Podcaster: Richard Drumm
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Title: UNAWE Space Scoop – Magnetars Origin Story
Organization: 365 Days Of Astronomy
Link : http://365daysofastronomy.org/ ; https://spacescoop.org/en/scoops/2320/magnetars-origin-story/
Description: Space scoop, news for children.
Far far away, in the constellation Monoceros, the unicorn, 3,000 light years away from us to be more exact, is an unusual star known as HD 45166. Which is preparing to become the most magnetic powerhouse known to exist in the Universe, a magnetar!
Magnetars are a type of neutron star that holds the record of the object with the strongest magnetic field in the cosmos. For a star to become a magnetar, astronomers initially thought that it had to be really massive.
As it turns out, not quite so much, actually.
Bio: Richard Drumm is President of the Charlottesville Astronomical Society and President of 3D – Drumm Digital Design, a video production company with clients such as Kodak, Xerox and GlaxoSmithKline Pharmaceuticals. He was an observer with the UVa Parallax Program at McCormick Observatory in 1981 & 1982. He has found that his greatest passion in life is public outreach astronomy and he pursues it at every opportunity.
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Transcript:
This is the 365 Days of Astronomy Podcast. Today we bring you a new episode in our Space Scoop series. This show is produced in collaboration with Universe Awareness, a program that strives to inspire every child with our wonderful cosmos.
Today’s story is…. Magnetars Origin Story
Far far away, in the constellation Monoceros, the unicorn, 3,000 light years away from us to be more exact, is an unusual star known as HD 45166.
Which is preparing to become the most magnetic powerhouse known to exist in the Universe, a magnetar!
Magnetars are a type of neutron star that holds the record of the object with the strongest magnetic field in the cosmos.
For a star to become a magnetar, astronomers initially thought that it had to be really massive.
As it turns out, not quite so much, actually.
Scientists have been studying 45166 for more than a century.
Little is known about the true nature of this star other than the fact that it’s rich in Helium, it’s more massive than our Sun and it’s part of a binary system.
Using several telescopes, including the CFHT, the Canada-France-Hawai‘i Telescope, on Mauna Kea, a team of international researchers began to look deeper into the ‘strangeness’ of 45166.
Its features are strikingly similar to that of a Wolf-Rayet star, but 45166 has a different spectral signature altogether.
Astronomers became super curious and began to investigate the reason behind the unusual nature of this star.
Well, it turns out 45166 is magnetic.
Tons of new data on the star were obtained when it was observed with a number of instruments at various observatories.
Such as:
– The “Echelle SpectroPolarimetric Device for the Observation of Stars” or ESPaDOnS spectropolarimeter at the 3.58 meter CFHT on Mauna Kea in Hawaii.
– The HERMES spectrograph on the 1.2 meter Mercator telescope at Observatorio del Roque de Los Muchachos on La Palma in the Canary Islands.
– The Fiber-fed Extended Range Optical Spectrograph, or FEROS, at the 1.52 meter telescope of the ESO’s La Silla Observatory in Chile.
– The Coudé spectrograph at the 1.6 m telescope of the Pico dos Dias Observatory of the LNA, the Laboratorio Nacional de Astrofisica in Brazil.
All these observations showed it has strong circular polarization and magnetic line splitting which indicates it has a powerful magnetic field, about 43,000 gauss.
Our Sun has a magnetic field of about 1 gauss.
This makes 45166 the most powerful ever found in a massive star that isn’t already a magnetar.
The astronomers think that this star is a massive magnetic helium star and its magnetic field is strong enough for it to leave a magnetar remnant when it goes supernova.
A few million years or so from now, HD 45166 will explode as a bright supernova.
Its core will shrink and trap all the star’s powerful magnetic field lines, creating a highly magnetic neutron star, a magnetar.
It’s current 43,000 gauss magnetic field will bloom to 100 trillion gauss!
Using archival data from La Silla Observatory, the team also measured 45166’s exact age and mass.
Massive helium stars are thought to be stripped products of massive stars that lost their hydrogen-rich envelopes through stellar winds, eruptions, or interactions with a binary companion.
The study’s authors exclude those possibilities, however.
They write:
“We exclude the possibly that it is the stripped descendant of a massive star, because to produce a 2 solar-mass stripped core, the progenitor star would need to have had an initial mass of approximately 10 solar masses.
Single-star evolution models do not predict that stars of that mass strip themselves, and the B7 V companion is too far away for binary interactions to have stripped it.
In addition, the total lifetime (including post main-sequence evolution) of a 10 solar mass star would be about 30 million years, well below the derived age of the B7 V component (105 ± 35 million years), so we reject the possibility that they could both be present in the same binary system.”
Another alternative is that massive helium stars may be produced through the merger of lower-mass objects.
This merger option is the one the team has settled on as the origin story of this magnetar progenitor.
The new research sheds light on how these magnetic powerhouses form and how, unlike previously thought, much less massive stars can also become magnetars under the right conditions.
Hey, here’s a cool fact!
Wolf-Rayet or WR stars are rare and have surfaces that have lots of helium and heavy elements like carbon, nitrogen and oxygen but very little hydrogen.
You see, they have run out of hydrogen and are fusing helium into those heavier elements.
They’re super bright, with thousands to millions of times our Sun’s brightness but most of this brightness is UV or ultra violet light.
About 500 WR stars have been found in the Milky Way, but with at least 100 billion stars in the galaxy, WR stars represent at most .0000005% of the galaxy’s stars.
Yeah, rare!
The long-term prognosis for a WR star is a core collapse type Ib or Ic supernova.
BOOM!
Thank you for listening to the 365 Days of Astronomy Podcast!
End of podcast:
365 Days of Astronomy
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