Starship Asterisk*

G'day Chris

You said

Certainly, that has been the standard model of star formation for decades. Supernovas play two roles: first, they supply the heavier elements that are part of the makeup of most stars, and second, they provide one of the trigger mechanisms for compacting interstellar clouds and beginning the process of collapse. This paper describes the second case, where the shock from a supernova is condensing material in an existing molecular gas cloud (which itself is not associated with the supernova). No star formation is observed, however, at this stage in the interaction.

You hit the nail on the head.

harry wrote:I'm going to post papers written on the subject rather than giving an opinion.

What's new?

G'day Makc


The price of eggs has gone up

Really? How far? If it's just a bit, maybe it's a good time for some shopping then.

makc wrote:What's new?

My home box. Its antique predecessor finally gave up the ghost. Never did find out why the old one choked, but that's all over now. For better or worse, it's nothin' but vista from now on.

apodman wrote:

makc wrote:What's new?

My home box. Its antique predecessor finally gave up the ghost. Never did find out why the old one choked, but that's all over now. For better or worse, it's nothin' but vista from now on.

If you just got it, you probably got a free upgrade for Windows 7. Take advantage of it; Win 7 is significantly better than Vista. I'm running it on a netbook, and quite like it. In most important respects it's more like XP than Vista. Win 7 should be formally released in a couple of months.

Chris Peterson wrote:you probably got a free upgrade for Windows 7 ... Win 7 should be formally released in a couple of months

Signed up. Thanks for the tip.

G'day

I may have to get the shopping list from the supermaket, my wife would love to discuss priceses.

well since you say they go up, they might get 'astronomic' soon enough to actually fit the forum topic.

G'day

Whats astronomic ??

G'day from the land of ozzzzzzzz

This may explain the process of a supernova and where the explosion comes from.

I thought it was interesting so I'm sharing the reading.

http://arxiv.org/abs/0903.0991
Astrophysical Implications of the QCD phase transition

Authors: Jurgen Schaffner-Bielich, Irina Sagert, Matthias Hempel, Giuseppe Pagliara, Tobias Fischer, Friedrich-Karl Thielemann, Anthony Mezzacappa, Matthias Liebendorfer
(Submitted on 5 Mar 2009)

Abstract: The possible role of a first order QCD phase transition at nonvanishing quark chemical potential and temperature for cold neutron stars and for supernovae is delineated. For cold neutron stars, we use the NJL model with nonvanishing color superconducting pairing gaps, which describes the phase transition to the 2SC and the CFL quark matter phases at high baryon densities. We demonstrate that these two phase transitions can both be present in the core of neutron stars and that they lead to the appearance of a third family of solution for compact stars. In particular, a core of CFL quark matter can be present in stable compact star configurations when slightly adjusting the vacuum pressure to the onset of the chiral phase transition from the hadronic model to the NJL model. We show that a strong first order phase transition can have strong impact on the dynamics of core collapse supernovae. If the QCD phase transition sets in shortly after the first bounce, a second outgoing shock wave can be generated which leads to an explosion. The presence of the QCD phase transition can be read off from the neutrino and antineutrino signal of the supernova.

G'day

Cosmology becomes so interesting when reading papers like these. Full credit goes to those people who research such papers.

http://arxiv.org/abs/0907.5040
Discovery of Extremely High Velocity "Molecular Bullets" in the HH 80-81 High-Mass Star-Forming Region
Authors: Keping Qiu, Qizhou Zhang
(Submitted on 29 Jul 2009)

Abstract: We present Submillimter Array 1.3 mm waveband continuum and molecular line observations of the HH 80-81 high-mass star-forming region. The dust continuum emission reveals two dominant peaks MM1 and MM2, and line emission from high-density tracers suggests the presence of another core MC. Molecular line emission from MM1, which harbors the exciting source of the HH 80-81 radio jet, yields a hot molecular core at a gas temperature of 110 K. The two younger cores MM2 and MC both appear to power collimated CO outflows. In particular, the outflow arising from MM2 exhibits a jet-like morphology and a broad velocity range of 190 km/s. The outflow contains compact and fast moving molecular clumps, known as "molecular bullets" first discovered in low-mass class 0 protostellar outflows. These "bullets" cannot be locally entrained or swept up from the ambient gas, but are more likely ejected from the close vicinity of the central protostar. The discovery of this remarkable outflow manifests an episodic, disk-mediated accretion for massive star formation.

G'day

This paper is quite informative and easy reading

Some Recent Progress on the Studies of Supernova Remnants
http://arxiv.org/abs/0909.0386
Authors: Jian-Wen Xu
(Submitted on 2 Sep 2009)

Abstract: We briefly reviewed some recent progress on the studies of supernova remnants (SNRs), including the radio SNRs (the structure, polarization, spectrum etc.), observational characteristics of X-ray emission, pulsar wind nebulae (PWNe), association properties between SNR and PSR, interaction of SNR and interstellar medium (ISM), cosmos ray and the SNRs in external galaxies, etc.. Correspondingly to the continue improvement of space and spectrum resolution of the on-ground and in-space astronomical equipments at wavelengthes as radio, optical, X-ray and so on, we know about SNRs more and deeper.

G'day

At what depth do scientists go to study Supernova. Down under depth just to measure those little suckers.

http://arxiv.org/abs/0907.4183
Report on the Depth Requirements for a Massive Detector at Homestake

Authors: Adam Bernstein, Mary Bishai, Edward Blucher, David B. Cline, Milind V. Diwan, Bonnie Fleming, Maury Goodman, Zbigniew J. Hladysz, Richard Kadel, Edward Kearns, Joshua Klein, Kenneth Lande, Francesco Lanni, David Lissauer, Steve Marks, Robert McKeown, William Morse, Regina Rameika, William M. Roggenthen, Kate Scholberg, Michael Smy, Henry Sobel, James Stewart, Gregory Sullivan, Robert Svoboda, Mark Vagins, Brett Viren, Christopher Walter, Robert Zwaska
(Submitted on 23 Jul 2009 (v1), last revised 9 Aug 2009 (this version, v2))

Abstract: This report provides the technical justification for locating a large detector underground in a US based Deep Underground Science and Engineering Laboratory. A large detector with a fiducial mass in the mega-ton scale will most likely be a multipurpose facility. The main physics justification for such a device is detection of accelerator generated neutrinos, nucleon decay, and natural sources of neutrinos such as solar, atmospheric and supernova neutrinos. In addition to the physics justification there are practical issues regarding the existing infrastructure at Homestake, and the stress characteristics of the Homestake rock formations.
The depth requirements associated with the various physics processes are reported for water Cherenkov and liquid argon detector technologies. While some of these physics processes can be adequately studied at shallower depths, none of them require a depth greater than 4300 mwe which corresponds to the 4850 ft level at Homestake. It is very important to note that the scale of the planned detector is such that even for accelerator neutrino detection (which allows one to use the accelerator duty factor to eliminate cosmics) a minimum depth is needed to reduce risk of contamination from cosmic rays. After consideration of the science and the practical issues regarding the Homestake site, we strongly recommend that the geotechnical studies be commenced at the 4850ft level in a timely manner.

Supernova is the most energetic explosive that happens in solar system. This happens due to the end of a life of a star. This activity plays a significant role in enriching the interstellar medium with higher mass elements.

G'day hronstve

Not in the solar system.

Some think that it ends the life of a Star others take it as a phase in Star sequence.

It also depends on whether there is any remnant left.

Sometimes a huge explosion only serves to explode the Solar Envelope leaving behind a compact core, such as a Neutron or a Quark Star.

G'day from the land of ozzzzzz

Science in the next few years may understand the workings of a Supernova and the properties of the remnants. In addition to understanding the Sun's dynamo and its origin as a possible supernova remnant. Mainstream has the opinion that the Sun's origin is from a collapsed cloud. Either way the formation and properties of the Sun's dynmo needs more research.

Gyroid Phase in Nuclear Pasta
May-09
http://adsabs.harvard.edu/abs/2009arXiv0905.2016N
http://adsabs.harvard.edu/cgi-bin/nph-d ... db_key=PRE

Nuclear matter is considered to be inhomogeneous at sub-nuclear densities realized, e.g., in supernova cores and neutron star crusts and change structures from sphere to cylinder, slab, cylindrical hole and spherical hole as the density increases. In this letter, we discuss other possibilities, that is, gyroid and double-diamond morphologies, which are periodic bicontinuous structures discovered in a block copolymer. Utilizing the compressible liquid drop model, we evaluate their surface and Coulomb energies and show that there is a chance of gyroid appearance near the transition point from cylinder to slab. This interesting analogy between the nuclear and polymer systems is not just qualitative. The volume fraction at the phase transition is also quite similar for the two systems. Although the five shapes listed initially have been long thought to be the only major constituents of the so-called nuclear pasta at sub-nuclear densities, our findings imply that this may not be the case and suggest that more detailed studies on the nuclear pasta including the gyroid phase is needed.

G'day

Supernova remnants hold the key to understanding the formation of various sequences of stars and the possible impact to Earth.
The question is this: Do the extreme magnetic fields exist during the life of the Star or during the supernova process that creates the Neutron Star.

The giant flare of 2004 Dec 27 from SGR1806-20 and fundamental physics from magnetars
00/2009
http://adsabs.harvard.edu/abs/2009MmSAI..80..186S

In the last decade strong evidence has been found for the existence of magnetars, neutron stars whose electromagnetic emission is powered by their extremely high magnetic field. Two classes of X-ray/gamma-ray sources, the Soft Gamma Repeaters (SGRs) and the Anomalous X-ray Pulsars (AXPs) have been identified with isolated, slowly spinning magnetars. A new perspective in this field was brought about by the 2004 December 27 giant flare from SGR 1806-20. The enormous energy liberated in this event ( 5 × 1046 ergs) points to an internal magnetar field of >1016 Gauss. Some of implications of this extraordinary event are surveyed here. These include: (a) the opening of the new field of neutron star astroseismology; (b) the detection of the highest luminosity derivative ever from a non-expanding source, with implication for radiative transfer effects in very strong magnetic fields; (c) newborn fast spinning magnetars can be very powerful sources of gravitational waves, detectable up to Virgo Cluster distances with Advanced LIGO/Virgo; (d) a sizable fraction of Short Gamma Ray bursts might be due to very powerful giant flares from magnetars in the nearby universe; (e) The effects of a nearby very powerful giant flare on the Earth are of interest for understanding the past and future of life.

Supernova remnants hold the key to understanding the formation of various sequences of stars and the possible impact to Earth.
The question is this: Do the extreme magnetic fields exist during the life of the Star or during the supernova process that creates the Neutron Star.

Magnetic fields, as I understand them, appear to be a side-effect of certain materials under the pressures and temperatures within stars, planets, ect. These temperatures and pressures are created by the balancing act between gravity and forces that resist gravity (such as radiation pressure in stars). The dynamo effect in Earth's mantle and the inner layers of stars are the source of magnetic fields (moving charged particles create magnetic fields). If the dynamo effect stops the magnetic field dies, as it did on Mars. The battle between gravity and radiation pressure (or atomic forces for small-mass things like planets) has nothing to do with magnetic fields that may or may not exist depending on the circumstances.

When a high-mass star reaches the end of its life, when it gets to iron burning, the star begins to collapse...because fusing iron requires the addition of more energy than it releases. The balancing act is at and end; the radiation pressure cannot hold off gravity any longer and the star falls in on itself. In the process its magnetic field can be increased as it is condensed along with the dying star. Magnetars are formed in this way.

I will buy the possibility that a condensing magnetic field may have some bearing on the behavior of the material left over in the supernova remnants; but I fail to see how the magnetic fields themselves create supernovas.

G'day Orca

Mate you may be right.

Collapsing is a process that involves electromagnetic reconnection as a process of breaking down ordinary matter to Neutron matter and feeding it into a zone such as the core that is able to contain it.

It is the magnetic field that is created by this neutron matter in the core, creating a soliton in this situation a vector soliton, more so as a dilaton, having two vector soliton going through the axis, resulting in an axion.

It is the combination of the magnetic field and the infalling matter that needs to be understood. Research into this area is prime.

If you want information on any topic above, just let me know.


This may be of interest

http://arxiv.org/abs/0910.0972
Recent breakthroughs in Skyrme-Hartree-Fock-Bogoliubov mass formulas

Authors: S. Goriely, N. Chamel, J. M. Pearson
(Submitted on 6 Oct 2009)

Abstract: We review our recent achievements in the construction of microscopic mass tables based on the Hartree-Fock-Bogoliubov method with Skyrme effective interactions. In the latest of our series of HFB-mass models, we have obtained our best fit ever to essentially all the available mass data, by treating the pairing more realistically than in any of our earlier models. The rms deviation on the 2149 measured masses of nuclei with N and Z>8 has been reduced for the first time in a mean field approach to 0.581 MeV. With the additional constraint on the neutron-matter equation of state, this new force is thus very well-suited for the study of neutron-rich nuclei and for the description of astrophysical environments like supernova cores and neutron-star crusts.

Briefly describe how a type I supernova might occur.

maarthaardy wrote:Briefly describe how a type I supernova might occur.

All supernovas occur when a star is unable to generate enough pressure through fusion to prevent gravitational collapse. The details of the collapse and subsequent explosion are broadly understood, although many details remain to be worked out.

Type I supernovas (there are several kinds) differ from Type II supernovas mainly in the mechanism by which the progenitor reaches the limit of collapse. Type I supernovas almost certainly involve binary systems, and the exploding star reaches its collapse threshold by accreting additional mass from its companion.

G'day from the land of ozzzzz

Chris may be right in what he says.

Astrophysics and cosmology are going through some rapid changes in the type of information and data. With that in mind we need to step back a little and try to understand the information.

Having alternative processes at hand.

One process is as follows.
Supernova is a result of an inbalance between the core (dynamo or should I say dynamotor) and the solar envelope.

Once the solar envelope accumulates heavier elements and the core loses its gravity control over the solar envelope, the solar envelope expands. While this is happening the core becomes unstable releasing extreme magnetic fields that create jets and create hour glass forms before the supernova explosion.

The many elements in the solar envelope are broken down by the combination of gravity and electromagnetic reconnection down to Neutrons that are collected and confined in the solar core. Once the core reaches a critical mass the electromagnetic reconnections create massive solar flares shooting (exploding) off parts or all of the solar envelope.

The explanation of the explosion can be read in alternative processes such as a the solar envelope collapsing due to gravity and rebouncing.

I would go deeper in this explanation, but! I have to go.

harry wrote: Once the solar envelope accumulates heavier elements and the core loses its gravity control over the solar envelope, the solar envelope expands.

The core doesn't lose gravity control. On the contrary, it's 'gravity control' is increased. If heavy elements accumulate in the solar envelope, that should increase the core's gravitational control, not decrease it. So what would cause your posited resulting envelope expansion???

Here is my simplified explanation.
Fusion (exothermic) in the core creates radiation pressure pushing outwards, counteracting the effects of gravity pulling inwards. Once the fusion fuel is used up, gravity collapses the core, increasing its pressure and therefore temperature. For large stars destined to become supernovae, this temperature increases enough to begin the next level of fusion, creating the radiation pressure anew.

This process continues with each collapse creating the increased temperature required for the next level of fusion to occur. When all fuel is consumed, or when the temperature cannot be raised high enough for the next level of fusion to occur, or when the heaviest element for which fusion is exothermic has been exhausted, the final collapse of the outer layers 'bounces off' the dense core and ka-boom!!!

There are many more details that I don't understand but this is the generally accepted description, I believe.

harry wrote: The many elements in the solar envelope are broken down by the combination of gravity and electromagnetic reconnection down to Neutrons that are collected and confined in the solar core.

Elements are not broken down in the core. Elements are created in the core due to nuclear fusion reactions. The break down into neutrons with the resulting creation of a neutron star occurs after the supernova has occurred (or during the supernova explosion?)

I've never heard of elements being broken down by either gravity or 'electromagnetic reconnection', whatever that is. Admittedly, I'm not an astronomer but I do have a very old physics degree and worked in nuclear physics for a while so though my knowledge is very rusty, I do have a grip on the rudiments.

harry wrote: The explanation of the explosion can be read in alternative processes such as a the solar envelope collapsing due to gravity and rebouncing.

I believe that this is the main process, not an alternative reading of the process.

I don't know why folks waste their time and energy reading and believing pseudo-scientific gobbledygook !!!

If you study and or work with scientists for a while, you would see that their theories are exhaustively debated and meticulously researched ant tested. Sure, theories can be superseded by newer, better ones and corrections are made. But generally accepted descriptions of processes become generally accepted through processes of intense scrutiny and debate. Scientists are not in some dogmatic conspiracy to advance only one set of ideas, believe me!!!

G'day Cancuk 100

You said

The core doesn't lose gravity control. On the contrary, it's 'gravity control' is increased. If heavy elements accumulate in the solar envelope, that should increase the core's gravitational control, not decrease it. So what would cause your posited resulting envelope expansion???

The core has a high density, its grvity controlls the heat release and the prevention of the solar envelope from expanding.

Over billions of years the core loses mass and thus the ability to control the heat release from the core and the temp lid within the solar envelope, this temp expands the solar envelope.

The high energy photons originating from the core and reconnecting electromagnetic fields break up the heavier elements by photodisintergration.

During the process the core is rejuvinated and may even go through a phase transition to Neutrons or a pasta of subatomic particles that may include quarks. The composition of the core is complicated by the size of the Star.

as for your comment

I don't know why folks waste their time and energy reading and believing pseudo-scientific gobbledygook !!!

This type of talk has lead some scientists on the wrong path.