Radio Pinwheel

National Radio Astronomy Observatory -- Socorro, Jan. 9, 2001, Press Release: "New Images Show Unprecedented Detail of Neighbor Galaxy's Gas" 

M-33 Rotation revealed by Doppler shifted Hydrogen emissions -- NRAO.

Results of a high-resolution radio telescope study of the nearby "Pinwheel Galaxy" (M-33) were reported at the recent American Astronomical Society's meeting in San Diego, CA.  The National Radio Astronomy Observatory (NRAO) Very Large Array radio telescope in Socorro, New Mexico, was teamed up with the Westerbork Synthesis Radio Telescope, in the Netherlands, to produce a map showing the distribution of neutral atomic Hydrogen in M33.

Both radio telescopes were tuned to the 21-cm wavelength emitted by Hydrogen and to Doppler shifted wavelengths to detect galaxy rotation.  Details as small as 130 light-years are evident in the images.  "Bubbles" caused by redistribution of hydrogen due to supernovae are expected to become evident when the images are further computer processed to reveal features at the 65 light-year scale. 

According to NRAO's David Thilker, "An image with the level of detail we have achieved opens the door to learning fundamental new facts about the relationship between massive stars and the galaxy's complicated gaseous environment. This, in turn, will help us better understand how galaxies age." 

Roughly half the size of the Milky Way, the 60,000 light-years diameter galaxy is 2.7 million light-years from Earth in the constellation Triangulum.  The 6.3 magnitude object is an easy target for amateur optical telescopes.  

New Moons Rise

Sky & Telescope; Dec. 29, 2000; (E-mail) News Bulletin: "Saturn's Satellites: 30 and Counting" 

Discovery.com; Jan. 10, 2001; News: "10 More Moons Orbiting Jupiter"

What is fascinating about astronomy are the constant new discoveries surrounding "well-known" celestial objects.  Continuing revelations concerning our planetary system makes "accepted fact" rather mercurial.  For instance what two gas-giant planets have been under ground-based scrutiny for centuries, Hubble observation for a decade, visited by various space probes since the 70's, and are still full of "looney" surprises?  Jupiter and Saturn of course.  In the past few months there have been announced dozens of new moons orbiting those planets. 

An international team led by Brett Gladman of Nice Observatory, using the 1.2-m at Whipple Observatory in Arizona and the 3.6-m Canada-France-Hawaii in Hawaii, reported discovering two new Saturn moons at the end of last year.  The Arizona scope found S/2000 S 11 to be about 35-km in diameter.  S/2000 S 12, found by the Hawaii telescope, is probably only 5-km in diameter.

Of the 19 new moons of Saturn discovered in the past 20-years about a dozen were discovered by Gladman's team.  Gladman's discoveries cluster in three groups: the first two with prograde orbits with inclinations of 35 and 48-degrees to the planet, the last in retrograde orbits of 170-degrees inclination. 

A two-week observing run at the 2.2-m University of Hawaii telescope turned up 10 new moons around Jupiter: the largest number of moon discoveries at one time.  Graduate student Sam Sheppard and faculty advisor David Jewitt discovered the moons at the end of last-year by computer analyzing wide-field images around the planet.  An 11th moon discovery turned out to be a Jovan satellite first detected in 1975. 

All the new Jupiter moons are no more than 5-km in diameter and orbit at inclinations of 15 and 30-degrees to the planet.  One of the fresh discoveries is in a retrograde orbit. 

"At some point the bigger question of what is a satellite and what isn't will have to be addressed. "
-- Sam Sheppard, Jovian moon discoverer. 

The reader will note that these tiny moons were discovered with telescopes that are on the small-end for professional observatories.  That's because recent discoveries are driven by new imaging technologies and processing techniques.  Sheppard notes that, "At some point the bigger question of what is a satellite and what isn't will have to be addressed. Basically, as you are able to image fainter and fainter light, you can find more and more moons." 

As of this report Jupiter is the "Moon King" runner-up with 28 confirmed moons -- trailing just behind Saturn that reigns with 30 orbital "subjects".  Don't bother memorizing these numbers and rankings for astronomy trivia as no doubt they will change in the new Millennium.  

Don't Tell California About This...

BBC News Online; Jan. 15, 2001; Sci/Tech:"Bright idea detects space blasts"

Power-starved and environmentally conscious Californians would be pleased to know that "Solar Two" -- a facility in the Mojave Desert that uses 1,800 mirrors to focus the Sun's energy -- produced 10-megawatts of clean power in 1998.  But that was the last year the largest solar furnace ever built was used for power purposes.  California's loss is astronomy's gain as modifications are being made to use the giant power-station as a gamma-rays detector.  

Where once temperatures of thousands of degrees were concentrated, the array will now capture the fleeting flash of " Cherenkov radiation" caused by gamma-rays striking our atmosphere.  Gamma-rays can produce energetic particles of electrons and anti-electrons that move faster than the speed-limit for light traveling though our atmosphere.  This results in the Cherenkov "flash" that lasts a billionth of a second and -- at the ground -- spreads out over a circle the size of a football-field.  Hence the solar furnace was a ready-made collector large enough for studying this phenomena.  

Scientists want to use the facility to solve the mystery of gamma-ray bursters.  Bursters pour forth as much energy in a few seconds or minutes as the Sun would generate in its lifetime.  The former Compton Gamma-Ray Observatory was used to study these objects, but Solar Two may finally discover the secret of these objects. 

Tests have shown that the former power-plant can already detected gamma-rays from the Crab Nebula -- a known source that will be used to calibrate this gigantic gamma-ray telescope.

Galaxy Wars

Space Telescope Science Institute; Jan. 9, 2001; Press Release: "'Pipeline' funnels matter between colliding galaxies"

NGC-1410 & 1409 - NASA

"A long, long, time-ago (100-million years), in a galaxy far, far away (300-million light-years from Earth)... ," could be the opening line of a story about a galaxies-spanning struggle between two forces.  In the case of galaxies NGC-1409 and 1410 the story is quite real!  100-million years ago these two galaxies had their first glancing collision and became gravitationally bound to each other.  Before they merge, in another 200-million years, they are expected to collide and pull apart several times.  The galaxy centers are currently only 23,000 light-years apart -- akin to Earth's distance from the center of the our Milky Way galaxy.  Blue galactic arms in NGC-1410 indicate star-forming activity as a result of gravitational interaction with its partner galaxy. 

Recent Hubble Telescope images reveal what's most fascinating about this interaction: a 500 light-year wide "pipeline" that crosses over 20,000 light-years of space from NGC-1410  and wraps around NGC-1409.  The pipeline has transferred 1-million solar masses of gas and dust material to NGC-1410 over the course of time.  The Imaging Spectrograph on Hubble confirmed that the pipeline is continuous between galaxies.

This galaxy saga is much a mystery story: researchers do not know the originating location of the pipeline in NGC-1410 or why the material is flowing to NGC-1409.  Also there is no star formation occurring at the NGC-1410 side of the pipeline.  The speculation is that the gas flow is too hot to gravitationally collapse and form stars; it is also too little: only 0.02 solar masses of mater a year is transferred. 

These results were presented at the American Astronomical Society meeting in San Diego, CA.