Supernova

[harry]

G'day from the land of ozzzzzzzzz

Supernova, what do we really know about its formation. I'm going to post papers written on the subject rather than giving an opinion.

http://arxiv.org/abs/0904.2228
Rebrightening Phenomenon in Classical Novae

Authors: Taichi Kato (Kyoto U), Kazuhiro Nakajima (VSOLJ), Hiroyuki Maehara (Kyoto U), Seiichiro Kiyota (VSOLJ)
(Submitted on 15 Apr 2009)

Abstract: Two classical novae V1493 Aql and V2362 Cyg were known to exhibit unprecedented large-amplitude rebrightening during the late stage of their evolution. We analyzed common properties in these two light curves. We show that these unusual light curves are very well expressed by a combination of power-law decline, omnipresent in fast novae, and exponential brightening. We propose a schematic interpretation of the properties common to these rebrightenings can be a consequence of a shock resulting from a secondary ejection and its breakout in the optically thick nova winds. This interpretation has an advantage in explaining the rapid fading following the rebrightening and the subsequent evolution of the light curve. The exponential rise might reflect emerging light from the shock front, analogous to a radiative precursor in a supernova shock breakout. The consequence of such a shock in the nova wind potentially explains many kinds of unusual phenomena in novae including early-stage variations and potentially dust formation.

I hope in time we may get to understand its formation and what are the mechanism (or S) that take part.

[harry]

G'day from the land of ozzz

Although we know that Gravity and gravitational wave and magnetic fields play a part in the mechansim to produce a supernova of varies types and novas. The actual mechanism has not been resolved.


http://arxiv.org/abs/0905.2797
Probing the Core-Collapse Supernova Mechanism with Gravitational Waves

Authors: C. D. Ott (TAPIR, California Institute of Technology)
(Submitted on 18 May 2009)

Abstract: The mechanism of core-collapse supernova explosions must draw on the energy provided by gravitational collapse and transfer the necessary fraction to the kinetic and internal energy of the ejecta. Despite many decades of concerted theoretical effort, the detailed mechanism of core-collapse supernova explosions is still unknown, but indications are strong that multi-D processes lie at its heart. This opens up the possibility of probing the supernova mechanism with gravitational waves, carrying direct dynamical information from the supernova engine deep inside a dying massive star. I present a concise overview of the physics and primary multi-D dynamics in neutrino-driven, magnetorotational, and acoustically-driven core-collapse supernova explosion scenarios. Discussing and contrasting estimates for the gravitational-wave emission characteristics of these mechanisms, I argue that their gravitational-wave signatures are clearly distinct and that the observation (or non-observation) of gravitational waves from a nearby core-collapse event could put strong constraints on the supernova mechanism.

[harry]

G'day from the land of ozzzzzzz


This is very interesting paper. The ABS speaks for itself.

http://arxiv.org/abs/astro-ph/0409453
Magnetic Field Amplification in Tycho and other Shell-type Supernova Remnants

Authors: H.J. Voelk, E.G. Berezhko, L.T. Ksenofontov
(Submitted on 19 Sep 2004 (v1), last revised 7 Dec 2004 (this version, v2))

Abstract: It is shown that amplification of the magnetic field in supernova remnants (SNRs) occurs in all six objects where morphological measurements are presently available in the hard X-ray continuum at several keV. For the three archetypical objects (SN 1006, Cas A and Tycho's SNR) to which nonlinear time-dependent acceleration theory has been successfully applied up to now, the global theoretical and the local observational field strengths agree very well, suggesting in addition that all young SNRs exhibit the amplification effect as a result of very efficient acceleration of nuclear cosmic rays (CRs) at the outer shock. Since this appears to be empirically the case, we may reverse the argument and consider field amplification as a measure of nuclear CR acceleration and it has indeed been argued that acceleration in the amplified fields allows the CR spectrum from SNRs to reach the knee in the spectrum or, in special objects, even beyond. The above results are furthermore used to investigate the time evolution of field amplification in young SNRs. Although the uncertainties in the data do not allow precise conclusions regarding this point, they rather clearly show that the ratio of the magnetic field energy density and the kinetic energy density of gas flow into the shock is of the order of a few percent if the shock speed is high enough V_s > 10^3 km/s, and this ratio remains nearly constant during the SNR evolution. The escape of the highest energy nuclear particles from their sources becomes progressively important with age, reducing also the cutoff in the \pi^0 -decay gamma-ray emission spectrum with time after the end of the sweep-up phase. Simultaneously the leptonic gamma-ray channels will gain in relative importance with increasing age of the sources.

[harry]

G'day from the land of ozzzzzz

Sometime ago we discussed the possible impact of supernova on our weather and the implication on the evolution on earth.
Along those thoughts I ame across this paper. Just sharing the reading and not trying to prove a point.


http://arxiv.org/abs/0905.3919
The evidence for and against astronomical impacts on climate change and mass extinctions: A review

Authors: C.A.L. Bailer-Jones (1) ((1) Max Planck Institute for Astronomy, Heidelberg)
(Submitted on 24 May 2009)

Abstract: Numerous studies over the past 30 years have suggested there is a causal connection between the motion of the Sun through the Galaxy and terrestrial mass extinctions or climate change. Proposed mechanisms include comet impacts (via perturbation of the Oort cloud), cosmic rays and supernovae, the effects of which are modulated by the passage of the Sun through the Galactic midplane or spiral arms. Supposed periodicities in the fossil record, impact cratering dates or climate proxies over the Phanerozoic (past 545 Myr) are frequently cited as evidence in support of these hypotheses. This remains a controversial subject, with many refutations and replies having been published. Here I review both the mechanisms and the evidence for and against the relevance of astronomical phenomena to climate change and evolution. This necessarily includes a critical assessment of time series analysis techniques and hypothesis testing. Some of the studies have suffered from flaws in methodology, in particular drawing incorrect conclusions based on ruling out a null hypothesis. I conclude that there is little evidence for intrinsic periodicities in biodiversity, impact cratering or climate on timescales of tens to hundreds of Myr. Furthermore, Galactic midplane and spiral arm crossings seem to have little or no impact on biological or climate variation above background level. (truncated)

[Chris Peterson]

Supernova, what do we really know about its formation. I'm going to post papers written on the subject rather than giving an opinion.

http://arxiv.org/abs/0904.2228
Rebrightening Phenomenon in Classical Novae

It would truly be helpful if you'd state just what point you are making when you post these papers. Here you have created a topic called "Supernova", referred to them in a comment, and then posted a paper that has absolutely nothing to do with supernovas!

[Chris Peterson]

Although we know that Gravity and gravitational wave and magnetic fields play a part in the mechansim to produce a supernova of varies types and novas. The actual mechanism has not been resolved.

The mechanism of core-collapse supernova explosions must draw on the energy provided by gravitational collapse and transfer the necessary fraction to the kinetic and internal energy of the ejecta. Despite many decades of concerted theoretical effort, the detailed mechanism of core-collapse supernova explosions is still unknown...

My reading of this is that the "actual mechanism" is generally understood, and we have a paper here that proposes some of the detailed mechanisms that may be present, and how we might use gravity wave observations to test that proposal.

Furthermore, there is no discussion of novas, nor any suggestion that magnetic fields are involved in the actual formation of supernovas, only in the resultant structure after the gravitational collapse has begun.

[Chris Peterson]

This is very interesting paper. The ABS speaks for itself.

http://arxiv.org/abs/astro-ph/0409453
Magnetic Field Amplification in Tycho and other Shell-type Supernova Remnants

Indeed, it does. What it says is that observationally, supernova remnants behave as theory predicts. That is, it bolsters support for prevailing theory and suggests that we do, indeed, have a good level of understanding about supernovas.

[bystander]

Supernova may be in a new class
Science News - 2009 June 17

Stars that die an explosive death generally fall into two categories: young, massive stars that collapse under their own weight and hurl their outer layers into space, and older, sunlike stars that undergo a thermonuclear explosion. But the stellar explosion recorded in January 2005 and known as SN 2005E doesn’t fit either class, according to a new analysis reported online June 11 at arXiv.org.
...
Perets, Gal-Yam and their collaborators report that SN 2005E resembles a few other peculiar supernova, notably an explosion found last year and known as SN 2008ha.

The story about SN2008ha

On November 13th 2008, Caroline Moore a member of the Puckett Observatory Supernova Search team was recognized by the International Astronomical Union for discovering a supernova. Their discovery has been named Supernova 2008ha in galaxy UGC 12682. And at the ripe old age of 14, Caroline has also been recognized as most likely the youngest person to discover a supernova.
...
Considering the extremely low absolute magnitude and low ejecta velocity, which imply a very low total energy release, Foley et al. wonder if 2008ha is a true supernova that destroyed the progenitor star; if it is, then 2008ha is possibly the least luminous supernova ever observed.

[harry]

G'day from the land of ozzzzzz

Chris said

Indeed, it does. What it says is that observationally, supernova remnants behave as theory predicts. That is, it bolsters support for prevailing theory and suggests that we do, indeed, have a good level of understanding about supernovas.

Mate, we are just starting to learn about supernova and I think you are mistaken if you think magnetic fields do not play a main part in the formation. May I suggest you read up on Toroidal Magnetic fields using arXiv or the NASA ADS.

Modeling Magnetic Field Amplification in Nonlinear Diffusive Shock Acceleration
http://arxiv.org/abs/0904.3760
Authors: Andrey Vladimirov
(Submitted on 23 Apr 2009)

Abstract: This research was motivated by the recent observations indicating very strong magnetic fields at some supernova remnant shocks, which suggests in-situ generation of magnetic turbulence. The dissertation presents a numerical model of collisionless shocks with strong amplification of stochastic magnetic fields, self-consistently coupled to efficient shock acceleration of charged particles. Based on a Monte Carlo simulation of particle transport and acceleration in nonlinear shocks, the model describes magnetic field amplification using the state-of-the-art analytic models of instabilities in magnetized plasmas in the presence of non-thermal particle streaming. The results help one understand the complex nonlinear connections between the thermal plasma, the accelerated particles and the stochastic magnetic fields in strong collisionless shocks. Also, predictions regarding the efficiency of particle acceleration and magnetic field amplification, the impact of magnetic field amplification on the maximum energy of accelerated particles, and the compression and heating of the thermal plasma by the shocks are presented. Particle distribution functions and turbulence spectra derived with this model can be used to calculate the emission of observable nonthermal radiation.

and

http://arxiv.org/abs/0904.1938
Magnetic fields of non-degenerate stars

Authors: JF Donati, JD Landstreet
(Submitted on 13 Apr 2009)

Abstract: Magnetic fields are present in a wide variety of stars throughout the HR diagram and play a role at basically all evolutionary stages, from very-low-mass dwarfs to very massive stars, and from young star-forming molecular clouds and protostellar accretion discs to evolved giants/supergiants and magnetic white dwarfs/neutron stars. These fields range from a few microG (e.g., in molecular clouds) to TeraG and more (e.g., in magnetic neutron stars); in non-degenerate stars in particular, they feature large-scale topologies varying from simple nearly-axisymmetric dipoles to complex non-axsymmetric structures, and from mainly poloidal to mainly toroidal topology. After recalling the main techniques of detecting and modelling stellar magnetic fields, we review the existing properties of magnetic fields reported in cool, hot and young non-degenerate stars and protostars, and discuss our understanding of the origin of these fields and their impact on the birth and life of stars.

[Chris Peterson]

Mate, we are just starting to learn about supernova and I think you are mistaken if you think magnetic fields do not play a main part in the formation. May I suggest you read up on Toroidal Magnetic fields using arXiv or the NASA ADS.

Do you even bother to read the papers you link? Neither of these says that magnetic fields play any role in causing supernovas. They are about other magnetic effects, including how they influence supernova remnants.

The cause of supernovas is known, to the point of being fact. It is the details of the process that are being studied (and of course, magnetic fields are part of those details). That they are caused by gravitational collapse is a given.

[harry]

G'day from the land of ozzzzzzzz

Chris do you ever think of what the actual process is during gravitational collapse. You need further understanding. Just saying gravitational collapse does not mean much. You got to get inside the process.

I think you thinking like a junior high school pupil.

Maybe this will help you.

http://arxiv.org/abs/0805.0426
Self-Feeding Turbulent Magnetic Reconnection on Macroscopic Scales

Authors: Giovanni Lapenta (Centrum voor Plasma-Astrofysica, Departement Wiskunde, Katholieke Universiteit Leuven, Belgium)
(Submitted on 4 May 2008)

Abstract: Within a MHD approach we find magnetic reconnection to progress in two entirely different ways. The first is well-known: the laminar Sweet-Parker process. But a second, completely different and chaotic reconnection process is possible. This regime has properties of immediate practical relevance: i) it is much faster, developing on scales of the order of the Alfv\'en time, and ii) the areas of reconnection become distributed chaotically over a macroscopic region. The onset of the faster process is the formation of closed circulation patterns where the jets going out of the reconnection regions turn around and forces their way back in, carrying along copious amounts of magnetic flux.

In the next 10 years we may get a bit closer to understanding what the heck is going on.

[Chris Peterson]

Chris do you ever think of what the actual process is during gravitational collapse.

As I said before, the supernova is caused by gravitational collapse, which is well understood. What is not well understood are the complex physics present during and after the collapse that are ultimately responsible for the structure of the explosion itself, and of the remnants. Supernovas are not dependent on any magnetic phenomena- they happen whether or not there is a significant magnetic field.

Maybe this will help you.

http://arxiv.org/abs/0805.0426
Self-Feeding Turbulent Magnetic Reconnection on Macroscopic Scales

It does not, and I really wish you would stop linking papers that have nothing to do with the forum topic or the point you are trying to make. It wastes everybody's time.

[harry]

G'day Chris

Mate you remind of the dark ages. Just by your response tells me how little you know of the subject. Not once have you read the papers. Not once have you understood other peoples work.

You speak of gravitational collapse and yet you do not explain the process.

Do we believe that the king wears invisble robes on your say so.

Or do we question the make up of the robes.

One more thing.

Do a bit of research on magnetic reocnnection on the SUN and sunspots. Look deep into the sunspot and tell me what you see. What happens when magnetic fields connect?

Hubble site has some fantastic movies on this.

[Chris Peterson]

You speak of gravitational collapse and yet you do not explain the process.

There was no question posed about this, and it has been discussed in some detail elsewhere on this forum. But if you have some questions, all you need to do is ask.

Do a bit of research on magnetic reocnnection on the SUN and sunspots.

You created this topic about supernovas. What has a magnetohydrodynamic effect found on the Sun and other (normally operating) stars got to do with supernovas?

[bystander]

Source of Cosmic Rays Pinned Down
Space.com - 2009 June 25

As astronomers have long expected, exploding stars called supernovas can accelerate particles up to almost the speed of light, a new study shows. The discovery helps explain where the extremely energetic cosmic rays we find near Earth come from.

Cosmic Protons Gone Wild
ScienceNow - 2009 June 25

Shock waves launched into space by a supernova--the explosive death of a giant star--produce cosmic-ray particles carrying tremendous amounts of energy, astronomers have confirmed. The findings, reported today in Science, will give astronomers and physicists a better understanding of some of the universe's more bizarre phenomena.

Astronomers have suspected for more than a decade that supernova shock waves can act like giant particle accelerators. The basic idea is this: As the remnant of a dead star hurtles through space at up to 30 million kilometers per hour, it creates a shock wave as it interacts with the so-called interstellar medium (ISM). Protons in the shock wave get trapped by the magnetic field of the ISM, which bounces the protons back toward the remnant. But the remnant has its own magnetic field, which repels the protons.

Milky Way's super-efficient particle accelerators caught in the act
ESO 23/09 - Science Release - 2009 June 25

Thanks to a unique "ballistic study" that combines data from ESO's Very Large Telescope and NASA's Chandra X-ray Observatory, astronomers have now solved a long-standing mystery of the Milky Way’s particle accelerators. They show in a paper published today on Science Express that cosmic rays from our galaxy are very efficiently accelerated in the remnants of exploded stars.

[harry]

G'day bystander

That was good info mate.

Thanks


Time to put a shrimp on the barbi

[harry]

G'day from the land of ozzzzzzz

NGC 6543:
Chandra Reveals The X-Ray Glint In The Cat's Eye
http://chandra.harvard.edu/photo/2001/1220/

The following image shows a dipole jet (Axiom) that allows us to see the power of the jets change their surroundings.
NGC 6543:
The Cat's Eye Nebula Redux
http://chandra.harvard.edu/photo/2008/catseye/

http://arxiv.org/abs/astro-ph/0511711

Magnetar giant flares and afterglows as relativistic magnetized explosions

Authors: Maxim Lyutikov (UBC, University of Rochester)
(Submitted on 25 Nov 2005)

Abstract: (Abridged) We propose that giant flares on Soft Gamma-Ray Repeaters produce relativistic, strongly magnetized, weakly baryon loaded magnetic clouds, somewhat analogous to solar coronal mass ejection (CME) events. Flares are driven by unwinding of internal non-potential magnetic fields which leads to slow build-up of magnetic energy outside of the neutron star. For large magnetospheric currents, corresponding to a large twist of external magnetic field, magnetosphere becomes dynamically unstable on \Alfven crossing times scale of inner magnetosphere, $t_A \sim R_{NS}/c \sim 30 \mu$sec. Released magnetic energy results in formation of a strongly magnetized, pair-loaded, quasi-spherically expanding flux rope, topologically connected by magnetic field to the neutron star during the prompt flare emission. Magnetic stresses of the tied flux rope lead to late collimation of the expansion, on time scales longer than giant flare duration. Relativistic bulk motion of the expanding magnetic cloud, directed at an angle $\theta \sim 135^\circ$ to the line of sight (away from the observer), results in a strongly non-spherical forward shock with observed non-relativistic apparent expansion and bulk motion velocities $\beta_{app} \sim \cot \theta/2 \sim 0.4 $ at times of first radio observations approximately one week after the burst. Interaction with a shell of wind-shocked ISM and then with the unshocked ISM leads to deceleration to non-relativistic velocities approximately one month after the flare.

[harry]

G'day from the land of ozzzzzzz

Please excuse the links

This interesting, I would say what the ABS says, but! its self explaining.


http://arxiv.org/abs/0906.4407
Characteristics of EUV coronal jets observed with STEREO/SECCHI

Authors: G.Nistico, V. Bothmer, S. Patsourakos, G. Zimbardo
(Submitted on 24 Jun 2009)

Abstract: In this paper we present the first comprehensive statistical study of EUV coronal jets observed with the SECCHI imaging suites of the two STEREO spacecraft. A catalogue of 79 polar jets is presented, identified from simultaneous EUV and white-light coronagraph observations, taken during the time period March 2007 to April 2008. The appearances of the coronal jets were always correlated with underlying small-scale chromospheric bright points. A basic characterisation of the morphology and identification of the presence of helical structure were established with respect to recently proposed models for their origin and temporal evolution. A classification of the events with respect to previous jet studies shows that amongst the 79 events there were 37 Eiffel tower-type jet events commonly interpreted as a small-scale (about 35 arcsec) magnetic bipole reconnecting with the ambient unipolar open coronal magnetic fields at its looptops, and 12 lambda-type jet events commonly interpreted as reconnection with the ambient field happening at the bipoles footpoints. Five events were termed micro-CME type jet events because they resembled the classical coronal mass ejections (CMEs) but on much smaller scales. A few jets are also found in equatorial coronal holes. The typical lifetimes in the SECCHI/EUVI (Extreme UltraViolet Imager) field of view between 1.0 to 1.7 solar radius and in SECCHI/COR1 field of view between 1.4 to 4 solar radius are obtained, and the derived speed are roughly estimated. In summary, the observations support the assumption of continuous small-scale reconnection as an intrinsic feature of the solar corona, with its role for the heating of the corona, particle acceleration, structuring and acceleration of the solar wind remaining to be explored in more details in further studies.

and

http://arxiv.org/abs/0906.3043
The Meissner Effect and Vortex Expulsion in Color-Superconducting Quark stars, and its Role for Re-heating of Magnetars
Authors: Brian Niebergal, Rachid Ouyed, Rodrigo Negreiros, Fridolin Weber
(Submitted on 16 Jun 2009)

Abstract: Compact stars made of quark matter rather than confined hadronic matter, are expected to form a color superconductor. This superconductor ought to be threaded with rotational vortex lines within which the star's interior magnetic field is confined. The vortices (and thus magnetic flux) would be expelled from the star during stellar spin-down, leading to magnetic reconnection at the surface of the star and the prolific production of thermal energy. In this Letter, we show that this energy release can re-heat quark stars to exceptionally high temperatures, such as observed for Soft Gamma Repeaters (SGRs), Anomalous X-Ray pulsars (AXPs), and X-ray dim isolated neutron stars (XDINs). Moreover, our numerical investigations of the temperature evolution, spin-down rate, and magnetic field behavior of such superconducting quark stars suggest that SGRs, AXPs, and XDINs may be linked ancestrally. Finally, we discuss the possibility of a time delay before the star enters the color superconducting phase, which can be used to estimate the density at which quarks deconfine. We find this density to be five times that of nuclear saturation.

[harry]

G'day from the land of ozzzzzzz

As time goes on, we find that the more we learn the more we find how lttle we know.
Supernova is yet to be fully understood.

The following forces allow us to study.

http://arxiv.org/abs/0906.3043
The Meissner Effect and Vortex Expulsion in Color-Superconducting Quark stars, and its Role for Re-heating of Magnetars

Authors: Brian Niebergal, Rachid Ouyed, Rodrigo Negreiros, Fridolin Weber
(Submitted on 16 Jun 2009)

Abstract: Compact stars made of quark matter rather than confined hadronic matter, are expected to form a color superconductor. This superconductor ought to be threaded with rotational vortex lines within which the star's interior magnetic field is confined. The vortices (and thus magnetic flux) would be expelled from the star during stellar spin-down, leading to magnetic reconnection at the surface of the star and the prolific production of thermal energy. In this Letter, we show that this energy release can re-heat quark stars to exceptionally high temperatures, such as observed for Soft Gamma Repeaters (SGRs), Anomalous X-Ray pulsars (AXPs), and X-ray dim isolated neutron stars (XDINs). Moreover, our numerical investigations of the temperature evolution, spin-down rate, and magnetic field behavior of such superconducting quark stars suggest that SGRs, AXPs, and XDINs may be linked ancestrally. Finally, we discuss the possibility of a time delay before the star enters the color superconducting phase, which can be used to estimate the density at which quarks deconfine. We find this density to be five times that of nuclear saturation.

This image is a classsic example of its force

http://antwrp.gsfc.nasa.gov/apod/ap080617.html
APOD: 2008 June 17- Eta Carinae and the Homunculus Nebula

Notice the dipole axiom.

[Loco]

This image is a classsic example of its force

http://antwrp.gsfc.nasa.gov/apod/ap080617.html
APOD: 2008 June 17- Eta Carinae and the Homunculus Nebula

Notice the dipole axiom.

A blossomed rose .. the bottom half of the seeming mirror image explosion looks like a blossomed rose. What really is energy and how it expresses itself, how time relates to the expression of energy and vise versa, is really very vaguely understood. What would we become if we were at the centre of that energy? Imagination needs to work overtime unless one is of a religious nature .. but even the imagining, from a scientific point of view, brings into mind images of roses.

[The Code]

If, from now on i see Loco at the reply to any post,,,, im not going to read it...aris please kill loco..

I hate Him!

mark

[Loco]

If, from now on i see Loco at the reply to any post,,,, im not going to read it...aris please kill loco..

I hate Him!

mark

Mark .. why do you hate loco? You can send me an email to the address you have, in fact, please do, because I might miss your reply. I'm very curious. Or do you really hate Loco? In any case, I can't kill him, as he's too big a part of me ..but I might allow him to migrate to the other side.

[harry]

G'day from the land of ozzzz

Formation of star or a trigger may be answered by this post. The ABS explains my meaning.

http://arxiv.org/abs/astro-ph/0508243
Chandra X-ray Observation of a Mature Cloud-Shock Interaction in the Bright Eastern Knot Region of Puppis A

Authors: Una Hwang, Kathryn A. Flanagan, Robert Petre
(Submitted on 10 Aug 2005)

Abstract: We present Chandra X-ray images and spectra of the most prominent cloud-shock interaction region in the Puppis A supernova remnant. The Bright Eastern Knot (BEK) has two main morphological components: (1) a bright compact knot that lies directly behind the apex of an indentation in the eastern X-ray boundary and (2) lying 1' westward behind the shock, a curved vertical structure (bar) that is separated from a smaller bright cloud (cap) by faint diffuse emission. Based on hardness images and spectra, we identify the bar and cap as a single shocked interstellar cloud. Its morphology strongly resembles the ``voided sphere'' structures seen at late times in Klein et al.'s experimental simulations of cloud-shock interactions, when the crushing of the cloud by shear instabilities is well underway. We infer an interaction time of roughly 3 cloud-crushing timescales, which translates to 2000-4000 years, based on the X-ray temperature, physical size, and estimated expansion of the shocked cloud. This is the first X-ray identified example of a cloud-shock interaction in this advanced phase. Closer to the shock front, the X-ray emission of the compact knot in the eastern part of the BEK region implies a recent interaction with relatively denser gas, some of which lies in front of the remnant. The complex spatial relationship of the X-ray emission of the compact knot to optical [O III] emission suggests that there are multiple cloud interactions occurring along the line of sight.

Could the death of one star give birth to another?

[Chris Peterson]

http://arxiv.org/abs/astro-ph/0508243
Chandra X-ray Observation of a Mature Cloud-Shock Interaction in the Bright Eastern Knot Region of Puppis A

Could the death of one star give birth to another?

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.

The paper also provides observational support for a class of simulations and lab experiments supporting this mode of star formation.

[neufer]

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.

The paper also provides observational support for a class of simulations and lab experiments supporting this mode of star formation.

Lab experiments

That reminds me of a Sophomore Physics lab instructor at MIT who once told me:
"If you ever graduate and work in a laboratory somewhere I hope it is far far out in the desert."

Six years later I was in the Army working at a laboratory out at White Sands Missile Range (safely behind the Organ Mts.).