The Explosive Cosmos

by Paul Gilster on June 26, 2008

By Larry Klaes

Just how dangerous a place is our universe? As Larry Klaes notes, the apparent calm of a quiet summer sky masks events that can dwarf the imagination. New instruments, particularly those in space, are now giving us an unprecedented look at stellar flares and exploding stars, allowing us to observe the earliest phases of their activity. The implications for life are also striking, as flaring red dwarfs and titanic supernova can attest.

When we look up at the night sky with our eyes alone, everything about it seems calm and even peaceful. Aside from a passing airplane or satellite, only the occasional meteor or twinkling star indicate any natural activities up there. Otherwise, the Universe seems almost immobile and permanent, even when we watch the stars for a long while.

Recent news by the astronomy community shows just how much of an illusion this perception actually is. On May 14, NASA announced the discovery of the youngest local supernova remnant yet known, an object unpoetically known as G1.9+0.3, located near the center of our Milky Way galaxy about 26,000 light years from Earth.

Though most stars exist for ages far longer than human minds can conceive, they are not immortal. Some last for billions of years and eventually more-or-less quietly fade away; this will be the fate of our Sun.

More massive suns do not exist for quite so long, nor do they leave the Universe peacefully. These natural fusion reactors often end up in a titanic explosion called a supernova. Some lose their nuclear fuel, causing their cores to collapse and release huge amounts of energy in the process, leaving a neutron star or black hole in their wake. Other large suns that are part of a binary system where one star is a white dwarf create their death act when too much material from the giant star is pulled onto the white dwarf companion, causing its core to heat enough to create runaway nuclear fusion and tear itself apart.

Artist\'s conception of a supernova

Image: This artist’s impression shows what the supernova explosion that resulted in the formation of the supernova remnant G1.9+0.3 might have looked like. The expanding debris from the supernova explosion is shown in white, including some interaction with the surrounding gas (green). The crowded environment near the center is shown by diffuse gas (red) and dust (brown) as well as large numbers of stars with different masses and colors. Credit: NASA/CXC/M.Weiss.

While these explosions mean certain destruction and death for these suns and anything near them in space, the event also means life for any new systems that form in their wake. The debris expelled from the destroyed star contains many heavy elements that become part of other nebulae of gas and dust that collapse into new solar systems triggered by the shockwave of the supernova. This is recycling on a cosmic scale.

Such an important process for the creation of stars, worlds, and life has naturally led scientists to want to know more about the complete cycle of supernovae. Finding that G1.9+0.3 is only about 140 years old, several centuries younger than the previously youngest known supernova, is a major boon to this field.

Astronomers did not know about this particular supernova before the 1980s due to the heavy amounts of dark interstellar dust and gas that lie between Earth and that stellar remnant. The gas and dust being spewed into space from the stellar explosion did heat up the surrounding environment, which allowed the supernova to be detected by the Chandra X-Ray satellite and the Very Large Array (VLA) group of radio telescopes in the desert of New Mexico. The scientists were able to witness the rapid expansion of the supernova debris cloud moving at five percent of light speed (186,000 miles per second) over the last two decades, enabling them to determine the relatively young age of this celestial phenomenon.

Meanwhile, a supernova in the spiral galaxy NGC 2770 labeled SN2008D was recently caught by the X-ray telescope of NASA’s Swift Observatory satellite while the space sentinel was gathering data on a different supernova in that same galaxy. This fortuitous situation allowed astronomers to witness a supernova in the act of first forming, though that galaxy and SN2008D are over 90 million light years from our Milky Way.

Regarding one of the results of a major stellar explosion, in particular a pulsar (a rapidly rotating neutron star), a sky survey named PALFA (for Pulsar Arecibo L-band Feed Array), conducted with the Arecibo Radio Observatory in Puerto Rico managed by Cornell University, came across an unusual type of pulsar named PSR J1903+0327 situated 21,000 light years from Earth.

This particular pulsar has a companion star, which in itself is not terribly unusual: The first binary pulsar was discovered in 1974 using the giant Arecibo radio telescope. Even though PSR J1903+0327 spins on its axis 465 times each second (2.15 milliseconds), which makes it among the fastest known such rapidly rotating neutron stars, this feature also does not make that pulsar so terribly unusual among its kind.

What does set PSR J1903+0327 apart from its fellow supernova remnants is the fact that it has a very elongated 95-day orbit around its companion sun, which happens to be a fairly “normal” star similar to our Sun. All other known millisecond binary pulsars orbit in nearly perfect circles around other neutron stars.

Astronomers have several theories as to why this pulsar system is so different from the rest. One idea involves the binary pulsar having formed in a globular star cluster and becoming disrupted and ejected from that large collection of suns by a close encounter with another star in that cluster. The other theory postulates a third companion to that system, perhaps another neutron star or even a white dwarf. If the latter idea turns out to be true, then PSR J1903+0327 would become the first known triple pulsar system.

Huge flare on EV Lacertae

The details on this strange pulsar were published in the May 15 issue of Science Express, the online version of Science magazine (the paper is also available at the arXiv site). As if to bring home the fact that our Universe is anything but a quiet, unchanging realm, astronomers reported late last month that the Swift satellite, which observed the supernova “birth” in galaxy NGC 2770, also detected a massive flare from EV Lacertae, a faint red dwarf star just 16 light years from our planet.

Image : An artist’s depiction of the red dwarf EV Lacertae and its enormous flare. Credit: Casey Reed/NASA.

How big was the flare? The huge amount of gas and other particles that erupted from this young star were so bright that they caused Swift to automatically shut down its observing telescope for safety reasons. Astronomers noted that had the EV Lacertae flare occurred on our Sun, it would have stripped away Earth’s atmosphere and sterilized our planet’s surface.

{ 13 comments }

James M. Essig June 27, 2008 at 16:23

Hi Folks;

The idea of cosmic catastrophes or at least supernova + sized events needs to be given at least some attention I believe. The universe according to the Big Bang theory and in many of its versions proposed hold that the universe rests in a meta stable minimum within a scalar field wherein the background scalar field has ultramicroscopic vacuum field fluctuations that in general cancel each other out because their random orientations result in a washout of larger scale fluctuations.

One concern I have is that as we build ever more powerful particle accelerators in the coming decades, centuries, millennia +, we might acquire the ability to produce particle collisions so energetic that the meta stable state of the vacuum state of our universe might be locally perturbed in such a manner that the effect runs away, so to speak, in a phase change that might do anything ranging from causing photons to suddenly acquire mass to a run away scrambling of the fabric of space time and mattergy within our universe and perhaps even scrambling the integrity and order of cause and effect within our universe. Such effects, if they were accidentally produced, might race throughout the Bulk in p-brane theory or our entire multiverse in Chaotic Inflation Theory and perhaps scramble it as well.

One might well argue that events in nature already occur far more energetically than any thing our particle accelerators can produce, however, particle energy is not the only consideration here. The energy of collision coupled with the types of particles collided coupled with the decay products produced might be much more important along with the scale at which such collisions occur then the simple energy of isolated events..

Events in nature such as neutron star collisions, super nova, black hole evaporations and the like may produce large effects that are quickly washed out or filtered or screened out of existence because of the possible smaller differential gradients of their effects on space time and mattergy relative to super intense quantum level, microscopic level, mesoscopic level, or small macroscopic level artificial events.. An analogous example is the greatly reduced tidal forces near the event horizon of a super massive black holes relative to that of a small black hole.

In neutron star collisions and supernova, perhaps the tendency of any such phase changes is washed out or is screened by intense gravity, intense mass energy concentration, or some sort of spatial temporal blunting or smoothing of such effects by large gravity fields and/or by the huge bulk of matter contained in the mass undergoing reaction.

Thanks;

Jim

James M. Essig June 29, 2008 at 0:35

Hi Folks;

Another possible but probably highly improbable, perhaps with probability approaching the level of 1/(infinity) per differential volumetric element of space-time on the Planck volume scale [i.e., of the cubic volumetric element of (10 EXP -35 m)x(10 EXP -35 m)x(10 EXP - 35)x(10 EXP -43 sec)], is the possibility that a Big Bang could form within our universe and not become decoupled from our universe in terms of causality and thermodynamic information exchange.

Such a new Big Bang might inflate within our universe with its mattergy and expanding space time being superposed and intermeshed with that of our Big Bang. This could have disastrous consequences for us especially if such a new Big Bang intrusion happened relatively locally, even if our universe extends to infinity spatially. At worst, the laws of physics and the fabric of space time and mattergy could be scrambled within our universe.

Even in cases where such a new Big Bang would happen in a relatively remote corner of our universe, the superposed mattergy and space-time might push our combined universe over the critical density of omega = unity and thus perhaps resulting in an eventual collapse of our universe.

Another consideration involves the concept of random thermodynamic concentration of mattergy that could occur in one local region of the universe based on statistical probability by which the energy would become so concentrated within a galaxy, or even a whole entire light cone region within our universe in such a manner that all life, planets, stars, traveling space craft therein would be fried out of existence. The concept is similar to the old argument that given enough time, the water on the bottom of a glass of water at STP would suddenly freeze to become ice while the water on top would blast away at the speed of a rifle bullet.

An even more radical version of this idea involve the extremely remote thermodynamic possibility that all of the atoms or most of the atoms within our universe, or at least our observable universe or any other light cone extending temporally the age of our universe, could suddenly decay such as by proton decay, thus releasing torrents of energy.

Thanks;

Jim

ljk July 1, 2008 at 13:33

A “Crib Sheet” for Supernova Events

Authors: D. Arnett

(Submitted on 26 Jun 2008)

Abstract: This paper summarizes our theoretical understanding of supernova events in a “back of the envelope” way. It is intended to aid in the recognition and understanding of those events which are not “standard”, and which may provide the most insight.

Comments: 6 pages, no figures, Conference Proceedings of 2008 meeting in Kolkata, India

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0806.4376v1 [astro-ph]

Submission history

From: David Arnett [view email]

[v1] Thu, 26 Jun 2008 19:33:39 GMT (23kb)

http://arxiv.org/abs/0806.4376

ljk July 3, 2008 at 23:38

NGC 2770 – a supernova Ib factory?

Authors: Christina C. Thoene, Michal J. Michalowski, Giorgos Leloudas, Nick L. J. Cox, Johan P. U. Fynbo, Jesper Sollerman, Jens Hjorth, Paul M. Vreeswijk

(Submitted on 3 Jul 2008)

Abstract: NGC 2770 has been the host of three supernovae of Type Ib during the last 10 years, SN 1999eh, SN 2007uy and SN 2008D. SN 2008D attracted special attention due to the serendipitous discovery of an associated X-ray transient.

In this paper, we study the properties of NGC 2770 and specifically the three SN sites to investigate whether this galaxy is in any way peculiar to cause a high frequency of SNe Ib. We model the global SED of the galaxy from broadband data and derive a star-formation and SN rate comparable to the values of the Milky Way. We further study the galaxy using longslit spectroscopy covering the major axis and the three SN sites.

From the spectroscopic study we find subsolar metallicities for the SN sites, a high extinction and a moderate star-formation rate. In a high resolution spectrum, we also detect diffuse interstellar bands in the line-of-sight towards SN 2008. A comparison of NGC 2770 to the global properties of a galaxy sample with high SN occurance (at least 3 SN in the last 100 years) suggests that NGC 2770 is not particularly destined to produce such an enhancement of observed SNe observed. Its properties are also very different from gamma-ray burst host galaxies. Statistical considerations on SN Ib detection rates give a probability of ~1.5% to find a galaxy with three Ib SNe detected in 10 years. The high number of rare Ib SNe in this galaxy is therefore likely to be a coincidence rather than special properties of the galaxy itself.

NGC 2770 has a small irregular companion, NGC 2770B, which is highly starforming, has a very low mass and one of the lowest metallicities detected in the nearby universe as derived from longslit spectroscopy. In the most metal poor part, we even detect Wolf-Rayet features, against the current models of WR stars which require high metallicities.

Comments: 15 pages, 10 figures, submitted to ApJ

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0807.0473v1 [astro-ph]

Submission history

From: Christina C. Th\”one [view email]

[v1] Thu, 3 Jul 2008 01:46:24 GMT (1988kb,D)

http://arxiv.org/abs/0807.0473

ljk July 7, 2008 at 23:25

Supernova VLBI

Authors: Norbert Bartel (York University)

(Submitted on 4 Jul 2008)

Abstract: We review VLBI observations of supernovae over the last quarter century and discuss the prospect of imaging future supernovae with space VLBI in the context of VSOP-2. From thousands of discovered supernovae, most of them at cosmological distances, ~50 have been detected at radio wavelengths, most of them in relatively nearby galaxies.

All of the radio supernovae are Type II or Ib/c, which originate from the explosion of massive progenitor stars. Of these, 12 were observed with VLBI and four of them, SN 1979C, SN 1986J, SN 1993J, and SN 1987A, could be imaged in detail, the former three with VLBI.

In addition, supernovae or young supernova remnants were discovered at radio wavelengths in highly dust-obscured galaxies, such as M82, Arp 299, and Arp 220, and some of them could also be imaged in detail. Four of the supernovae so far observed were sufficiently bright to be detectable with VSOP-2.

With VSOP-2 the expansion of supernovae can be monitored and investiated with unsurpassed angular resolution, starting as early as the time of the supernova’s transition from its opaque to transparent stage. Such studies can reveal, in a movie, the aftermath of a supernova explosion shortly after shock breakout.

Comments: Comments: 9 pages, 4 figure. Invited Review. To be published in “Approaching Micro-Arcsecond Resolution with VSOP-2: Astrophysics and Technology,” Astronomical Society of the Pacific Conference Series. Eds. Y. Hagiwara, E. Fomalont, M. Tsuboi, and Y. Murata

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0807.0791v1 [astro-ph]

Submission history

From: Norbert Bartel [view email]

[v1] Fri, 4 Jul 2008 16:48:54 GMT (350kb)

http://arxiv.org/abs/0807.0791

ljk November 13, 2008 at 0:12

Stellar mass ejections

Authors: M. Jardine, J.-F. Donati, S.G. Gregory

(Submitted on 12 Nov 2008)

Abstract: It has been known for some time now that rapidly-rotating solar-like stars possess the stellar equivalent of solar prominences. These may be three orders of magnitude more massive than their solar counterparts, and their ejection from the star may form a significant contribution to the loss of angular momentum and mass in the stellar wind. In addition, their number and distribution provide valuable clues as to the structure of the stellar corona and hence to the nature of magnetic activity in other stars.

Until recently, these “slingshot prominences” had only been observed in mature stars, but their recent detection in an extremely young star suggests that they may be more widespread than previously thought. In this review I will summarise our current understanding of these stellar prominences, their ejection from their stars and their role in elucidating the (sometimes very non-solar) behaviour of stellar magnetic fields.

Comments: 10 pages, 6 figures

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0811.1906v1 [astro-ph]

Submission history

From: Moira Jardine [view email]

[v1] Wed, 12 Nov 2008 14:33:28 GMT (340kb,D)

http://arxiv.org/abs/0811.1906

ljk February 23, 2009 at 18:12

http://arxivblog.com/?p=1239

First evidence of a supernova in an ice core

February 23, 2009 | by KFC |

There hasn’t been a decent supernova in our part of the universe in living memory but astronomers in the 11th century were a little more fortunate. In 1006 AD, they witnessed what is still thought to be the brightest supernova ever seen on Earth (SN 1006) and just 48 years later saw the birth of the Crab Nebula (SN 1054).

Our knowledge of these events come from numerous written accounts, mainly by Chinese and Arabic astronomers (and of course from the observations we can make today of the resultant nebulae).

Now we can go one better. A team of Japanese scientists has found the first evidence of supernovae in an ice core.

The gamma rays from nearby supernova ought to have a significant impact on our atmosphere, in particular by producing an excess of nitrogen oxide. This ought to have left its mark in the Earth’s ice history, so the team went looking for it in Antarctica.

The researchers took an ice core measuring 122 metres from Dome Fuji station, an inland site in Antarctica. At a depth of about 50 metres, corresponding to the 11th century, they found three nitrogen oxide spikes, two of which were 48 years apart and easily identifiable as belonging to SN 1006 and SN 1054. The cause of the third spike is not yet known.

That’s impressive result and their ice core was obligingly revealing about other major events in the Earth’s past. The team saw a 10 year variation in the background levels of nitrogen oxide, almost certainly caused by the 11-year solar cycle (an effect that has been seen before in ice cores). They also saw a number of sulphate spikes from known volcanic eruptions such as Taupo, New Zealand, in 180 AD and El Chichon, Mexico, in 1260 AD.

The team speculate that the mysterious third spike may have been caused by another supernova, visible only from the southern hemisphere or hidden behind a cloud.

That would make the 11th century a truly bounteous time for supernovae. Of course, statistically, there ought to be a supernova every 50 years or so in a galaxy the size of the Milky Way, which means that the Antarctic ice is due another shower of nitrogen oxide any day now.

Ref: http://arxiv.org/abs/0902.3446: An Antarctic Ice Core Recording both Supernovae and Solar Cycles

ljk March 19, 2009 at 23:50

Unsolved Problems about Supernovae

Authors: Nino Panagia (STScI – Inaf/CT – SN Ltd – Icranet)

(Submitted on 19 Mar 2009)

Abstract: A number of unsolved problems and open questions about the nature and the properties of supernovae are identified and briefly discussed. Some suggestions and directions toward possible solutions are also considered.

Comments: 7 pages, Proceedings of ‘Probing Stellar Populations out to the Distant Universe’, Cefalu, Italy, Sep 7-19, 2008, AIP Conf. Proc. Series

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Cosmology and Extragalactic Astrophysics (astro-ph.CO)

Cite as: arXiv:0903.3378v1 [astro-ph.SR]

Submission history

From: Nino Panagia [view email]

[v1] Thu, 19 Mar 2009 17:56:30 GMT (10kb)

http://arxiv.org/abs/0903.3378

ljk March 23, 2009 at 10:22

March 22, 2009

Star Exploded Too Early, May Blow Apart Supernova Theory

Written by Anne Minard

Ground-based Image of NGC 266 with Sn 2005gl. Credit: Puckett Observatory
NASA’s Hubble Space Telescope has identified a star a million times brighter than the sun that exploded as a supernova in 2005 — well before it should have, according to current theories of stellar evolution.

The doomed star, estimated at about 100 times our sun’s mass, was not mature enough, according to theory, to have evolved a massive iron core of nuclear fusion ash. This is the supposed prerequisite for a core implosion that triggers a supernova blast.

“This might mean that we are fundamentally wrong about the evolution of massive stars, and that theories need revising,” says Avishay Gal-Yam of the Weizmann Institute of Science, in Rehovot, Israel. The finding appears in the online version of Nature Magazine.

The explosion, called supernova SN 2005gl, was seen in the barred-spiral galaxy NGC 266 on October 5, 2005. NGC 266 is about 200 million light years away, in the constellation Pisces.

Full article here:

http://www.universetoday.com/2009/03/22/star-exploded-too-early-may-blow-apart-supernova-theory/

ljk March 24, 2009 at 7:34

The Origin Of Supernovae Confirmed

Copenhagen, Denmark (SPX) Mar 24, 2009 – Where do supernovae come from?

Astronomers have long believed they were exploding stars, but by analysing a series of images, researchers from the Dark Cosmology Centre at the Niels Bohr Institute, University of Copenhagen and from Queens University, Belfast have proven that two dying red supergiant stars produced supernovae. The results are published in the prestigious scientific journal, Science … more

http://www.spacedaily.com/reports/The_Origin_Of_Supernovae_Confirmed_999.html

ljk August 18, 2009 at 11:28

A Stellar Flare during the Transit of the Extrasolar Planet OGLE-TR-10b

Authors: Samuel Bentley, Coel Hellier, Pierre Maxted, Vik Dhillon, Tom Marsh, Chris Copperwheat, Stuart Littlefair

(Submitted on 17 Aug 2009)

Abstract: We report a stellar flare occurring during a transit of the exoplanet OGLE-TR-10b, an event not previously reported in the literature. This reduces the observed transit depth, particularly in the u’-band, but flaring could also be significant in other bands and could lead to incorrect planetary parameters.

We suggest that OGLE-TR-10a is an active planet-hosting star and has an unusually high X-ray luminosity.

Comments: 3 pages, 1 figure

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

Cite as: arXiv:0908.2329v1 [astro-ph.EP]

Submission history

From: Samuel Bentley B.Sc. M.Sc [view email]

[v1] Mon, 17 Aug 2009 11:25:53 GMT (23kb)

http://arxiv.org/abs/0908.2329

ljk August 20, 2009 at 22:06

The Early Asymmetries of Supernova 2008D / XRF 080109

Authors: J.R. Maund, J.C. Wheeler, D.Baade, F. Patat, P.A. Hoflich, L. Wang, A. Clocchiatti

(Submitted on 20 Aug 2009)

Abstract: Spectropolarimetry of the Type Ib SN 2008D, associated with the XRF 080109, at two separate epochs, are presented. The epochs of these observations correspond to V-band light curve maximum and 15 days after light curve maximum (or 21 and 36 days after the XRF).

We find SN 2008D to be significantly polarized, although the largest contribution is due to the interstellar polarization component of Q_ISP=0+/-0.1% and U_ISP=-1.2+/-0.1%. At the two epochs, the spectropolarimetry of SN 2008D is classified as being D1+L(HeI)+L(Ca II). The intrinsic polarization of continuum wavelength regions is <0.4%, at both epochs, implying an asymmetry of the photosphere of <10%.

Similar to other Type Ibc SNe, such as 2005bf, 2006aj and 2007gr, we observed significant polarization corresponding to the spectral features of Ca II, He I, Mg I, Fe II and, possibly, O I 7774, about a close-to-spherically-symmetric photosphere.

We introduce a new plot showing the chemically distinct line forming regions in the ejecta and comment on the apparent ubiquity of highly polarized high-velocity Ca II features in Type Ibc SNe. The polarization angle of Ca II IR triplet was significantly different, at both epochs, to those of the other species, suggesting high-velocity Ca II forms in a separate part of the ejecta.

The apparent structure in the outer layers of SN 2008D has implications for the interpretation of the early-time X-ray emission associated with shock break-out. (abridged)

Comments: ApJ Subm., 45 pages, 13 figures

Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

Cite as: arXiv:0908.2841v1 [astro-ph.SR]

Submission history

From: Justyn Maund [view email]

[v1] Thu, 20 Aug 2009 01:23:39 GMT (1011kb)

http://arxiv.org/abs/0908.2841

ljk October 4, 2009 at 23:11

Foundations of Supernova Cosmology

Authors: Robert P. Kirshner

Submitted on 1 Oct 2009)

Abstract: This is a brief sketch of the use of supernovae to measure cosmological parameters. It traces the early work, the events surrounding the discovery and verification of cosmic acceleration using SN Ia, and the efforts today to make sound inferences about the nature of dark energy.

The prospects for minimizing systematics by using near-infrared observations in the supernova restframe are emphasized. This could be an important point in the design of a JDEM that employs supernovae to measure the history of cosmic expansion.

Comments: A chapter contributed to “Dark energy– observational and theoretical approaches” edited by Pilar Ruiz-Lapuente (ISBN-13: 9780521518888) available in March 2010 from Cambridge University Press

Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO)

Cite as: arXiv:0910.0257v1 [astro-ph.CO]

Submission history

From: Robert Kirshner [view email]

[v1] Thu, 1 Oct 2009 20:06:29 GMT (292kb)

http://arxiv.org/abs/0910.0257

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