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NASA’s Fermi Mission Nets 300 Gamma-Ray Pulsars … and Counting
A new catalog produced by a French-led international team of astronomers shows that NASA’s Fermi Gamma-ray Space Telescope has discovered 294 gamma-ray-emitting pulsars, while another 34 suspects await confirmation. This is 27 times the number known before the mission launched in 2008.
This visualization shows 294 gamma-ray pulsars, first plotted on an image of the entire starry sky as seen from Earth and then transitioning to a view from above our galaxy. The symbols show different types of pulsars. Young pulsars blink in real time except for the Crab, which pulses slower than in real time because its rate is only slightly lower than the video’s frame rate. Millisecond pulsars remain steady, pulsing too quickly to see. The Crab, Vela, and Geminga were among the 11 gamma-ray pulsars known before Fermi launched. Other notable objects are also highlighted. Distances are shown in light-years (abbreviated ly). Download high-resolution video and images from NASA’s Scientific Visualization Studio. Credit: NASA’s Goddard Space Flight Center “Pulsars touch on a wide range of astrophysics research, from cosmic rays and stellar evolution to the search for gravitational waves and dark matter,” said study coordinator David Smith, research director at the Bordeaux Astrophysics Laboratory in Gironde, France, which is part of CNRS (the French National Center for Scientific Research). “This new catalog compiles full information on all known gamma-ray pulsars in an effort to promote new avenues of exploration.”
The catalog was published on Monday, Nov. 27, in The Astrophysical Journal Supplement.
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Narrow beams of energy emerge from hot spots on the surface of a neutron star in this artist’s concept. When one of these beams sweeps past Earth, astronomers detect a pulse of light. Credit: NASA’s Goddard Space Flight Center Conceptual Image Lab Pulsars are a type of neutron star, the city-sized leftover of a massive sun that has exploded as a supernova. Neutron stars, containing more mass than our Sun in a ball less than 17 miles wide, represent the densest matter astronomers can study directly. They possess strong magnetic fields, produce streams of energetic particles, and spin quickly – 716 times a second for the fastest known. Pulsars, in addition, emit narrow beams of energy that swing lighthouse-like through space as the objects rotate. When one of these beams sweeps past Earth, astronomers detect a pulse of emission.
The new catalog represents the work of 170 scientists across the globe. A dozen radio telescopes carry out regular monitoring of thousands of pulsars, and radio astronomers search for new pulsars within gamma-ray sources discovered by Fermi. Other researchers have teased out gamma-ray pulsars that have no radio counterparts through millions of hours of computer calculation, a process called a blind search.
More than 15 years after its launch, Fermi remains an incredible discovery machine, and pulsars and their neutron star kin are leading the way.
Fermi Project Scientist
Of the 3,400 pulsars known, most of them observed via radio waves and located within our Milky Way galaxy, only about 10% also pulse in gamma rays, the highest-energy form of light. Visible light has energies between 2 and 3 electron volts. Fermi’s Large Area Telescope can detect gamma rays with billions of times this energy, and other facilities have observed emission thousands of times greater still from the nearby Vela pulsar, the brightest persistent source in the sky for Fermi.
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This movie shows the Vela pulsar in gamma rays detected by the Large Area Telescope aboard NASA’s Fermi observatory. A single pulsar cycle is repeated. Bluer colors indicate gamma rays with higher energies. Credit: NASA/DOE/Fermi LAT Collaboration The Vela pulsar and its famous sibling in the Crab Nebula are young, solitary objects, formed about 11,000 and 970 years ago, respectively. Their emissions arise as their magnetic fields spin through space, but this also gradually slows their rotation. The younger Crab pulsar spins nearly 30 times a second, while Vela clocks in about a third as fast.
The Old and the Restless
Paradoxically, though, pulsars that are thousands of times older spin much faster. One example of these so-called millisecond pulsars (MSPs) is J1824-2452A. It whirls around 328 times a second and, with an age of about 30 million years, ranks among the youngest MSPs known.
Thanks to a great combination of gamma-ray brightness and smooth spin slowdown, the MSP J1231-1411 is an ideal “timer” for use in gravitational wave searches. By monitoring a collection of stable MSPs, astronomers hope to link timing changes to passing low-frequency gravitational waves – ripples in space-time – that cannot be detected by current gravitational observatories. It was discovered in one of the first radio searches targeting Fermi gamma-ray sources not associated with any known counterpart at other wavelengths, a technique that turned out to be exceptionally successful.
“Before Fermi, we didn’t know if MSPs would be visible at high energies, but it turns out they mostly radiate in gamma rays and now make up fully half of our catalog,” said co-author Lucas Guillemot, an associate astronomer at the Laboratory of Physics and Chemistry of the Environment and Space and the University of Orleans, France.
Along Come the Spiders
The presence of MSPs in binary systems offers a clue to understanding the age-spin paradox. Left to itself, a pulsar’s emissions slow it down, and with slower spin its emissions dim. But if closely paired with a normal star, the pulsar can pull a stream of matter from its companion that, over time, can spin up the pulsar.
“Spider” systems offer a glimpse of what happens next. They’re classified as redbacks or black widows – named for spiders known for consuming their mates. Black widows have light companions (less than about 5% of the Sun’s mass), while redbacks have heavier partners. As the pulsar spins up, its emissions and particle outflows become so invigorated that – through processes still poorly understood – it heats and slowly evaporates its companion. The most energetic spiders may fully evaporate their partners, leaving only an isolated MSP behind.
J1555-2908 is a black widow with a surprise – its gravitational web may have ensnared a passing planet. An analysis of 12 years of Fermi data reveals long-term spin variations much larger than those seen in other MSPs. “We think a model incorporating the planet as a third body in a wide orbit around the pulsar and its companion describes the changes a little better than other explanations, but we need a few more years of Fermi observations to confirm it,” said co-author Colin Clark, a research group leader at the Max Planck Institute for Gravitational Physics in Hannover, Germany.
Other curious binaries include the so-called transitional pulsars, such as J1023+0038, the first identified. An erratic stream of gas flowing from the companion to the neutron star may surge, suddenly forming a disk around the pulsar that can persist for years. The disk shines brightly in optical light, X-rays, and gamma rays, but pulses become undetectable. When the disk again vanishes, so does the high-energy light and the pulses return.
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This artist’s concept illustrates a possible model for the transitional pulsar J1023. When astronomers can detect pulses in radio (green), the pulsar’s energetic outflow holds back its companion’s gas stream. Sometimes the stream surges, creating a bright disk around the pulsar that can persist for years. The disk shines brightly in X-rays, and gas reaching the neutron star produces jets that emit gamma rays (magenta), obscuring the pulses until the disk eventually dissipates. Credit: NASA’s Goddard Space Flight Center Some pulsars don’t require a partner to switch things up. J2021+4026, a young, isolated pulsar located about 4,900 light-years away, underwent a puzzling “mode change” in 2011, dimming its gamma rays over about a week and then, years later, slowly returning to its original brightness. Similar behavior had been seen in some radio pulsars, but this was a first in gamma rays. Astronomers suspect the event may have been triggered by crustal cracks that temporarily changed the pulsar‘s magnetic field.
Farther afield, Fermi discovered the first gamma-ray pulsar in another galaxy, the neighboring Large Magellanic Cloud, in 2015. And in 2021, astronomers announced the discovery of a giant gamma-ray flare from a different type of neutron star (called a magnetar) located in the Sculptor galaxy, about 11.4 million light-years away.
“More than 15 years after its launch, Fermi remains an incredible discovery machine, and pulsars and their neutron star kin are leading the way,” said Elizabeth Hays, the mission’s project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
Explore the Fermi gamma-ray pulsar catalog on WorldWide Telescope
Max Planck Institute release
By Francis Reddy
NASA’s Goddard Space Flight Center, Greenbelt, Md.
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Last Updated Nov 28, 2023 Editor Francis Reddy Location Goddard Space Flight Center Related Terms
Astrophysics Binary Stars Fermi Gamma-Ray Space Telescope Gamma Rays Goddard Space Flight Center Neutron Stars Pulsars Stars The Universe Keep Exploring Discover More Topics From NASA
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9 Min Read Temperatures Across Our Solar System
An illustration of our solar system. Planets and other objects are not to scale. Credits:
NASA What’s the weather like out there? We mean waaaay out there in our solar system – where the forecast might not be quite what you think.
Let’s look at the mean temperature of the Sun, and the planets in our solar system. The mean temperature is the average temperature over the surface of the rocky planets: Mercury, Venus, Earth, and Mars. Dwarf planet Pluto also has a solid surface. But since the gas giants don’t have a surface, the mean is the average temperature at what would be equivalent at sea level on Earth.
An illustration of planets in our solar system showing their mean temperatures. Planets and dwarf planet Pluto are not to scale. NASA Let’s start with our Sun. You already know the Sun is hot. OK, it’s extremely hot! But temperatures on the Sun also are a bit puzzling.
An image of the Sun taken Oct. 30, 2023, by NASA’s Solar Dynamics Observatory. NASA/SDO The hottest part of the Sun is its core, where temperatures top 27 million°F (15 million°C). The part of the Sun we call its surface – the photosphere – is a relatively cool 10,000° F (5,500°C). In one of the Sun’s biggest mysteries, the Sun’s outer atmosphere, the corona, gets hotter the farther it stretches from the surface. The corona reaches up to 3.5 million°F (2 million°C) – much, much hotter than the photosphere.
So some temperatures on the Sun are a bit upside down. How about the planets? Surely things are cooler on the planets that are farther from the Sun.
Well, mostly. But then there’s Venus.
As it sped away from Venus, NASA’s Mariner 10 spacecraft captured this seemingly peaceful view of a planet the size of Earth, wrapped in a dense, global cloud layer. But, contrary to its serene appearance, the clouded globe of Venus is a world of intense heat, crushing atmospheric pressure and clouds of corrosive acid. NASA/JPL-Caltech Venus is the second closest planet to the Sun after Mercury, with an average distance from the Sun of about 67 million miles (108 million kilometers). It takes sunlight about six minutes to travel to Venus.
Venus also is Earth’s closest neighbor and is similar in size. It has even been called Earth’s twin. But Venus is shrouded in clouds and has a dense atmosphere that acts as a greenhouse and heats the surface to above the melting point of lead. It has a mean surface temperature of 867°F (464°C).
So Venus – not Mercury – is the hottest planet in our solar system. Save that bit of info for any future trivia contests.
Maybe Venus is hotter, but Mercury is the closest planet to the Sun. Surely it gets hot, too?
Mercury as seen from NASA’s MESSENGER, the first spacecraft to orbit Mercury. NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington Mercury is about 36 million miles (57 million kilometers) from the Sun. From this distance, it takes sunlight about three minutes to travel to Mercury. Even though it’s sitting right next to the Sun – relatively speaking – Mercury gets extremely cold at night. It has a mean surface temperature of 333°F (167°C). Daytime temperatures get much hotter than the mean, and can reach highs of 800°F (430°C). But without an atmosphere thick enough to hold in the heat at night, temperatures can dip as low as -290°F (-180°C).
Ahhh, Earth. We know about the weather here, right? Even Earth has some temperatures you may not have heard about.
An image of Earth from the Deep Space Climate Observatory, or DSCOVR. NASA Earth is an average of 93 million miles (150 million kilometers) from the Sun. It takes about eight minutes for light from the Sun to reach our planet.
Our homeworld is a dynamic and stormy planet with everything from clear, sunny days, to brief rain showers, to tornados, to raging hurricanes, to blizzards, and dust storms. But in spite of its wide variety of storms – Earth generally has very hospitable temperatures compared to the other planets. The mean surface temperature on Earth is 59°F (15°C). But Earth days have some extreme temperatures. According to NOAA, Death Valley holds the record for the world’s highest surface air temperature ever recorded on Earth: 134°F (56.7°C) observed at Furnace Creek (Greenland Ranch), California, on July 10, 1913. Earth’s lowest recorded temperature was -128.6°F (89.2°C) at Vostok Station, Antarctica, on July 21, 1983, according to the World Meteorological Organization.
NASA missions have found lots of evidence that Mars was much wetter and warmer, with a thicker atmosphere, billions of years ago. How about now?
Side-by-side animated images show how a 2018 global dust storm enveloped the Red Planet. The images were taken by NASA’s Mars Reconnaissance Orbiter (MRO). NASA/JPL-Caltech/MSSS Mars is an average distance of 142 million miles (228 million kilometers) from the Sun. From this distance, it takes about 13 minutes for light to travel from the Sun to Mars.
The median surface temperature on Mars is -85°F (-65°C). Because the atmosphere is so thin, heat from the Sun easily escapes Mars. Temperatures on the Red Planet range from the 70s°F (20s°C) to -225°F (-153°C). Occasionally, winds on Mars are strong enough to create dust storms that cover much of the planet. After such storms, it can be months before all of the dust settles.
Two NASA rovers on Mars have weather stations. You can check the daily temps at their locations:
Mars Weather Report From Perseverance Curiosity Daily Weather Report The ground temperature around the Perseverance rover ranges from about -136°F to 62°F (-93°C to 17°C). The air temperature near the surface ranges from about -118°F to 8°F (-83°C to -13°C).
As planets move farther away from the Sun, it really cools down fast! Since gas giants Jupiter and Saturn don’t have a solid surface, temperatures are taken from a level in the atmosphere equal in pressure to sea level on Earth. The same goes for the ice giants Uranus and Neptune.
NASA’s Juno spacecraft took this image during a flyby of Jupiter. This view highlights Jupiter’s most famous weather phenomenon, the persistent storm known as the Great Red Spot. Citizen scientist Kevin M. Gill created this image using data from the spacecraft’s JunoCam imager. Enhanced image by Kevin M. Gill (CC-BY) based on images provided courtesy of NASA/JPL-Caltech/SwRI/MSSS Jupiter’s stripes and swirls are beautiful, but they are actually cold, windy clouds of ammonia and water, floating in an atmosphere of hydrogen and helium. The planet’s iconic Great Red Spot is a giant storm bigger than Earth that has raged for hundreds of years. The mean temperature on Jupiter is -166°F (-110°C).
Jupiter is an average distance of 484 million miles (778 million kilometers) from the Sun. From this distance, it takes sunlight 43 minutes to travel from the Sun to Jupiter. Jupiter has the shortest day in the solar system. One day on Jupiter takes only about 10 hours (the time it takes for Jupiter to rotate or spin around once), and Jupiter makes a complete orbit around the Sun (a year in Jovian time) in about 12 Earth years (4,333 Earth days).
Jupiter’s equator is tilted with respect to its orbital path around the Sun by just 3 degrees. This means the giant planet spins nearly upright and does not have seasons as extreme as other planets do.
As we keep moving out into the solar system, we come to Saturn – the sixth planet from the Sun and the second largest planet in our solar system. Saturn orbits the Sun from an average distance of 886 million miles (1.4 billion kilometers). It takes sunlight 80 minutes to travel from the Sun to Saturn.
This series of images from NASA’s Cassini spacecraft shows the development of the largest storm seen on Saturn since 1990. These true-color and composite near-true-color views chronicle the storm from its start in late 2010 through mid-2011, showing how the distinct head of the storm quickly grew large but eventually became engulfed by the storm’s tail. NASA/JPL-Caltech/Space Science Institute Like fellow gas giant Jupiter, Saturn is a massive ball made mostly of hydrogen and helium and it doesn’t have a true surface. The mean temperature is -220°F (-140°C).
In addition to the bone-chilling cold, the winds in the upper atmosphere of Saturn reach 1,600 feet per second (500 meters per second) in the equatorial region. In contrast, the strongest hurricane-force winds on Earth top out at about 360 feet per second (110 meters per second). And the pressure – the same kind you feel when you dive deep underwater – is so powerful it squeezes gas into a liquid.
This colorful movie made with images from NASA’s Cassini spacecraft is the highest-resolution view of the unique six-sided jet stream at Saturn’s north pole known as “the hexagon.” NASA/JPL-Caltech/SSI/Hampton University Saturn’s north pole has an interesting atmospheric feature – a six-sided jet stream. This hexagon-shaped pattern was first noticed in images from the Voyager I spacecraft and was more closely observed by the Cassini spacecraft. Spanning about 20,000 miles (30,000 kilometers) across, the hexagon is a wavy jet stream of 200-mile-per-hour winds (about 322 kilometers per hour) with a massive, rotating storm at the center. There is no weather feature like it anywhere else in the solar system.
Crane your neck to the side while we go check out the weather on Uranus, the sideways planet.
This is an image of the planet Uranus taken by the spacecraft Voyager 2 in 1986. NASA/JPL-Caltech The seventh planet from the Sun with the third largest diameter in our solar system, Uranus is very cold and windy. It has a mean temperature of -320°F (-195°C). Uranus rotates at a nearly 90-degree angle from the plane of its orbit. This unique tilt makes Uranus appear to spin sideways, orbiting the Sun like a rolling ball. And like Saturn, Uranus has rings. The ice giant is surrounded by 13 faint rings and 27 small moons.
Now we move on to the last major planet in our solar system – Neptune. What’s the weather like there? Well you would definitely need a windbreaker if you went for a visit. Dark, cold, and whipped by supersonic winds, giant Neptune is the eighth and most distant major planet orbiting our Sun. The mean temperature on Neptune is -330°F (-200°C).
And not to be outdone by Jupiter and its Great Red Spot, Neptune has the Great Dark Spot – and Scooter. Yep, Scooter.
Voyager 2 photographed these features on Neptune in 1989. NASA/JPL-Caltech This photograph of Neptune was created from two images taken by NASA’s Voyager 2 spacecraft in August 1989. It was the first and last time a spacecraft came close to Neptune. The image shows three of the features that Voyager 2 monitored. At the north (top) is the Great Dark Spot, accompanied by bright, white clouds that undergo rapid changes in appearance. To the south of the Great Dark Spot is the bright feature that Voyager scientists nicknamed “Scooter.” Still farther south is the feature called “Dark Spot 2,” which has a bright core.
More than 30 times as far from the Sun as Earth, Neptune is not visible to the naked eye. In 2011, Neptune completed its first 165-year orbit of the Sun since its discovery.
That wraps up forecasting for the major planets.
But there is one more place we need to check out. Beyond Neptune is a small world, with a big heart – dwarf planet Pluto.
New Horizons scientists use enhanced color images to detect differences in the composition and texture of Pluto’s surface. NASA/JHUAPL/SwRI With a mean surface temperature of -375°F (-225°C), Pluto is considered too cold to sustain life. Pluto’s interior is warmer, however, and some think there may be an ocean deep inside.
From an average distance of 3.7 billion miles (5.9 billion kilometers) away from the Sun, it takes sunlight 5.5 hours to travel to Pluto. If you were to stand on the surface of Pluto at noon, the Sun would be 1/900 the brightness it is here on Earth. There is a moment each day near sunset here on Earth when the light is the same brightness as midday on Pluto.
So the next time you’re complaining about the weather in your spot here on Earth, think about Pluto and all the worlds in between.
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By European Space Agency
ESA has committed further 'Boost! Programme' funding to German startup Rocket Factory Augsburg, known as RFA, for the development of commercial space transportation services based on the RFA One launch vehicle at sites in Portugal, Germany and the UK.
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By European Space Agency
Video: 00:03:44 Nestled between the colossal martian ‘Grand Canyon’ (Valles Marineris) and the tallest volcanoes in the Solar System (the Tharsis region) lies Noctis Labyrinthus – a vast system of deep and steep valleys that stretches out for around 1190 km (roughly the length of Italy here on Earth).
This video visualises a flight over the eastern part of Noctis Labyrinthus as seen by Mars Express’s High Resolution Stereo Camera (HRSC). It presents a perspective view down and across this fascinating landscape, showing distinctive ‘graben’ – parts of the crust that have subsided in relation to their surroundings. The intense volcanism in the nearby Tharsis region is to blame for the formation of these features; this volcanism caused large areas of martian crust to arch upwards and become stretched and tectonically stressed, leading to it thinning out, faulting and subsiding.
The highest plateaus seen here represent the original surface level before chunks of surface fell away. The intersecting canyons and valleys are up to 30 km wide and six km deep. In many places, gigantic landslides can be seen covering the valley slopes and floors, while other valley slopes show large dune fields created by sands blown both down and upslope by martian winds.
ESA has highlighted Mars Express images of Noctis Labyrinthus before, in 2006 and 2015. Mars Express has orbited the Red Planet since 2003, imaging Mars’s surface, mapping its minerals, studying its tenuous atmosphere, probing beneath its crust, and exploring how various phenomena interact in the martian environment. For more from the mission and HRSC, see ESA's Mars Express releases.
Processing notes: The video was created using an image mosaic built over eight orbits (0442, 1085, 1944, 1977, 1988, 10497, 14632 and 16684) by ESA’s Mars Express and its HRSC. This mosaic is combined with topographic information from a digital terrain model to generate a three-dimensional landscape, with every second of the video comprising 50 separate frames rendered according to a pre-defined camera path. The opening credits (Mars globe, first 24 seconds) were created using the recent 20-year Mars global colour mosaic; this opening sequence has a three-fold vertical exaggeration, while the subsequent flight animation has a 1.5-fold exaggeration. Haze has been added to conceal the limits of the terrain model, and starts building up at distance of between 150 and 200 km. The video is centred at the martian coordinates of 7°S, 265°E.
Alt-text: The video begins on a rotating full-globe of Mars, with white polar caps and mottled tan surface visible. It then zooms in on the westernmost part of the large Valles Marineris canyon system, a region highlighted by a white box, and swaps to a new Mars Express visualisation of Noctis Labyrinthus. The camera then flies slowly across a landscape that is broken apart by deep intersecting valleys and canyons.
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By European Space Agency
More than 15 000 visitors are getting ready to pass through ESA's gateways during ESA Open Days 2023. This Europe-wide series of events promises to connect space enthusiasts, bringing space closer to them than ever before. Unforgettable days of discoveries, inspiration, and scientific divulgation await thousands of European citizens, who are eagerly gearing up for a fantastic journey through the wonders of space.
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