Astronomy Thread

[Flyaway]

Related to the news of a possible exoplanet around Alpha Centauri A.

http://www.eso.org/sci/publications/messenger/archive/no.169-sep17/messenger-no169-16-20.pdf

 

[Flyaway]

Solar System’s most distant known member confirmed

A team of astronomers, including Carnegie’s Scott Sheppard, David Tholen from the University of Hawaiʻi Institute for Astronomy, and Chad Trujillo from Northern Arizona University have discovered discovered the most distant object ever observed in our Solar System. Officially called 2018 AG37...

carnegiescience.edu

 

[FighterJock]

Solar System’s most distant known member confirmed

A team of astronomers, including Carnegie’s Scott Sheppard, David Tholen from the University of Hawaiʻi Institute for Astronomy, and Chad Trujillo from Northern Arizona University have discovered discovered the most distant object ever observed in our Solar System. Officially called 2018 AG37...

carnegiescience.edu

So despite this new discovery of Farfarout it looks like the hunt for the official ninth planet in the Solar System is still on going according to the article.

 

[Grey Havoc]

We already have nine planets; it's only for some pretty dubious reasons that currently only eight of them are recognised.


On another note, a short clip of the 2021 Valentine's Day meteor:

Meteor lights up Melbourne skies

The celestial spectacle occurred on Valentine's Day, during the city's five-day lockdown.

www.bbc.com

 

[Flyaway]

The first Australian evidence of a major shift in Earth's magnetic poles may help researchers predict the next

About 41,000 years ago, something remarkable happened: Earth's magnetic field flipped and, for a temporary period, magnetic north was south and magnetic south was north.

sciencex.com

 

[Flyaway]

Planet nine looks in a bad way as a theory.

No Evidence for Orbital Clustering in the Extreme Trans-Neptunian Objects

The apparent clustering in longitude of perihelion ϖ and ascending node Ω of extreme trans-Neptunian objects (ETNOs) has been attributed to the gravitational effects of an unseen 5-10 Earth-mass planet in the outer solar system. To investigate how selection bias may contribute to this clustering, we consider 14 ETNOs discovered by the Dark Energy Survey, the Outer Solar System Origins Survey, and the survey of Sheppard and Trujillo. Using each survey's published pointing history, depth, and TNO tracking selections, we calculate the joint probability that these objects are consistent with an underlying parent population with uniform distributions in ϖ and Ω. We find that the mean scaled longitude of perihelion and orbital poles of the detected ETNOs are consistent with a uniform population at a level between 17% and 94%, and thus conclude that this sample provides no evidence for angular clustering.

[2102.05601] No Evidence for Orbital Clustering in the Extreme Trans-Neptunian Objects

'Any evidence for Planet Nine is gone': Scientists dispute probability of mystery planet

Is there a hidden ninth planet far from the sun? New research pours cold water on the theory.

www.cnet.com

 

[Grey Havoc]

Long since time to bring back the real 'Planet Nine', methinks.

 

[Flyaway]

To see the counter argument follow this thread by one of the original proposers of the Planet Nine theory.

https://twitter.com/i/web/status/1360381088216936451

View: https://mobile.twitter.com/kbatygin/status/1360381088216936451

 

[Flyaway]

In this thread he explains further on the matter.

https://twitter.com/i/web/status/1360390787653980161

View: https://mobile.twitter.com/kbatygin/status/1360390787653980161

 

[Hobbes]

Long since time to bring back the real 'Planet Nine', methinks.

There is no definition (based in astronomy rather than tradition) in which the solar system has exactly 9 planets. It's either 8 or hundreds.

 

[Flyaway]

Detailed response to the Planet Nine paper posted above.

Is Planet Nine finally dead?

Konstantin and I have a recurring conversation. One of us says "Wait! I think we're wrong about the evidence for Planet Nine. Here's why......

findplanetnine.blogspot.com

 

[Grey Havoc]

Long since time to bring back the real 'Planet Nine', methinks.

There is no definition (based in astronomy rather than tradition) in which the solar system has exactly 9 planets. It's either 8 or hundreds.

Pluto was arguably demoted from planetary status solely because of a combination of rather dodgy science and even more toxic politics. Its later redesignation as a minor planet was an belated (and unsuccessful) attempt to mollify the critics of that move which only helped to illustrate just how wrong headed the IAU's original decision was.

 

[Nik]

I'd like a better estimate for mass / composition of tau Ceti 'f', which is currently Sin(i) due to uncertainties in the system's inclination.

Can't always be lucky and have an inner planet transiting to constrain the geometry...

 

[Flyaway]

https://twitter.com/i/web/status/1361754940121640962

View: https://twitter.com/plutokiller/status/1361754940121640962

 

[Flyaway]

Breakup of a long-period comet as the origin of the dinosaur extinction

The origin of the Chicxulub impactor, which is attributed as the cause of the K/T mass extinction event, is an unsolved puzzle. The background impact rates of main-belt asteroids and long-period comets have been previously dismissed as being too low to explain the Chicxulub impact event. Here, we show that a fraction of long-period comets are tidally disrupted after passing close to the Sun, each producing a collection of smaller fragments that cross the orbit of Earth. This population could increase the impact rate of long-period comets capable of producing Chicxulub impact events by an order of magnitude. This new rate would be consistent with the age of the Chicxulub impact crater, thereby providing a satisfactory explanation for the origin of the impactor. Our hypothesis explains the composition of the largest confirmed impact crater in Earth’s history as well as the largest one within the last million years. It predicts a larger proportion of impactors with carbonaceous chondritic compositions than would be expected from meteorite falls of main-belt asteroids.

Breakup of a long-period comet as the origin of the dinosaur extinction

The origin of the Chicxulub impactor, which is attributed as the cause of the K/T mass extinction event, is an unsolved puzzle. The background impact rates of main-belt asteroids and long-period comets have been previously dismissed as being too low to explain the Chicxulub impact event. Here...

www.nature.com

Other researchers did not agree with the new study's findings and still say several clues point to an asteroid creating the Chicxulub crater.
For one, Iridium -- along with a handful of other chemical elements -- was found scattered around the globe after the impact, said David Kring, principal scientist at the Lunar and Planetary Institute in Houston, who was not involved with the comet study.
Kring said the proportions of those elements are the same proportions seen in meteorite samples of asteroids.
The comet piece would have also been too small to make a crater of that size, said Natalia Artemieva, senior scientist at the Planetary Science Institute, who also was not involved in the study.
The study estimated the size of the comet piece to be about 4 miles wide, and Artemieva argued the comet would need to be at least 7.5 miles wide to make a crater the size of Chicxulub. With the small comet piece, she said, "it is absolutely impossible," and the crater size from the impact would be at least half the size.

Dinosaurs may have been killed off by a comet instead of an asteroid

Researchers theorized that a piece of a comet, rather than an asteroid, hit Earth and caused the extinction of many species 66 million years ago.

edition.cnn.com

 

[FighterJock]

Breakup of a long-period comet as the origin of the dinosaur extinction

The origin of the Chicxulub impactor, which is attributed as the cause of the K/T mass extinction event, is an unsolved puzzle. The background impact rates of main-belt asteroids and long-period comets have been previously dismissed as being too low to explain the Chicxulub impact event. Here, we show that a fraction of long-period comets are tidally disrupted after passing close to the Sun, each producing a collection of smaller fragments that cross the orbit of Earth. This population could increase the impact rate of long-period comets capable of producing Chicxulub impact events by an order of magnitude. This new rate would be consistent with the age of the Chicxulub impact crater, thereby providing a satisfactory explanation for the origin of the impactor. Our hypothesis explains the composition of the largest confirmed impact crater in Earth’s history as well as the largest one within the last million years. It predicts a larger proportion of impactors with carbonaceous chondritic compositions than would be expected from meteorite falls of main-belt asteroids.

Breakup of a long-period comet as the origin of the dinosaur extinction

The origin of the Chicxulub impactor, which is attributed as the cause of the K/T mass extinction event, is an unsolved puzzle. The background impact rates of main-belt asteroids and long-period comets have been previously dismissed as being too low to explain the Chicxulub impact event. Here...

www.nature.com

Other researchers did not agree with the new study's findings and still say several clues point to an asteroid creating the Chicxulub crater.
For one, Iridium -- along with a handful of other chemical elements -- was found scattered around the globe after the impact, said David Kring, principal scientist at the Lunar and Planetary Institute in Houston, who was not involved with the comet study.
Kring said the proportions of those elements are the same proportions seen in meteorite samples of asteroids.
The comet piece would have also been too small to make a crater of that size, said Natalia Artemieva, senior scientist at the Planetary Science Institute, who also was not involved in the study.
The study estimated the size of the comet piece to be about 4 miles wide, and Artemieva argued the comet would need to be at least 7.5 miles wide to make a crater the size of Chicxulub. With the small comet piece, she said, "it is absolutely impossible," and the crater size from the impact would be at least half the size.

Dinosaurs may have been killed off by a comet instead of an asteroid

Researchers theorized that a piece of a comet, rather than an asteroid, hit Earth and caused the extinction of many species 66 million years ago.

edition.cnn.com

I always had a suspicion that the dinosaurs were killed of by a comet instead of an asteroid.

 

[Flyaway]

Scientists see ‘bright flash’ as object smashes into Jupiter

Scientists have spotted an object smashing into Jupiter, leaving behind a bright flash.

www.google.co.uk

 

[Flyaway]

Great article on what Avi Loeb is actually trying to across with his recent book, and not what the press would have you believe he’s saying.

We are, as a matter of fact, taking the hypothesis of extraterrestrial life, even intelligent extraterrestrial life, more seriously now than ever before, and this is true not just among the general public but also within the community of working scientists. But I don’t see Avi Loeb saying anything that discounts that work. What I do see him saying in Extraterrestrial is that in the case of ‘Oumuamua, scientists are reluctant to consider a hypothesis of extraterrestrial technology even though it stands up to scrutiny — as a hypothesis — and offers as good an explanation as others I’ve seen. Well actually, better, because as Loeb says, it checks off more of the needed boxes.

Invariably, critics quote Sagan: “Extraordinary claims require extraordinary evidence.” Loeb is not overly impressed with the formulation, saying “evidence is evidence, no?” And he goes on: “I do believe that extraordinary conservatism keeps us extraordinarily ignorant. Put differently, the field doesn’t need more cautious detectives.” Fighting words, those. A solid rhetorical strategy, perhaps, but then caution is also baked into the scientific method, as well it should be. So let’s talk about caution and ‘Oumuamua.

Can we discuss this alien artifact hypothesis in a rational way? Loeb is not sure we can, at least in some venues, given the assumptions and accumulated inertia he sees plaguing the academic community. He describes pressure on young postdocs to choose career paths that will fit into accepted ideas. He asks whether what we might call the science ‘establishment’ is simply top-heavy, a victim of its own inertia, so that the safer course for new students is not to challenge older models.

Now we’re at the heart of the book, for as we’ve seen, Extraterrestrial is less about ‘Oumuamua itself and more about how we do science, and what the author sees as a too conservative approach that is fed by the demands of making a career. He’s compelled to ask: Shouldn’t the possibility of ‘Oumuamua being an extraterrestrial artifact, a technological object, be a bit less controversial than it appears to be, given the growth in our knowledge in recent decades?

Isn’t communicating ideas part of the job description of anyone employed to do scientific research? So much of that research is funded by the public through their tax dollars, after all. If Loeb’s prickly book is forcing some scientists to take the time to explain why they think his hypothesis is unlikely, I cannot see that as a bad thing. Good for Avi Loeb, I’d say.

Extraterrestrial: On ‘Oumuamua as Artifact

The reaction to Avi Loeb’s new book Extraterrestrial (Houghton Mifflin Harcourt, 2021) has been quick in coming and dual in nature. I’m seeing a certain animus being directed at the author in social media venues frequented by scientists, not so much for suggesting the possibility that ‘Oumuamua...

www.centauri-dreams.org

 

[Flyaway]

View: https://youtu.be/x-Ikmr5IPys

 

[Flyaway]

Scientists claim that all high-energy cosmic neutrinos are born by quasars

Scientists of the P. N. Lebedev Physical Institute of the Russian Academy of Sciences (LPI RAS), the Moscow Institute of Physics and Technology (MIPT) and the Institute for Nuclear Research of RAS (INR RAS) studied the arrival directions of astrophysical neutrinos with energies more than a trillion electronvolts (TeV) and came to an unexpected conclusion: all of them are born near black holes in the centers of distant active galaxies powerful radio sources. Previously, only neutrinos with the highest energies were assumed to be obtained in sources of this class.

Scientists claim that all high-energy cosmic neutrinos are born by quasars

Scientists of the P. N. Lebedev Physical Institute of the Russian Academy of Sciences (LPI RAS), the Moscow Institute of Physics and Technology (MIPT) and the Institute for Nuclear Research of RAS (INR RAS) studied the arrival directions of astrophysical neutrinos with energies more than a...

www.eurekalert.org