A fast radio telescope 201 new pulsars is discovered. Astronomers using the 500-meter aperture spherical radio telescope (FAST) have discovered 201 pulsars, including the currently weakest pulsars, which cannot be detected by other telescopes, coinciding with the remnants of pulsars supernovae. There are 40 millisecond pulsars and 16 binary pulsars.
A fast radio telescope 201
Pulsar footprint of an artist. Image Credit: Science News. FAST is located in the Davodang Depression, a natural basin in Pingtang County, Guizhou, southwest China. It has the largest radio wave collection area with an aperture of 300 meters in diameter and is housed with a 19-beam receiver with a system temperature of approximately 20 K.
The fast current is the most sensitive radio telescope of the binary systems for the detection of a weak pulsar, a distant pulsar, or a pulsar. Since most of these objects originated on the disk of the galaxy, and therefore their distribution is concentrated in the galactic plane, the Fast team designed the Galactic Plane Pulsar Snapshot Study (GPPS).
They discovered the pulsar in the galactic latitude range of + -10 ° from the galactic plane, with the inner galactic disk within the galactic latitude giving the highest priority to + – 5 °. So far, GPPS has discovered about 5% of the planned sky and discovered 201 pulsars. At this initial phase of the project, it’s an impressive total, said Professor Richard Norman Manchester.
An astronomer at CSIRO Astronomy and Astronomy Australia, who was not involved in the study. In the newly discovered pulsars, many match known supernova debris, and some have strange pulse-scattering properties. Deflection is a measure of the total electron density along a path from a pulsar to Earth and is a good indicator of the distance from the pulsar.
The greater the measure of dispersion, the greater the distance- the astronomers said. GPPS has revealed pulsars with very high scattering measurements that challenge the best current model of electron density distribution in the galaxy.
“Based on the best information on the distribution of electrons in the Milky Way, these pulsars should be located outside the galaxy. However, it is more likely that these pulsars are located within the galaxy.” The electron density in the Milky Way, especially in the direction of its spiral arms, is probably underestimated.
“In other words, the newly discovered pulsars reveal more electrons than ever before in the spiral arms of the Milky Way.” The researchers discovered pulsars of 40 milliseconds lasting less than 30 milliseconds. “The GPPS survey has already increased the number of known millisecond pulsars by approximately 10%, a remarkable achievement,” said Professor Manchester.
“Of them, there is a companion about 14, as well as two long-term pulsars. There is no doubt that some of them will prove to be excellent investigations of the principles of gravity.” Scientists also discovered many pulsars with special characteristics. For example, some produce emissions that spin or emit only a few pulses for several minutes.
In addition to the new discoveries, they detected more than 330 previously known pulsars and improved their parameters. “Fast holds the promise of studying compact objects in the universe and helps us learn more about fundamental physics and astrophysics,” said Professor Jim Cordes, an astronomer at Cornell University. The team’s article was published in the journal Research in Astronomy and Astrophysics.
NASA’s TESS discovered new worlds in a river of young stars. Using observations from NASA’s Transiting Exoplanet Study Satellite (TESS), an international team of astronomers has discovered a trio of hotter worlds larger than Earth orbiting TOI 451, a much smaller version of our Sun.
The system resides in the recently discovered Pisces-Eridanus stream, a collection of stars less than 3% the age of our solar system that spans a third of the sky. This illustration shows the main features of TOI 451, a system of three planets located in the constellation Eridanus, 400 light years away.
NASA’s TESS discovered
The planets were discovered in TESS images taken between October and December 2018. Follow-up studies of TOI 451 and its planets included observations made in 2019 and 2020 using NASA’s Spitzer Space Telescope, which has since been withdrawn, as well as several terrestrial ones. Mod cons.
Archival infrared data from NASA’s NEOWISE (Wide-field Infrared Exploration Explorer) satellite, collected between 2009 and 2011 under its former name, WISE, suggests that the system is a silent mass of dust and rocky rubble. Preserve the disk. Other observations suggest that TOI 451 likely has two distant stellar companions orbiting each other very far from the planets.
“This system ticks a lot of boxes for astronomers,” said Elizabeth Newton, assistant professor of physics and astronomy at Dartmouth College in Hanover, New Hampshire, who led the research. It is only 120 million years old and only 400 light years distant, allowing detailed observations of this young planetary system.
And because there are three planets between two and four times the size of Earth, they are known to have planetary atmospheres. they are a particularly promising target for testing theories of evolution. An article reporting the findings was published Jan. 14 in The Astronomical Journal and is available online.
Stellar currents are formed when the gravity of our galaxy, the Milky Way, pulls apart star clusters or dwarf galaxies. Individual stars move along the cluster’s original orbit, forming an elongated cluster that gradually expands.
In 2019, a team led by Stefan Meingast at the University of Vienna used data from the European Space Agency’s Gaia mission to search for the Pisces-Eridanus current, named for the constellations with the highest concentration of stars. Spread over 14 constellations, this stream is approximately 1,300 light-years long. However, the initially prescribed age for transmission was now much older than we thought.
Later in 2019, researchers led by Jason Curtis at Columbia University in New York City analyzed TESS data for dozens of members of the stream. Younger stars rotate faster than their older counterparts, and they also have major stars – darker, cooler regions like sunspots. As these points move in and out of our view, they can cause slight changes in the star’s brightness that TESS can measure.
TESS measurements revealed excessive evidence of starspots and rapid rotation between stars in the stream. Based on this result, Curtis and his colleagues found that the stream was only 120 million years old, similar to the famous Pleiades cluster and eight times younger than previous estimates.
The mass, pubescence and proximity of the Pisces-Eridanus current make it an exciting foundational laboratory for studying the formation and evolution of stars and planets. Thanks to TESS’s near-total sky coverage, measurements that can support the search for planets orbiting members of this stream were already available to us when the stream was identified, the paper said.
NASA Exoplanet Archive, a facility to investigate worlds beyond our solar system managed by Caltech in Pasadena, California. The TESS data will continue to allow us to push the limits of what we know about exoplanets and their systems for years to come. The young star TOI 451, better known to astronomers as CD-38 1467, is located about 400 light-years away in the constellation Eridanus.
It is 95% the mass of our Sun, but it is 12% smaller, slightly cooler, and emits 35% less energy. TOI 451 makes one revolution every 5.1 days, which is five times brighter than the Sun. TESS explores new worlds looking for transits, the slight and regular dimming that occurs when a planet passes in front of its star from our point of view.
The transits of the three planets are clear from the TESS data. Newton’s team obtained measurements from Spitzer that supported the TESS findings and helped rule out possible alternative explanations. Additional follow-up observations came from the Las Cumbres Observatory, a global telescope network based in Goleta, California, and the Perth Exoplanet Survey Telescope in Australia.
Even the farthest planet from TOI 451 comes three times closer to the Sun than Mercury, making all of these worlds hot and inhospitable to life as we know it. Temperature estimates range from about 2,200 degrees Fahrenheit (1,200 degrees Celsius) for the innermost planet to about 840 F (450 C) for the outermost planet.
TOI 451b orbits every 1.9 days, is approximately 1.9 times the size of Earth, and has an estimated mass of two to 12 times that of Earth. The next planet, TOI 451 c, completes one orbit every 9.2 days, is about three times more massive than Earth, and is between three and 16 times the mass of Earth.
The largest and most distant world, TOI 451 d, orbits the star every 16 days, is four times the size of our planet, and weighs between four and 19 Earth masses. Astronomers expect such massive planets to retain most of their atmospheres despite the intense heat from their nearby star.
When a planetary system reaches the age of TOI 451, different theories about how the atmosphere evolved predict a wide range of properties. Observing starlight passing through the atmospheres of these planets provides an opportunity to study this stage of evolution and can help narrow down existing models.
The Pisces-Eridanus stream spans 1,300 light-years, covering 14 constellations and a third of the sky. The yellow dots show the locations of known or suspected limbs, including those orbiting TOI 451. TESS observations show that the stream is about 120 million years old, comparable to the famous Pleiades cluster in Taurus (top left). Credits: NASA Goddard Space Flight Center.
Alyssa Quintana, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said: “By measuring the light from stars entering a planet’s atmosphere at different wavelengths, we can determine its chemical composition and presence high-altitude cloud or haze. “” The planets of TOI 451 provide excellent targets for such studies with Hubble and the upcoming James Webb Space Telescope. “
The WISE observations show that the system is unusually bright in infrared light at 12 and 24 micron wavelengths, which are invisible to the human eye. This suggests the presence of a debris disk, where objects such as rocky asteroids collide and coalesce into dust. Although Newton and his team cannot determine the extent of the disk, they see it as an expanding ring of rock and dust, orbiting Jupiter away from our Sun.
The researchers also examined a faint neighboring star that is visible in the TESS images about two pixels from TOI 451. Based on the Gaia data, Newton’s team determined that this star is a gravitationally bound companion located so far away from TOI 451 that It takes 27 days for your light to get there.
NASA’s Ames Research Center
In fact, the researchers believe that the companion is a binary system of two M-type dwarf stars, each of which contains about 45% of the Sun’s mass and emits only 2% of its energy. TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA’s Goddard Space Flight Center. Additional partners include Northrop Grumman based in Falls Church, Virginia.
NASA’s Ames Research Center in Silicon Valley, California; Astrophysics Center | Harvard and Smithsonian in Cambridge, Massachusetts; The Lincoln Laboratory at MIT; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes and observatories around the world are mission partners.
NASA’s Jet Propulsion Laboratory in Southern California manages NEOWISE for NASA’s Science Mission Directorate in Washington. Ball Aerospace and Technologies Corporation of Boulder, Colorado built the spacecraft. Scientific data processing takes place at IPAC at Caltech in Pasadena. Caltech manages JPL for NASA.
NASA’s Webb to Study Young Exoplanets on the Edge. Before the discovery of planets around other stars for the first time in the 1990s, these distant alien worlds lived only in the imagination of science fiction writers. But even their creative minds couldn’t imagine the worlds astronomers have discovered. Many of these worlds, called exoplanets, are quite different from the family of planets in our solar system.
They range from the “hot Jupiters” that hug the stars to the massive rocky planets called “super Earths.” Our universe is clearly stranger than fiction. These distant worlds are not easy to see as they are lost in the glow of their host stars. Trying to locate them is like straining to see a firefly hovering next to a glowing headlamp of a lighthouse.
NASA’s Webb to Study
This is why astronomers have so far identified most of the more than 4,000 exoplanets detected using indirect techniques, such as the slight wobble of a star or the unexpected darkening of a planet as it passes in front of it, blocking the light of some stars. This is an image of the star HR 8799 taken by Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS) in 1998.
A mask (the coronagraph) inside the camera blocks most of the star’s light. . The astronomers also used software to digitally subtract excess starlight. However, scattered light dominates the image of HR 8799, the four faint planets later discovered from ground-based observations. Right: Reanalysis of the NICMOS data in 2011 revealed three exoplanets that were not seen in the 1998 images.
Webb will probe planetary atmospheres at infrared wavelengths that astronomers rarely use to image distant worlds. However, these techniques work best for planets orbiting close to their stars, where astronomers can detect changes over weeks or even days as the planet completes its orbit on the race track. But simply finding star-brushing planets does not provide astronomers with a complete picture of all possible worlds in star systems.
Another technique researchers use to search for exoplanets, which are planets that orbit other stars, is to focus on planets that are far from a star’s glare. Scientists have discovered young exoplanets that are so hot that they glow in infrared light using special imaging techniques that block the glare from the star. In this way, some exoplanets can be directly observed and studied.
NASA’s upcoming James Webb Space Telescope will help astronomers further investigate this bold new frontier. Webb, like some ground-based telescopes, is equipped with special optical systems called coronagraphs, which use masks designed to block out as much starlight as possible to study faint exoplanets and discover new worlds.
This diagram shows the positions of four exoplanets orbiting away from the nearby star HR 8799. The orbits appear elongated due to the slight inclination of the plane of the orbits with respect to our line of sight. The HR 8799 planetary system is comparable in size to our Solar System, as indicated by the orbit of Neptune, shown on the scale.
Webb has two targets at the start of the mission, the 51 Eridani and HR 8799 planetary systems. Of the few dozen directly reflected planets, astronomers plan to use Webb to analyze in detail the systems closest to Earth and the most distant planets of their planets. Stars This means that they are visible far enough away from a star’s glare to be seen directly. The HR 8799 system resides 133 light years from Earth and 51 Eridani 96 light years away.
The two observing programs at the beginning of Webb’s mission combine the spectroscopic capabilities of the near-infrared spectrograph (NIRSPC) and the imaging of the near-infrared camera (NIRCAM) and the mid-infrared instrument (MIRI) to study the four planets. giants in the HR. System 8799. In the third program, researchers will use NIRCam to analyze the giant planet at 51 Eridani.
The four giant planets of the HR 8799 system have approximately 10 Jupiter masses. They orbit more than 14 billion miles from a star that is slightly more massive than the Sun. The giant planet at 51 Eridani is twice as massive as Jupiter and orbits about 11 billion miles from a Sun-like star. .
Both planetary systems have Earth-oriented orbits. This orientation gives astronomers a unique opportunity to get a bird’s eye view of the top of the system, much like seeing the concentric rings on an archery target.
Many of the exoplanets found in the outer orbits of their stars are quite different from the planets in our solar system. Most of the exoplanets discovered in this outer region, including HR 8799, have between 5 and 10 Jupiter masses, making them the most massive planets ever discovered.
These outer exoplanets are relatively young, ranging in age from tens of millions to millions of years, much younger than the 4.5 billion years of our solar system. So they are still glowing with the heat of their training. The images of these exoplanets are essentially photographs of children, revealing planets in their youth.
Webb will explore the mid-infrared, a wavelength range that astronomers rarely use to image distant worlds. This infrared “window” is difficult to see from the ground due to thermal emissions and absorption from the Earth’s atmosphere.
A Jupiter-sized extrasolar planet
“Webb’s strong suit is uninhibited light coming through space in the mid-infrared range,” said Klaus Hodapp of the University of Hawaii at Hilo, principal investigator of the NIRSPC observations of the HR 8799 system. “Working through of the Earth’s atmosphere is very difficult. The main absorption molecules in our own atmosphere prevent us from seeing interesting features on the planets. “
This discovered image of a Jupiter-sized extrasolar planet orbiting the nearby star 51 Eridani was taken in near-infrared light by the Gemini Planet Imager in 2014. This discovered image of a Jupiter-sized extrasolar planet orbiting the star nearby 51 Eridani was taken in near-infrared light by Gemini Planet Imager in 2014.
The bright central star in the center of the image is hidden behind a mask to allow detection of the exoplanet, which is 1 million times smaller than that of 51 Eridani. The exoplanet is on the outskirts of the planetary system, 11 billion miles from its star. Webb will probe the planet’s atmosphere at infrared wavelengths that astronomers rarely use to image distant worlds.
The “mid-infrared” is the area where Webb will make a fundamental contribution to really understanding what special molecules are, what are the properties of the atmosphere that we hope to find that we don’t get from really small near-infrared wavelengths. said Charles Beechman of NASA’s Jet Propulsion Laboratory in Pasadena, California, principal investigator of the NIRCAM and MIRI observations of the HR 8799 system. Impossible without the web. “
How are planets formed?
One of the main goals of the researchers in both systems is to use Webb to help determine how exoplanets formed. Were they created through an accumulation of material in the disk around the star, which was rich in heavy elements like carbon, as Jupiter did? Or did they form from the collapse of a star-like hydrogen cloud and got smaller under the relentless pull of gravity?
Atmospheric composition can provide clues to the birth of a planet. “One of the things we want to understand is the proportion of the elements that were involved in the formation of these planets,” Beechman said.
Specifically, carbon versus oxygen tells you a lot about where the gas that made the planet comes from. Does it come from a disk that has accumulated a lot of heavy elements or does it come from the interstellar medium? So this is what we call the relationship carbon-oxygen, which is quite indicative of the mechanism of formation.
To answer these questions, the researchers will use Webb to explore the atmospheres of exoplanets more deeply. For example, NIRCam will measure the atmospheric footprints of elements like methane. You will also observe the characteristics of the clouds and the temperatures of these planets.
“We already have a lot of information about these near-infrared wavelengths from ground-based facilities,” said Marshall Perrin of the Space Telescope Science Institute in Baltimore, Maryland, principal investigator of 51 NIRCAM observations from Eridani b. “But the Webb data will be more accurate, more sensitive.
We will have a more complete set of wavelengths, including filling in the gaps where you can’t get those wavelengths from the ground.” This video shows four Jupiter-sized exoplanets orbiting the nearby HR 8799 system, billions of miles from their star. The planetary system is oriented face-to-face toward Earth, giving astronomers a unique bird’s-eye view of planetary motion.
Exoplanets orbit so far from their star that it takes decades or centuries to complete one orbit. During a seven-year period in the video W.M. There are seven images of the system taken with the Keck Observatory on Mauna Kea, Hawaii. The Keck coronagraph blocks most of the star, so that very few small exoplanets can be seen.
Astronomers will also use Webb and his brilliant sensitivity to search for less giant planets far from their star. “From ground-based observations, we know that these giant planets are relatively rare,” Perrin said. But we also know that for the interior of systems, planets with less mass are dramatically more common than planets with larger masses. So the question is, is this also true for these new separations?
“Webb’s operation in the cold atmosphere of space enables the discovery of smaller planets, impossible to detect from the ground,” Beechman said. Another goal is to understand how the many planetary systems discovered so far were formed. “I think what we are looking for is that there is a lot of diversity in the solar system,” Perrin said. “You have systems where you have these hot Jupiter planets in very close orbits. You have systems where you don’t have them.
You have systems where you have a planet with a mass of 10 Jupiters and where you have There is nothing more massive than many Earths. Ultimately, we want to understand how the diversity of planetary system formation depends on the star’s atmosphere, the star’s mass, all kinds of other things, and ultimately through these population-level studies, we can find our own solar system. Hope to keep it in context. “
This video shows a Jupiter-sized exoplanet orbiting very far, about 11 billion miles, from the nearby sun-like star, 51 Eridani. The planetary system is oriented face-to-face towards Earth, giving astronomers a unique bird’s-eye view of the movement of the planet.
The video features five images taken over four years with the Gemini Planet Imager from the Gemini South Telescope in Chile. The Gemini coronagraph blocks most of the starlight so much fainter and smaller exoplanets can be seen. Image Credit: Gemini Planet Imager Exoplanet Survey
The NIRSPEC spectroscopic observations of HR 8799 and the NIRCAM observations of 51 Eridani are part of the Time Guaranteed Observations program that will take place shortly after Webb’s launch later this year. The NIRCAM and MIRI observations of HR 8799 are a collaboration of two instruments teams and are also part of the Time Guaranteed Observation Program.
The James Webb Space Telescope will be the world’s leading space science observatory when it launches in 2021. Webb will solve the mysteries of our solar system, observe distant worlds around other stars, and investigate the mysterious structures and origins of our universe and space. . in this. Webb is an international program run by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.