BOW TIE IN THE SKY: The rapidly expanding shell of V445 Puppis marks a violent explosion that likely arose from a white dwarf accreting material from a nearby helium star. The image above shows the ejected shell from the nova as it appeared in 2005.
Image: ESO/P.A. Woudt
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A stellar explosion known as a nova that was detected in 2000 formed a two-lobed shell of material ejected from the star. Shaped like a bow tie, it continues to swell at great velocity. But, curiously, the coat of ejecta flowing outward from the star lacks hydrogen, the most common gas in the universe.
Such a nova had never been observed before, says Danny Steeghs, an astrophysicist at the University of Warwick in England. The object, known as V445 Puppis, is known as a helium nova after the gas that dominates its makeup in the absence of hydrogen.
Helium novae are thought to arise from a binary star system in which one member is a hydrogen-depleted star, which relies mostly on helium to generate light, and one is a white dwarf, an ultradense remnant of an exhausted star. The white dwarf steadily accretes helium from its neighbor until it reaches a density and temperature sufficient to trigger a nuclear explosion. If the white dwarf grows large enough to exceed the critical so-called Chandrasekhar limit—roughly 1.4 times the mass of the sun—it will ignite in a catastrophic nuclear blast known as a type Ia supernova. But if the explosion is localized to a compressed shell of accreted helium on a somewhat smaller white dwarf, a helium nova is the result, and the dwarf survives. Such novae had been predicted to occur but had never been seen before the 2000 V445 Puppis detonation.
In the November 20 issue of the Astrophysical Journal, Steeghs and his colleagues, led by astronomer Patrick Woudt of the University of Cape Town in South Africa, describe the rapidly expanding shell of the helium nova V445 Puppis and what it indicates about the progenitor system. Drawing on years of ground-based observations, Steeghs and his co-authors estimate that V445 Puppis is some 27,000 light-years distant. The lobes of the shell, the authors conclude from their campaign, are moving at more than 6,000 kilometers per second, with knots at the end of each lobe zooming outward even faster.
One consideration making helium novae more than just an astronomical curiosity is the suggestion that they might serve to explain anomalously young binary star systems that yield type Ia supernovae. That class of explosions is hotly studied, because as so-called standard candles, type Ia supernovae form the basis of cosmological distance measurements, although their underlying mechanisms are not well understood.
The white dwarf in V445 Puppis has been estimated to be close to the 1.4–solar mass limit, the point at which a white dwarf is thought to explode in a type Ia supernova. So assuming the white dwarf continues to feed on its helium-rich neighbor, and that it did not eject too much mass in the nova outburst, it might one day become a type Ia. "While we can't guarantee it, all the ingredients are there in the V445 Puppis system," Steeghs says. "You are basically loading up a white dwarf in this binary system, and it's receiving material at a rather large rate from this helium star."
University of Oklahoma astrophysicist David Branch calls the observations of the nova "exquisite" but stops short of calling the binary a compelling candidate for a type Ia precursor. The rate of mass transfer in the system is unclear, so it is not known how the binary will evolve. But the new study provides "significant observational support" for the model in which a helium star, bound in an orbital pair with a white dwarf, could indeed lend the compact white dwarf enough matter to initiate an explosion.
If V445 Puppis is on the path to supernova, just how long that path will be is an open question, Steeghs acknowledges. The problem in solidly pinning down the system's future is that astronomers have yet to take a clear look into the heart of the nova, where its stellar progenitors reside. The stars remain clouded by a haze of obscuring dust. "We need to wait for that to become visible when the shell thins," Steeghs says. "If we knew the mass of the white dwarf and the mass of the star next to it, and its orbital period, then we could sort of forward calculate how long it would take in that configuration to explode. But at this point we don't know that number."
It may be a few years yet before the binary system in V445 Puppis becomes visible. Ordinary novae containing hydrogen usually open up to view in a year or two, Steeghs notes. "It's been nine years, and we still can't see the binary whatsoever," he says. "Because it's the first time we've seen a helium nova, there is no real benchmark. I guess we should maybe not be surprised that we don't quite know how long it will take and what it's doing."
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Add CommentWith science wrong, and no binary system as the supernova, slip in a 1 ¼ size star. The first sign of trouble would be the heliosphere losing energy from its N/S pole’s Coronal Axis. The axis normally reaches out to define the heliosphere of vibrating, Standing Magnetic Waves (SMW) filled with solar wind pos. protons. That material, and vibrating effects combination, created a force field sphere; with a bright gas ribbon around the interior equatorial circle; from the energy depleted system of galaxy-like arms interactions with the energy direct from the radiative zone’s fusion reactors. Each of the 16 arms had received induced on/off electromagnetic (EM) energy from its one of 16 swirls of ionized plasma dynamo’s, upper central surface’s SMW induction zone: SMW are likely created of helium by pulsing energy forcing electrons away.
Reply | Report Abuse | Link to thisThe wrapping around the star; electromagnetic field lines (EM-FL); in ever increasing size spiraled arms; had been suppositioned as Interplanetary Magnetic Fields (IMF). Being an AC-EM energy, then their magnetic surround would have been little with not much proton mass being attached and visible: But, there would have been enough induced energy to alter neutrinos flavor.
Our star’s dynamos are seen in NG mag, July 2004 P 19. The equatorial belt rolls across the dynamos, while the dynamos roll across the helium tachocline. The 3 items resemble a roller bearing, with tachocline as inner race, the belt as outer race and dynamos as rollers. From the rollers, 16 EM-FL rise up and back to left to exit to corona and back to opposed di-polarity dynamo end. That is because the belt drags the 16 dynamos as a unit to advance around the star, but the convection zone EM-FL, hold the works from rotating with the belt. Spicule’s bases are the small cyclonic storms at high latitudes.
When the core’s hydrogen is depleted, and with no reactor effluent being produced, the helium tachocline collapses, which drops the rotating dynamos of proton/electron mix to merge with the heavier helium. At the same time the heliosphere loses its fusion reaction energy, and begins to draw back, dragging any planets along towards the central mass until the sudden stop increases material’s pressure and temperature.
As there is much helium to be fed pulses of created fusion reaction energy; then the helium’s electrons would vibrate and flee away from the atom’s other particals, and continue to do that as long as the laser-like pulses continue to affect the helium. That effect is called, ‘Ponderomotive Force.’ So, looking at the two lobes, it is conceivable we look from the side of V’s, open circles, or of U’s of helium; minus the forced away knots of electrons that are pressed away faster than helium atom’s other large massed particles; the more visible parts termed as lobes.
Possibly U. Eichmann and associates; whose letter to the Journal Nature of Vol. 461- 29 Oct. 2009 on P. 1261, could explain what occurs to helium when pulsations of an energy; much stronger than the laser they used against a helium atom; are presented.
eddierleram -- so ... It's all good then?
Reply | Report Abuse | Link to thisI'm just sayin'
'cause the Real Housewife audition couple got INTO the White House Dinner.
Most definately it is, Monsieur Quinn the Eskimo, because so far the event hasn't destroyed your possible reception moment at the White House Dinner Party. Would that you arrived there, would you wear the traditional Furs, or the green and gold of the Edmonton Eskimoe's branch?
Reply | Report Abuse | Link to thisEddie R. The Ancient One