Astronomy Archives

November 26, 2013December 23, 2015 by Elizabeth Howell

Home Computers Discover Gamma-Ray Pulsars

Gamma-ray pulsars in the Milky Way's plane, found by volunteers using Einstein@Home. The sky map is from Fermi's Large Area Telescope. The brighter the color you see, the more intense the radiation in that spot. The small flags show the nationality of the volunteers whose computers spotted the pulsars. Credit: Knispel/Pletsch/AEI/NASA/DOE/Fermi LAT Collaboration

Imagine that you’re innocently running your computer in pursuit of helping data crunch a huge science project. Then, out of the thousands of machines running the project, yours happens to stumble across a discovery. That’s what happened to several volunteers with Einstein@Home, which seeks pulsars in data from the Fermi Gamma-Ray Space Telescope, among other projects.

“At first I was a bit dumbfounded and thought someone was playing a hoax on me. But after I did some research,” everything checked out. That someone as insignificant as myself could make a difference was amazing,” stated Kentucky resident Thomas M. Jackson, who contributed to the project.

Pulsars, a type of neutron star, are the leftovers of stars that exploded as supernovae. They rotate rapidly, with such precision in their rotation periods that they have sometimes been likened to celestial clocks. Although the discovery is exciting to the eight volunteers because they are the first to find these gamma-ray pulsars as part of a volunteer computing project, the pulsars also have some interesting scientific features.

Artist's illustration of a neutron star, a tiny remnant that remains after its predecessor star explodes. Here, the 12-mile (20-kilometer) sphere is compared with the size of Hannover, Germany. Credit: NASA's Goddard Space Flight Center — Artist’s illustration of a neutron star, a tiny remnant that remains after its predecessor star explodes. Here, the 12-mile (20-kilometer) sphere is compared with the size of Hannover, Germany. Credit: NASA’s Goddard Space Flight Center

The four pulsars were discovered in the plane of the Milky Way in an area that radio telescopes had looked at previously, but weren’t able to find themselves. This means that the pulsars are likely only visible in gamma rays, at least from the vantage point of Earth; the objects emit their radiation in a narrow direction with radio, but a wider stripe with gamma rays. (After the discoveries, astronomers used the Max Planck Institute for Radio Astronomy’s 100-meter Effelsberg radio telescope and the Australian Parkes Observatory to peer at those spots in the sky, and still saw no radio signals.)

Two of the pulsars also “hiccup” or exhibit a pulsar glitch, when the rotation sped up and then fell back to the usual rotation period a few weeks later. Astronomers are still learning more about these glitches, but they do know that most of them happen in young pulsars. All four pulsars are likely between 30,000 and 60,000 years old.

Artist's conception of a gamma-ray pulsar. Gamma rays are shown in purple, and radio radiation in green. Credit: NASA/Fermi/Cruz de Wilde — Artist’s conception of a gamma-ray pulsar. Gamma rays are shown in purple, and radio radiation in green. Credit: NASA/Fermi/Cruz de Wilde

“The first-time discovery of gamma-ray pulsars by Einstein@Home is a milestone – not only for us but also for our project volunteers. It shows that everyone with a computer can contribute to cutting-edge science and make astronomical discoveries,” stated co-author Bruce Allen, principal investigator of Einstein@Home. “I’m hoping that our enthusiasm will inspire more people to help us with making further discoveries.”

Einstein@Home is run jointly by the Center for Gravitation and Cosmology at the University of Wisconsin–Milwaukee and the Albert Einstein Institute in Hannover, Germany. It is funded by the National Science Foundation and the Max Planck Society. As for the volunteers, their names were mentioned in the scientific literature and they also received certificates of discovery for their work.

Source: Max Planck Institute for Gravitational Physics

November 26, 2013December 23, 2015 by Elizabeth Howell

NASA Plans To Deepen Asteroid Searches With Planetary Resources

An artist's conception of two tidally locked objects orbiting the Sun from afar. The system: 2010 WG9 may likely look like this. Credit: zmescience

Planetary Resources Inc. — that company that is developing a crowdsourced space telescope to search for asteroids — is planning to work on “crowdsourced software solutions” to make it easier to find asteroids and other near-Earth objects, using NASA-funded data.

NASA announced that Planetary Resources will receive a non-reimbursable Space Act Agreement to help NASA characterize near-Earth objects. It’s the first initiative announced under NASA’s Asteroid Grand Challenge, which the agency announced this summer as a vehicle to find threats to Earth.

A contest is planned in 2014 that will also include participation from the Zooniverse’s forthcoming Asteroid Zoo platform (which includes participation from Planetary Resources). Zooniverse is known for providing ordinary people the chance to participate in astronomical searches, including galaxies and asteroid features.

NASA’s role will be to “develop and manage” the contest, while Planetary Resources is expected to “facilitate the use of NASA-funded sky survey data and help support the algorithm competition and review results,” the agency stated.

NASA is trying mightily to move forward with its plans to capture an explore an asteroid in the next few years, but there’s no guarantee that the agency will receive the funds it wants for it in the fiscal 2014 budget. Politicians have expressed concern that the mission is not interesting the public; besides which, the agency is already battling for funds for its commercial crew and planetary science programs, among others.

Source: NASA

November 25, 2013December 23, 2015 by Elizabeth Howell

Speedy Science: Here’s Four Years Of Herschel Telescope Work In A Short Video

ESA's Herschel telescope used liquid helium to keep cool while it observed heat from the early Universe. Credit: ESA

In just one minute, you can watch the Herschel space telescope painting the sky blue, green and yellow! The colors in this new video represent four years of observations from the European Space Agency telescope, which was active between 2009 and 2013.

“In total, Herschel observed almost a tenth of the entire sky for over 23,500 hours, providing new views into the previously hidden universe, pointing to unseen star birth and galaxy formation, and tracing water through the universe from molecular clouds to newborn stars and to their planet-forming discs and belts of comets,” ESA stated on a video explanation.

As ESA explains, Herschel had two cameras and imaging spectrometers on board, called PACS (Photoconductor Array Camera and Spectrometer, in blue) and SPIRE (Spectral and Photometric Imaging Receiver, in green). When they worked together, their observations are shown in yellow.

Herschel was officially shut down on June 17 — check out the video of those commands here — but the scientific information the telescope produced is still being plumbed by astronomers.

Source: ESA

November 23, 2013December 23, 2015 by Ken Kremer

NASA’s LADEE Probe Starts Science Study of Thin Lunar Atmosphere and Dusty Mystery

Artist’s concept of NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft in orbit above the moon as dust scatters light during the lunar sunset. Credit: NASA Ames / Dana Berry

KENNEDY SPACE CENTER, FL – NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) has descended to its planned low altitude orbit and begun capturing science data on its ground breaking mission to study the Moon’s ultra tenuous atmosphere and dust using a spacecraft based on a revolutionary new design aimed at speeding development and cutting costs.

LADEE set sail for Earth’s nearest neighbor during a spectacular night time launch atop the maiden flight of an Air Force Minotaur V rocket on Sept. 6 from NASA’s Wallops Island launch facility on Virginia’s Eastern shore.

The flawless launch thrilled spectators up and down virtually the entire US East coast region and yielded many memorable snapshots.

Following a month long voyage and three and a half long looping orbits of the Earth, LADEE successfully fired its main engine for 4 minutes and 12 seconds on Oct. 6 and successfully entered lunar orbit, Dawn McIntosh, LADEE deputy project manager at NASA Ames Research Center, told Universe Today in an exclusive interview.

A series of engine firings over the past month gradually circularized and lowered LADEE into its final science orbit around our Moon while engineers checked out the spacecraft during the commissioning phase of the mission.

The do or die initial Lunar Orbit Insertion burn (LOI-1) allowed LADEE to be captured into a highly elliptical, equatorial lunar orbit, said McIntosh.

Launch of NASA’s LADEE lunar orbiter on Friday night Sept. 6, at 11:27 p.m. EDT on the maiden flight of the Minotaur V rocket from NASA Wallops, Virginia. Credit: Ken Kremer/kenkremer.com

“Two additional LOI burns on Oct. 6 and Oct 9 lowered LADEE to an approximately 4 hour orbit with a periapsis altitude of 234 Kilometers (km) and apoapsis altitude of 250 km” McIntosh told me.

The trio of LOI main engine firings used up most of LADEE’s precious on board fuel.

“LADEE launched with 134.5 kilograms (kg) of fuel. Post LOI-3, 80% of our fuel has been consumed,” said McIntosh.

“Additional orbit-lowering maneuvers with the orbital control system (OCS) and reaction control system (RCS) of approximately 40 seconds were used to get LADEE into the science orbit.

The spacecraft finally entered its planned two hour science orbit around the moon’s equator on Nov. 20.

Its flying at an extremely low altitude ranging from merely eight to 37 miles (12-60 kilometers) above the moon’s surface.

By circling in this very low altitude equatorial orbit, the washing machine sized probe will make frequent passes crossing from lunar day to lunar night enabling it to precisely measure changes and processes occurring within the moon’s tenuous atmosphere while simultaneously sniffing for uplifted lunar dust in the lunar sky.

The remaining fuel will be used to maintain LADEE’s orbit during the approximately 100 day long science mission. The mission length is dictated by the residual fuel available for thruster firings.

The purpose of LADEE is to collect data that will inform scientists in unprecedented detail about the ultra thin lunar atmosphere, environmental influences on lunar dust and conditions near the surface. In turn this will lead to a better understanding of other planetary bodies in our solar system and beyond.

“A thorough understanding of the characteristics of our lunar neighbor will help researchers understand other small bodies in the solar system, such as asteroids, Mercury, and the moons of outer planets,” said Sarah Noble, LADEE program scientist at NASA Headquarters in Washington.

By studying the raised dust, scientists also hope to solve a 40 year old mystery – Why did the Apollo astronauts and early unmanned landers see a glow of rays and streamers at the moon’s horizon stretching high into the lunar sky.

The $280 million probe is built on a revolutionary ‘modular common spacecraft bus’, or body, that could dramatically cut the cost of exploring space and also be utilized on space probes to explore a wide variety of inviting targets in the solar system.

“LADEE is the first in a new class of interplanetary exploration missions,” NASA Ames Director Worden told Universe Today. “It will study the pristine moon to study significant questions.”

“This is probably our last best chance to study the pristine Moon before there is a lot of human activity there changing things.”

The 844 pound (383 kg) robot explorer was assembled at NASA’s Ames Research Center, Moffett Field, Calif., and is a cooperative project with NASA Goddard Spaceflight Center in Maryland.

LADEE arrived at the Moon last month in the midst of the US government shutdown – which negatively impacted a host of other NASA missions. Only a ‘skeleton crew’ was available.

“All burns went super well,” Worden told me. And he is extremely proud of the entire team of “dedicated” professional men and women who made it possible during the shutdown.

“It says a lot about our people’s dedication and capability when a skeleton crew’ can get a new spacecraft into lunar orbit and fully commissioned in the face of a shutdown!” Worden said to Universe Today.

Now the real science begins for LADEE and the team.

Stay tuned here for continuing LADEE news

Ken Kremer

…………….

Learn more about LADEE, MAVEN, MOM, Mars rovers, Orion and more at Ken’s upcoming presentations

Nov 22-25: “SpaceX launch, MAVEN Mars Launch and Curiosity Explores Mars, Orion and NASA’s Future”, Kennedy Space Center Quality Inn, Titusville, FL, 8 PM

Dec 11: “Curiosity, MAVEN and the Search for Life on Mars”, “LADEE & Antares ISS Launches from Virginia”, Rittenhouse Astronomical Society, Franklin Institute, Phila, PA, 8 PM

November 21, 2013December 23, 2015 by David Dickinson

NASA Halts Work on its New Nuclear Generator for Deep Space Exploration

MSL's MMRTG in the laboratory. (Credit: NASA).

Another blow was dealt to deep space exploration this past weekend. The announcement comes from Jim Green, NASA’s Planetary Science Division Director. The statement outlines some key changes in NASA’s radioisotope program, and will have implications for the future exploration of the outer solar system.

An Advanced Stirling Converter prototype in the laboratory. (Credit: NASA).

We’ve written about the impending plutonium shortage and what it means for the future of spaceflight, as well as the recent restart of plutonium production. NASA is the only space agency that has conducted missions to the outer planets — even the European Space Agency’s Huygens lander had to hitch a ride with Cassini to get to Titan — and plutonium made this exploration possible. Continue reading “NASA Halts Work on its New Nuclear Generator for Deep Space Exploration”

November 21, 2013March 16, 2017 by Fraser Cain

What is a Pulsar?

They are what is known as the “lighthouses” of the universe – rotating neutron stars that emit a focused beam of electromagnetic radiation that is only visible if you’re standing in it’s path. Known as pulsars, these stellar relics get their name because of the way their emissions appear to be “pulsating” out into space.

Not only are these ancient stellar objects very fascinating and awesome to behold, they are very useful to astronomers as well. This is due to the fact that they have regular rotational periods, which produces a very precise internal in its pulses – ranging from milliseconds to seconds.

Description:

Pulsars are types of neutron stars; the dead relics of massive stars. What sets pulsars apart from regular neutron stars is that they’re highly magnetized, and rotating at enormous speeds. Astronomers detect them by the radio pulses they emit at regular intervals.

An artist’s impression of an accreting X-ray millisecond pulsar. The flowing material from the companion star forms a disk around the neutron star which is truncated at the edge of the pulsar magnetosphere. Credit: NASA / Goddard Space Flight Center / Dana Berry

Formation:

The formation of a pulsar is very similar to the creation of a neutron star. When a massive star with 4 to 8 times the mass of our Sun dies, it detonates as a supernova. The outer layers are blasted off into space, and the inner core contracts down with its gravity. The gravitational pressure is so strong that it overcomes the bonds that keep atoms apart.

Electrons and protons are crushed together by gravity to form neutrons. The gravity on the surface of a neutron star is about 2 x 10¹¹ the force of gravity on Earth. So, the most massive stars detonate as supernovae, and can explode or collapse into black holes. If they’re less massive, like our Sun, they blast away their outer layers and then slowly cool down as white dwarfs.

But for stars between 1.4 and 3.2 times the mass of the Sun, they may still become supernovae, but they just don’t have enough mass to make a black hole. These medium mass objects end their lives as neutron stars, and some of these can become pulsars or magnetars. When these stars collapse, they maintain their angular momentum.

But with a much smaller size, their rotational speed increases dramatically, spinning many times a second. This relatively tiny, super dense object, emits a powerful blast of radiation along its magnetic field lines, although this beam of radiation doesn’t necessarily line up with it’s axis of rotation. So, pulsars are simply rotating neutron stars.

And so, from here on Earth, when astronomers detect an intense beam of radio emissions several times a second, as it rotates around like a lighthouse beam – this is a pulsar.

History:

The first pulsar was discovered in 1967 by Jocelyn Bell Burnell and Antony Hewis, and it surprised the scientific community by the regular radio emissions it transmitted. They detected a mysterious radio emission coming from a fixed point in the sky that peaked every 1.33 seconds. These emissions were so regular that some astronomers thought it might be evidence of communications from an intelligent civilization.

Although Burnell and Hewis were certain it had a natural origin, they named it LGM-1, which stands for “little green men”, and subsequent discoveries have helped astronomers discover the true nature of these strange objects.

Astronomers theorized that they were rapidly rotating neutron stars, and this was further supported by the discovery of a pulsar with a very short period (33-millisecond) in the Crab nebula. There have been a total of 1600 found so far, and the fastest discovered emits 716 pulses a second.

Later on, pulsars were found in binary systems, which helped to confirm Einstein’s theory of general relativity. And in 1982, a pulsar was found with a rotation period of just 1.6 microseconds. In fact, the first extrasolar planets ever discovered were found orbiting a pulsar – of course, it wouldn’t be a very habitable place.

Interesting Facts:

When a pulsar first forms, it has the most energy and fastest rotational speed. As it releases electromagnetic power through its beams, it gradually slows down. Within 10 to 100 million years, it slows to the point that its beams shut off and the pulsar becomes quiet.

When they are active, they spin with such uncanny regularity that they’re used as timers by astronomers. In fact, it is said that certain types of pulsars rival atomic clocks in their accuracy in keeping time.

Pulsars also help us search for gravitational waves, probe the interstellar medium, and even find extrasolar planets in orbit. In fact, the first extrasolar planets were discovered around a pulsar in 1992, when astronomers Aleksander Wolszczan and Dale Frail announced the discovery of a multi-planet planetary system around PSR B1257+12 – a millisecond pulsar now known to have two extrasolar planets.

Artist's impression of the planets orbiting PSR B1257+12. Credit: NASA/JPL-Caltech/R. Hurt (SSC) — *Artist’s impression of the planets orbiting PSR B1257+12. Credit: NASA/JPL-Caltech/R. Hurt (SSC)*

It has even been proposed that spacecraft could use them as beacons to help navigate around the Solar System. On NASA’s Voyager spacecraft, there are maps that show the direction of the Sun to 14 pulsars in our region. If aliens wanted to find our home planet, they couldn’t ask for a more accurate map.

We have written many articles about stars here on Universe Today. Here’s an article about a newly discovered gamma ray pulsar, and here’s an article about how millisecond pulsars spin so fast.

If you’d like more information on stars, check out Hubblesite’s News Releases about Stars, and here’s the stars and galaxies homepage.

We have recorded several episodes of Astronomy Cast about stars. Here are two that you might find helpful: Episode 12: Where Do Baby Stars Come From, and Episode 13: Where Do Stars Go When they Die?

November 20, 2013December 23, 2015 by Tammy Plotner

Exploring Our Galaxy’s Ancient Brown Dwarfs

A brown dwarf from the thick-disk or halo is shown. Although astronomers observe these objects as they pass near to the solar system, they spend much of their time away from the busiest part of the Galaxy, and the Milky Way's disk can be seen in the background. Credit: John Pinfield

As the name implies, a brown dwarf is small… only about 7% the size of the Sun. As far as stellar senior citizens go, they’re cool. Zipping along through space at speeds of 100 to 200 kilometers per second, they may have formed back when our galaxy was young – perhaps 10 billion years ago. Now a team of astronomers headed by Dr. David Pinfield at the University of Hertfordshire has identified a pair of the oldest brown dwarfs known… a set of orbs which could be the harbinger of a huge amount of new, unseen objects.

Although we sometimes refer to them as stars, brown dwarfs are in a class of their own. Because they didn’t ignite in nuclear fusion, they don’t generate internal heat like an ordinary star. After they are formed, they continue to cool and fade as time passes. This process makes them very difficult to observe and the discovery of two very old brown dwarfs, with temperatures of 250-600 C is cause for astronomical excitement.

Just how did Pinfield’s team pick such tiny objects out of the vastness of space? The discovery was facilitated thanks to a survey made by the Wide-field Infrared Survey Explorer (WISE), a NASA observatory that scanned the mid-infrared sky from orbit in 2010 and 2011. The ancient objects are cataloged as WISE 0013+0634 and WISE 0833+0052, and they are located in the constellations of Pisces and Hydra. Because they are so elusive, they were also confirmed by large ground-based telescopes (Magellan, Gemini, VISTA and UKIRT).

However, identifying the pair wasn’t easy. Seeing through the eyes of infrared reveals a crowded space – one populated with reddened stars, distant background galaxies and pockets of nebulous gas and dust. Picking out such a small character from a stellar cast would be like finding one tiny pearl in the vastness of an ocean. But Pinfield’s researchers employed a new method which utilizes WISE’s capabilities. As it scanned the sky over and over again, it revealed the cool, brown dwarfs – picking up the faint signature that other searches had missed.

These two particular brown dwarfs are different from the other slow movers of their type. By studying their spectra, the astronomers have identified atmospheres almost entirely comprised of hydrogen. This sets them apart from younger stars which have an abundance of heavier elements. Does being lighter make them speedier? According to Pinfield, “Unlike in other walks of life, the galaxy’s oldest members move much faster than its younger population.”

Stars near to Sun are considered the “local volume” and are created with three overlapping populations – the thin disk, the thick disk and the halo. Each of these layers has a certain amount of age associated with it: the oldest being the thickest and its member stars move up and down at a higher rate of speed. The halo contains both disks, along with the initial materials which formed the very first stars. Thin disk objects abound in the local volume and account for about 97% of the local stars, while thick disk and halo objects are a meager 3%. Chances are, brown dwarfs belong to that smaller percentage which explains why these fast-moving thick-disk/halo objects are only now being revealed.

Just how many may await discovery? Scientists surmise there may be as many as 70 billion brown dwarfs in the galaxy’s thin disk, and the thick disk and halo take up significantly larger galactic volumes. Even at a tiny 3%, this means there could be an army of ancient brown dwarfs in the galaxy. “These two brown dwarfs may be the tip of an iceberg and are an intriguing piece of astronomical archaeology,” said Pinfield. “We have only been able to find these objects by searching for the faintest and coolest things possible with WISE. And by finding more of them we will gain insight into the earliest epoch of the history of the galaxy.”

Original Story Source: Royal Astronomical Society News Release. For further study: “A deep WISE search for very late type objects and the discovery of two halo/thick-disk T dwarfs: WISE 0013+0634 and WISE 0833+0052”, D. J. Pinfield et al, Monthly Notices of the Royal Astronomical Society, in press.

November 20, 2013December 23, 2015 by David Dickinson

Get Out Your Comet Scorecards: Comet Nevski Now Visible With Binoculars

Capture of Comet Nevski shortly after discovery using the ITelescope Observatory in New Mexico. (Credit: Ernesto Guido, Nick Howes & Martino Nicolini).

Is 2013 truly the “Year of the Comet?” Perhaps “Comets” might be a better term, as no less than five comets brighter than +10^th magnitude grace the pre-dawn sky for northern hemisphere observers.

Comet C/2013 V3 Nevski has just brightened up 6 magnitudes — just over a 250-fold increase in brightness — and now sits at around magnitude +8.8. Comet Nevski was just recently discovered by Vitali Nevski using a 0.4 metre reflecting telescope 12 days ago on November 8^th. If that name sounds familiar, it’s because Nevski discovered the comet from the Kislovodsk observatory located near Kislovodsk, Russia which is part of the International Scientific Optical Network survey which located comet ISON last year. In fact, there was some brief controversy early on in its discovery that Comet C/2012 S1 ISON should have had the moniker Comet Nevski-Novichonok.

At the time of discovery, Comet Nevski appeared to be nothing special: shining at magnitude +15.1, it was well below our +10 magnitude limit for consideration as “interesting,” and was projected to linger there for the duration of its passage through the inner solar system. About a dozen odd such comet discoveries crop up per year, most of which give astronomers a brief pause as the orbit and size of the comet become better known, only to discern that they’re most likely to be nothing extraordinary.

The orbit of comet Nevski, as seen during the closest approach to the Earth on December 21st. (Credit: The Solar System Dynamics JPL Small-Body Database Browser).

Such was to be the case with Comet Nevski, until it suddenly flared up this past weekend.

Observer Gianluca Masi caught Comet Nevski in outburst, using a Celestron C14 remotely as part of the Virtual Telescope 2.0 project:

Comet Nevski captured on November 14th by Gianluca Masi. (Credit: The Virtual Telescope 2.0 Project).

You’ll note that Comet Nevski shows a small, spiky tail on the brief exposure. As of this writing, it currently sits at between magnitudes +8 and +9 and should remain there for the coming week if this current outburst holds.

Comet Nevski is well placed for northern hemisphere observers high in the morning sky, and will spend the remainder of November and early December crossing the astronomical constellation of Leo.

The celestial path of Comet Nevski from mid-November to the end of December. (Created by the author using Starry Night Education simulation software).

Here’s a blow-by-blow rundown on noteworthy events for this comet for the remainder of 2013:

November 23rd: Passes the +5.3 magnitude star Psi Leonis and crosses north of the ecliptic plane.

December 1st: Passes +3.4 magnitude star Eta Leonis.

December 6th: Passes +4.8 magnitude 40 Leonis and the bright +2nd magnitude star Algieba.

December 15th: Crosses into the constellation Leo Minor.

December 17th: Passes near the +5.5^th magnitude star 40 Leonis Minoris.

December 21st: Passes closest to Earth, at 0.847 Astronomical Units (A.U.s), or 126 million kilometres distant.

December 30th: Passes into the constellation Ursae Majoris.

Note that a “close pass” denotes a passage of the comet within a degree of a bright or interesting object.

The orbit of Comet Nevski is inclined 31.5 degrees relative to the ecliptic, and it will be headed for circumpolar for observers based in high northern latitudes as it dips back down below our “interesting” threshold of magnitude +10 in early 2014.

This comet passed perihelion on October 27^th, 2013 just over a week prior to discovery. Comet Nevski is Halley-type comet, with a 27.5 year orbit.

So, looking at the “Comet Scorecard,” we currently have:

Comet C/2012 X1 LINEAR: Still undergoing a moderate outburst at magnitude +8.2, very low to the north east for northern hemisphere observers at dawn in the constellation Boötes.

Comet 2P/Encke: Reaches perihelion tomorrow at 0.33 AU’s from the Sun, shining at magnitude +7.7 near Mercury in the dawn sky but is now mostly lost in the Sun’s glare.

Comet C/2013 R1 Lovejoy: is currently well placed in the constellation Ursa Major crossing into Canes Venatici in the hours before dawn. Currently shining at magnitude +5.4, Comet R1 Lovejoy is visible to the unaided eye from a dark sky site. We caught sight of the comet last week with binoculars, looking like an unresolved globular cluster as it passed through the constellations of Leo and Leo Minor.

And of course, Comet C/2012 S1 ISON: As of this writing, ISON is performing up to expectations as it approaches Mercury low in the dawn shining at just above +4^th magnitude. We’ve seen some stunning pictures as of late as ISON unfurls its tail, and now the eyes of the astronomical community will turn towards the main act: perihelion on November 28^th. Will it fizzle or dazzle? More to come next week!

The recent outbursts of Comets X1 LINEAR and V3 Nevski are reminiscent of the major outburst of Comet Holmes back in 2007. Of course, the inevitable attempts to link these outbursts to the current sputtering solar max will ensue, but to our knowledge, no conclusive correlations exist. Remember, the outburst from Comet Holmes occurred as we were approaching what was to become a profound solar minimum.

Also, it might be tempting to imagine that all of these comets are somehow related, but they are in fact each on unique and very different orbits, and only appear in the rough general direction in the sky as seen from our Earthly vantage point… a boon for dawn patrol sky watchers!

Got pics? Send ‘em in to Universe Today!

November 19, 2013December 23, 2015 by Ken Kremer

How to Watch the Spectacular Minotaur Night Launch on Nov. 19 with Record Setting 29 Satellite Payload

Elevation viewing map for Minotaur 1 rocket launch on Nov. 19 from NASA Wallops Island facility. Credit: Orbital Sciences

Tonight, Tuesday, Nov. 19, tens of millions of residents up and down the US East coast have another opportunity to watch a spectacular night launch from NASA’s Wallops Island facility in Virginia – weather permitting.

See a collection of detailed visibility and trajectory viewing maps, as well as streaming video of the launch, courtesy of rocket provider Orbital Sciences and NASA Wallops Flight Facility.

And to top that off, the four stage Minotaur 1 rocket is jam packed with a record setting payload of 29 satellites headed for Earth orbit.

And if that’s not enough to pique your interest, the Virginia seaside launch will also feature the first cubesat built by high school students.

And viewing is open to the public.

Minotaur 1 launch trajectory map for the US Capitol, Washington, DC. Credit: Orbital Sciences

Blastoff of the Minotaur I rocket for the Department of Defense’s Operationally Responsive Space Office on the ORS-3 mission is on target for tonight, Nov. 19, from the Mid-Atlantic Regional Spaceport’s Pad-0B at NASA’s Wallops Flight Facility on the eastern shore of Virginia.

The launch window for the 70 foot tall booster opens at 7:30 pm EST and extends until 9:15 pm EST.

Minotaur 1 launch trajectory map for Rockefeller Center N.Y.C.

The ORS-3 mission is a combined US Air Force and NASA endeavor that follows the flawless Nov. 18 launch of NASA’s MAVEN Mars orbiter from Florida by just 1 day.

However the pair of East coast launch pads are separated by some 800 miles.

Minotaur 1 launch trajectory map for Charleston S.C.

According to NASA and Orbital Sciences, the launch may be visible along a wide swatch from northern Florida to southern Canada and well into the Midwest stretching to Indiana – if the clouds are minimal and atmospheric conditions are favorable from your particular viewing site.

The primary payload is the Space Test Program Satellite-3 (STPSat-3), an Air Force technology-demonstration mission, according to NASA.

Minotaur 1 launch trajectory map for Raleigh N.C.

Also loaded aboard are thirteen small cubesats being provided through NASA’s Cubesat Launch Initiative, NASA said in a statement. Among the cubesats is NASA’s Small Satellite Program PhoneSat 2 second generation smartphone mission and the first ever cubesat assembled by high schooler’s.

Minotaur 1 launch trajectory map for Philadelphia P.A.

Locally, the NASA Visitor Center at Wallops and the Chincoteague National Wildlife Refuge/Assateague Island National Seashore will be open for viewing the launch. Visitors to Assateague need to be on the island by 6 p.m. before the entrance gate closes.

Live coverage of the launch is available via UStream beginning at 6:30 p.m. EST on launch day. Watch below:

Ken Kremer

November 19, 2013December 23, 2015 by Shannon Hall

Using the ‘Missing Physics’ of Stellar Feedback to Accurately Simulate Galaxies from the Big Bang to Today

A simulated dwarf galaxy when the universe was 0.5 billion years old. Magenta represents cool gas, green is warm ionized gas, and red is hot gas. Check out the movie. Image credit: Hopkins et al. 2013.

For the first time, astronomers are able to accurately simulate galaxies from shortly after the big bang to today by including a realistic treatment of the effects stars have on their host galaxies.

For the past few decades astronomers have simulated galaxies by mixing the basic physical ingredients — gravity, gas chemistry and the evolution of the universe — into their models.

For years their simulations have shown that gas cools off quickly and falls to the center of the galaxy. Eventually all of the gas forms stars. But observations show only “10 percent of the gas in the universe actually does so,” CalTech astronomer Dr. Philip Hopkins explained. “And in very small or very large galaxies, the number can go down to well below a percent.”

Models of galaxies create far too many stars and as a result end up weighing more than real galaxies in the observable universe. But in theory the solution is simple: the missing physics is a process known as stellar feedback.

For that, astronomers have to look at how stars help shape the evolution of the galaxies in which they reside. And what they have found is that stars affect their environments drastically.

When stars are very young they are extremely hot and blast off a high amount of radiation into space. This radiation heats up and pushes on the nearby interstellar gas. Later on stellar winds – particles streaming from the surface of stars — also push on the gas, further disrupting nearby star formation. Finally, explosions as supernovae can push the gas to nearly sonic speeds.

While astronomers have understood the missing physics for quite a while, they have not been able to successfully incorporate it a priori into their models. Despite their efforts their simulated galaxies have always weighed more than observed galaxies actually weigh.

Understanding the missing physics is a completely different question than being able to incorporate the missing physics directly into their models.

Instead, astronomers made big assumptions based on what galaxies should look like. At some point in their simulations, they had to go in by hand and tune certain parameters. They would get rid of so much gas until the results roughly matched the galaxies we observe.

“Basically, they (astronomers) said ‘we need there to be winds to explain the observations, so we’re going to insert those winds by hand into our models, and adjust the parameters until it looks like what’s observed,’ ” Hopkins told Universe Today.

At the time tuning their models in this way was the best astronomers could do and their models did help improve our understanding of galaxy evolution. But Hopkins and a team of astronomers from across North America have found a way to incorporate the missing physics — stellar feedback — directly into their models.

The research team is creating simulations that draw from stellar feedback explicitly. The FIRE (Feedback in Realistic Environments) project is a multi-year, multi-institution effort.

While it was no easy task, they incorporated the necessary and dare I say messy physics into their models, allowing for unprecedented accuracy. They tracked the affects radiation and stellar winds have on their environments and included a realistic supernovae rate.

“The result is that we see these stars pushing on the gas, and supernovae explosions sweeping up and ‘blowing out’ large amounts of material from galaxies,” Hopkins explained. “When you follow all of this, the story holds together, and indeed we can explain the observed masses of galaxies just from the input of stars.”

A simulated galaxy when the universe was 11.7 billion years old. Make sure the check out the move by clicking on the image above. Image credit: Hopkins et al. 2013 — A simulated galaxy when the universe was 11.7 billion years old. Blue regions are young star clusters that have blown away their gas. Red regions are obscured by dust. Make sure the check out the movie by clicking on the image above. Image credit: Hopkins et al. 2013.

The results have been rewarding — providing some pretty cool videos of galaxies forming across the observable universe — and surprising.

It has become clear that the different types of stellar feedback don’t work alone. While the energy given off by stellar winds can push away interstellar gas, it cannot launch the gas out of the galaxy entirely. The necessary propulsion occurs, instead, when a supernova explosion happens nearby.

But this isn’t to say that supernova explosions play a larger role than stellar winds. If the authors left out any stellar feedback mechanism (the radiation from hot young stars, stellar winds, or supernova explosions) the results were equally poor — with too many stars and masses much too large.

“We’ve just begun to explore these new surprises, but we hope that these new tools will enable us to study a whole host of open questions in the field.”

The paper has been submitted for publication in the Monthly Notices of the Royal Astronomical Society and is available for download here.

Hopkins discusses the “Cosmological zoom-in simulation using new stellar feedback” at at workshop at the University of California, Santa Cruz earlier this year: