@UCBerkeley’s NaSt1 Star – How a Wolf-­Rayet Stars may be Binary System Future Past Private Nebulae X-Ray-ted Lambada

“We were excited to see this disk­like structure because it may be evidence for a Wolf­Rayet Star forming from a binary interaction. There are very few examples in the galaxy of this process in action because this phase is short­lived, perhaps lasting only a hundred thousand years, while the timescale over which a resulting disk is visible could be only ten thousand years or less”

Study leader Dr. Jon Mauerhan of the University of California, Berkeley whose team observed NaSt1 using the Hubble Space Telescope

NASA (National Aeronautical Space Administration) Hubble Space Telescope is still full of surprises.

NASA (National Aeronautical Space Administration) is celebrating the 25^th Anniversary of the Hubble Space Telescope as reported in the article “Celebrate With NASA as Agency Commemorates Hubble Space Telescope’s 25th Anniversary”, published April 16, 2015, NASA.

Even at 25, the Hubble Space Telescope is still making discoveries that make us question the origin of some of the strangest anomalies in the Universe as noted in the article “The Hubble Space Telescope: A 25th Anniversary Photo Celebration”, published April 20, 2015 07:15am ET By Space.com Staff , Space.

One of these anomalies is the Star NaSt1, otherwise nicknamed Nasty 1, as reported in the article “Hubble observes one­of­a­kind Star nicknamed 'Nasty'”, published May 21, 2015 by Ray Villard, Physorg. This stellar anomaly is shedding new insight into the formation of Wolf­Rayet Stars, all thanks to the Hubble Space Telescope.

This new insight is based on the work of a team led by Dr. Jon Mauerhan and his fellow astronomers at the University of California, Berkeley. Their work is currently published in the Monthly Notices of the Royal Astronomical Society since Thursday May 21^st 2015.

So what makes this Nasty 1 Star so exciting? It may provide insights into the formation of one of the most enigmatic objects in the universe, that being the Wolf­Rayet Stars.

NaSt1 the Wolf­-Rayet Star – Origins of Nebulae may be a Future Past

Discovered by Jason Nassau and Charles Stephenson back in 1963, NaSt1, located some 3000 Light Years from Earth, gets its name from the concatenation of the first letters of the surnames of the co-discoverers.

They identified it as a Wolf­Rayet Star, a type of Star that tends to be much larger than our Sun but with a very short lifespan. Wolf–Rayet stars have an abundance of Helium, Nitrogen, Carbon, Silicon and Oxygen, all of which are unsuitable for Nuclear Fusion and indicate a star that has spend most of its Hydrogen.

This is based on the missing spectra from Spectroscopy analysis of the emission from these heavenly bodies, the telltale sign that the star is a Wolf-Rayet star!.

Because of its massive size, its life is short lived, dying as it supposedly runs out of hydrogen, causing the outer layers of hydrogen to be ejected, leaving behind the shimmering embers of its helium rich core.

Until now scientists have not been sure how these exotic Wolf­Rayet Stars, particularly what causes it to lose so much mass in the first place. This is where studying the Nasty 1, as it’s remarkably similar to another possible Wolf­Rayet Star called Eta Carinae.

NaSt1 has two (2) gas jets emanating from opposite sides of the Star, like a pulsar only not rotating at all. Instead, inspection by the Hubble Space Telescope team at the University of California revealed nebulae of gas in a disc shape nearly 2 trillion miles wide. This is completely different from most Wolf­Rayet Stars, which makes it rather interesting to study.

So how did that particular Wolf­Rayet Star end up with such a huge nebulae so quickly? Maybe the Star had a dancing partner!

University of California’s NaSt1 Star – How a Wolf­Rayet Stars forms from Binary Star Private Nebulae Dancer

The Team from the University of California knew that typically, a Wolf­Rayet Star were once super-massive Stars, which are usually unstable and fast-burning, deplete their Hydrogen close to their central core.

But rather than collapse under the weight or its outer core and rebound outward, causing a Super Nova, it begins to eject its outer layer via a series of violent eruptions from within the Star. These eruptions create jets of charged particles, called a stellar wind, that stream outwards from the center of the Star, carrying away the outer layers as it streams outwards.

However, Direct-mass ejection as this is called, cannot sufficiently explain the presence of the huge and widely dispersed 1 trillion mile wide nebulae surrounding NaSt1 or the number of Wolf­Rayet Stars that have already been confirmed. Thus a more plausible theory has been proposed that accounts for this particular anomaly as well as a suspected 70% of all other Wolf­Rayet Stars.

The new model, which the Team from the University of California has formulated, suggests that the Star once hands a binary partner. As it began to transition toward becoming a Wold-Rayet Star in the usual manner, this other companion Star began to feed on the ejected outer layers of NaSt1.

These outer layers, now very loosely bound, would be pulled apart from the Star by its binary partner in a Gravitational stripping process similar to stripping off the outer layers of an onion.

Co-author of the NaSt1 paper Dr. Nathan Smith of the University of Arizona in Tucson, supports this hypothesis, quote: “We're finding that it is hard to form all the Wolf­Rayet stars we observe by the traditional wind mechanism, because mass loss isn't as strong as we used to think. Mass exchange in binary systems seems to be vital to account for Wolf­Rayet stars and the supernovae they make, and catching binary stars in this short­lived phase will help us understand this process”.

The result is that the binary partner begins to get bigger while NaSt1 gets smaller, rapidly stripped off its outer more loosely-bound hydrogen layers until only the naked Helium core is left. In so doing, it becomes a Wolf­Rayet Star and many Astronomers agree that this hypothesis is a more likely explanation for the prevalence of this type of Star.

Like a baby eating too much food at once, the companion Binary Star doesn’t eat everything that it strips from its dying companion. Instead, that excess hydrogen gas may linger about the two Stars and Start swirling outwards, encircling them both in thick hazy nebulae.

Observations using the Hubble Telescope as well as from previous observations indicate that the gas in the outer part of the nebulae is moving at a rate of 22,000 miles per hour. This is a lot slower than the gas in the nebulae swirling about Eta Carinae, another Wolf-Rayet Candidate. .

It’s nebula gas cloud is clocking speeds n the thousands of miles per hour, suggesting a less violent event created the nebula for NaSt1 and thus making the binary companion theory more plausible.

There may be another star orbiting NaSt1, a binary companion that making the surrounding environment nasty with remnant from stripping away its outer core.

NaSt1 feeding a Binary Baby Star – Figure Skater draws her arms inwards in X-Ray-ted Lambada

Through observations made by Dr. Mauerhan at the University of California and colleagues at the University of Arizona using the Magellan telescope at Las Campanas Observatory in Chile, they've come to realize that a recently formed large pocket of dust and gas may be obscuring the light of the binary Stars within the nebulae.

This large pocket of dust and gas is still hot after thousands of years, suggesting that it was formed recently, possibly while Humans were on Earth. Dr. Jon Mauerhan believes that Nasty 1 is a Wolf­Rayet star in sheep's clothing, quote: “That's what we think is happening in Nasty 1. We think there is a Wolf­Rayet star buried inside the nebula, and we think the nebula is being created by this mass­transfer process. So this type of sloppy stellar cannibalism actually makes Nasty 1 a rather fitting nickname”.

This large pocket of dust and gas is obscuring our view of the two (2) Stars locked in their dance to the death, with the stellar winds mixing things up a bit, leaving the dust and gas shaken but not stirred.

Thus the clumps and knots in the nebulae disc and the gaps in-between may be due to the sporadic changes in the stellar wind. These observations provides more evidence of a companion Star's gravitational tug and thus suggesting that the mechanism of the formation of the Wolf­Rayet Star NaSt1.

Realizing that they needed a clearer picture of what is going on inside of the gaseous envelope, the Team from the University of California had enlisted the help of NASA's Chandra X-ray Observatory.

Scorching hot plasma jets, the same pair observed coming from both ends of the NaSt1, seem to be colliding with plasma jets from the companion Star. As the gas stripped from NaSt1 begins to swirl around the companion Star, it accelerates, creating friction between itself and the surface of the companion Star.

Like a figure skater pulling in her hands, the gas coming closer accelerates the rate of spin of the swirling gas and thus the friction between the gas and the Star causes a gas to rebound off the surface. This rebounding of gas createws shock-waves on the surface of NaSt1 and is also accompanied by bursts of radiation in the X-Ray spectrum.

Dr. Jon Mauerhan is clearly excited about what the future holds as it relates to this chance of observing this rare event, quote: “What evolutionary path the star will take is uncertain, but it will definitely not be boring. Nasty 1 could evolve into another Eta Carinae­type system. To make that transformation, the mass­gaining companion star could experience a giant eruption because of some instability related to the acquiring of matter from the newly formed Wolf­Rayet”.

The super-nova even, interestingly, is still on the cards.

So too is a merger with the companion star, if it is massive enough, to quote Dr. Mauerhan: “Or, the Wolf­Rayet could explode as a supernova. A stellar merger is another potential outcome, depending on the orbital evolution of the system. The future could be full of all kinds of exotic possibilities depending on whether it blows up or how long the mass transfer occurs, and how long it lives after the mass transfer ceases”.

This observation is consistent with other known Wolf-Rayet Stars. As NaSt1 runs out of gas, the disk will dissipate, hopefully providing astronomers with a view of the binary dancers in their death like embrace sometime in the future.

Here’s the link:

Hubble Space Telescope YouTube Page