It’s time once again for another Where In The Universe Challenge. Name where in the Universe this image was taken and give yourself extra points if you can name the telescope or spacecraft responsible for the image. Post your guesses in the comments section, and check back on later at this same post to find the answer. To make this challenge fun for everyone, please don’t include links or extensive explanations with your answer. Good luck!
UPDATE: The answer has now been posted below.
This is a thin crescent of Saturn’s third largest moon, Dione, taken by the Cassini spacecraft’s narrow-angle camera on May 17, 2010, and just released on Sept. 1. Cassini was about 394,000 kilometers (245,000 miles) from Dione, and the image scale is 2 kilometers (1 mile) per pixel. Just like seeing our own Moon as a crescent allows us to better see the craters along the terminator, the lit terrain seen here highlights the craters on Dione, as well.
Racing is rarely the term that comes to mind when one considers astronomy. However, many events are a race to reach stability before a system flies apart or implodes. The formation of stars from gigantic interstellar clouds is just such a race in which stars struggle to form before the cloud is dispersed. Although a rough estimation of the requirements for collapse are discussed in introductory astrophysics classes (See: Jeans Mass Criterion) this formulation leaves out several elements that come into play in the real universe. Unfortunately for astronomers, these effects can be subtle but significant but untangling them is the subject of a recent paper uploaded to the arXiv preprint server.
The Jeans Mass Criterion only takes into consideration a gas cloud in isolation. Whether or not it will collapse will depend on whether or not the density is sufficiently high. But as we know, stars don’t form in isolation; They form in stellar nurseries which form hundreds to thousands of stars. These forming stars contract under self gravity, and in doing so, heat up. This increases the local pressure and slows contraction as well as giving off additional radiation that also affects the cloud at large. Similarly, solar winds (particles streaming from the surface of formed stars) and supernovae can also disrupt further formation. These feedback mechanisms are the target of a new study by a group of astronomers led by Laura Lopez from the University of California Santa Cruz.
To investigate how each feedback mechanism operated, the group selected the Tarantula Nebula (aka, 30 Doradus or NGC 2070), one of the largest star forming regions easily accessible to astronomers since it resides in the Large Magellanic Cloud. This region was selected due to its large angular size which allowed the team to have good spatial resolutions (down to scales smaller than a parsec) as well as being well above the plane of our own galaxy to minimize interference from gas sources in our own galaxy.
To conduct their study, Lopez’s team broke 30 Dor into 441 individual regions to assess how each feedback mechanism worked in different portions of the nebula. Each “box” consisted of a column slicing through the nebula that was a mere 8 parsecs to a side to ensure sufficient quality of the data across the entire spectrum since observations were used from radio telescopes to X-ray and used data from Spitzer and Hubble.
Perhaps unsurprisingly, the team found that different feedback mechanisms played varying roles in different places. Close the the central star cluster (<50 parsecs), radiation pressure dominated the effects on the gas. Further out, pressure from the gas itself played the stronger role. Another potential feedback mechanism was that of “hot” gas being excited by X-ray emission. What the team uncovered is that, although there is a significant amount of this material, the nebula’s density is insufficient to entrap it and allow it to have a large effect on the overall pressure. Rather, they described this portion as “leaking out of the pores”.
This research is some of the first to observationally explore, on a large scale, many of the mechanisms that have been proposed by theorists in the past. Although such research may seem inconsequential, these feedback mechanisms will have large effects on the distribution of stellar masses (known as the Initial Mass Function). This distribution determines which the relative amounts of massive stars which help to create heavy elements and drive the chemical evolution of galaxies as a whole.
UPDATE: Three hostages have been released unharmed, and the suspect, James J. Lee, was shot at about 4:50 p.m. EDT by police. The latest reports say he was killed.
Lee, armed with a gun and an explosive device entered the Discovery Communications building in Silver Spring on Wednesday afternoon and took several people hostage including a security guard, Montgomery County Police said.
Some breaking news via former UT writer Ian O’Neill who now works for Discovery Space News: A protester has taken at least one hostage at the Discovery Channel building in Silver Spring, Maryland. Reportedly a man entered the lobby and may have fired a weapon and declared, “Nobody is going anywhere,” according to Montgomery County police. Other reports said the gunman may have had explosives attached to his chest. The building has been evacuated, including an in-house daycare center, but a live news feed on TBD recently showed medical personnel bringing in a stretcher. Via Twitter, there is link to a list of demands to the Discovery Channel by someone named “Lee.” NBC just reported that the alleged gunman is James Jay Lee, who has a history of protesting outside the Discovery Channel building.
We’ll provide an update when it becomes available. Thankfully, Ian is not at the building.
If you didn’t have the chance to see Brian Cox’s series “Wonders of the Solar System” which aired on the BBC earlier this year and the Science Channel in August, we’ve got some good news for you: it comes out on DVD and Blu-ray in the US on September 7. But there’s even better news for readers of Universe Today: We have five – count ‘em – five copies to give away, courtesy of the BBC and Bender Helper Impact marketing agency. “Wonders” is an extraordinary look at our world and solar system, and is rich with breathtaking images beamed back from the fleet of probes, rovers and telescopes currently in space, and is a “must-see” for any space and astronomy enthusiast.
To enter the contest, send an email to [email protected] with “Wonders DVD” in the subject line. Deadline for entry is Wednesday, September 8 at 12 pm PDT. Winners will have their choice of “Wonders” on DVD or Blu-ray.
See more info below about this remarkable series, including a video trailer that will give a taste of this great series.
Wonders of the Solar System” is a 3-disc set, and the series is presented by renowned physicist Brian Cox who will explore some of the most amazing features of our planet’s own backyard. Witness how forces of nature carved out beauty and order from the chaos of space and learn how our home planet is not isolated, but intimately connected with the rest of the solar system. Using the latest scientific knowledge, state of the art CGI, along with stunning images paired up with some of the most spectacular, extreme locations on Earth to help reveal wonders never thought possible. Included are two bonus programs, “What on Earth Is Wrong with Gravity?” and “Do You Know What Time It Is?”
The idea of the “Theory of Everything” is enticing – that we could somehow explain all that is. String theory has been proposed since the 1960’s as a way to reconcile quantum mechanics and general relativity into such an explanation. However, the biggest criticism of String Theory is that it isn’t testable. But now, a research team led by scientists from the Imperial College London unexpectedly discovered that that string theory also seems to predict the behavior of entangled quantum particles. As this prediction can be tested in the laboratory, the researchers say they can now test string theory.
“If experiments prove that our predictions about quantum entanglement are correct, this will demonstrate that string theory ‘works’ to predict the behavior of entangled quantum systems,” said Professor Mike Duff, lead author of the study.
String theory was originally developed to describe the fundamental particles and forces that make up our universe, and has a been a favorite contender among physicists to allow us to reconcile what we know about the incredibly small from particle physics with our understanding of the very large from our studies of cosmology. Using the theory to predict how entangled quantum particles behave provides the first opportunity to test string theory by experiment.
But – at least for now – the scientists won’t be able to confirm that String Theory is actually the way to explain all that is, just if it actually works.
“This will not be proof that string theory is the right ‘theory of everything’ that is being sought by cosmologists and particle physicists,” said Duff. “However, it will be very important to theoreticians because it will demonstrate whether or not string theory works, even if its application is in an unexpected and unrelated area of physics.”
String theory is a theory of gravity, an extension of General Relativity, and the classical interpretation of strings and branes is that they are quantum mechanical vibrating, extended charged black holes.The theory hypothesizes that the electrons and quarks within an atom are not 0-dimensional objects, but 1-dimensional strings. These strings can move and vibrate, giving the observed particles their flavor, charge, mass and spin. The strings make closed loops unless they encounter surfaces, called D-branes, where they can open up into 1-dimensional lines. The endpoints of the string cannot break off the D-brane, but they can slide around on it.
Duff said he was sitting in a conference in Tasmania where a colleague was presenting the mathematical formulae that describe quantum entanglement when he realized something. “I suddenly recognized his formulae as similar to some I had developed a few years earlier while using string theory to describe black holes. When I returned to the UK I checked my notebooks and confirmed that the maths from these very different areas was indeed identical.”
Duff and his colleagues realized that the mathematical description of the pattern of entanglement between three qubits resembles the mathematical description, in string theory, of a particular class of black holes. Thus, by combining their knowledge of two of the strangest phenomena in the universe, black holes and quantum entanglement, they realized they could use string theory to produce a prediction that could be tested. Using the string theory mathematics that describes black holes, they predicted the pattern of entanglement that will occur when four qubits are entangled with one another. (The answer to this problem has not been calculated before.) Although it is technically difficult to do, the pattern of entanglement between four entangled qubits could be measured in the laboratory and the accuracy of this prediction tested.
The discovery that string theory seems to make predictions about quantum entanglement is completely unexpected, but because quantum entanglement can be measured in the lab, it does mean that there is way – finally – researchers can test predictions based on string theory.
But, Duff said, there is no obvious connection to explain why a theory that is being developed to describe the fundamental workings of our universe is useful for predicting the behavior of entangled quantum systems. “This may be telling us something very deep about the world we live in, or it may be no more than a quirky coincidence”, said Duff. “Either way, it’s useful.”
NASA’s Ice, Cloud, and land Elevation (ICESat) mission is now on ice, so to speak, or perhaps we should say, it ultimately became an inferno. The satellite was intentionally deorbited and burned up in the atmosphere on August 30, after completing a very productive seven-year scientific stint in orbit. And talk about the ultimate high-stakes, high-adventure, hands-on student project: students at the University of Colorado Boulder conducted the final maneuvers to send the spacecraft to its fiery death.
ICESat’s science mission ended in February 2010 when its primary instrument failed. NASA lowered the satellite’s orbit this summer and then decommissioned the spacecraft in preparation for re-entry. The satellite largely burned up, (NASA calculated that no more than 90 kg (200 pounds) of the ICESat’s original 900 kg (2,000 pounds) would survive re-entry) with pieces of debris falling into the Barents Sea, part of the Arctic Ocean north of Norway and Russia.
Originally a slated for 3 year mission, it continued for seven years and 15 laser-operations campaigns. While the GLAS instrument failed, the spacecraft itself remained in operating condition, so NASA could fire its thrusters to lower its orbit. This began in June, and reduced the lowest point of the spacecraft’s orbit to 125 miles (200 km) above Earth’s surface. The orbit then naturally decayed, but the final maneuvering was controlled by a group of students from the University of Colorado, working at the school’s Laboratory for Atmospheric and Space Physics (LASP). They sent it successfully plummeting through Earth’s atmosphere at just the right moment so that the satellite’s remains would land in the chilly – and uninhabited — seas north of Norway and Russia.
“They ran calculations to determine where the spacecraft was located,” said Darrin Osborne, flight director for ICESat.
The student operators provide a lower cost to NASA, and CU students at LASP receive hands-on training and experience that helps position them for a future in space-related careers.
“It’s amazing for an undergraduate like me to get hands-on experience controlling multimillion-dollar NASA satellites,” said third-year aerospace engineering sciences student Katelynn Finn, quoted in an article in The Register. ICESat orbital image. Credit: NASA
ICESat was launched in January, 2003, and was the first mission of its kind, designed to study Earth’s polar regions with a space-based laser altimeter called the Geoscience Laser Altimeter System, or GLAS. ICESat has helped in our understanding of ice sheet and sea ice dynamic, leading to scientific advances in measuring changes in the mass of the Greenland and Antarctic ice sheets, polar sea ice thickness, vegetation-canopy heights, and the heights of clouds and aerosols. Using ICESat data, scientists identified a network of lakes beneath the Antarctic ice sheet. ICESat introduced new capabilities, technology and methods such as the measurement of sea ice freeboard – or the amount of ice and snow that protrudes above the ocean surface – for estimating sea ice thickness.
A final eulogy for the satellite was offered by NASA’s Earth Science Mission Operations office: “The ICESat mission operations team is commended for its exceptional performance, working tirelessly for the past eleven years (four years of preparation and seven years of operations), overcoming several obstacles in the early years of the mission, and closing out the mission with a flawless series of orbital maneuvers before final decommissioning. The positive control maintained over the mission right to the end shows the quality and effort that went into designing, building, qualifying, launching, and operating a tremendously successful mission such as ICESat.”
The six SJ-06 series satellites in Earth orbit. Credit: The Space Review
[/caption]
Data from the US military shows that two Chinese satellites likely performed multiple rendezvous 600 kilometers above Earth this summer, and may have even bumped into each other. The rendezvous have taken place over the past several months, between two Chinese “Shi Jian” (Practice) spacecraft, SJ-06F and SJ-12, that are officially listed as science satellites.
Weeden said the maneuvers could be a rehearsal for the technology needed to build a space station, but it also shows China may now have the ability to approach and potentially interfere with other satellites.
“On-orbit rendezvous is a complex operation, and one that has only been done a few of times before, most notably by the US satellite XSS-11,” Weeden wrote, “which inspected the rocket body that placed it in LEO, and one of the US MiTEx satellites, which inspected the failed DSP-23 satellite in GEO. The rendezvous of two Chinese satellites demonstrates that China is broadening its space capabilities, but also touches on the greater issue of perceptions, trust, and safety in space activities that could impact the long-term sustainability of the space regime.”
Weeden said US military data suggests that one satellite may have been bumped and its orbit altered slightly on August 19. The change in its orbit can’t be explained by the usual things that affect satellites, such as the drag from the Earth’s atmosphere.
In January 2007, China destroyed a derelict satellite with a ballistic missile, which the US also did in February 2008.
For now, one can only speculate about the reasons for China performing these types of difficult and rare maneuvers with their satellites. You can read more about the technical nature of the events on The Space Review.
Hurricane Earl (lower left), Tropical Storm Fiona located to Earl's east, and Tropical Storm Danielle far in the Northern Atlantic. Credit: NASA/GOES Project
[/caption]
My father had a favorite adage when life was hectic: “There’s lots of commotion in the ocean.” That saying was never more true than the current situation in the busy Atlantic Ocean. The GOES-13 satellite captured this image earlier today (Tuesday Aug. 31) and visible are three areas of tropical commotion. The large and powerful Hurricane Earl (lower left) is passing Puerto Rico, Tropical Storm Fiona located to Earl’s east, and Tropical Storm Danielle far in the Northern Atlantic. Below is footage taken by the International Space Station of the action.
Hurricane Earl is a storm that’s about 640 km (400 miles) in diameter and the hurricane force winds are about 225 km (140 miles) in diameter from side-to-side of the storm’s eye. Earl is still a Category Four hurricane on the Saffir-Simpson scale, one category stronger than Hurricane Katrina was when she made landfall in Mississippi in 2005.
A tropical storm warning is in effect for Turks and Caicos Islands and a tropical storm watch is in effect for the southeastern Bahamas. Meanwhile, residents from the Carolinas northward to New England in the US should be watchful of where Earl is heading. A hurricane watch could be required for portions of the mid-Atlantic coast later today.
Tropical Storm Fiona is moving through the same areas that Hurricane Earl battered a few days ago, but with less force. A tropical storm warning is in effect for St. Martin and St. Barthelemy. A tropical storm watch is in effect for, Antigua, Barbuda, Montserrat, St. Kitts, Nevis, and Anguilla and St. Maarten, Saba, and St. Eustatius. The National Hurricane Center noted in its forecast this morning, August 31, that Tropical storm conditions could spread over portions of the Northern Leeward Islands tonight or early Wednesday.
At 11 a.m. EDT, Tropical Storm Fiona had maximum sustained winds near 65 kph (40 mph) and some strengthening is possible. Fiona is moving west-northwest near 38 kph (24 mph) and is expected to slow down.
Tropical cyclones are warm-core systems, so when the core temperatures change, the dynamics of the system also changes. Today, Danielle transitioned into a cold-core low pressure area in the Northern Atlantic Ocean. Her sustained winds were near 112 kph (70 mph), but waning.
Danielle’s effects are being felt along the shores of Newfoundland with heavy surf and waves up to 3 meters (10 feet).
The Geostationary Operational Environmental Satellite project was developed by NASA for the National Oceanic and Atmospheric Administration (NOAA). The GOES satellites are funded by NOAA, while the Goddard Space Flight Center procures and manages the development and launch of the GOES satellites while NOAA manages the operational environmental satellite program and establishes requirements, provides all funding and distributes environmental satellite data for the United States.
Keck II image of the young extrasolar planet HR 8799 b, seen as the point source in center of image.Credit: Brendan Bowler and Michael Liu, IfA/Hawaii
[/caption]
Back in 2008, the first multi-planet system of extrasolar planets was imaged, and further study of the planets in this very young system is yielding some puzzling results. Astronomers using the Keck Observatory have been able to obtain the spectrum of one planet, HR 8799 b, revealing the temperature, chemical composition, and atmospheric properties of the planet. The planet’s atmosphere is unlike that of any previously studied extrasolar planet, and it appears the planet is extremely cloudy, and also quite hot, even though it is very far from its host star.
“We are at a point where not only can we directly image planets around other stars, but we can begin to study the properties of their atmospheres in detail. Direct spectroscopy of exoplanets is the future of this field,” said Brendan Bowler, a graduate student at the University of Hawaii and the lead author of the study.
Although over 500 planets have been discovered around other stars, only six planets have been directly imaged.
Three exoplanets orbiting a young star 140 light years away are captured using Keck Observatory near-infrared adaptive optics. The planets are labeled and the two outer ones have arrows showing the size of their motion over a 4 year period.
HR 8799 b, is one of those imaged, and is one of three gas-giant planets orbiting the star HR 8799, located 130 light-years away from Earth in the constellation Pegasus. Bowler and his team said the properties of the planet’s atmosphere can’t be explained by current theoretical models of gas giant exoplanets, even those with what is considered a normal amount of thick or dusty atmospheres. From the new data on this planet, the astronomers believe that this exoplanet is extremely cloudy, and perhaps, all young gas-giant planets exhibit the same type of cloud cover in their atmospheres.
The technique the team used to determine the planet’s temperature relies on the chemistry of the planet’s atmosphere. Specifically, the presence or absence of gaseous methane can be used as a thermometer. The team found that HR 8799 b shows little or no methane in its atmosphere. Based on their spectrum and previously obtained images of the planet, and by comparing the observations to theoretical models of low-temperature atmospheres, they estimate the coolest possible temperature for the planet is about 1200 Kelvin (about 1,700 degrees Fahrenheit).
This planet is quite far from the star, 67 times the Earth-sun separation from the host star.
Current theoretical models predict HR 8799 b should be about 400 Kelvin cooler than they measured, based on the age of the planet and the amount of energy it is currently emitting. The team suspects the discrepancy arises because the planet is much more dusty and cloudy than expected by current models.
“Direct studies of extrasolar planets are just in their infancy. But even at this early stage, we are learning they are a different beast than objects we have known about previously,” said University of Hawaii astronomy professor Michael Liu, coauthor of the study.
The planets around HR 8799 are incredibly faint, about 100,000 times dimmer than their parent star. To obtain the spectrum of HR 8799 b, the team relied on the adaptive optics system of the Keck II Telescope, and focused on the star for several hours. Then they used the Keck facility instrument called OSIRIS, a special kind of spectrograph, to precisely separate the spectrum of the planet from the light of its parent star.
A paper describing the study will be published in the Astrophysical Journal later this year, but you can read the team’s abstract here.
We’ve hinted that it was going to be made, and then we warned you that a sneak preview would be aired on August 29th. Well, now I’ve seen the first episode of Phil Plait’s Bad Universe, and I’m here to solemnly judge it. Continue reading “Bad Universe Review”
