Stars, supernovae, black holes and stellar remnants

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caltrek
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Re: Stars, supernovae, black holes and stellar remnants

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Scientists Just Detected a Colossal Gamma-Ray Burst, And It's a Record-Breaker
by Michele Starr
October 12, 2022

Introduction:
(Science Alert) Observatories around the world have just detected a colossal flare of extremely energetic radiation described as "record-breaking".

The event, first detected on October 9, was so bright that it was initially confused for an event closer to home. Initially dubbed Swift J1913.1+1946, it was thought to be a brief flash of X-rays from a not-too-distant source. It was only through further analysis that astronomers discovered the true nature of the glow – a gamma-ray burst, one of the most violent explosions in the Universe, now re-named GRB221009A.

Though further away, it was still one of the closest seen yet, just 2.4 billion light-years away. Moreover, this exceptionally bright gamma-ray burst appears to be the most energetic ever detected, coming in at up to 18 teraelectronvolts.

To be clear, though this proximity happens to be 20 times closer than the average long gamma-ray burst, it poses absolutely no danger to life on Earth.

Rather, it's tremendously exciting – an event that could shed new light (pun intended) on these fascinating explosions. Although its closeness makes it appear brighter in our sky, GRB221009A is possibly the most intrinsically bright gamma-ray burst we've ever seen.
Read more here: https://www.sciencealert.com/scientist ... d-breaker
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caltrek
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Re: Stars, supernovae, black holes and stellar remnants

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Astronomers Think They've Developed an 'Early Warning System' For Supernovae
by Michele Starr
October 17, 2022

Introduction:
(Science Alert) Don't you just hate it when you're just minding your own business, and a star suddenly decides to go supernova? Well, good news: Scientists have figured out what these stars look like right before they die.

According to new simulations, the massive stars that are the progenitors of neutron stars dim dramatically in the last few months before they explode. So, if a massive star fades into complete obscurity without fanfare, the odds are good that there's a supernova on the horizon.

Red supergiant stars clocking in at around 8 to 20 times the mass of the Sun are some of the most interesting to watch. These beasts are at the end of their lifespan, running dangerously low on the fuel they need to support nuclear fusion in their cores.

That fusion provides outward pressure against the inward pressure of gravity. Take the fusion away, and things get violent. The star goes kaboom, star guts explode into space, and the stellar core collapses (for most stars).

For the red supergiants in question here, that core turns into an ultradense neutron star, something between around 1.1 and 2.3 times the mass of the Sun, packed into a sphere just 20 kilometers (12 miles) across.
Read more here: https://www.sciencealert.com/astronome ... upernovae
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Re: Stars, supernovae, black holes and stellar remnants

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FAST discovers largest atomic gas structure around a galaxy group
https://phys.org/news/2022-10-fast-larg ... alaxy.html
by Li Yuan, Chinese Academy of Sciences
Atomic gas is the basic material that all galaxies are formed from. The evolution of galaxies is mostly a procedure of accreting atomic gas from the intergalactic medium and then converting it into stars.

For this reason, observation and exploration of atomic gas in and around galaxies is crucial to the study of galaxy formation and evolution models. The most direct method of exploring atomic gas is through observation of the 21-cm fine structure line emission of atomic hydrogen in the radio waveband.

Recently, using the Five-hundred-meter Aperture Spherical Telescope (FAST) 19-beam receiver, an international team led by Xu Cong, a researcher from the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC), carried out deep mapping observations of 21-cm line emission in a region around the famous compact group of galaxies "Stephan's Quintet," and discovered a very large atomic gas structure with a length of about 2 million light years (about 20 times the size of the Milky Way).

Their findings were published in Nature on Oct. 19.

FAST is currently the largest and most sensitive single-dish radio telescope in the world, and its 19-beam receiver is the largest L-band multibeam feed array for 21-cm line observations. The full commissioning of the FAST 19-beam receiver opened a new window on atomic gas in the universe, particularly for low density diffuse gas far away from galaxies.
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Re: Stars, supernovae, black holes and stellar remnants

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Hubble Telescope Captures Rare ‘Light Echo’ From Star Explosion
October 31, 2022

Introduction:
(Eurasia Review) When a star explodes (a supernova), it sends its intense burst of light out in all directions. On rare occasions, in the months and years that follow, rings of light or ‘light echoes’ spread out from the original supernova position.

This is what is described in a recent paper in Astrophysical Journal Letters based on observations with the Hubble Space Telescope (HST) by a collaboration of astronomers from Dublin, Barcelona, Aarhus, New York and Garching. The paper, ‘Hubble Space Telescope Reveals Spectacular Light Echoes Associated with the Stripped-envelope Supernova 2016adj in the Iconic Dust Lane of Centaurus A,’ was published this week.

The scientists merged the HST images in a short gif-video, showing first the supernova explosion at the very centre, followed by light rings which appeared when light from the explosion hit various layers of dust in the vicinity.

Lead scientist Professor Maximillian Stritzinger of Aarhus University, Denmark, said: “The data set is remarkable and enabled us to produce very impressive colored images and animations that exhibit the evolution of the light echoes over a five-year period. It is a rarely seen phenomenon previously only documented in a handful of other supernovae.”
Read more here: https://www.eurasiareview.com/31102022 ... xplosion/
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Re: Stars, supernovae, black holes and stellar remnants

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Astronomers Discover Closest Black Hole to Earth
November 4, 2022

Introduction:
(EurekAlert) Astronomers using the International Gemini Observatory, operated by NSF’s NOIRLab, have discovered the closest-known black hole to Earth. This is the first unambiguous detection of a dormant stellar-mass black hole in the Milky Way. Its close proximity to Earth, a mere 1600 light-years away, offers an intriguing target of study to advance our understanding of the evolution of binary systems.

Black holes are the most extreme objects in the Universe. Supermassive versions of these unimaginably dense objects likely reside at the centers of all large galaxies. Stellar-mass black holes — which weigh approximately five to 100 times the mass of the Sun — are much more common, with an estimated 100 million in the Milky Way alone. Only a handful have been confirmed to date, however, and nearly all of these are ‘active’ – meaning they shine brightly in X-rays as they consume material from a nearby stellar companion, unlike dormant black holes which do not.

Astronomers using the Gemini North telescope on Hawai‘i, one of the twin telescopes of the InternationalGemini Observatory, operated by NSF’s NOIRLab, have discovered the closest black hole to Earth, which the researchers have dubbed Gaia BH1. This dormant black hole is about 10 times more massive than the Sun and is located about 1600 light-years away in the constellation Ophiuchus, making it three times closer to Earth than the previous record holder, an X-ray binary in the constellation of Monoceros. The new discovery was made possible by making exquisite observations of the motion of the black hole’s companion, a Sun-like star that orbits the black hole at about the same distance as the Earth orbits the Sun.

“Take the Solar System, put a black hole where the Sun is, and the Sun where the Earth is, and you get this system,” explained Kareem El-Badry, an astrophysicist at the Center for Astrophysics | Harvard & Smithsonianand the Max Planck Institute for Astronomy, and the lead author of the paper describing this discovery. “While there have been many claimed detections of systems like this, almost all these discoveries have subsequently been refuted.
Read more here: https://www.eurekalert.org/news-releases/970250
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Re: Stars, supernovae, black holes and stellar remnants

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Astronomers discover closest black hole to Earth
https://phys.org/news/2022-11-astronome ... earth.html
by National Optical-Infrared Astronomy Research Laboratory
Black holes are the most extreme objects in the universe. Supermassive versions of these unimaginably dense objects likely reside at the centers of all large galaxies. Stellar-mass black holes—which weigh approximately five to 100 times the mass of the sun—are much more common, with an estimated 100 million in the Milky Way alone.

Only a handful have been confirmed to date, however, and nearly all of these are "active"—meaning they shine brightly in X-rays as they consume material from a nearby stellar companion, unlike dormant black holes which do not.

Astronomers using the Gemini North telescope on Hawai'i, one of the twin telescopes of the International Gemini Observatory, operated by NSF's NOIRLab, have discovered the closest black hole to Earth, which the researchers have dubbed Gaia BH1. This dormant black hole weighs about 10 times the mass of the sun and is located about 1,600 light-years away in the constellation Ophiuchus, making it three times closer to Earth than the previous record holder, an X-ray binary in the constellation of Monoceros.

The new discovery was made possible by making exquisite observations of the motion of the black hole's companion, a sun-like star that orbits the black hole at about the same distance as the Earth orbits the sun.
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Re: Stars, supernovae, black holes and stellar remnants

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New radio-loud high-redshift quasar discovered
https://phys.org/news/2022-11-radio-lou ... uasar.html
by Tomasz Nowakowski , Phys.org

European astronomers report the detection of a new powerful radio-loud quasar at a redshift of about 5.32. The newfound object, designated PSO J191.05696+86.43172, turns out to be one of the brightest radio quasars identified at such a high redshift. The finding is reported in a paper published October 26 on arXiv.org.

Quasars, or quasi-stellar objects (QSOs), are extremely luminous active galactic nuclei (AGN) containing supermassive central black holes with accretion disks. Their redshifts are measured from the strong spectral lines that dominate their visible and ultraviolet spectra.

Astronomers are especially interested in finding new high-redshift quasars (at redshift higher than 5.0) as they are the most luminous and most distant compact objects in the observable universe. Spectra of such QSOs can be used to estimate the mass of supermassive black holes that constrain the evolution and formation models of quasars. Moreover, high-redshift QSOs that are also radio-bright are unique signposts of supermassive black hole activity in the early universe.

Now, a team of researchers led by Silvia Belladitta of the Brera Astronomical Observatory in Milan, Italy, has discovered a new high-redshift quasar. The detection is a result of a cross-matching of the data from three different surveys.

"In this paper we present the discovery and the first observations of PSO J191.05696+86.43172 (hereafter PSO J191+86), a powerful jetted QSOs at z=5.32, which has been selected from the cross-correlation of the NRAO VLA Sky Survey (NVSS, Condon et al. 1998) in the radio, the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS PS1, Chambers et al. 2016) in the optical and the AllWISE Source Catalog (Wright et al. 2010; Mainzer et al. 2011) in the mid-infrared (MIR)," the astronomers explained.
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Re: Stars, supernovae, black holes and stellar remnants

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Star found to have solid surface

21st November 2022

Astronomers using the IXPE space observatory report that a magnetar found 13,000 light-years away has a solid surface with no atmosphere.

Read more: https://www.futuretimeline.net/blog/202 ... urface.htm


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Re: Stars, supernovae, black holes and stellar remnants

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Direct observations of a complex coronal web uncover an important clue as to what mechanism drives solar wind
https://phys.org/news/2022-11-complex-c ... rtant.html
by Max Planck Society

Using observational data from the U.S. weather satellites GOES, a team of researchers led by the Max Planck Institute for Solar System Research (MPS) in Germany has taken an important step toward unlocking one of the sun's most persevering secrets: How does our star launch the particles constituting the solar wind into space? The data provide a unique view of a key region in the solar corona to which researchers have had little access so far.

The team has for the first time captured a dynamic web-like network of elongated, interwoven plasma structures. Together with data from other space probes and extensive computer simulations, a clear picture emerges: where the elongated coronal web structures interact, magnetic energy is discharged—and particles escape into space.

The Geostationary Operational Environmental Satellites (GOES) of the U.S. National Oceanic and Atmospheric Administration (NOAA) have traditionally concerned themselves with other things than the sun. Since 1974, the system has been orbiting our planet at an altitude of about 36,000 kilometers and continuously providing Earth-related data for example for weather and storm forecasting.
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Re: Stars, supernovae, black holes and stellar remnants

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'Black widow' PSR J1544+4937 investigated in detail
https://phys.org/news/2022-12-black-wid ... 44937.html
by Tomasz Nowakowski , Phys.org
Indian astronomers have performed long-term radio observations of a "black widow" millisecond pulsar known as PSR J1544+4937. Results of the observational campaign, published November 25 on the arXiv pre-print server, shed more light on the properties of this pulsar.

The most rapidly rotating pulsars, those with rotation periods below 30 milliseconds, are known as millisecond pulsars (MSPs). Researchers assume that they are formed in binary systems when the initially more massive component turns into a neutron star that is then spun up due to accretion of matter from the secondary star.

A class of extreme binary pulsars with semi-degenerate companion stars is dubbed "spider pulsars." These objects are further categorized as "black widows" if the companion has extremely low mass (less than 0.1 solar masses), while they are called "redbacks" if the secondary star is heavier.

Discovered by the Giant Meterwave Radio Telescope (GMRT) in 1991, PSR J1544+4937 is a black widow MSP with a spin period of 2.16 milliseconds. The pulsar is in a binary system with an orbital period of 2.9 hours orbiting around a low-mass companion star (with a mass of at least 0.017 solar masses).
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