra (thanks, Lou!) and the tutorials have described, the SETILive data that are coming from the ATA originate in the crowded bands; small portions of the terrestrial microwave window that we have historically skipped over.  That’s because our SonATA system gets confused there – it detects LOTS of signals, but it cannot finish clustering them, and classifying them by comparing them to signals that are detected in the other two (or maybe one as is now the case) beams on the sky being observed simultaneously, or finish looking them up in a database of all the signals that have been tagged as RFI in the past week.  Rather than conduct our observations with non-uniform sensitivity, or continuously restart software modules that have given up in exhaustion, we have chosen to ignore these crowded bands – at these frequencies we’ve been blind and deaf.  Ultimately that might turn out to be the best strategy – after all, why are those bands crowded?  They are crowded because they have been allocated to different types of terrestrial communications services.  We are the ones making all those signals.  Or are we?

IF (of course it’s a huge if) there is a technological civilization near enough to us – its distance in light years is less than half the time over which our technology has been transmitting at a particular frequency band – perhaps that civilization has noticed that the Earth is very ‘radio bright’ at certain frequencies. Perhaps it has transponded back a reply at the same frequencies, knowing that we would have receivers that work there.  A bit more speculation suggests that their message may be crafted to be detectable against this background of terrestrial transmissions.  With this scenario in mind, we could try to code and implement all sorts of clever, non-linear anomaly detectors that inter-compare the signals received from the multiple beams on the sky – but remember we are trying to do this in near-real-time.  The detector has to finish this task significantly before the observations move on to the next frequency band, because the system still needs to match whatever the detector has found against recently detected RFI from other directions on the sky.  We don’t know what we are looking for, but we do want to invoke logical constraints that insure that the signal is only coming from one direction on the sky and not many.

Before we throw a whole lot of new computing resources (that we actually don’t happen to have) at this problem, we should take a look at what’s actually going on in the crowded bands as a guide to what might be the most effective strategy – that’s where you come in!  We are hoping to use the amazing pattern recognition of your eyes and brains to look for signals (patterns of some sort) that appear in only one beam and not in any of the others.  We hope you can help us set up a sort of rogues’ gallery of signal patterns detected over the past week (fortnight, month, 3 days ??) that can be collectively ‘remembered’ to assess whether this particular signal pattern has been seen before from other directions on the sky. That’s why we want you to mark the RFI in multiple beams as well as any pattern that only shows up in one beam.  And then if enough of you mark the same single-beam pattern (so we are fairly confident it’s real, not noise), we’ll decide that it’s an interesting candidate signal and follow up on it immediately.  That means that instead of moving on to the next frequency in the observing sequence, we will reobserve in the same directions, at the same frequency.  SonATA is still blind, so you will have to tell us whether the pattern persists – is it still there?  Is it still only in one beam?  If so, the next observation will observe at the same frequency, but looking at different directions.  Is the pattern still there? Well, that’s too bad, it means it really was some form of interference and isn’t associated with the target we were pointing at on the sky. BE PREPARED – WE THINK THIS WILL HAPPEN A LOT.  Just like your eyes have peripheral vision, a radio telescope has ‘sidelobes’ into which signals can scatter and be confused with signals entering from the direction the telescope is pointing.  The sidelobes are complicated in the way they cover the sky; it may appear that a signal is coming from only one beam out of three, but moving ‘off source’ can reposition the sidelobes so that the interference is once again detectable.

But what if the signal/pattern persists when we reobserve ‘on source’, and disappears when we go ‘off source’? That’s getting interesting! We’ll start up a cycle of ‘ons’ and ‘offs’ that will stop when the signal fails to be detected, or not be detected, at the right time, or when we’ve completed five cycles.   If the system successfully completes five cycles, then the team at the Center for SETI Research will be alerted and we’ll be right there with you using our eyes and brains to figure out what to do next.  Since we’ve begun SETI observing on the ATA this has not happened in the less crowded bands that SonATA has been exploring automatically.  Now that we are trying to probe the crowded bands, we’ll have to see how it goes.

By now I hope you are convinced that your efforts can only help us.  There’s a slight chance that you just might discover a signal from another technology buried underneath all the terrestrial interference and we will all celebrate.  But at the very least you’ll help us better understand what it is that humans are doing as they manage to look at complex patterns and isolate sub-patterns that are unique to one of multiple samples.  There may well be neurologists or psychophysicists out there who already know that answer, but my team doesn’t.  If we can learn from you, we can be better equipped to train future automated detectors.  And if it turns out that this is not a task at which humans are particularly adept, well we haven’t lost anything.  After all, our previous strategy was to ignore the crowded bands.  There is only an up side to your participation.

Thanks for being willing to help out, and good luck!

5 March 2012 by

About Chandra

Since its launch on July 23, 1999, the Chandra X-ray

Observatory has been NASA’s flagship mission for X-ray astronomy, taking its place in the fleet of “Great Observatories.”

Who we are
NASA’s Chandra X-ray Observatory is a telescope specially designed to detect X-ray emission from very hot regions of the Universe such as exploded stars, clusters of galaxies, and matter around black holes. Because X-rays are absorbed by Earth’s atmosphere, Chandra must orbit above it, up to an altitude of 139,000 km (86,500 mi) in space. The Smithsonian’s Astrophysical Observatory in Cambridge, MA, hosts the Chandra X-ray Center which operates the satellite, processes the data, and distributes it to scientists around the world for analysis. The Center maintains an extensive public web site about the science results and an education program.
What we do
Chandra carries four very sensitive mirrors nested inside each other. The energetic X-rays strike the insides of the hollow shells and are focussed onto electronic detectors at the end of the 9.2- m (30-ft.) optical bench. Depending on which detector is used, very detailed images or spectra of the cosmic source can be made and analyzed.
What we are excited about

Chandra has imaged the spectacular, glowing remains of exploded stars, and taken spectra showing the dispersal of elements. Chandra has observed the region around the supermassive black hole in the center of our Milky Way, and found black holes across the Universe. Chandra has traced the separation of dark matter from normal matter in the collision of galaxies in a cluster and is contributing to both dark matter and dark energy studies. As its mission continues, Chandra will continue to discover startling new science about our high-energy Universe.

A Tour of SN 1979C (High Definition)

 

  • SN 1979C, a supernova in the galaxy M100, may be the youngest black hole in the so-called local Universe.
  • Astronomers have seen many gamma-ray bursts, which are likely the births of young black holes, but these are much more distant.
  • If SN 1979C does indeed contain a black hole, it will give astronomers a chance to learn more about which stars make black holes and which create neutron stars.
  • SN 1979C was first reported by an amateur astronomer, and some 25 years later space-based telescopes picked up the case.

This composite image shows a supernova within the galaxy M100 that may contain the youngest known black hole in our cosmic neighborhood. In this image, Chandra’s X-rays are colored gold, while optical data from ESO’s Very Large Telescope are shown in yellow-white and blue, and infrared data from Spitzer are red. The location of the supernova, known as SN 1979C, is labeled (roll your mouse over the image above to view the labeled image).

SN 1979C was first reported to be seen by an amateur astronomer in 1979. The galaxy M100 is located in the Virgo Cluster about 50 million light years from Earth. This approximately 30-year age, plus its relatively close distance, makes SN 1979C the nearest example where the birth of a black hole has been observed, if the interpretation by the scientists is correct.

Data from Chandra, as well as NASA’s Swift, the European Space Agency’s XMM-Newton and the German ROSAT observatory revealed a bright source of X-rays that has remained steady for the 12 years from 1995 to 2007 over which it has been observed. This behavior and the X-ray spectrum, or distribution of X-rays with energy, support the idea that the object in SN 1979C is a black hole being fed either by material falling back into the black hole after the supernova, or from a binary companion.

The scientists think that SN 1979C formed when a star about 20 times more massive than the Sun collapsed. It was a particular type of supernova where the exploded star had ejected some, but not all of its outer, hydrogen-rich envelope before the explosion, so it is unlikely to have been associated with a gamma-ray burst (GRB). Supernovas have sometimes been associated with GRBs, but only where the exploded star had completely lost its hydrogen envelope. Since most black holes should form when the core of a star collapses and a gamma-ray burst is not produced, this may be the first time that the common way of making a black hole has been observed.

The very young age of about 30 years for the black hole is the observed value, that is the age of the remnant as it appears in the image. Astronomers quote ages in this way because of the observational nature of their field, where their knowledge of the Universe is based almost entirely on the electromagnetic radiation received by telescopes.

Fast Facts for SN 1979C:
Credit X-ray: NASA/CXC/SAO/D.Patnaude et al, Optical: ESO/VLT, Infrared: NASA/JPL/Caltech
Scale Image is 5 by 4 arcmin, (72,000 x 58,000 light years)
Category Supernovas & Supernova Remnants , Black Holes
Coordinates (J2000) RA 12h 22m 54.9s | Dec +15° 49′ 21”
Constellation Coma Berenices
Observation Date Feb 18, 2006 & Apr 20, 2008
Observation Time 15 hours 16 min
Obs. ID 6727, 9121
Color Code X-ray (Gold); Optical (Yellow-white, Blue), Infrared (Red)
Instrument ACIS
References Patnaude, D, et al. 2010, New Astronomy (in press); arXiv:0912.1571
Distance Estimate About 50 million light years
Release Date November 15, 2010

Arp 147 in 60 Seconds (High Definition)

  • Arp 147 contains a spiral galaxy (right) that collided with an elliptical galaxy (left), triggering a wave of star formation.
  • Many of these newly-born massive stars raced through their lives and ended with supernova explosions, some as black holes.
  • A ring of these black holes can be seen in the Chandra data (pink) around the spiral galaxy.

Just in time for Valentine’s Day comes a new image of a ring — not of jewels — but of black holes. This composite image of Arp 147, a pair of interacting galaxies located about 430 million light years from Earth, shows X-rays from the NASA’s Chandra X-ray Observatory (pink) and optical data from the Hubble Space Telescope (red, green, blue) produced by the Space Telescope Science Institute (STScI) in Baltimore, Md.

Arp 147 contains the remnant of a spiral galaxy (right) that collided with the elliptical galaxy on the left. This collision has produced an expanding wave of star formation that shows up as a blue ring containing in abundance of massive young stars. These stars race through their evolution in a few million years or less and explode as supernovas, leaving behind neutron stars and black holes.

A fraction of the neutron stars and black holes will have companion stars, and may become bright X-ray sources as they pull in matter from their companions. The nine X-ray sources scattered around the ring in Arp 147 are so bright that they must be black holes, with masses that are likely ten to twenty times that of the Sun.

An X-ray source is also detected in the nucleus of the red galaxy on the left and may be powered by a poorly-fed supermassive black hole. This source is not obvious in the composite image but can easily be seen in the X-ray image. Other objects unrelated to Arp 147 are also visible: a foreground star in the lower left of the image and a background quasar as the pink source above and to the left of the red galaxy.

Infrared observations with NASA’s Spitzer Space Telescope and ultraviolet observations with NASA’s Galaxy Evolution Explorer (GALEX) have allowed estimates of the rate of star formation in the ring. These estimates, combined with the use of models for the evolution of binary stars have allowed the authors to conclude that the most intense star formation may have ended some 15 million years ago, in Earth’s time frame.

These results were published in the October 1st, 2010 issue of The Astrophysical Journal. The authors were Saul Rappaport and Alan Levine from the Massachusetts Institute of Technology, David Pooley from Eureka Scientific and Benjamin Steinhorn, also from MIT.

Fast Facts for Arp 147:
Credit X-ray: NASA/CXC/MIT/S.Rappaport et al, Optical: NASA/STScI
Scale Image is 54 arcsec across. (about 115,000 light years across)
Category Normal Galaxies & Starburst Galaxies
Coordinates (J2000) RA 03h 11m 18.9s | Dec +01° 18′ 52.99”
Constellation Cetus
Observation Date 9/13/2009, 9/15/2009
Observation Time 11 hours 49 min
Obs. ID 11280, 11887
Color Code Optical (Red, Green, Blue); X-ray (Magenta)
Instrument ACIS
Also Known As Ring Galaxy
Distance Estimate 440 million light years
Release Date February 9, 2011

Cassiopeia A in 60 Seconds (High Definition)

  • Evidence for a bizarre state of matter – known as a superfluid – has been found in Cassiopeia A.
  • Cassiopeia A (Cas A for short) is a supernova remnant located about 11,000 light years away from Earth.
  • Chandra observations taken over a decade show significant cooling in the dense core left behind after the explosion.

This composite image shows a beautiful X-ray and optical view of Cassiopeia A (Cas A), a supernova remnant located in our Galaxy about 11,000 light years away. These are the remains of a massive star that exploded about 330 years ago, as measured in Earth’s time frame. X-rays from Chandra are shown in red, green and blue along with optical data from Hubble in gold.

At the center of the image is a neutron star, an ultra-dense star created by the supernova. Ten years of observations with Chandra have revealed a 4% decline in the temperature of this neutron star, an unexpectedly rapid cooling. Two new papers by independent research teams show that this cooling is likely caused by a neutron superfluid forming in its central regions, the first direct evidence for this bizarre state of matter in the core of a neutron star.

The inset shows an artist’s impression of the neutron star at the center of Cas A. The different colored layers in the cutout region show the crust (orange), the core (red), where densities are much higher, and the part of the core where the neutrons are thought to be in a superfluid state (inner red ball). The blue rays emanating from the center of the star represent the copious numbers of neutrinos — nearly massless, weakly interacting particles — that are created as the core temperature falls below a critical level and a neutron superfluid is formed, a process that began about 100 years ago as observed from Earth. These neutrinos escape from the star, taking energy with them and causing the star to cool much more rapidly.

This new research has allowed the teams to place the first observational constraints on a range of properties of superfluid material in neutron stars. The critical temperature was constrained to between one half a billion to just under a billion degrees Celsius. A wide region of the neutron star is expected to be forming a neutron superfluid as observed now, and to fully explain the rapid cooling, the protons in the neutron star must have formed a superfluid even earlier after the explosion. Because they are charged particles, the protons also form a superconductor.

Using a model that has been constrained by the Chandra observations, the future behavior of the neutron star has been predicted. The rapid cooling is expected to continue for a few decades and then it should slow down.

Fast Facts for Cassiopeia A:
Credit X-ray: NASA/CXC/UNAM/Ioffe/D.Page,P.Shternin et al; Optical: NASA/STScI; Illustration: NASA/CXC/M.Weiss
Scale Image is 8.91 arcmin across (about 26 light years)
Category Supernovas & Supernova Remnants
Coordinates (J2000) RA 23h 23m 26.7s | Dec +58° 49′ 03.00″
Constellation Cassiopeia
Observation Date Nine observations in 2004: Feb 8, Apr 14, 18, 20, 22, 25 28, May 01, 05
Observation Time 278 hours
Obs. ID 4634-4639, 5196, 5319-5320
Color Code X-ray: Red 0.5-1.5 keV; Green 1.5-2.5; Blue 4.0-6.0, Optical: Gold
Instrument ACIS
Also Known As Cas A
References Page, D. et al., 2011, Phys.Rev.Lett. 106, 081101 (http://lanl.arxiv.org/abs/1011.6142) Shternin, P. et al. 2011, MNRAS, L206S (http://lanl.arxiv.org/abs/1012.0045)
Distance Estimate 11,000 light years
Release Date February 23, 2011

Tycho in 60 Seconds(High Definition)

Fast Facts for Tycho’s Supernova Remnant:
Credit NASA/CXC/Chinese Academy of Sciences/F. Lu et al
Scale Image is 10 arcmin across (about 38 light years)
Category Supernovas & Supernova Remnants
Coordinates (J2000) RA 00h 25m 17s | Dec +64° 08′ 37″
Constellation Cassiopeia
Observation Date 2 pointings between April 29, 2003 and May 3, 2009
Observation Time 283 hours
Obs. ID 3837, 7639, 8551, 10093-10097; 10902-10904; 10906
Color Code Energy: Red 1.6-2.0 keV, Green 2.2-2.6 keV, Blue 4-6 keV
Instrument ACIS
Also Known As G120.1+01.4, SN 1572
References Lu, F.J. et al, 2011, ApJ, 732:11
Distance Estimate About 13,000 light years
Release Date April 26, 2011

Pitica alba in formare


Aceasta imagine a Nebuloasei Helix ne arata o stea muribunda, fiind surprinsa tranzitia spre o pitica alba. Inelele colorate reprezinta gazele expulzate in in perioada de tranzitie, ca si cum si-ar da ultima suflare. Vederea acestei stele apropiata ca masa de soarele nostu, ne ofera un indiciu, despre cum ar putea soarele nostru sa arate intr-o buna zi, atunci cand va fi aproape de sfarsitul vietii sale. Sistemul se afla la aproximativ 650 ani-lumina in constelatia Varsatorului.

Imagine: NASA, WIYN, NOAO, ESA, Hubble Helix Nebula Team, M. Meixner (STScI), & T. A. Rector (NRAO)

Pitica alba care mananca comete


O pitica alba numita G29-38 pare ca mananca cometele orbitand in jurul ei, aparent lasand in urma doar un nor de praf, ramasite care au fost detectate de Spitzer Space Telescope al NASA. Descoperirea ofera prima dovada observationala a faptului ca unele comete ar putea trai mai mult de cat sorii lor. Oamenii de stiinta cred ca G29-38 a murit devenind o pitica alba acum 500 milioane de ani, inghitindu-si planetele interioare. Cometele, totusi, orbitand mult in afara zonei interioare, pot supravietui. Praful identificat de Spitzer, a fost creat atunci cand o cometa a fost prinsa in zona interioara a sistemului, si a fost pur si simplu pulverizata de fortele gravitationale imense.

Imagine : NASA/JPL-Caltech/T. Pyle (SSC)

Perechea catapulta


Un alt sistem binar cu comportament ciudat, numit AE Aquarii, este compus dintr-o stea normala si o pitica alba. Mult mai mica si mai densa, pitica alba pare ca absoarbe materie din companioana sa mai mare. In timp ce acest lucru, in mod normal, ar determina pitica alba sa acumuleze masa, i acest caz pare sa arunce cu putere materia in loc s-o acumuleze. Astronomii considera ca, datorita vitezei mari de rotatie si a unui camp electromagnetic foarte puternic, sunt elementele ce stau in spatele acestui comportament ciudat, determinand steau sa arunce un flux de materie care emite un spectru larg de radiatie, vizibila chiar daca este aflata la 330 ani-lumina, in celalalt capat al galaxiei.

Credit: Casey Reed