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The object we call now SN 1006 which 1st appeared on May 1, 1006 A.D was the brightest observed stellar event in recorded history, reaching an estimated −7.5 visual magnitude. It was far brighter than Venus and visible during the daytime for weeks, exceeding roughly sixteen times the brightness of Venus. Appearing between April 30 and May 1, 1006 AD in the constellation of Lupus. This "Guest Star" was described by Astronomers in China, Japan, Europe, and the Arab world and they all documented this spectacular sight. Some observers reported it was clearly visible in the daytime even though it was blazing about 7,200 light-years away from earth.

Maunakea, Hawai‘i – Astronomers have discovered the second-most distant quasar ever found using three Maunakea Observatories in Hawai‘i: W. M. Keck Observatory, the international Gemini Observatory, a Program of NSF’s NOIRLab, and the University of Hawai‘i-owned United Kingdom Infrared Telescope (UKIRT). It is the first quasar to receive an indigenous Hawaiian name, Pōniuāʻena, which means “unseen spinning source of creation, surrounded with brilliance” in the Hawaiian language.

Pōniuāʻena is only the second quasar yet detected at a distance calculated at a cosmological redshift greater than 7.5 and it hosts a black hole twice as large as the other quasar known in the same era. The existence of these massive black holes at such early times challenges current theories of how supermassive black holes formed and grew in the young universe.

The research has been accepted in The Astrophysical Journal Letters and is available in preprint format on arXiv.org.

Quasars are the most energetic objects in the universe powered by their supermassive black holes and since their discovery, astronomers have been keen to determine when they first appeared in our cosmic history. By systematically searching for these rare objects in wide-area sky surveys, astronomers discovered the most distant quasar (named J1342+0928) in 2018 and now the second-most distant, Pōniuāʻena (or J1007+2115, at redshift 7.515). The light seen from Pōniuāʻena traveled through space for over 13 billion years since leaving the quasar just 700 million years after the Big Bang.

Spectroscopic observations from Keck Observatory and Gemini Observatory show the supermassive black hole powering Pōniuāʻena is 1.5 billion times more massive than our Sun.

“Pōniuāʻena is the most distant object known in the universe hosting a black hole exceeding one billion solar masses,” said Jinyi Yang, a postdoctoral research associate at the Steward Observatory of the University of Arizona and lead author of the study.

For a black hole of this size to form this early in the universe, it would need to start as a 10,000 solar mass “seed” black hole about 100 million years after the Big Bang, rather than growing from a much smaller black hole formed by the collapse of a single star.

“How can the universe produce such a massive black hole so early in its history?” said Xiaohui Fan, Regents’ professor and associate department head of the Department of Astronomy at the University of Arizona. “This discovery presents the biggest challenge yet for the theory of black hole formation and growth in the early universe.”

Current theory holds the birth of stars and galaxies as we know them started during the Epoch of Reionization, beginning about 400 million years after the Big Bang. The growth of the first giant black holes is thought to have occurred during that same era in the universe’s history.

The discovery of quasars like Pōniuāʻena, deep into the reionization epoch, is a big step towards understanding this process of reionization and the formation of early supermassive black holes and massive galaxies. Pōniuāʻena has placed new and important constraints on the evolution of the matter between galaxies (intergalactic medium) in the reionization epoch.


“Pōniuāʻena acts like a cosmic lighthouse. As its light travels the long journey towards Earth, its spectrum is altered by diffuse gas in the intergalactic medium which allowed us to pinpoint when the Epoch of Reionization occurred,” said co-author Joseph Hennawi, a professor in the Department of Physics at the University of California, Santa Barbara.

METHODOLOGY
Yang’s team first detected Pōniuāʻena as a possible quasar after combing through large area surveys such as the UKIRT Hemisphere Survey and data from the University of Hawai‘i Institute for Astronomy’s Pan-STARRS1 telescope on the Island of Maui.

In 2019, the researchers observed the object using Gemini Observatory’s GNIRS instrument as well as Keck Observatory’s Near Infrared Echellette Spectrograph (NIRES) to confirm the existence of Pōniuāʻena.

“The preliminary data from Gemini suggested this was likely to be an important discovery. Our team had observing time scheduled at Keck just a few weeks later, perfectly timed to observe the new quasar using Keck’s NIRES spectrograph in order to confirm its extremely high redshift and measure the mass of its black hole,” said co-author Aaron Barth, a professor in the Department of Physics and Astronomy at the University of California, Irvine.

In honor of its discovery from atop Maunakea, 30 Hawaiian immersion school teachers named the quasar Pōniuāʻena through the ‘Imiloa Astronomy Center of Hawai‘i’s A Hua He Inoa program led by renowned Hawaiian language expert Dr. Larry Kimura.

“We recognize there are different ways of knowing the universe,” said John O’Meara, chief scientist at Keck Observatory. “Pōniuāʻena is a wonderful example of interconnectedness between science and culture, with shared appreciation for how different knowledge systems enrich each other.”

“I am extremely grateful to be a part of this educational experience – it is a rare learning opportunity,” said Kauʻi Kaina, a high school Hawaiian immersion teacher from Kahuku, Oʻahu who was involved in the naming workshop. “Today it is relevant to apply these cultural values in order to further the well-being of the Hawaiian language beyond ordinary contexts such as in school, but also to ensure the language lives throughout the universe.”

Astronomers tend to have a slightly different sense of time than the rest of us. They regularly study events that happened millions or billions of years ago, and objects that have been around for just as long. That's partly why the recently discovered neutron star known as Swift J1818.0−1607 is remarkable: A new study in the journal Astrophysical Journal Letters estimates that it is only about 240 years old — a veritable newborn by cosmic standards.

NASA's Neil Gehrels Swift Observatory spotted the young object on March 12, when it released a massive burst of X-rays. Follow-up studies by the European Space Agency's XMM-Newton observatory and NASA's NuSTAR telescope, which is led by Caltech and managed by the agency's Jet Propulsion Laboratory, revealed more of the neutron star's physical characteristics, including those used to estimate its age.

A neutron star is an incredibly dense nugget of stellar material left over after a massive star goes supernova and explodes. In fact, they're some of the densest objects in the universe (second only to black holes): A teaspoon of neutron star material would weigh 4 billion tons on Earth. The atoms inside a neutron star are smashed together so tightly, they behave in ways not found anywhere else. Swift J1818.0−1607 packs twice the mass of our Sun into a volume more than one trillion times smaller.

With a magnetic field up to 1,000 times stronger than a typical neutron star — and about 100 million times stronger than the most powerful magnets made by humans — Swift J1818.0−1607 belongs to a special class of objects called magnetars, which are the most magnetic objects in the universe. And it appears to be the youngest magnetar ever discovered. If its age is confirmed, that means light from the stellar explosion that formed it would have reached Earth around the time that George Washington became the first president of the United States.

"This object is showing us an earlier time in a magnetar's life than we've ever seen before, very shortly after its formation," said Nanda Rea, a researcher at the Institute of Space Sciences in Barcelona and principal investigator on the observation campaigns by XMM Newton and NuSTAR (short for Nuclear Spectroscopic Telescope Array).

While there are over 3,000 known neutron stars, scientists have identified just 31 confirmed magnetars — including this newest entry. Because their physical properties can't be re-created on Earth, neutron stars (including magnetars) are natural laboratories for testing our understanding of the physical world.

"Maybe if we understand the formation story of these objects, we'll understand why there is such a huge difference between the number of magnetars we've found and the total number of known neutron stars," Rea said.

Swift J1818.0−1607 is located in the constellation Sagittarius and is relatively close to Earth — only about 16,000 light-years away. (Because light takes time to travel these cosmic distances, we are seeing light that the neutron star emitted about 16,000 years ago, when it was about 240 years old.) Many scientific models suggest that the physical properties and behaviors of magnetars change as they age and that magnetars may be most active when they are younger. So finding a younger sample close by like this will help refine those models.


Though neutron stars are only about 10 to 20 miles (15 to 30 kilometers) wide, they can emit huge bursts of light on par with those of much larger objects. Magnetars in particular have been linked to powerful eruptions bright enough to be seen clear across the universe. Considering the extreme physical characteristics of magnetars, scientists think there are multiple ways that they can generate such huge amounts of energy.

The Swift mission spotted Swift J1818.0−1607 when it began outbursting. In this phase, its X-ray emission became at least 10 times brighter than normal. Outbursting events vary in their specifics, but they usually begin with a sudden increase in brightness over the course of days or weeks that is followed by a gradual decline over months or years as the magnetar returns to its normal brightness.

That's why astronomers have to act fast if they want to observe the period of peak activity from one of these events. The Swift mission alerted the global astronomy community to the event, and XMM-Newton (which has NASA participation) and NuSTAR performed quick follow-up studies.

In addition to X-rays, magnetars have been known to release great bursts of gamma rays, the highest energy form of light in the universe. They can also emit steady beams of radio waves, the lowest energy form of light in the universe. (Neutron stars that emit long-lived radio beams are called radio pulsars; Swift J1818.0−1607 is one of five known magnetars that are also radio pulsars.)

"What's amazing about [magnetars] is they're quite diverse as a population," said Victoria Kaspi, director of the McGill Space Institute at McGill University in Montreal and a former member of the NuSTAR team, who was not involved with the study. "Each time you find one it's telling you a different story. They're very strange and very rare, and I don't think we've seen the full range of possibilities."

The new study was led by Paolo Esposito with the School for Advanced Studies (IUSS) in Pavia, Italy.


NuSTAR recently celebrated eight years in space, having launched on June 13, 2012. A Small Explorer mission led by Caltech and managed by JPL for NASA's Science Mission Directorate in Washington, NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp. in Dulles, Virginia. NuSTAR's mission operations center is at the University of California, Berkeley, and the official data archive is at NASA's High Energy Astrophysics Science Archive Research Center. ASI provides the mission's ground station and a mirror archive. Caltech manages JPL for NASA.

ESA's XMM-Newton observatory was launched in December 1999 from Kourou, French Guiana. NASA funded elements of the XMM-Newton instrument package and provides the NASA Guest Observer Facility at Goddard, which supports use of the observatory by U.S. astronomers.

NASA's Goddard Space Flight Center manages the Swift mission in collaboration with Penn State in University Park, the Los Alamos National Laboratory in New Mexico and Northrop Grumman Innovation Systems in Dulles, Virginia. Other partners include the University of Leicester and Mullard Space Science Laboratory of the University College London in the United Kingdom, Brera Observatory and ASI.

Source : NASA

Did you know that many of the galaxies, nebulas and star clusters observed by the Hubble Space Telescope can also be seen in backyard telescopes?

A new gallery of Hubble images highlights some of these celestial objects visible to amateur and professional astronomers alike. All of the objects are from a collection known as the Caldwell catalog, assembled by English amateur astronomer and science communicator Sir Patrick Caldwell-Moore and published in December 1995 by Sky & Telescope magazine. It complements the popular Messier catalog, which includes only objects visible from the Northern Hemisphere. The Caldwell catalog includes 109 interesting objects visible in amateur-sized telescopes in both the northern and southern skies that are not included in the Messier catalog.

Hubble’s Caldwell gallery currently contains 56 objects from the catalog and includes 12 newly processed images never before released by NASA. The images were extracted from more than 1.4 million observations that reside in Hubble’s data archive. Some of these images are the first or only ones captured by Hubble of these objects, while some are updated, higher-resolution views using the telescope’s newer cameras.
This image of spiral galaxy NGC 6946 (Caldwell 12) is one of a dozen previously unreleased images in the new Hubble gallery of Caldwell catalog objects.
Credits: NASA, ESA and L. Ho (Peking University); processing: Gladys Kober (NASA/Catholic University of America)

While Hubble has not imaged all 109 objects in the Caldwell catalog, it has observed 95 of them as of late 2019. The remaining Caldwell objects have yet to earn enough scientific interest to warrant Hubble’s time, which is in extremely high demand, but some might be targeted in the future. Many Caldwell objects also appear so large in the sky that they do not fit in Hubble’s field of view (which examines tiny portions of the sky at high resolution). So while some of Hubble’s photographs capture a given object in its entirety, most images focus on smaller, more specific areas of interest.


This new gallery will be updated as more of Hubble’s images are processed. For each Caldwell member already in Hubble’s collection, a basic star chart shows observers when and where they can find that object in the night sky. All of the Caldwell objects can be seen with amateur telescopes, but some can also be spotted in binoculars or even with the unaided eye. Anyone can go outside under a clear, dark sky, look up, and gaze at some of the same celestial gems with their own eyes that Hubble has so beautifully captured in its images.