“So, there are a lot of mysteries left, and there are a lot of problems for you students to solve, and I want to be a president who makes sure you have the teachers and the tools that you need to solve them. That’s why we’re working to reinvigorate math and science in your schools and attract new and qualified science teachers in your classrooms, some with lifetimes of experience […] That’s how we’ll move American students to the top of the pack in math and in science over the next decade to guarantee that America will lead the world in discovery in this new century.” –President Barack Obama, Oct. 3rd.
Was there ever an astronomy party on the White House lawn during the previous administration?
HC 271791 is a star with a problem, it’s moving so fast through our galaxy that it will eventually escape from the Milky Way all together. However, there is a growing question mark hanging over the reasons as to why HD 271791 is travelling faster than the galactic escape velocity.
So-called hyper-velocity stars were first predicted to exist back in 1988 when astrophysicist Jack Hills at Los Alamos National Laboratories pondered what would happen if a binary star system should stray too close to the supermassive black hole lurking in the galactic nucleus. Hills calculated that should one of the stars get swallowed by the black hole, the binary partner would be instantly released from the gravitational bind, flinging it away from the black hole.
This would be analogous to a hammer thrower spinning around, accelerating the ball of the hammer rapidly in a circle around his body. When the thrower releases the hammer at just the right moment, the weight is launched into the air, travelling tens of meters across the stadium. The faster the hammer thrower spins the ball, the greater the rotational velocity; when he releases the hammer, rotational velocity is converted to translational velocity, launching the ball away from him. Gold medals all ’round.
So, considering Hills’ model, when one of the stars are lost through black hole death, the other star is launched, hammer-style, at high velocity away from the galactic core. The fast rotational velocity is converted into a hyper-velocity star blasting through interstellar (and eventually intergalactic) space.
Hills actually took his theory and instructed the astronomical community to keep an eye open for speeding stellar objects, and sure enough they were out there. HD 271791 is one of these stars, travelling at a whopping 2.2 million kilometres per hour, a speed far in excess of the galactic escape velocity.
However, the 11 solar mass star didn’t originate from the Milky Way’s supermassive black hole (inside the radio source Sgr. A*), it was propelled from the outermost edge of the galactic disk. There is absolutely no evidence of a supermassive black hole out there, so what could have accelerated HD 271791 to such a high velocity? After all, stars aren’t exactly easy objects to throw around.
If HD 271791 used to be part of a binary pair, its partner would have had to suddenly disappear, releasing its gravitational grip rapidly. One idea is that HD 271791’s sibling exploded as a supernova. This should have provided the sudden loss in a gravitational field — the rapidly expanding supernova plasma will have dispersed the gravitational influence of the star.
However, according to Vasilii Gvaramadze at Moscow State University, the supernova theory may not be sound either; by his calculations a binary pair simply cannot produce such a large velocity. Gvaramadze thinks that a far more complex interaction between two binary pairs (four stars total) or one binary pair and another single star some 300 solar masses. Somehow, this “strong dynamical encounter” caused HD 271791 to be catapulted out of the system, propelling it at a galactic escape velocity.
Although this complex slingshot theory sounds pretty interesting, the supernova theory still sounds like the most plausible answer. But how could a sufficient rotational velocity be attained? As Gvaramadze points out, even an extreme rapidly orbiting binary pair cannot produce a star speeding at 530-920km/s.
This is in contrast to research carried out by scientists at the Max Planck Institute for Astrophysics and the University of Erlangen-Nuremberg. In a January 2009 press release, Maria Fernanda Nieva points out that this hyper-velocity star possesses the chemical fingerprint of having been in the locality of a supernova explosion. This leads Nieva to conclude that HD 271791 was ejected after its binary partner exploded. What’s more, a Wolf-Rayet may have been the culprit.
Up to now such a scenario has been dismissed for hyper-velocity stars, because the supernova precursor usually is a super-giant star and any companion has to be at large distance in order to orbit the star. Hence the orbital velocities are fairly modest. The most massive stars in the Galaxy, however, end their lives as quite compact so-called Wolf-Rayet stars rather than as super-giants. The compactness of the primary leaves room for a companion to move rapidly on a close orbit of about 1 day-period. When the Wolf-Rayet-star exploded its companion HD 271791 was released at very high speed. In addition, HD 271791 made use of the Milky Way rotation to finally achieve escape velocity. —Maria Fernanda Nieva
Even though Gvaramadze’s stellar pinball theory sounds pretty compelling, the fact that HD 271791 contains a hint of supernova remnant in its atmosphere, the supernova-triggered event sounds more likely. But there is the fact that just because this 11 solar mass star was near a supernova some time in its past, it certainly doesn’t indicate that a supernova was the cause of it’s high speed.
Triton, Neptune’s largest moon, hasn’t been studied in detail since Voyager 2 did a flyby in 1989. That was until a team headed by Will Grundy, a Lowell Observatory planetary scientist, did a 10-year study into the distribution of the moon’s ices.
Soon to be published in the journal Icarus, the team has found that concentrations of nitrogen and carbon monoxide mix together and form a covering of ice on the Neptune-facing side of Triton. This is in contrast to the methane content of the atmosphere. For some reason, methane is concentrated on the non-facing Neptune hemisphere of the moon. It appears that methane doesn’t like to mix with the other volatile ices.
This is in stark contrast to the non-volatile ices, such as water and carbon dioxide. Both appear to have a homogeneous distribution, regardless of phase or geographical location.
These are incredible observations of a moon that was once a Kuiper Belt Object. However, the infrared analysis carried out on Triton could be a test-run before observations are carried out on other, more exotic, targets.
“This type of long-term, detailed analysis would be equally valuable for small icy planets like Pluto, Eris, and Makemake, all of which are similar to Triton in having volatile ices like methane and nitrogen on their surfaces,” said Grundy. “We have been monitoring Pluto’s spectrum in parallel with that of Triton, but Eris and Makemake are quite a bit fainter. It is hard to get time on large telescopes to monitor them year after year. We expect that Lowell Observatory’s Discovery Channel Telescope will play a valuable role in this type of research when it comes on line.”
I first came across Ralf Vandebergh’s outstanding astrophotography when I was inquiring about a “mystery” object that appeared to be stalking the International Space Station (ISS) in July. As it turned out, it wasn’t a UFO, it was in fact a Russian Progress re-supply space vehicle testing out a new automated docking procedure with the orbiting outpost. Vandebergh managed to image the ISS and Progress vehicle with amazing clarity from his home in Wittem, the Netherlands.
Today, he’s done it again, only this time his target was the first flight of the robotic Japanese H-II Transfer Vehicle, HTV-1.
On day 3 of the mission (Sept. 13th) to supply the ISS with over 4 tonnes of food, water, fuel and equipment, Vandebergh captured this incredibly detailed picture of the vehicle, speeding overhead at an altitude of just under 300km (pictured top). He also took a shot of the HTV-1 as it was approaching the ISS on Sept. 17th (right).
I’m totally in awe of these shots, and there’s a lot more where this came from. In Vandebergh’s gallery there are pictures of spacewalking astronauts, shuttle cockpits and amazingly detailed portraits of the ISS… all taken with a camera, through a telescope, on terra firma. Enjoy.
For reference, here’s a shot of the HTV-1 from the ISS shortly before docking:
The observatory, located approximately 5 miles north east of the larger Mt. Wilson Observatory, was built and is run by amateur astronomers. Also, the site is a lot smaller, meaning the single observatory dome couldn’t receive the same amount of fire fighting attention as the historic Mt. Wilson site. Fortunately, it would appear the 30-inch Newtonian-Cassegrain telescope is safe inside it’s domed home.
“For those of you who have expressed your support for Stony Ridge Observatory — thank you! As you can imagine, it’s been a stressful time for all of us, and we very much appreciate all the kind thoughts and expressions of support we’ve received. Although we’ve not been able to look inside the buildings yet, it appears at least from the outside that Stony Ridge has been spared damage but will require extensive cleanup. Keep checking the website every so often. More info/photos will be posted there as we get them.” —Kay Meyer, Stony Ridge Observatory webmaster
Tonight, Pam Sable, a member of the Stony Ridge Observatory, sent me a message confirming that the site was safe. However, the wildfire has left its mark.
“Our site is in what used to be, a lovely forest only 50 minutes from my home in Glendale, which itself is an area only 20 minutes from Downtown L.A. Once in the Angeles Forest, all the sights and sounds of the city are gone. The damage to the forest is very sad but at least it will return in time. Yet if Stony Ridge had been destroyed, it would have been irreplaceable by today’s costs. We are very, very fortunate.” –Pam Sable, Stony Ridge Observatory astronomer.
Indeed, the fire is still burning. Unfortunately, fire fighters are hurrying to extinguish the blaze as hot weather is forecast for the next week. There’s also the spectre of the Santa Ana winds that could cause some complications.
Of all the amazing things I plan to look at through my future telescope (yes, I’m still saving), this event didn’t even cross my mind. Not surprising really, it’s probably never been observed before: Io’s whole shadow transiting across the large Jovian moon, Ganymede.
But on August 16th, that changed when Christopher Go from Cebu, Philippines used his 11-inch Celestron telescope to capture the sequence of events as Io passed in front of the Sun, casting a near-perfect shadow on the large moon of Ganymede. If you were standing on Ganymede’s surface, looking at the Sun, you would have seen an Io solar eclipse.
My favourite thing about this animation is that both moons are very detailed, even at this resolution. You can see mottled shades on Ganymede, and I think the spin of Io may even have been captured.
A wonderful testament to Christopher Go’s astronomy skills and a fantastic example of how advanced our amateur astronomical equipment is becoming…
UPDATE: It turns out that little Io is getting its own back for last July’s eclipse by Ganymede, plunging the smaller moon into darkness. In the following video by OccultDave on YouTube, over a period of about 16 minutes, Io (the dot to the far-right) dims dramatically as Ganymede (the dot in the middle, next to the bright disk of Jupiter) blocks the sunlight:
The funny thing about being involved in a doomsday documentary is trying to find a suitable balance between entertainment and science. This is the conclusion I reached after the interview I did for KPI productions in New York for the upcoming 2012 documentary on the Discovery Channel last week (just in case you were wondering why Astroengine.com was being a little quiet these last few days).
Naturally, the production team was angling for what it might be like to be hit by a “killer” solar flare, what kinds of terror and destruction a brown dwarf could do to Earth and what would happen if our planet’s magnetic poles decided to do a 180°. It’s always fun to speculate after all. However, I wasn’t there to promote half-baked theories of 2012 doom, I was there to bring some reality to the nonsensical doomsday claims. But with real science comes some unexpected concerns for the safety of our planet — not in 2012, but sometime in the future.
An added bonus to my NYC trip was meeting the awesome Alex Young, a solar physicist from NASA’s Goddard Space Flight Center. Alex was asked to New York for the same reasons I was, but he has a current and comprehensive understanding of solar dynamics (whereas my solar physics research is so 2006). He actually works with SOHO data, a mission I have massive respect for.
My interview was carried out on Wednesday morning, and Alex’s was in the afternoon. The KPI guys were great, a joy to be involved in such a professional project. The documentary producer, Jonathan, asked me the questions in a great location, a huge Brooklyn building that was undergoing renovation. Very dusty with a post-apocalyptic twist. If I was going to shoot a movie about the end of the world, this building would be it.
The KPI documentary will certainly be very different from the Penn & Teller: Bullshit! episode I was involved with, but it was just as much fun, if not more so (it was like a day-long science fest).
Of particular note was Alex’s sobering words about the woeful lack of funds in solar physics (i.e. Earth-damaging solar flares and CMEs). I hope his closing statement about NOAA space weather prediction funding makes the final cut; it was nothing less than chilling.
Although we both hammered home the point that the fabled Earth-killing solar flare wont happen in 2012 (let’s face it, our Sun is still going through an epic depression, why should solar maximum be anything spectacular?), it is probably the one theory that holds the most scientific merit. In fact, as both Alex and I agreed, for a civilization that depends on sensitive technology in space and on the ground, we really need to prepare for and understand solar storms far better than we do at present.
I won’t go into any more details, but the documentary will be on the Discovery Channel in November, so I’ll give plenty of warning to fire up those DVRs.
Thank you Sarah, Jonathan and the rest of the crew from KPI for making the New York visit so memorable…
Interesting thing happened tonight. Not only did I accidentally pour dish soap into the dishwasher (yes, I know), two bottles of Pellegrino exploded in my fridge. Call it ‘applied physics’ if you like; water expands when it’s frozen, fizzy water explodes when frozen in a glass bottle! Hmmm… I never said my Ph.D. was in Common Sense… But in my defence, how was I supposed to know it was that cold in my refrigerator?
Barney was a little shaken from the loud bangs, but I think he’ll get over it (actually, he is over it, nom nomming on a bit of banana for his troubles).
“The jet-black mark is near Jupiter’s south pole (south is up in the image). I have imagery of that same location from two nights earlier without the impact mark, so this is a very recent event. The material has already begun to spread out in a fan shape on one side, and should be rapidly pulled apart by the fast jetstream winds.” — Anthony Wesley
Although this was all very exciting, and conjured up memories from the Shoemaker-Levy 9 Jupiter impact in 1994 (as documented by Hubble), I think the majority of blogs and news websites were initially reluctant to proclaim that this new dark spot was the site of an impact by a comet or asteroid. Why? Well, these events aren’t supposed to happen very often. That’s why the Shoemaker-Levy 9 impact was termed “a once in a lifetime” event.
But, 15 years later (a dog’s lifetime, perhaps), it’s been confirmed by JPL (pending an official release) that the dark patch is in fact an impact site, and not some crazy weather system:
Glenn Orton from JPL has imaged this site using the NASA Infrared Telescope on Hawaii and confirms that it is an impact site and not a localised weather event. — Update by Anthony Wesley
UPDATE (14:00 PST):Sky & Telescope Magazine is tracking developments, and reports that Leigh Fletcher, a scientist at the InfraRed Telescope Facility in Hawaii, is tweeting his findings from analysis of the Jupiter impact site. From the high infrared emissions in reflected sunlight off the dark spot, it is almost conclusive that the spot was caused by an impact by a comet or asteroid.
“This has all the hallmarks of SL-9 in 1994 (15 years to the day!). High altitude particulates, looks nothing like weather phenom.” —@LeighFletcher
The most astounding thing for me is that this impact was initially observed by an amateur astronomer, and not a space agency. We await further word from Glenn Orton at JPL and Leigh Fletcher at Hawaii, but all indications suggest this black patch IS another impact crater…
Of course, 2009 is the International Year of Astronomy, and half-way through this important year, we’ve seen some amazing feats of science. We’ve been fixing telescopes in orbit, assembling space stations, peering deep into the cosmos with a vast suite of telescopes, we’ve acquired new and improved techniques to analyse data and we’re on course for even bigger discoveries in the run-up to 2010.
So this evening, I receive word from science comedian Brian Malow that he hosted a TIME.com video all about Galileo and the history of astronomy.
If you wanted a one-stop overview of the spirit behind IYA2009, this is it. It’s witty, informative and above all, it’s entertaining — all the things this special year for science should be about.