What is Supernova: Definition and 197 Discussions

A supernova ( plural: supernovae or supernovas, abbreviations: SN and SNe) is a powerful and luminous stellar explosion. This transient astronomical event occurs during the last evolutionary stages of a massive star or when a white dwarf is triggered into runaway nuclear fusion. The original object, called the progenitor, either collapses to a neutron star or black hole, or is completely destroyed. The peak optical luminosity of a supernova can be comparable to that of an entire galaxy before fading over several weeks or months.
Supernovae are more energetic than novae. In Latin, nova means "new", referring astronomically to what appears to be a temporary new bright star. Adding the prefix "super-" distinguishes supernovae from ordinary novae, which are far less luminous. The word supernova was coined by Walter Baade and Fritz Zwicky in 1929.
The most recent directly observed supernova in the Milky Way was Kepler's Supernova in 1604, but the remnants of more recent supernovae have been found. Observations of supernovae in other galaxies suggest they occur in the Milky Way on average about three times every century. These supernovae would almost certainly be observable with modern astronomical telescopes. The most recent naked-eye supernova was SN 1987A, the explosion of a blue supergiant star in the Large Magellanic Cloud, a satellite of the Milky Way.
Theoretical studies indicate that most supernovae are triggered by one of two basic mechanisms: the sudden re-ignition of nuclear fusion in a degenerate star such as a white dwarf, or the sudden gravitational collapse of a massive star's core. In the first class of events, the object's temperature is raised enough to trigger runaway nuclear fusion, completely disrupting the star. Possible causes are an accumulation of material from a binary companion through accretion, or a stellar merger. In the massive star case, the core of a massive star may undergo sudden collapse, releasing gravitational potential energy as a supernova. While some observed supernovae are more complex than these two simplified theories, the astrophysical mechanics are established and accepted by the astronomical community.
Supernovae can expel several solar masses of material at speeds up to several percent of the speed of light. This drives an expanding shock wave into the surrounding interstellar medium, sweeping up an expanding shell of gas and dust observed as a supernova remnant. Supernovae are a major source of elements in the interstellar medium from oxygen to rubidium. The expanding shock waves of supernovae can trigger the formation of new stars. Supernova remnants might be a major source of cosmic rays. Supernovae might produce gravitational waves, though thus far, gravitational waves have been detected only from the mergers of black holes and neutron stars.

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  1. jml53

    I Release of trapped light during supernova

    I was talking with my 14 year old son and he asked me a great question. He said he was thinking about the fact that it takes 100,000-1,000,000 years for energy released in the core of a star to reach the surface and be released as a photon. The journey is a random walk of microsteps of...
  2. S

    B What caused the recent supernova in the Pinwheel Galaxy?

  3. S

    I What Milky Way stars could go supernova to < +3 at any time?

    (I use +3 as the cutoff as that seems to be the limit of easily visible stars.) Yes, I know that Betelgeuse could go up in a < -10 blaze of glory, but I wonder what other ones are out there. On a side note, how fast could the big observatories move to it to observe it? And how quickly would...
  4. debs1

    I Electron-Positron Pair Instability Supernova

    How does the formation of electron positron pairs increase the energy density and softens the EOS? I trrying to understand the pair instability supernova. In many texts and articles, it is written that the formation of electron positron pairs lead to instability, the energy density is increased...
  5. R

    I Why does the core collapse happen so fast in a supernova?

    I just started my master's degree and I'm currently taking a course in astrophysics. However, it seems like I have misunderstood what prevents stars from collapsing (I will elaborate below). Why is it, that as soon as a massive star has finished the fusion processes, the collapse will happen in...
  6. L

    Stargazing Is There a Reliable Supernova Alert System?

    I was wondering if there are any reliable Supernova alert systems, where they notify me as soon as a supernova happens. I have a 20 inch telescope, and I have SNEWS installed. However, since SNEWS is only a detection for nearby galaxies, I was wondering if there is any alert system for...
  7. Oldman too

    Stargazing Upcoming Supernova? | Nature News

    This will be interesting to watch unfold. https://www.nature.com/articles/d41586-022-00425-8
  8. Nugatory

    Exploring Cassiopeia A: The 17th Century Supernova Remnant

    From the Washington Post's coverage of the IXPE orbiting telescope:
  9. Astronuc

    I SN 2019hgp, new type of supernova? Wolf-Rayet progenitor?

    A WC/WO star exploding within an expanding carbon-oxygen-neon nebula https://arxiv.org/abs/2111.12435 https://www.wis-tns.org/object/2019hgp https://www.universetoday.com/154116/a-new-kind-of-supernova-has-been-discovered/ https://ui.adsabs.harvard.edu/abs/2021TNSAN..76...1G/abstract...
  10. T

    I We watched a red supergiant explode to ordinary type II supernova

    First suspicious activity of SN 2020tlf (in the NGC 5731 galaxy) was noted 130 days prior, which prompted astronomers to keep an eye on it. "This is a breakthrough in our understanding of what massive stars do moments before they die," said lead study author Wynn Jacobson-Galán, a National...
  11. Paige_Turner

    B The Impact of Tidal Force on a Star's Magnetic Field and Supernova

    And if a star is severely stretched by tidal force, how does that affect its magnetic field and the process of it collapsing at the start of a supernova?
  12. M

    I What happens to the material not involved in the core collapse of a supernova?

    What happens to the material not involved in the core collapse of a supernova? This would be the outer portion of a star or any cloud that surrounds the star. All material to infinity or does some material remain close -- gravitationally close that might collapse if it could. thanks
  13. TimeSkip

    Stargazing Will the supernova explosion of Betelgeuse influence the Earth?

    Will the supernova explosion of Betelgeuse influence the Earth's climate and temperature or even the sun in any significant way?
  14. S

    I Will the Sun end as a Type 1a supernova?

    I had read that the Sun will become a white dwarf and then gradually cool down to a black dwarf, but this figure at Wikipedia says it will go supernova. (Yes, I know I should not trust Wikipedia, which is why I'm posting the question.)...
  15. S

    I The stellar system genesis & supernova cycle

    AIUI, the early universe, after the Great Recombination, was a fairly, but not absolute, isotropic cloud of mostly H, with some He. Eventually regions of the cloud coalesced into stars, and if the mass was big enough, the temperature & pressure in the star core was sufficient enough for H in...
  16. S

    I How big will the Betelgeuse supernova appear?

    I was looking at the seemingly very bright full Moon this early morning, and it got me thinking about how Betelgeuse will be as bright as the full Moon when it goes supernova (i.e., at its brightest). I suppose that first there is the question of the size of the bright exploding matter (but I...
  17. V

    I Supernova 100,000 Light Years Away: Agree on Time?

    If on Earth we detect the light from a supernova 100,000 light years away, we can say that the supernova happened 100,000 years ago (ignoring any dust etc. that might slow down the light). However, would all observers agree that the event happened 100,000 years ago? If a spaceship was traveling...
  18. jim mcnamara

    Possible extinction event: nearby supernova

    A popular science article on the end of the Devonian era examines the likelihood of an extinction event mediated by a nearby supernova. https://www.sciencedaily.com/releases/2020/08/200818142104.htm Per the article - A convincing argument can be made by finding Samarium 146 and/or Plutonium 244...
  19. F

    A Can a single star with 6 to 8 solar masses end up as a supernova 1a?

    Can a single star with 6 to 8 solar masses end up as a supernova 1 (having a remnant mass slightly above the Chandrasekhar limit) and being completely disrupted? This idea is presented by John Gribbin in his books “Stardust” and “The Universe”, but I can’t find any other reference or source...
  20. virgil1612

    I What is the current understanding of supernova mechanisms in 2020?

    Hello, Could someone explain or post some links for the current status-quo of the mechanisms that make a massive star explode?I know that the prompt mechanism doesn't work, that the shock stalls and must be revived by something (neutrinos, presumably), but where are they (the researchers) as...
  21. D

    B Could Earth's Atmosphere Survive a Close Gamma Ray Burst?

    I'm watching an episode of "How the universe works" and they explained the nightmare scenario where a star supernovas and turns into a black hole, emitting such a powerful burst of gamma rays, that if it were any closer than 6000 light years then it would be capable of stripping the entire Earth...
  22. Cerenkov

    B Other lines of evidence for Dark Energy? (Besides supernova data)

    Hello. My current understanding (please correct, if wrong) is that the expansion of the universe is observed to be accelerating, rather than coasting or slowing down. The tentative cause of this acceleration has been given the placeholder name of 'Dark Energy'. One line of evidence for this...
  23. R

    I Fitting a SiII curve in a supernova spectra

    Hello guys (and girls), I'm trying to determine the dark phase of a type Ia supernovae. In order to do that I need to calculate the photosphere's velocity. So I'm trying to determine the redshift of the Si II in the spectra, by finding the minima in the absorption line. But what kind of...
  24. Jarvis323

    A Where to Find the Best Records of Past Supernova Events

    I attended an interesting talk the other day about supernova archeology, and the discovery of strong evidence that Earth was showered with debris from a nearby supernova ~60-300 light years, about 2 to 3 Mya. The evidence is the presence of 60Fe in deep ocean crust at multiple sites, as well as...
  25. S

    I Isn't planetary rock dating really supernova dating?

    The age of the oldest rocks on Earth & Moon are about 4.5 Gy old. But doesn't the material that made the Earth come from the supernova that had occurred prior to the formation of the Solar System, and doesn't the radioactivity dating measure the age of the creation of that material in that...
  26. K

    I Positions of distant supernova explosions false?

    I'm googling and reading about Shape Dynamics and I came across this site about Julian Barbour research: http://discovermagazine.com/2012/mar/09-is-einsteins-greatest-work-wrong-didnt-go-far Can you find flaw in the following arguments about possible error in the computations of the...
  27. T

    B Why will Betelgeuse go supernova?

    Betelgeuse is a red supergiant, yet I have heard that Betelgeuse will go supernova in the next million years. How is this possible? Wouldn't Betelgeuse be too cool to go supernova? Normally red supergiants produce white dwarfs and planetary nebulae.
  28. Islam Hassan

    I Spherical Symmetry/Simultaneity of Supernova Explosions

    If the timing of detonation of nuclear weapons’ numerous implosive lenses must to be kept to within a microsecond or so in order to avoid asymmetrical detonation, does the timing of a supernova explosion similarly have tight constraints on its simultaneity and hence the sphericity of its...
  29. N

    I Core collapse of a supernova: the "void" left by the collapsed core?

    When core collapse occurs, a ~10000km diameter core of the star collapses into neutron star or a black hole. Let's look at NS case here: the resulting neutron star is on the order of 20 km across. And this happens in a few seconds. The upper layers of the star cannot immediately fall onto the...
  30. W

    I Frequency of nearby Supernova Explosions

    I have heard an interesting claim that looks fishy to me. The claim is that during the last 10,000 years there hasn't been a single Supernova eruption closer than about 5,000 light years. And that somehow this is an anomaly. That the background rate of nearby supernovas is much higher. And so...
  31. wolram

    B Lack of time dilation in type 1a supernova

    Here is one for every one to pull apart, it goes beyond every thing I have learnt. arXiv:1804.10274 [pdf, other] Lack of time dilation in type Ia supernovae and Gamma-Ray Bursts David F. Crawford Comments: 4 pages, 2 figures and 1 table Subjects: High Energy Astrophysical Phenomena...
  32. Z

    B Revealing Secrets of Distant Supernova DES16C2nm: 10.5 Billion Years Ago

    Astronomers said a star named DES16C2nm exploded 10.5 billion years ago. https://phys.org/news/2018-02-astronomers-reveal-secrets-distant-supernova.html Do they also mean that at the time the event happened, the star was 10.5 billion light-years away from Earth?
  33. T

    I Supernova - the Birth of One is Spotted

    An amateur astronomer was testing a new camera and spotted it. Originally posted in Nature. (paywall, but you can capture some images from the page) http://nature.com/articles/doi:10.1038/nature25151 His discovery, reported Wednesday in the journal Nature, is a landmark for astronomy. Buso’s...
  34. bbbl67

    I Type Ia supernova involving binary white dwarfs?

    Okay, so for years the typical mechanism used to describe a white dwarf supernova explosion was that a white dwarf accumulates matter from a main sequence binary companion. Then a few years later, the concept of two white dwarfs crashing into each other came up. With the main sequence companion...
  35. A

    I Can a supernova produce multiple stars?

    Can a supernova produce some number of stars after it explodes or will it always produce just one, single star? Can the matter it ejects form multiple stars and solar systems or will there always be just one new star and its only new solar system?
  36. S

    A How Does the Stiffness of Supernova EOS Change with Various Parameters?

    On what does the stiffnes/softness of the SN EOS depends? How does it change with temperature, progenitor mass, or other parameters like compresibility, symmetry energy etc? Would softening in NS EOS lead to softening in SN EOS? Tnx, Cheers
  37. B

    I Supernova - What would you see if watching one from close by?

    I know supernovae can create some very heavy elements (such as Uranium, Plutonium, Gold and so on...) Supposing you could watch such a colossal explosion from closeby without getting vaporized, would you see lumps of molten heavy metals (and other elements) flying everywhere in outer space and...
  38. S

    I Direct collapse to black hole without supernova?

    Hi. I saw this: https://www.forbes.com/sites/startswithabang/2017/05/29/surprise-the-universe-has-a-third-way-to-form-black-holes/#52d7225f216d suggesting they saw a star undergo a "direct collapse" to a black hole with no supernova. Now this seems like it could be sensible -- if there's...
  39. FallenApple

    I Is angular momentum conserved in a Supernova?

    I can see how it would be conserved for the situation of a star turning into a white dwarf since the object is just contracting. Just like the classic ice skater example. But what about a super nova? Say a star with spin up goes supernova and that the remaining black hole also has spin up but...
  40. K. Doc Holiday

    Stargazing Researching AN Ursae Majoris B for Supernova Possibilities

    I have read that IK Pegasi B is the white dwarf most likely to supernova in our galactic neighborhood. Are any other white dwarfs under consideration? My vote goes to AN Ursae Majoris B. (a polar white dwarf about 124 light years away, I think) Has this star ever been considered by anyone...
  41. Irfan Nafi

    B What kind of supernova do binary neutron stars produce?

    I was wondering if a binary system of neutron stars were to collide what kind of nova or supernova would it be. Is it different if the final mass of the neutron star is sufficient enough for a black hole or if it still a neutron star?
  42. Erenjaeger

    I Rate of Supernovae in the Milky Way Galaxy: Scientists' Best Estimate

    Which option is closest to scientists' current best estimate for the rate at which a supernova explosions occur somewhere in the milky way galaxy? a) once a day b) once a year c) once every hundred years d) once every thousand years From what I have found online, the current estimate is one...
  43. davenn

    Stargazing What is the difference between a type IIP and type IIL supernova?

    Supernova in M66 in Leo, announced 30/5/2016: https://Earth'sky.org/todays-image/supernova-erupts-in-m66 cheers Dave
  44. S

    What would a supernova sound like?

    I obviously realize that sound requires a medium to go through. However, suppose that there was a supernova and it was magically surrounded by an atmosphere that has the same composition and density as Earth's atmosphere. Now, if you were far enough away so you didn't get wiped out, then what...
  45. henrco

    Estimate gravitational energy from supernova

    Homework Statement Suppose that a 15 M(solar masses) star finally runs out of nuclear fuel in its core and undergoes a Type II supernova explosion. You are going to analyse the energy budget, calculating all the quantities in Joules. a) Estimate the amount of gravitational energy that would be...
  46. Greg Bernhardt

    B How was the KSN 2011d Supernova Detected?

    http://www.jpl.nasa.gov/news/news.php?feature=6166 Caught for the First Time: The Early Flash of an Exploding Star by Greg Bernhardt posted Mar 22, 2016 at 8:53 AM My question is what exactly were they looking for when analyzing stars to determine one that was about to blow?
  47. davenn

    Was a New Supernova Discovered in the Galaxy Centaurus A?

    hi gang @russ_watters @Drakkith @Andy Resnick meant to post this last week, been really busy A new supernova was discovered last Sunday, 7 Feb 2016 in the galaxy, Centaurus A radio galaxy (NGC5128). Currently it is around a 14th magnitude object a couple of pix from fellow Australian amateur...
  48. C

    Info on Supernova Acceleration

    I have a simple question regarding the acceleration of the universe. My textbook says that the acceleration was discovered through the supernova's light appearing dimmer than expected. In a constant expanding universe, it would be brighter. My textbook also tells me that the supernova was...
  49. E

    Will VY Canis Majoris be the next massive star to go supernova?

    I was looking at the article about Sirius Wikipedia, and it said that Sirius A would become a red giant in about a billion years, then settle down to a white dwarf. I felt this can't be right! If Sirius A becomes a red giant, how long until Sirius B passes the Chandrasekhar limit and becomes a...