Asteroid sprouts comet-like tail

[JohnD]

Asteroid 6478 Gault has sprouted a tail.
https://www.lagranepoca.com/news/423844 ... 00-km.html

It is suggested that this is the result of a collision with another body out there.

But why a 'tail'? And not a cloud of debris around it? Same mechanism as a comet's tail, solar wind?

JOhn

[BDanielMayfield]

Perhaps a geyser(s) has(have) erupted. The collision provided heat and broke the surface open so that no longer trapped gasses are released. The tail is streaming out due to the solar wind, as you asked. The particles are small enough to be swept away, but larger debris might still be surrounding the 'roid.

That's my story, at least until someone corrects it.

Bruce

See next comment for correction on solar radiation as opposed to solar wind producing the tail.

[Chris Peterson]

Asteroid 6478 Gault has sprouted a tail.
https://www.lagranepoca.com/news/423844 ... 00-km.html

It is suggested that this is the result of a collision with another body out there.

But why a 'tail'? And not a cloud of debris around it? Same mechanism as a comet's tail, solar wind?

Not the solar wind. Radiation pressure is what creates a dust tail, whether from comets where the dust is released by evaporating gas, or in an asteroid collision, where it is released by the energy of the collision itself. Either way, we're talking very small particles- mostly in the micrometer range, not unlike smoke. A long, thin tail is indicative of a narrow range of particle sizes. A broad tail suggest a wider range of particle sizes. A collision probably creates a lot of fine dust, whereas a comet is simply releasing material of different sizes. That's why collisions appear to produce narrower tails (I know of at least one other asteroid collision, which also produced a long skinny tail). If we could aim Hubble at it we might see more complex debris patterns at the head, but with Hubble damaged and the shutdown preventing its repair, that may not happen.

[Ann]

Asteroid 6478 Gault has sprouted a tail.
https://www.lagranepoca.com/news/423844 ... 00-km.html

It is suggested that this is the result of a collision with another body out there.

But why a 'tail'? And not a cloud of debris around it? Same mechanism as a comet's tail, solar wind?

Not the solar wind. Radiation pressure is what creates a dust tail, whether from comets where the dust is released by evaporating gas, or in an asteroid collision, where it is released by the energy of the collision itself. Either way, we're talking very small particles- mostly in the micrometer range, not unlike smoke. A long, thin tail is indicative of a narrow range of particle sizes. A broad tail suggest a wider range of particle sizes. A collision probably creates a lot of fine dust, whereas a comet is simply releasing material of different sizes. That's why collisions appear to produce narrower tails (I know of at least one other asteroid collision, which also produced a long skinny tail). If we could aim Hubble at it we might see more complex debris patterns at the head, but with Hubble damaged and the shutdown preventing its repair, that may not happen.

Sorry. How does radiation pressure differ from the solar wind?

Ann

[JohnD]

Thanks, Chris!
John

[Chris Peterson]

Not the solar wind. Radiation pressure is what creates a dust tail, whether from comets where the dust is released by evaporating gas, or in an asteroid collision, where it is released by the energy of the collision itself. Either way, we're talking very small particles- mostly in the micrometer range, not unlike smoke. A long, thin tail is indicative of a narrow range of particle sizes. A broad tail suggest a wider range of particle sizes. A collision probably creates a lot of fine dust, whereas a comet is simply releasing material of different sizes. That's why collisions appear to produce narrower tails (I know of at least one other asteroid collision, which also produced a long skinny tail). If we could aim Hubble at it we might see more complex debris patterns at the head, but with Hubble damaged and the shutdown preventing its repair, that may not happen.

Sorry. How does radiation pressure differ from the solar wind?

Radiation pressure is caused by light- the transfer of momentum from photons to particles of matter. The solar wind consists of charged particles ejected from the corona.

Radiation pressure pushes around dust from comets and influences the rotation of small bodies. The solar wind directs the ion tail of comets and creates the auroras.

[neufer]

John Gault encased postage stamp

---

<<6478 Gault, provisional designation 1988 JC1, is a Phocaea (foh-SEE-ə) asteroid from the inner regions of the asteroid belt, approximately 3.7 kilometers in diameter. The body's rotation period, pole and shape remain unknown. In October 2018, it was possibly impacted by an unidentified more than 500-meter-sized asteroid, causing it to become a main-belt comet with a tail. The likely S-type asteroid was discovered on 12 May 1988, by astronomer couple Carolyn and Eugene Shoemaker at the Palomar Observatory in California. It was named in memory of American planetary geologist Donald Gault (1923–1999), an expert in the field of impact crater forming processes. Gault conducted field experiments and applied his insight to the interpretation of impact data from the Moon, Earth, Mars and Mercury.

Gault is a core member of the Phocaea family. The large asteroid family consists of nearly 2,000 known stony asteroids, and was named after its largest member, 25 Phocaea. The old family formed up to 2.2 billion years ago and has the highest inclination of all families in the inner asteroid belt. Several of its members are also Mars-crossing asteroids with high eccentricities. The Phocaea family region contains other collisional families such as the recently identified carbonaceous, Tamara family, named after its potentially largest member 326 Tamara. The family has an estimated age of 264 million years.

Gault orbits the Sun at a distance of 1.9–2.8 AU once every 3 years and 6 months. Its orbit has an eccentricity of 0.19 and an inclination of 23° with respect to the ecliptic. The body's observation arc begins with its official discovery observation at Palomar in May 1988. In January 2019, it was discovered, that Gault possesses a comet tail, which had not been present in previous images. There is evidence that the asteroid became active in November 2018, and that material had been ejected from its surface, and that a collision or impact is responsible for its tail.>>

[JohnD]

Even this Limey can recognise Benjamin Franklin, and a little googling finds that there were two John Gaults, almost exactly 100 years apart!
The first, earlier Gault tried to exploit Civil War currency inflation by encasing stamps in buttons, in a way that doubled his profits by advertising!
http://cliffhoyt.com/encased_postage.htm


Tiny bit off subject, but anyway.
John

[bystander]

... If we could aim Hubble at it we might see more complex debris patterns at the head, but with Hubble damaged and the shutdown preventing its repair, that may not happen.

Hubble's Wide Field Camera 3 Recovered and Collecting Science
NASA | GSFC | Hubble | WFC3 | 2019 Jan 17

[JohnD]

Good news, bystander!
If the wide field camera isn't the right instrument for something as close as this, does Hubble carry something better?
John

[Chris Peterson]

... If we could aim Hubble at it we might see more complex debris patterns at the head, but with Hubble damaged and the shutdown preventing its repair, that may not happen.

Hubble's Wide Field Camera 3 Recovered and Collecting Science
NASA | GSFC | Hubble | WFC3 | 2019 Jan 17

That's great. Most of those guys aren't allowed to work, but they're also about 100 times smarter than the people they work for and who administer the rules. I'll bet they manage to work around the administrators.