Posted on by Jean Tate

Magnetic Fields in Spiral Galaxies – Explained at Last?

M51 (Hubble) overlaid by 6cm radio intensity contours and polarization vectors (Effelsberg and VLA) Credit: MPIfR Bonn

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That spiral galaxies have magnetic fields has been known for well over half a century (and predictions that they should exist preceded discovery by several years), and some galaxies’ magnetic fields have been mapped in great detail.

But how did these magnetic fields come to have the characteristics we observe them to have? And how do they persist?

A recent paper by UK astronomers Stas Shabala, James Mead, and Paul Alexander may contain answers to these questions, with four physical processes playing a key role: infall of cool gas onto the disk, supernova feedback (these two increase the magnetohydrodynamical turbulence), star formation (this removes gas and hence turbulent energy from the cold gas), and differential galactic rotation (this continuously transfers field energy from the incoherent random field into an ordered field). However, at least one other key process is needed, because the astronomers’ models are inconsistent with the observed fields of massive spiral galaxies.

“Radio synchrotron emission of high energy electrons in the interstellar medium (ISM) indicates the presence of magnetic fields in galaxies. Rotation measures (RM) of background polarized sources indicate two varieties of field: a random field, which is not coherent on scales larger than the turbulence of the ISM; and a spiral ordered field which exhibits large-scale coherence,” the authors write. “For a typical galaxy these fields have strengths of a few μG. In a galaxy such as M51, the coherent magnetic field is observed to be associated with the optical spiral arms. Such fields are important in star formation and the physics of cosmic rays, and could also have an effect on galaxy evolution, yet, despite their importance, questions about their origin, evolution and structure remain largely unsolved.”

This field in astrophysics is making rapid progress, with understanding of how the random field is generated having become reasonably well-established only in the last decade or so (it’s generated by turbulence in the ISM, modeled as a single-phase magnetohydrodynamic (MHD) fluid, within which magnetic field lines are frozen). On the other hand, the production of the large-scale field by the winding of the random fields into a spiral, by differential rotation (a dynamo), has been known for much longer.

The details of how the ordered field in spirals formed as those galaxies themselves formed – within a few hundred million years of the decoupling of baryonic matter and radiation (that gave rise to the cosmic microwave background we see today) – are becoming clear, though testing these hypotheses is not yet possible, observationally (very few high-redshift galaxies have been studied in the optical and NIR, period, let alone have had their magnetic fields mapped in detail).

“We present the first (to our knowledge) attempt to include magnetic fields in a self-consistent galaxy formation and evolution model. A number of galaxy properties are predicted, and we compare these with available data,” Shabala, Mead, and Alexander say. They begin with an analytical galaxy formation and evolution model, which “traces gas cooling, star formation, and various feedback processes in a cosmological context. The model simultaneously reproduces the local galaxy properties, star formation history of the Universe, the evolution of the stellar mass function to z ~1.5, and the early build-up of massive galaxies.” Central to the model is the ISM’s turbulent kinetic energy and the random magnetic field energy: the two become equal on timescales that are instantaneous on cosmological timescales.

The drivers are thus the physical processes which inject energy into the ISM, and which remove energy from it.

“One of the most important sources of energy injection into the ISM are supernovae,” the authors write. “Star formation removes turbulent energy,” as you’d expect, and gas “accreting from the dark matter halo deposits its potential energy in turbulence.” In their model there are only four free parameters – three describe the efficiency of the processes which add or remove turbulence from the ISM, and one how fast ordered magnetic fields arise from random ones.

Are Shabala, Mead, and Alexander excited about their results? You be the judge: “Two local samples are used to test the models. The model reproduces magnetic field strengths and radio luminosities well across a wide range of low and intermediate-mass galaxies.”

And what do they think is needed to account for the detailed astronomical observations of high-mass spiral galaxies? “Inclusion of gas ejection by powerful AGNs is necessary in order to quench gas cooling.”

SKA central region with separate core stations for the two aperture arrays for low and mid frequencies and for the dish array. Graphics: Xilostudios and SKA Project Development Office

It goes without saying that the next generation of radio telescopes – EVLA, SKA, and LOFAR – will subject all models of magnetic fields in galaxies (not just spirals) to much more stringent tests (and even enable hypotheses on the formation of those fields, over 10 billion years ago, to be tested).

Source: Magnetic fields in galaxies: I. Radio disks in local late-type galaxies

Posted on by Ken Kremer

Silent Spirit … Long Winter Ahead

Mosaic of the area adjacent to ‘Home Plate’ where Spirit remains stuck as 4th Martain winter experienced by Spirit approaches. Spirit has entered hibernation as of March 30, 2010 due to tripping a low power fault as a result of declining sunlight. Mosiac shows smooth area, foreground, that concealed slippery water related sulfate material where rover became stuck. Will Spirit survive the extremely harsh bone chilling cold temperatures of winter ? Credit: Kenneth Kremer, Marco DiLorenzo, NASA/JPL/Cornell/Spaceflight Now

[/caption]The Mars rover Spirit has entered her long anticipated low power hibernation mode according to a statement released by NASA’s Jet Propulsion Laboratory late Wednesday (March 31). Spirit skipped her scheduled downlink on Sol 2218 (March 30, 2010) via the Ultra-High Frequency (UHF) relay through the Mars Odyssey orbiter from her location on the Martian surface at Gusev crater. No telemetry was received from Spirit and there was no evidence of a UHF signal.

“Well, we knew it was coming… in fact, I’m surprised it didn’t happen earlier”, Steve Squyres told me today, April 1. Squyres is the Chief Scientist for the Mars rover twins, Spirit and Opportunity.

“The vehicle is all tucked in and ready to hibernate, and we have high hopes that we’ll be back in business come springtime. But it’s gonna be a long winter,” Squyres added.

The team was anticipating Spirit to experience a low-power fault about this time due to declining energy production from the wing-like solar panels. As winter approaches in the Martian southern hemisphere, the daily quantity of sunlight impinging on the power producing panels declines daily.

Energy production from the solar arrays had dropped to only 134 watt-hours on March 22. So, the most likely explanation for the missing downlink is that Spirit did go into that low-power fault taking her batteries off-line, sometime between the last downlink on Sol 2210 (March 22, 2010), and Sol 2218 (March 30, 2010).

Mosaic of microscopic images of Spirit underbelly on Sol 1925 (June 2009) showing the predicament of being stuck at Troy with wheels buried in the sulfate-rich martian soil. The sulfate deposits formed by aqueous (water-related) processes when this area dubbed “Home Plate’ was volcanically active. This false color mosaic has been enhanced and stretched to bring out additional details about the surrounding terrain and embedded wheels and distinctly show a pointy rock perhaps in contact with the underbelly. Spirit fortuitously discovered extensive new evidence for an environment of flowing liquid water at this location on Mars adjacent to ‘Home Plate’, an eroded over volcanic feature. Credit: Marco Di Lorenzo, Ken Kremer - NASA/JPL/Cornell

In hibernation mode, Spirits master clock keeps on ticking, but communications and other activities are suspended in order to channel all available energy into powering the critical survival heaters necessary to save the rovers electronics as well as to try to recharge the batteries and attempt to wake up. When the battery charge is adequate, the rover attempts to wake up and communicate on a schedule it knows.

“Components within the rover electronic module (REM) inside the rover’s warm electronic box (WEB) are experiencing record low temperatures,” says Doug McCuistion, the director of Mars Exploration at NASA Headquarters in Washington, DC, in an interview about Spirit’s predicament. “So far, the coldest temperatures recorded within the REM by one reached a low temperature of -41.5 degrees Celsius (-42.7 degrees Fahrenheit)”. This occurred just prior to the loss in communications.

“The REM electronics rack is located inside the WEB and is about a half meter cube in size”, McCuistion told me. “The expectation is for the REM hardware to reach -55C at the coldest part of the winter. We have tested the REM down to -55C”.

“Spirit’s lowest power production during a single sol (so far) was during a dust storm in November of 2008. For that one sol, Spirit’s solar arrays produced only 89 watt-hours of energy,” McCuistion said.

“We may not hear from Spirit again for weeks or months, but we will be listening at every opportunity, and our expectation is that Spirit will resume communications when the batteries are sufficiently charged,” said John Callas of NASA’s Jet Propulsion Laboratory who is project manager for Spirit and Opportunity.

Spirit has been stuck at a place called ‘Troy’ since becoming mired in a sand trap of soft soil in April 2009. While driving on the western edge of ‘Home Plate’, she unknowingly broke through a hard surface crust (perhaps 1 cm thick) of water related sulfate materials and sank into hidden soft sand beneath. At Troy she made a great science discovery by finding evidence of the past flow of liquid water on the surface of Mars.

Earlier Mars articles by Ken Kremer:

Spirit Freezing; We Will Move Her if We Can

Spirit Hunkered Down for Winter; Stuck Forever ? Maybe Not !

Phoenix Still Silent as Martian Ice Recedes

If Phoenix Arises, Science could flow quickly

Mars 2016 Methane Orbiter: Searching for Signs of Life

Posted on by Tammy Plotner

Weekend SkyWatcher’s Forecast: April 2-4, 2010

Greetings, fellow SkyWatchers! Have you been out enjoying the Sun? You better be, because the Sun has been enjoying you and putting on quite a show! Once it sets, be sure to look for both Venus and Mercury decorating the western skyline. With the Moon gone off the early evening scene, it’s also time to take on a couple of new galactic open cluster studies to tease your eye with photons! Whenever you’re ready, I’ll see you in the dark…

April 2, 2010 – On this date in 1889, the Harvard Observatory’s 13″ refractor arrived at Mt. Wilson. Just one month later, it went into astronomical service at Lick Observatory, located at Mt. Hamilton. It was here that the largest telescopes in the world resided from 1908 to 1948 – the 60″ for the first decade, then the 100″. This latter mirror is still the largest solid piece ever cast in plate glass, and weighed 4.5 tons. Would you believe it’s just 13″ thick?

This date in 1845, the first photograph of the Sun was taken. Although solar photography and observing is the domain of properly filtered telescopes, no special equipment is necessary to see some effects of the Sun, only the correct conditions. Right now Earth’s magnetosphere and magnetopause (the point of contact) are positioned correctly to interact with the Sun’s influencing interplanetary magnetic field (IMF), and the plasma stream that flows past us as the solar wind. During the time around equinox, this leaves the door wide open for one of the most awesome signs of spring – aurora! Visit the Geophysical Institute to sign up for aurora alerts, and use their tools to help locate the position of Earth’s auroral oval.


So is the Sun active right now? You betcha’. According to Spaceweather.com: “Amateur astronomers around the world are monitoring a huge prominence rising over the Sun’s northeastern limb. Magnetic fields underpinning this magnificent structure are in a state of fairly rapid motion, pulling the plasma to and fro, offering a different profile to every observer. The whole thing could become unstable and collapse.”

After you’ve enjoyed today’s Sun, be sure to watch as it sets for the brilliant appearance of Venus. Look closely to the northwest and you’ll see another planet, too. Mercury has come round from behind the Sun and is visible for a short time. If you don’t spot it at twilight, don’t despair. By week’s end, the two planets will be just 3 degrees apart!

April 3, 2010 – Tonight let’s try for a scattered open cluster, NGC 2281 (RA 06 48 18 Dec +41 05 00) toward the west in Auriga. At magnitude 5.4, NGC 2281 should be visible as a nebulous mist in binoculars on a dark night, but you’ll need a scope and high power to darken the sky enough to see the bright members found near its core.


NGC 2281 is around 1,500 light-years distant and 50 million years old. It can best be found by extending a line from Capella to Beta Aurigae an equal distance east to a pair of 5th magnitude stars separated by a finger-width. NGC 2281 lies less than a degree southeast of the eastern member of this pair (58 Aurigae). When studied photometrically, NGC 2281’s binary stars were found to congregate more toward the center of the cluster, and with more intensity than for single stars alone. With a population of no more than 60 stars, the binaries far outnumber their counterparts!

April 4, 2010 – Today we celebrate the 1809 birth on this date of astronomer Benjamin Peirce. Peirce was a professor of astronomy and mathematics for nearly 40 years and contributed greatly to the discovery of Neptune.

If you like challenging planetary nebulae studies, here’s a good one to try tonight – NGC 2610 (RA 08 33 23 Dec –16 08 58) near the Hydra/Puppis/Pyxis border.


At 13th magnitude, it’s not for the beginner, but a worthy study for seasoned veterans. Its position near two 7th magnitude stars will help reveal its location at low power. Magnify to catch a slightly elliptical shell, a stellar point on its northeast edge, and a wink of a central star. Note NGC 2610 is also cataloged as Herschel IV 65 – another to add to your ‘‘Herschel Hit List!’’

Have a terrific holiday weekend!

This week’s awesome images are: Hooker Telescope courtesy of NASA, latest H-Alpha image courtesy of SOHO, NGC 2281 and NGC 2610 from Palomar Observatory, courtesy of Caltech. We thank you so much!

Posted on by Nancy Atkinson

Skydiver Hopes to Break the Speed of Sound in Freefall

Felix Baumgartner during a test flight. Credit: Red Bull Stratos

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The speed of sound — historically called the ‘sound barrier’ – has been broken by rockets, various jet-powered aircraft and rocket-boosted land vehicles. Felix Baumgartner wants to break the sound barrier with his body, in freefall from the edge of space. He will travel inside a capsule with a stratospheric balloon to 36,500 meters (120,000 feet) step out and attempt a freefall jump targeted to reach – for the first time in history – supersonic speeds.

“After years of training with my team of dedicated Red Bull Stratos experts, I’ll be going on a journey that no one has ever done,” Baumgartner told Universe Today in an email message. “If I succeed, I will be the first person to break the sound barrier, alone. That will be a record for all eternity. As such, a piece of me will become immortal. That excites me.”

Baumgartner, left with Joe Kittinger. Credit: Red Bull Stratos

Back in 1960, a US Air Force captain named Joe Kittinger made aerospace history by making a jump from 31,000 meters (102,800 feet). His jump contributed valuable data that provided ground work for spacesuit technology and knowledge about human physiology for the US space program. There have been several attempts to surpass Kittinger’s record, but none have succeeded, and people have given their lives for the quest.

Sometime during 2010, Baumgartner will make an attempt in his “Red Bull Stratos” mission — named after the energy drink company that co-created the program with the Austrian skydiver. Red Bull Stratos team members say the mission will explore the limits of the human body in one of the most hostile environments known to humankind, in the attempt to deliver valuable lessons in human endurance and high-altitude technology.

“This is the biggest goal I can dream of,” Baumgartner said. “If we can prove that you can break the speed of sound and stay alive I think that is a benefit for future space exploration.”

If Baumgartner is successful, the Red Bull Stratos mission will break four world records: the altitude record for freefall, the distance record for longest freefall, the speed record for fastest freefall by breaking the speed of sound with the human body, and the altitude record for the highest manned balloon flight.

Baumgartner during a test flight. Credit: Red Bull Stratos

How fast will Baumgarter need to go to beat the speed of sound? Sound travels at different speeds through the atmosphere (as well as through different mediums), depending on atmospheric density and temperature. For example, at sea level, in average conditions of about 15 degrees C (59 degrees F), sound travels at around 1,223 kph (760 mph). But at higher altitudes, where the air is colder, sound travels more slowly.

Researchers with the Red Bull Stratos mission anticipate Baumgartner could break the sound barrier at about 30,480 meters (100,000 feet) above sea level, in temperatures of -23 to -40 C (-10 to -40 F) where sound travels at about 1,110 kph (690 mph) or roughly 304 meters per second (1,000 feet per second).

So, he’ll have to go faster than those speeds – or Mach 1 — to be supersonic.

While there is no literal “barrier,”the transition to supersonic speeds can cause problems for aircraft as transonic air movement creates disruptive shock waves and turbulence. Data obtained from Chuck Yeager’s first supersonic flight in 1947 allowed for changes in design of supersonic aircraft to avoid problems. Still, some aircraft still experience problems, and going supersonic has been attributed to some air disasters.

And the human body isn’t designed for supersonic speeds.

“Our biggest concern is that we don’t know how a human unencumbered by aircraft is going to transition through this,” said the project’s Medical Director Dr. Jonathan Clark, a flight surgeon for six space shuttle missions (and husband of astronaut Laurel Clark who died in the Columbia disaster in 2003), who has researched numerous aerospace disasters. “But it’s also exactly what we’re hoping to learn, for the benefit of future space flights.”

Documents provided by the Red Bull Stratos mission say that the data obtained from the mission will be shared with the scientific community, and Clark notes that he expects long-awaited medical protocols to be established as a result.

At the low temperatures and tenuous atmospheric conditions that Baumgartner will experience, he could suffer from hypothermia, the bends –if he gains altitude too fast during ascent –, or he could experience ebullism – the infamous condition where gas bubbles can form in the blood, and the blood basically “boils.”

Baumgartner wearing the David Clark Company suit. Credit: Red Bull Statos

That’s why his spacesuit is so important.

“I have absolute confidence the suit is going to work,” said Daniel McCarter, Program Manager for the David Clark Company, the same company that made Kittinger’s suit back in 1960, as well as full pressure suits for NASA astronauts and military pilots flying in aircraft that can reach the edge of the atmosphere. “Every time someone jumps a suit system like this there is something to learn. We learn knowledge for future systems.”

Art Thompson, the mission’s Technical Project Director, added, “We are ultimately risking life. Felix realizes that his life is on the line. Our job is to do everything we can from an engineering and technical point of view to keep him safe.”

The suit Baumgartner will use is custom-made for him, so there should be no pressure points caused by the suit that would make him uncomfortable, but any pressure suit restricts mobility and dexterity. He will have to avoid movements that could cause him to go into an uncontrollable spin.

Baumgartner is not new to jumping. He owns several world records for B.A.S.E. jumping and is well known for skydiving across the English Channel in 2003. He is also a parachutist, stunt coordinator and a commercial helicopter pilot.

“I think I’ve always been one of those guys who wanted to be in the places where no one has been before. It’s inside your body or brain,” Baumgartner said in a video on the Red Bull Stratos website. “When I was a kid, I liked to climb up trees –I always wanted to be on top of something.”

This will definitely be an attempt to go where no one has gone before.

For more information on the mission, visit the Red Bull Stratos website, or Felix Baumgartner’s website.

Posted on by Ken Kremer

Soyuz Blasts off with Russian American Crew for Easter ISS arrival

Expedition 23 crew members Tracy Caldwell Dyson, Alexander Skvortsov and Mikhail Kornienko launch aboard the Soyuz TMA-18 spacecraft from the Baikonur Cosmodrome in Kazakhstan.

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The Russian built Soyuz space TMA-18 capsule blasted off today (Good Friday, April 2) at 12:04 AM EDT (8:04 AM Moscow time) from the Baikonur Cosmodrome in Kazakhstan, with a Russian American crew for a 2 day trip through space that will carry them to the International Space Station (ISS) for a docking on Easter Sunday.

Soyuz TMA 18 launch
On board the capsule are an American female NASA astronaut on her 2nd trip to space, Tracy Caldwell Dyson and two male Russian rookies, cosmonauts Alexander Skvortsov and Mikhail Kornienko.

soyuz TMA 18 launch with russian american crew on April 2, 2010 bound for the ISS
Upon arrival at the ISS, this new space crew will restore the ISS to its full complement of six residents to complete the on orbit staffing of ISS Expedition 23. There is currently only a crew of three space flyers on board comprising Russian cosmonaut Oleg Kotov, NASA’s T.J. Creamer, and Soichi Noguchi of the Japan Aerospace Exploration Agency. They arrived aboard their Soyuz TMA-17 spacecraft on Dec 22 as Santas helpers bearing Christmas gifts.

The five man crew was reduced to three following the recent departure of Jeff Williams (NASA) and flight engineer Max Suraev (Russia) on March 17 who returned safely to Earth aboard the Soyuz TMA 16 capsule.

Expedition 23 launches aboard the Soyuz TMA-18. Credit: NASA TV
Less than 10 minutes after launch, the Soyuz reached orbit and its antennas and solar arrays were deployed. The crew arrives at the ISS on Easter Sunday April 4, orbiting some 200 miles above Earth. They will dock at the Poisk module.

Soyuz TMA 18 launch
It was from this historic launch pad that Soviet Cosmonaut Yuri Gagarin blasted into space in 1961 on mankind’s first manned space flight. The Soyuz crew capsule has been in use by Russia since 1967.

Posted on by Nancy Atkinson

ISS Crew Forgets Spacesuits in April 1 EVA

ISS crew April Fool's photo. Credit: NASA TV

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The crew of the International Space Station sent down an image of an unscheduled spacewalk that allegedly took place earlier today. “We wanted to welcome you guys to April, and hopefully we brought you guys some smiles and not a lot of nervousness,” T.J. Creamer radioed down to Mission Control in Houston.

“Yes, you welcomed us to April, and you did it in a grand way!” replied veteran astronaut Shannon Lucid, serving as Capcom. “You have a real problem, but you know it’s outside our ability to help you.”

Creamer and crewmates Soichi Noguchi and Oleg Kotav assured Lucid they were wearing eye protection and Lucid wondered if they put sunscreen on. “Getting vitamin D is great, but don’t stay out too long,” she said.

“Oh, Mom can’t we stay out longer?” Creamer joked.

This image is reminiscent of a picture fellow journalist Rachel Hobson took of me while we were at Kennedy Space Center, below. There was a model of the newly installed Cupola in the KSC press room, and several journalists took turns taking pictures of each other, and the images ended up looking similar to what the ISS crew created today. The astronauts obviously have some digital image editing software on board.

Nancy at KSC for the STS-130 launch. Image by Rachel Hobson.

Posted on by Ken Kremer

NASA: A possible Reprieve for Phoenix

This mosaic assembled from Phoenix images shows the spacecraft's three landing legs and patches of water ice exposed by the landing thrusters. Splotches of Martian material on the landing leg strut at left could be liquid saline-water. Larger version on Spaceflightnow.com .Credit: Kenneth Kremer, Marco Di Lorenzo, NASA/JPL/UA/Max Planck Institute and Spaceflightnow.com.

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Well my original thought for this piece was, “Last Chance for Phoenix”, since the third and final chance for NASA to reestablish radio contact with the long silent Phoenix Mars Lander was coming up soon on April 5 to 9.

Instead I was pleasantly surprised to just learn from the director of NASA’s Mars Program that NASA is seriously entertaining the idea of extending the listening campaign for Phoenix into May 2010. NASA’s first two listening campaigns in January and February 2010 failed to detect even a hint of a radio signal from the hugely successful Phoenix lander.

“NASA is considering the possibility of adding one final campaign, right around the summer solstice for the northern hemisphere of Mars, which occurs on May 13,” says Doug McCuistion, the director of Mars Exploration at NASA Headquarters in Washington, DC. “This would offer the best possible power/thermal conditions”, McCuistion told me in an interview.

“A final decision regarding this additional campaign will be made after completion of the April 5-9 campaign”, McCuistion said.

The 2010 listening campaign was timed to coincide with the onset of springtime and disappearance of ice at her location in the martian north polar regions. Theoretically the return of plentiful sunlight impinging onto the power producing solar arrays would reawaken the long dead robotic explorer.

“NASA has completed two campaigns of listening for the Phoenix Lander with the Odyssey orbiter – the first in January and the second in February”, McCuistion explained to me.

“During the five-day period of the second campaign of Feb 22-26, Odyssey passed over the Phoenix site 60 times, configuring its UHF relay radio to listen for any transmission from the surface”.

“In the unlikely event that the lander had returned to an operational, energy-positive condition after the Martian winter, it would have been in a state where it would awaken periodically and transmit to any orbiters in view, with a very high likelihood that one of those transmissions would have occurred during one or more of the 60 Odyssey overflights,” according to McCuistion.

“A third campaign is scheduled for early April (5-9), with improved power/thermal conditions as we approach summer in the northern hemisphere of Mars. For this third campaign, the sun will be continuously above the horizon at the high-latitude Phoenix site, corresponding to the solar illumination conditions just prior to Phoenix arrival at Mars as well as around sol 64 (within the primary 90-sol mission)” said McCuistion.

Phoenix set down successfully on the northern martian polar regions on May 25, 2008. During over five months of operations on top of the martian arctic plains, she made breakthrough science discoveries by finding patches of water and nutrients that could possibly sustain past or current martian life forms, if they exist.

Lets root for Phoenix !

Earlier Mars articles by Ken Kremer:

Spirit Freezing; We Will Move Her if We Can

Spirit Hunkered Down for Winter; Stuck Forever ? Maybe Not !

Phoenix Still Silent as Martian Ice Recedes

If Phoenix Arises, Science could flow quickly

Mars 2016 Methane Orbiter: Searching for Signs of Life

Posted on by Tammy Plotner

NGC 1097 Galaxy Jets: They Aren’t Just For Breakfast Anymore

Some 45 million light years away in the direction of the constellation of Fornax, a supermassive black hole is consuming its breakfast… and it doesn’t want just toast and tea. It has a hungry belly and the energetic area surrounding the central black hole is super-heated through its interaction with dust, gas, and other matter. Oh, dear. What can that matter be? Try a smaller galaxy that dared to get too close…

NGC1097 belongs a special class of galaxies called Seyfert – those that produce a specific type of spectrum and are thought to contain active galactic nuclei with super massive black holes. What makes this galaxy even more interesting is the very faint optical “jets” that may be the remnants of a smaller galaxy interaction many years ago.

Like a lingering smear of marmalade or a trail of toast crumbs, these optical jets leave visual and photographic clues as to their origin. In a deep search for neutral hydrogen gas associated with the faint optical “jets” of NGC 1097, researchers using the Very Large Array detected an H I source coincident with a small edge-on spiral or irregular galaxy (NGC 1097B) 12′ southwest of NGC 1097, situated between two jets. In addition, two other sources are noted – but not associated with the optical jets themselves. Click here for full size color image.

Could it be bacon?

According to James Higdon and John Wallin; “The jets’ radio-X-ray spectral energy distribution is most consistent with starlight. However, from their morphology, optical/near-infrared colors, and lack of H I, we argue that the jets are not tidal tails drawn out of NGC 1097’s disk or stars stripped from the elliptical companion NGC 1097A. We also reject in situ star formation in ancient radio jets as this requires essentially 100% conversion of gas into stars on large scales. Instead, we conclude that the jets represent the captured remains of a disrupted dwarf galaxy that passed through the inner few kiloparsecs of NGC 1097’s disk.

We present N-body simulations of such an encounter that reproduce the essential features of NGC 1097’s jets: A long and narrow “X”-shaped morphology centered near the spiral’s nucleus, right-angle bends, and no discernible dwarf galaxy remnant. A series of jetlike distributions are formed, with the earliest appearing ~1.4 Gyr after impact. Well-defined X shapes form only when the more massive galaxy has a strong disk component. Ram-pressure stripping of the dwarf’s interstellar medium would be expected to occur while passing through NGC 1097’s disk, accounting for the jets’ lack of H I and H II. The remnants’ (B-V) color would still agree with observations even after ~3 Gyr of passive evolution, provided the cannibalized dwarf was low-metallicity and dominated by young stars at impact.”

Bu that’s not all that’s on the table…

“The nucleus of the nearby galaxy NGC 1097 is known to host a young, compact (r < 9 pc) nuclear star cluster, as well as a low-luminosity active galactic nucleus (AGN). It has been suggested both that the nuclear stellar cluster is associated with a dusty torus and that low-luminosity AGNs like NGC 1097 do not have the torus predicted by the unified model of AGNs. To investigate these contradictory possibilities we have acquired Gemini/T-ReCS 11.7 and 18.3 ?m images of the central few hundred parsecs of this galaxy at <45 pc angular resolution, in which the nucleus and spectacular, kiloparsec-scale star-forming ring are detected in both bands." says R.E. Mason (et al). "The small-scale mid-IR luminosity implies thermal emission from warm dust close to the central engine. Fitting of torus models shows that the observed mid-IR emission cannot be accounted for by dust heated by the central engine. Rather, the principal source heating the dust in this object is the nuclear star cluster itself, suggesting that the detected dust is not the torus of AGN unified schemes (although it is also possible that the dusty starburst itself could provide the obscuration invoked by the unified model). Comparison of Spitzer IRS and Gemini GNIRS spectra shows that, although PAH bands are strong in the immediate circumnuclear region of the galaxy, PAH emission is weak or absent in the central 19 pc. The lack of PAH emission can probably be explained largely by destruction/ionization of PAH molecules by hard photons from the nuclear star cluster. If NGC 1097 is typical, PAH emission bands may not be a useful tool with which to find very compact nuclear starbursts even in low-luminosity AGNs." And starbursts as recently as 5 years ago from this early rising Seyfert are definitely on the menu... "We report evidence of a recent burst of star formation located within 9 pc of the active nucleus of NGC 1097. The observational signatures of the starburst include UV absorption lines and continuum emission from young stars observed in a small-aperture Hubble Space Telescope spectrum." says T. Storchi-Bergmann (et al). "The importance of this finding is twofold: (1) the proximity of the starburst to the active nucleus and thus its possible association with it, and (2) its obscuration by and apparent association with a dusty absorbing medium, while the broad emission lines appear unobscured, suggesting that the starburst could be embedded in a circumnuclear torus as predicted in the unified model of active galactic nuclei." Can I have eggs with that? Many thanks to NorthernGalactic member, Ken Crawford for his exclusive images. Be sure to check out Ken’s webpages at Imaging Deep Sky.

Posted on by Nancy Atkinson

Where In The Universe #98

Ready for another Where In The Universe Challenge? Here’s #98! Take a look and see if you can name where in the Universe this image iimage today, but won’t reveal the answer until tomorrow. This gives you a chance to mull over the image and provide your answer/guess in the comment section. Please, no links or extensive explanations of s from. Give yourself extra points if you can name the spacecraft responsible for the image. We provide the what you think this is — give everyone the chance to guess.

UPDATE: The answer has now been posted below.

This is a close-up view of the icy surface of Jupiter’s moon Europa, a moon of Jupiter, obtained on December 20, 1996, by the Solid State Imaging system on board the Galileo spacecraft during its fourth orbit around Jupiter. The view is about 11 kilometers by 16 kilometers (7 miles by 10 miles) and has a resolution of 26 meters (28 yards). The Sun illuminates the scene from the east (right).

For more info see the original image on the CICLOPS website.

Check back next week for another WITU challenge!