Daniel Fischer<p>Evidence for an Instability-induced Binary Merger in the Double-peaked, Helium-rich Type IIn <a href="https://scicomm.xyz/tags/Supernova" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Supernova</span></a> 2023zkd: <a href="https://iopscience.iop.org/article/10.3847/1538-4357/adea38" rel="nofollow noopener noreferrer" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">iopscience.iop.org/article/10.</span><span class="invisible">3847/1538-4357/adea38</span></a> -> AI Helps Astronomers Discover a New Type of Supernova: <a href="https://www.cfa.harvard.edu/news/ai-helps-astronomers-discover-new-type-supernova" rel="nofollow noopener noreferrer" translate="no" target="_blank"><span class="invisible">https://www.</span><span class="ellipsis">cfa.harvard.edu/news/ai-helps-</span><span class="invisible">astronomers-discover-new-type-supernova</span></a> - astronomers have discovered what may be a massive star exploding while trying to swallow a black hole, offering an explanation for one of the strangest supernovae ever seen.</p>
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Type Ia Supernovae
Roman will use type Ia supernovae to measure cosmic distances, which will help us understand how the universe has expanded over time.
* Video Credit:
NASA Goddard's Scientific Visualization Studio
Roman will see thousands of exploding stars called supernovae across vast stretches of time and space. Using these observations, astronomers aim to shine a light on several cosmic mysteries – primarily dark energy. Roman will use type Ia supernovae to measure cosmic distances, which will help us understand how the universe has expanded over time.
Roman’s supernova survey will help clear up clashing measurements of how fast the universe is currently expanding, and even provide a new way to probe the distribution of dark matter, which is detectable only through its gravitational effects. One of the mission’s primary science goals involves using supernovae to help pin down the nature of dark energy – the unexplained cosmic pressure that’s speeding up the expansion of the universe.
Roman will use multiple methods to investigate dark energy. One involves surveying the sky for a special type of exploding star, called a type Ia supernova.
Many supernovae occur when massive stars run out of fuel, rapidly collapse under their own weight, and then explode because of strong shock waves that propel out of their interiors. These supernovae occur about once every 50 years in our Milky Way galaxy. But evidence shows that type Ia supernovae originate from some binary star systems that contain at least one white dwarf – the small, hot core remnant of a Sun-like star. Type Ia supernovae are much rarer, happening roughly once every 500 years in the Milky Way.
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https://science.nasa.gov/mission/roman-space-telescope/type-ia-supernovae/
En réponse à grobi
"Type Ia supernovae are used as standard candles to establish the distance scale of the universe."
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2025 July 31
Supernova 2025rbs in NGC 7331
* Image Credit: Ben Godson (University of Warwick)
https://warwick.ac.uk/fac/sci/physics/research/astro/people/bengodson/
Explanation:
A long time ago in a galaxy 50 million light-years away, a star exploded. Light from that supernova was first detected by telescopes on planet Earth on July 14th though, and the extragalactic transient is now known to astronomers as supernova 2025rbs. Presently the brightest supernova in planet Earth's sky, 2025rbs is a Type Ia supernova, likely caused by the thermonuclear detonation of a white dwarf star that accreted material from a companion in a binary star system. Type Ia supernovae are used as standard candles to establish the distance scale of the universe. The host galaxy of 2025rbs is NGC 7331. Itself a bright spiral galaxy in the northern constellation Pegasus, NGC 7331 is often touted as an analog to our own Milky Way.
https://goto-observatory.org/bright-supernova-2025rbs-discovered-by-goto/
https://www.wis-tns.org/object/2025rbs
https://rochesterastronomy.org/supernova.html
A Double Detonation #Supernova
#Astronomy #Picture of the Day
Hubble Picture of the Week
The swirling spiral NGC 3285B on the outskirts of the Hydra I galaxy cluster. It is home of supernova SN 2023xqm, visible here as a blue-ish dot on the left edge of the galaxy’s disc.
Credit: ESA/Hubble & NASA, R. J. Foley (UC Santa Cruz)
https://esahubble.org/images/potw2529a/
2018 April 19
NGC 7635: The Bubble Nebula
* Image Credit: NASA, ESA, Hubble Heritage Team -
https://www.nasa.gov/
https://www.spacetelescope.org/
https://heritage.stsci.edu/
* Reprocessing by Maksim Kakitsev
https://www.flickr.com/photos/wildespace/39512823160/
Explanation:
Blown by the wind from a massive star, this interstellar apparition has a surprisingly familiar shape. Cataloged as NGC 7635, it is also known simply as The Bubble Nebula. Although it looks delicate, the 7 light-year diameter bubble offers evidence of violent processes at work. Above and left of the Bubble's center is a hot, O-type star, several hundred thousand times more luminous and some 45 times more massive than the Sun. A fierce stellar wind and intense radiation from that star has blasted out the structure of glowing gas against denser material in a surrounding molecular cloud. The intriguing Bubble Nebula and associated cloud complex lie a mere 7,100 light-years away toward the boastful constellation Cassiopeia. This sharp, tantalizing view of the cosmic bubble is a composite of Hubble Space Telescope image data from 2016, reprocessed to present the nebula's intense narrowband emission in an approximate true color scheme.
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2025 February 3
A starfield is shown with a large spherical nebula in the center. The nebula shows a great deal of internal structure.
Wolf-Rayet Star 124: Stellar Wind Machine
* Image Credit: Hubble Legacy Archive, NASA, ESA
https://hla.stsci.edu/
https://www.nasa.gov/
https://www.esa.int/
* Processing & License: Judy Schmidt
https://www.flickr.com/photos/geckzilla/
Explanation:
Some stars explode in slow motion. Rare, massive Wolf-Rayet stars are so tumultuous and hot that they are slowly disintegrating right before our telescopes. Glowing gas globs each typically over 30 times more massive than the Earth are being expelled by violent stellar winds. Wolf-Rayet star WR 124, visible near the featured image center, is thus creating the surrounding nebula known as M1-67, which spans six light years across. Details of why this star has been slowly blowing itself apart over the past 20,000 years remains a topic of research. WR 124 lies 15,000 light-years away towards the constellation of the Arrow (Sagitta). The fate of any given Wolf-Rayet star likely depends on how massive it is, but many are thought to end their lives with spectacular explosions such as supernovas or gamma-ray bursts.
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Type Ia supernova
From Wikipedia, the free encyclopedia
At the core of a planetary nebula, Henize 2-428, two white dwarf stars slightly under one solar mass each are expected to merge and create a Type Ia supernova destroying both in about 700 million years (artist's impression).
A Type Ia supernova (read: "type one-A") is a type of supernova that occurs in binary systems (two stars orbiting one another) in which one of the stars is a white dwarf. The other star can be anything from a giant star to an even smaller white dwarf.
Physically, carbon–oxygen white dwarfs with a low rate of rotation are limited to below 1.44 solar masses (M☉). Beyond this "critical mass", they reignite and in some cases trigger a supernova explosion; this critical mass is often referred to as the Chandrasekhar mass, but is marginally different from the absolute Chandrasekhar limit, where electron degeneracy pressure is unable to prevent catastrophic collapse. If a white dwarf gradually accretes mass from a binary companion, or merges with a second white dwarf, the general hypothesis is that a white dwarf's core will reach the ignition temperature for carbon fusion as it approaches the Chandrasekhar mass. Within a few seconds of initiation of nuclear fusion, a substantial fraction of the matter in the white dwarf undergoes a runaway reaction, releasing enough energy (1×1044 J) to unbind the star in a supernova explosion.
The Type Ia category of supernova produces a fairly consistent peak luminosity because of the fixed critical mass at which a white dwarf will explode. Their consistent peak luminosity allows these explosions to be used as standard candles to measure the distance to their host galaxies: the visual magnitude of a type Ia supernova, as observed from Earth, indicates its distance from Earth.
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More Info in ALT-Texts
GIF
![2)
G299 Type Ia supernova remnant.
G299 was left over by a particular class of supernovas called Type Ia. Astronomers think that a Type Ia supernova is a thermonuclear explosion – involving the fusion of elements and release of vast amounts of energy − of a white dwarf star in a tight orbit with a companion star. If the white dwarf’s partner is a typical, Sun-like star, the white dwarf can become unstable and explode as it draws material from its companion. Alternatively, the white dwarf is in orbit with another white dwarf, the two may merge and can trigger an explosion.
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The current view among astronomers who model Type Ia supernova explosions, however, is that this limit is never actually attained and collapse is never initiated. Instead, the increase in pressure and density due to the increasing weight raises the temperature of the core, and as the white dwarf approaches about 99% of the limit, a period of convection ensues, lasting approximately 1,000 years. At some point in this simmering phase, a deflagration flame front is born, powered by carbon fusion. The details of the ignition are still unknown, including the location and number of points where the flame begins. Oxygen fusion is initiated shortly thereafter, but this fuel is not consumed as completely as carbon.
Once fusion begins, the temperature of the white dwarf increases. [...]](https://files.defcon.social/dcsocial-s3/media_attachments/files/114/858/179/983/990/092/original/af65981fd9477bb9.png "2)
G299 Type Ia supernova remnant.
G299 was left over by a particular class of supernovas called Type Ia. Astronomers think that a Type Ia supernova is a thermonuclear explosion – involving the fusion of elements and release of vast amounts of energy − of a white dwarf star in a tight orbit with a companion star. If the white dwarf’s partner is a typical, Sun-like star, the white dwarf can become unstable and explode as it draws material from its companion. Alternatively, the white dwarf is in orbit with another white dwarf, the two may merge and can trigger an explosion.
[...]
The current view among astronomers who model Type Ia supernova explosions, however, is that this limit is never actually attained and collapse is never initiated. Instead, the increase in pressure and density due to the increasing weight raises the temperature of the core, and as the white dwarf approaches about 99% of the limit, a period of convection ensues, lasting approximately 1,000 years. At some point in this simmering phase, a deflagration flame front is born, powered by carbon fusion. The details of the ignition are still unknown, including the location and number of points where the flame begins. Oxygen fusion is initiated shortly thereafter, but this fuel is not consumed as completely as carbon.
Once fusion begins, the temperature of the white dwarf increases. [...]")
![The Progenitor of a Type Ia Supernova
CREDIT
NASA, ESA and A. Feild (STScI); vectorisation by chris
3)
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A main sequence star supported by thermal pressure can expand and cool which automatically regulates the increase in thermal energy. However, degeneracy pressure is independent of temperature; white dwarfs are unable to regulate temperature in the manner of normal stars, so they are vulnerable to runaway fusion reactions. The flare accelerates dramatically, in part due to the Rayleigh–Taylor instability and interactions with turbulence. It is still a matter of considerable debate whether this flare transforms into a supersonic detonation from a subsonic deflagration.
Regardless of the exact details of how the supernova ignites, it is generally accepted that a substantial fraction of the carbon and oxygen in the white dwarf fuses into heavier elements within a period of only a few seconds, with the accompanying release of energy increasing the internal temperature to billions of degrees. The energy released (1–2×1044 J) is more than sufficient to unbind the star; that is, the individual particles making up the white dwarf gain enough kinetic energy to fly apart from each other. The star explodes violently and releases a shock wave in which matter is typically ejected at speeds on the order of 5,000–20,000 km/s, roughly 6% of the speed of light. The energy released in the explosion also causes an extreme increase in luminosity. [...]](https://files.defcon.social/dcsocial-s3/media_attachments/files/114/858/207/295/301/749/original/8d9863452a3ff9a5.png "The Progenitor of a Type Ia Supernova
CREDIT
NASA, ESA and A. Feild (STScI); vectorisation by chris
3)
[...]
A main sequence star supported by thermal pressure can expand and cool which automatically regulates the increase in thermal energy. However, degeneracy pressure is independent of temperature; white dwarfs are unable to regulate temperature in the manner of normal stars, so they are vulnerable to runaway fusion reactions. The flare accelerates dramatically, in part due to the Rayleigh–Taylor instability and interactions with turbulence. It is still a matter of considerable debate whether this flare transforms into a supersonic detonation from a subsonic deflagration.
Regardless of the exact details of how the supernova ignites, it is generally accepted that a substantial fraction of the carbon and oxygen in the white dwarf fuses into heavier elements within a period of only a few seconds, with the accompanying release of energy increasing the internal temperature to billions of degrees. The energy released (1–2×1044 J) is more than sufficient to unbind the star; that is, the individual particles making up the white dwarf gain enough kinetic energy to fly apart from each other. The star explodes violently and releases a shock wave in which matter is typically ejected at speeds on the order of 5,000–20,000 km/s, roughly 6% of the speed of light. The energy released in the explosion also causes an extreme increase in luminosity. [...]")
![Supercomputer simulation of the explosion phase of the deflagration-to-detonation model of supernova formation.
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The typical visual absolute magnitude of Type Ia supernovae is Mv = −19.3 (about 5 billion times brighter than the Sun), with little variation. The Type Ia supernova leaves no compact remnant, but the whole mass of the former white dwarf dissipates through space.
The theory of this type of supernova is similar to that of novae, in which a white dwarf accretes matter more slowly and does not approach the Chandrasekhar limit. In the case of a nova, the infalling matter causes a hydrogen fusion surface explosion that does not disrupt the star.
Type Ia supernovae differ from Type II supernovae, which are caused by the cataclysmic explosion of the outer layers of a massive star as its core collapses, powered by release of gravitational potential energy via neutrino emission.
One model for the formation of this category of supernova is a close binary star system. The progenitor binary system consists of main sequence stars, with the primary possessing more mass than the secondary. Being greater in mass, the primary is the first of the pair to evolve onto the asymptotic giant branch, where the star's envelope expands considerably. If the two stars share a common envelope then the system can lose significant amounts of mass, reducing the angular momentum, orbital radius and period.
[...]](https://files.defcon.social/dcsocial-s3/media_attachments/files/114/858/292/746/664/789/original/a66a570d62d6c619.jpg "Supercomputer simulation of the explosion phase of the deflagration-to-detonation model of supernova formation.
4)
[...]
The typical visual absolute magnitude of Type Ia supernovae is Mv = −19.3 (about 5 billion times brighter than the Sun), with little variation. The Type Ia supernova leaves no compact remnant, but the whole mass of the former white dwarf dissipates through space.
The theory of this type of supernova is similar to that of novae, in which a white dwarf accretes matter more slowly and does not approach the Chandrasekhar limit. In the case of a nova, the infalling matter causes a hydrogen fusion surface explosion that does not disrupt the star.
Type Ia supernovae differ from Type II supernovae, which are caused by the cataclysmic explosion of the outer layers of a massive star as its core collapses, powered by release of gravitational potential energy via neutrino emission.
One model for the formation of this category of supernova is a close binary star system. The progenitor binary system consists of main sequence stars, with the primary possessing more mass than the secondary. Being greater in mass, the primary is the first of the pair to evolve onto the asymptotic giant branch, where the star's envelope expands considerably. If the two stars share a common envelope then the system can lose significant amounts of mass, reducing the angular momentum, orbital radius and period.
[...]")
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10 Years ago ..
2016 February 9
The Rise and Fall of Supernova 2015F
* Video Credit & Copyright: Changsu Choi & Myungshin Im (Seoul National University)
https://physics.snu.ac.kr/en
Explanation:
Sit back and watch a star explode. The actual supernova occurred back when dinosaurs roamed the Earth, but images of the spectacular event began arriving last year. Supernova 2015F was discovered in nearby spiral galaxy NGC 2442 by Berto Monard in 2015 March and was unusually bright -- enough to be seen with only a small telescope. The pattern of brightness variation indicated a Type Ia supernova -- a type of stellar explosion that results when an Earth-size white dwarf gains so much mass that its core crosses the threshold of nuclear fusion, possibly caused by a lower mass white-dwarf companion spiraling into it. Finding and tracking Type Ia supernovae are particularly important because their intrinsic brightness can be calibrated, making their apparent brightness a good measure of their distance -- and hence useful toward calibrating the distance scale of the entire universe. The featured video tracked the stellar disruption from before explosion images arrived, as it brightened, and for several months as the fission-powered supernova glow faded. The remnants of SN2015F are now too dim to see without a large telescope. Just yesterday, however, the night sky lit up once again, this time with an even brighter supernova in an even closer galaxy: Centaurus A.
EP 250108a/SN 2025kg - observations of the most nearby Broad-Line Type Ic #Supernova following an Einstein Probe Fast X-ray Transient / The kangaroo's first hop - the early fast cooling phase of EP250108a/SN 2025kg: https://arxiv.org/abs/2504.08889 / https://arxiv.org/abs/2504.08886 -> Supernova’s ‘Trapped’ Jet Reveals Source of Fast X-ray Transient / International Gemini Observatory and SOAR Discover Surprising Link Between Fast X-ray Transients and the Explosive Death of Massive Stars: https://keckobservatory.org/fxt/ / https://noirlab.edu/public/news/noirlab2520/ - mysterious cosmic explosion is traced to a massive stellar explosion / a breakthrough in astronomy’s understanding of how stars larger than our Sun explode.
arXiv.orgEP 250108a/SN 2025kg: Observations of the most nearby Broad-Line Type Ic Supernova following an Einstein Probe Fast X-ray TransientWith a small sample of fast X-ray transients (FXTs) with multi-wavelength counterparts discovered to date, the progenitors of FXTs and their connections to gamma-ray bursts (GRBs) and supernovae (SNe) remain ambiguous. Here, we present photometric and spectroscopic observations of SN 2025kg, the supernova counterpart to the FXT EP 250108a. At $z=0.17641$, this is the closest known SN discovered following an Einstein Probe (EP) FXT. We show that SN 2025kg's optical spectra reveal the hallmark features of a broad-lined Type Ic SN. Its light curve evolution and expansion velocities are also comparable to those of GRB-SNe, including SN 1998bw, and several past FXT SNe. We present JWST/NIRSpec spectroscopy taken around SN 2025kg's maximum light, and find weak absorption due to He I $λ1.0830, λ2.0581$ $μ$m and a broad, unidentified feature at $\sim$ 4-4.5 $μ$m. Further, we observe clear evidence for broadened H$α$ in optical data at 42.5 days that is not detected at other epochs, indicating interaction with hydrogen-rich material. From its light curve, we derive a $^{56}$Ni mass of 0.2 - 0.6 $M_{\odot}$. Together with our companion paper (Eyles-Ferris et al. 2025), our broadband data of EP 250108a/SN 2025kg are consistent with a trapped or low energy ($\lesssim 10^{51}$ ergs) jet-driven explosion from a collapsar with a zero-age main sequence mass of 15-30 $M_{\odot}$. Finally, we show that the sample of EP FXT SNe support past rate estimates that low-luminosity jets seen through FXTs are more common than successful (GRB) jets, and that similar FXT-like signatures are likely present in at least a few percent of the brightest Ic-BL SNe.
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How Stars Explode:
Four Ways to Make a Supernova
What makes a star go boom? By understanding supernovae – stellar explosions – scientists can unlock mysteries that are key to what we are made of and the fate of our universe.
https://exoplanets.nasa.gov/news/1493/kepler-beyond-planets-finding-exploding-stars/
CREDIT
Jet Propulsion Laboratory
Les astronomes captent enfin une double détonation : un anneau calcium dans SNR 0509‑67.5 confirme une supernova bimodale 
https://www.futura-sciences.com/sciences/actualites/astronomie-astronomes-confirment-existence-mysterieuses-doubles-explosions-etoiles-123361/
#espace #science #astronomie
#supernova #TypeIa #doubleDetonation
#SNR0509‑67_5 #VLT #calciumShell #doubleDetonation
Futura · Les astronomes confirment l'existence des mystérieuses doubles explosions d'étoiles
(02 Jul) New evidence that some supernovae may be a “double detonation”
It may be possible to blow up a white dwarf before it reaches a critical mass.
https://s.faithcollapsing.com/30pnn
Archive: ais: https://archive.md/wip/OWdmg ia: https://s.faithcollapsing.com/szdt2
#astronomy #astrophysics #science #supernova #type-ia-supernova #white-dwarf
MUSE observations that affirm the path to detonation of a Type Ia #supernova in a supernova remnant: https://www.eso.org/public/archives/releases/sciencepapers/eso2511/eso2511a.pdf -> Double detonation - new image shows remains of star destroyed by pair of explosions: https://www.eso.org/public/news/eso2511/
Want to photograph a supernova? (Southern hemisphere only.)
Here's a fairly bright one - magnitude 13. A long telephoto lens or small telescope should catch it, especially because it's about 30 arcseconds from the galaxy's core.
It's low in the east just before morning twilight, but it'll get higher in the sky day by day.
AT2025pht (= ASASSN-25cw), TNS discovered 2025/06/29.430 by All Sky Automated Survey for SuperNovae (ASAS-SN)
Found in NGC 1637 at R.A. = 04h41m28s.834, Decl. = -02°51'55".87
Located 9".7 east and 27".3 south of the center of NGC 1637
Mag 13.3:6/29, Type unknown (zhost=0.002392)
https://www.physics.purdue.edu/brightsupernovae/
https://en.wikipedia.org/wiki/NGC_1637
#Astronomy #Astrophysics #Supernova #Astrophotography #Photography #Science #CitizenScience @sundogplanets
What Will the Betelgeuse Supernova Be Like - And Will It Hurt Us? • Universe Today
｢ It will be visible during the day. It will be brighter than any planet. It will be almost as bright as the full moon. You'll be able to read a book by the light of the Betelgeuse supernova at midnight ｣
Universe TodayWhat Will the Betelgeuse Supernova Be Like - And Will It Hurt Us?When Betelgeuse goes off, it's going to be the show of a lifetime. But it's not going to hurt us.