Starship Asterisk*

bls0326 wrote:
Did any neutrino detectors report a rise in neutrino count associated with this supernova?

Ron-Astro Pharmacist wrote:I can't say I've ever heard of "high cadence monitoring observation" before attempting a search about neutrino detection of SN 2015F but this article claims to do it.

Ann wrote:

ta152h0 wrote:this is a great catch. Was there a clue this was going to happen ?

There were no clues.

A supernova explosion explosion is like a landmine. First there is nothing, then there is a bang. Yes, if astronomers could have carefully studied the particular progenitor of SN 2015F, they just might have caught some little signs that something was about to happen.

But the particular star system that gave rise to SN 2015F would have been far, far too faint even for Hubble to study in a meaningful way. The host galaxy is about 80 million light years away, and the progenitors of SN type Ia are typically relatively faint.

And what do we mean by saying that something is "about" to happen? That might just mean that a supernova could be happening very "soon" - like, say, in a thousand years. We can hardly expect the Hubble telescope to keep a unblinking eye on every moderately nearby galaxy for the next thousand years in order to catch any possible supernova as it happens before our descendants' eyes.

Ann

ta152h0 wrote:this is a great catch. Was there a clue this was going to happen ?

daddyo wrote:

Chris Peterson wrote:...Technology should allow us to mitigate many potentially harmful effects.

Maybe not the initial onslaught of radiation, we need a supernova duck & cover red alert system...

Chris Peterson wrote:...Technology should allow us to mitigate many potentially harmful effects.

JohnD wrote:(Are there any Type 1A supernova candidates in range of us?)

JohnD wrote:I've asked before if the Universe isn't, in the long run, too dangerous for life except in a few lucky places, to learn from Chris that massively energetic X-rays would be blocked by an atmosphere. But what would be the radius of destruction of a Supernova?

Tszabeau wrote:That is the most awesome video I've ever viewed. The galaxy appears as a living thing. I'm not sure if it's that we are, actually, seeing it's stars moving or if it's just an illusion of graininess and wishful thinking but, it sure works for me.

mister T wrote:

as the fission-powered supernova glow faded.

Am I correct in assuming this means the the "afterglow" is powered by the breakdown of the heavier (unstable?) isotopes created in the initial blast?

"First I'm gonna smack you with my fusion then I'm gonna pummel you with fission..."

• Yes.

https://en.wikipedia.org/wiki/Supernova#Light_curves wrote:

[b][color=#0000FF]Comparative supernova type light curves[/color][/b]

---

Click to play embedded YouTube video.

<<The visual light curves of the different supernova types all depend at late times on radioactive heating, but they vary in shape and amplitude on the underlying mechanisms of the explosion, the way that visible radiation is produced, the epoch of its observation, and the transparency of the ejected material. The light curves can be significantly different at other wavelengths. For example, at ultraviolet wavelengths there is an early extremely luminous peak lasting only a few hours corresponding to the breakout of the shock launched by the initial explosion, but that breakout is hardly detectable optically.

The light curves for type Ia are mostly very uniform, with a consistent maximum absolute magnitude and a relatively steep decline in luminosity. Their optical energy output is driven by radioactive decay of nickel-56 (half life 6 days), which then decays to radioactive cobalt-56 (half life 77 days). These radioisotopes from material ejected in the explosion excite surrounding material to incandescence. Studies of cosmology today rely on ⁵⁶Ni radioactivity providing the energy for the optical brightness of supernovae of Type Ia, which are the "standard candles" of cosmology but whose diagnostic 847keV and 1238keV gamma rays were first detected only in 2014, 47 years after the prediction of their emission by supernovae. The initial phases of the light curve decline steeply as the effective size of the photosphere decreases and trapped electromagnetic radiation is depleted. The light curve continues to decline in the B band while it may show a small shoulder in the visual at about 40 days, but this is only a hint of a secondary maximum that occurs in the infra-red as certain ionised heavy elements recombine to produce infra-red radiation and the ejecta become transparent to it. The visual light curve continues to decline at a rate slightly greater than the decay rate of the radioactive cobalt (which has the longer half life and controls the later curve), because the ejected material becomes more diffuse and less able to convert the high energy radiation into visual radiation. After several months, the light curve changes its decline rate again as positron emission becomes dominant from the remaining cobalt-56, although this portion of the light curve has been little-studied.

Type Ib and Ic light curves are basically similar to type Ia although with a lower average peak luminosity. The visual light output is again due to radioactive decay being converted into visual radiation, but there is a much lower mass of nickel-56 produced in these types of explosion.>>

as the fission-powered supernova glow faded.