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36

There are lots of possible ways that stars can end their life, even in the subset of cases where the end is violent. Eloff has given an excellent answer, but I wanted to add a few points. Summary (tl;dr): You need the right conditions (mass, angular momentum, metallicity, etc) to produce a proto-neutron-star which is able to resist complete collapse to a ...


18

Depends on the detection technology. Yes Cerenkov based detectors (SNO and Super-Kamiokande for instance, as well a many cosmic ray neutrino detector) are direction sensitive, and this is one of the design considerations that drive the use of this tricky technique. The best results come from quasi-elastic reactions like $\nu_l + n \to l^- + p$. The ...


15

The calculation is done for 1987A here. Basically, the neutrinos' fractional speed increase from the new paper is $2.48\pm0.28\pm0.30\times10^{-5}$ (statistical / systematic errors, respectively) . SN1987a was $166\,912\pm10.1$ ly away, so multiplying the fraction by the travel time gives $4.14\pm0.97$ years. In reality, we got the neutrinos a few hours ...


13

None of those stars can go supernova, so the question is rather moot. If you look at the classifications, the most luminous is Sirius A (an A sequence star even) you can get an idea of its mass. If you look at your source page, and link to the explanation you see that A stars range from 1.4 to 2.1 stellar masses. In order to go supernova though, you need ...


13

We think that most neutron stars are produced in the cores of massive stars and result from the collapse of a core that is already at a mass of $\sim 1.1-1.2 M_{\odot}$ and so as a result there is a minimum observed mass for neutron stars of about $1.2M_{\odot}$. See for example Ozel et al. (2012; http://adsabs.harvard.edu/abs/2012ApJ...757...55O ). The ...


10

What you are looking for is called the stellar mass function by astronomers. It is the distribution of masses for stars. There is a nice review of the definitions, measurements, and basic theory in Galactic Stellar and Substellar Initial Mass Function, Chabrier 2003, PASP 115 763. It discusses both the initial mass function (IMF) and the present-day mass ...


10

Supernovae can take well over a week to reach maximum luminosity, and they stay rather bright for months after the peak. This just goes to show how much energy is involved in these event. I was going to assemble a collage of light curves from my own research, but then I realized this has already been done at Wikimedia Commons: These are rather idealized ...


10

The short answer is probably "yes we can", and possibly "we've already seen supernovae from the first galaxies", in the form of long-duration gamma-ray bursts. GRB 090429B has been given a redshift z=9.4, beating the previous record-holder GRB 090423 at z=8.2. As we continue to watch the skies, we're seeing more and more of these objects, and we'll gradually ...


9

In answer to your question of "What happens to the neighboring star?", according to the Johns Hopkins folks, it gets blown away: (Credit Johns Hopkins) I would be a little skeptical of the certainty of this claim only because we have not been able to observe any of these Type Ia explosions up close while it is happening. That's why the Type Ia SN 2011fe is ...


9

You have to run a massively sophisticated supernova simulation to get that kind of data. Whole research groups work on them. The biggest unknowns are generally the details of neutrino physics. This is both because neutrino hard data doesn't come easy, and because solving the radiation field of a supernova is a function of seven or eight variables (x, y, z ...


9

You're correct that when fusion reactions decrease past a certain point because the fuel is used up, the outward pressure created by the fusion no longer counteracts the gravitational forces and the star collapses (rapidly) in on itself. In stars of the right mass (smaller than about 15 solar masses, but large enough to collapse into a neutron star) the ...


8

How do I stay alive to be killed by neutrinos? You wouldn't. The point is being made that even the beam of neutrinos with a supernova at one astronomical unit distance would be intense enough that enough of them would interact with the matter of your body to be lethal. So even the neutrinos would get you if all the other stuff - notably $\gamma$s didn't. ...


8

The biggest thing about this supernova is how CLOSE it is. A mere 21 million light years away (as opposed to being a billion light years away). The folks at John Hopkins think that studying a ype Ia supernova is valuable for several reasons. SNe Ia are also very bright compared to other standard candles, which means they can be seen at high redshifts ...


8

It's interesting you found Tycho as an example as this was one of the early recorded supernovas back in 1572...by Tycho of course. This is considered a Type Ia Supernova and the image you reference isn't really how it looks. That's a modified composite to visualize the microwave and infrared components of the remains together. As Kyle mentioned, you can ...


6

Be careful when trying to intuit how sensitive the integral formulation is to changes in $w$. The equation of state parameter only enters as part of the exponent of $1+z$, so for $z \approx 0$, $w$ has approximately no effect: $1^0 \approx 1^\epsilon$. To illustrate with equations, suppose you already know $\Omega_\mathrm{M}$ and $\Omega_\mathrm{DE}$ ...


6

Star are fighting against gravitational forces by pressure gradients due to fusion in the core (and the shells outwards). Once fusion stops, there is no pressure gradient and gravity wins the "battle." The classic picture of a massive star at the end of its life is (and obviously not to scale), But each star star started off with just hydrogen in the ...


5

http://profmattstrassler.com/2011/09/20/supernovas-and-neutrinos/ This website confirms what you said about the neutrinos from the 1987 supernova arriving before the light from the supernova. It doesn't specifically say which detectors detected the neutrinos. The reason the neutrinos reached earth before the light is not because the neutrinos were ...


5

If you're asking about the duration of the explosion of supernovae, then it's done within a few seconds (the number can still be less) - similar to a nuclear fission. But, the cloud surrounding the explosion (i.e) the matter remnant that is thrown off can still remain expanding for years and it can emit EM radiation in the form of $\gamma$-rays and X-rays ...


5

Here is the actual announcement of the redshift from Andrew Levan. For those unfamiliar with astronomy practices, circulars are generally where simple things like discoveries, first spectra, redshifts, etc. are announced just as soon as the data is gathered and a preliminary reduction is performed, usually issued the morning after the observation. In this ...


5

The time delay between neutrinos and photons does not tell us directly about the absolute mass of the neutrinos. The time delay between a neutrino of mass $m$ and a massless neutrino does: $$ \Delta t = \frac{d}{v} - \frac{d}{c} \approx 0.5 \left(\frac{mc^2}{E}\right)^2 d, $$ where $\Delta t$ is the time delay in seconds, $v \approx ...


5

When observing supernovae, often the bulk of the material is optically thick, so we only see the surface layers. These are moving at some speed $v_\mathrm{surf}$. When modeling supernovae, the very simplistic model everyone loves to use is that of homologous expansion of a uniformly dense (density $\rho$) sphere. That is, velocity of the material increases ...


5

You can fit a value for Dark Energy (DE) using near or far supernovae (SNe), the benefit of distant SNe is purely from a statistics perspective: you want to minimize your errors on your best fit value of DE ($\Omega_{DE}$). To determine the uncertainty in your fit ($\sigma_{\Omega_{DE}}$) you have to do error propagation which will show a dependence on the ...


5

I'm not an expert in stellar physics by any means, but I can say this: the velocity discrepancy observed by OPERA, $\frac{v - c}{c} = 2.9\times 10^{-5}$, would correspond to a delay ("prelay"?) of around 4 years for neutrinos coming from SN1987A. The observed delay was only 3 hours, which is smaller by a factor of roughly ten thousand. So if you assume that ...


5

Dr Phil Plait covers the effects of a supernova near a habited planet extensively in his book Death from the Skies. Basically, it would have to happen at a distance closer than 25 light years. Given that constraint, and looking at our system, no stars are candidates for a supernova explosion that would wipe us out. A GRB is a different beast entirely, and ...


5

A Type Ia supernova is different from many others because of the extremely close similarity of the circumstances leading up to it. First you begin with a white-dwarf star which is composed of the Carbon and Oxygen remnant core of a former main sequence star under extreme pressures and held up by electron degeneracy pressure. A white-dwarf which happens to be ...


5

Is it possible to estimate? Yes. I'll give it a quick try. But the details of whether the planet will be incinerated and so on will make the reality much more complicated. As a ballpark, I think supernovae release about $10^{53}$ erg of energy. Spread over a sphere of, say, 1 AU gives $3.55\times10^{22}$J.m$^{-2}$. This energy isn't all released in one go ...



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