Because here in the United States, many Americans are looking at tomorrow's election the way a man walking in a railway tunnel sees the headlights of an approaching train, today I'd like to direct your attention away from the Earth entirely, into the cold, desolate voids of outer space.
Which, all things considered, seem like a pretty congenial place by comparison.
In the past week we've had three cool astronomical discoveries announced, highlighting the exciting fact of how much more we have left to learn about the universe in which we live. The first comes from the European Southern Observatory, which got some fantastic new images of a nebula in the constellation Scorpio called the Dark Wolf Nebula, which (fitting to its name) they released on Halloween:
[Image credit: European Southern Observatory]
The Dark Wolf, and other dark nebulae -- such as the famous Coalsack Nebula in the constellation Crux -- are aggregations of dust and gas that shroud stars behind them. They're far from being passive light-blockers, however; dark nebulae are often the sites of rapid star formation, as the material collapses into clumps and fusion starts. Once this occurs, the radiation pressure from the newly-formed stars blows away the extra dust, revealing the newborn star cluster, such as what we see now in the Orion Nebula and the Pleaides.
The second study is a bit of a puzzle, and involves the star Vega, a bright star in the constellation Lyra easily visible in the Northern Hemisphere at this time of year. Vega is only 25 light years away, and was made famous as the origin of the alien signal in the movie Contact, which remains my all-time favorite movie.
Vega is a young A-class blue-white star about twice the Sun's mass, forty times brighter, and almost 4,000 C hotter (surface temperature). Because of its luminosity and proximity, it's one of the most intensively-studied stars in the sky, and a recent announcement by NASA (based on data from the Hubble and James Webb Space Telescopes) indicate that it's
got a feature that's peculiar by any standards -- and suggest that one scene in
Contact was downright prescient.
In the movie, astronomer Ellie Arroway intercepts a transmission from an advanced technological species which contains instructions on how to build a device that warps space and time, allowing a passenger to cross interstellar distances and drop in for a visit. When Arroway (after many twists and turns and setbacks) ends up taking a ride in the device, it brings her to Vega, where she sees a massive debris disk -- but no planets.
And that's exactly what Hubble and the JWST found. Having a debris disk isn't at all unusual; after all, current models indicate that planet formation occurs by gravitational clumping from a flat disk surrounding the parent star (much as stars coalesce from dust and gas in dark nebulae). But what's strange is that Vega's disk is almost entirely homogeneous, made up of a circular sheet of similar-sized particles. No planets at all.
"Between the Hubble and Webb telescopes, you get this very clear view of Vega," said team member Andras Gáspár of the University of Arizona. " It's a mysterious system because it's unlike other circumstellar disks we've looked at. The Vega disk is smooth, ridiculously smooth."
There appears to be a trend toward gradually decreasing size at the edges of the disk, thought to be because radiation pressure tends to blow small particles outward more efficiently than larger ones. But other than that, the disk is relatively featureless, which is something not seen in other stars of similar ages and characteristics, such as Fomalhaut in the constellation Piscis Australis.
"Given the physical similarity between the stars of Vega and Fomalhaut, why does Fomalhaut seem to have been able to form planets and Vega didn't?" said team member George Rieke, also of the University of Arizona. "What's the difference? Did the circumstellar environment, or the star itself, create that difference? What's puzzling is that the same physics is at work in both."
The last story will appeal to anyone who likes to think about the extremes which nature can sometimes achieve, and has to do with something that's pretty astonishing all by itself --
neutron stars. Neutron stars form from the gravitational core collapse of a star greater than about 1.4 solar masses; the outer atmosphere gets blown away in a supernova, and the core falls inward, overcoming electrostatic repulsion and
electron degeneracy pressure, which has the effect of crushing electrons into atomic nuclei, forming (in essence) a gigantic ball of neutrons.
This means neutron stars are some of the densest known objects. A matchbox-sized chunk of a typical neutron star would weigh three billion tonnes. But they have another wild characteristic, which is why the topic comes up today; most of them rotate like crazy.
The reason is conservation of angular momentum -- the same reason that a spinning figure skater increases her rotational speed as she brings her arms inward. When a neutron star collapses, this reduces its effective radius (what physicists call the
moment of inertia), and the rate of rotation increases to compensate.
When the neutron star is emitting jets of radiation, this creates an effect like the beams from a lighthouse -- which is how we get
pulsars.
The nebula surrounding the pulsar PSR B1509-58, which glows because of the radiation jets from the neutron star [Image is in the Public Domain courtesy of NASA]
And now, a team at the Technological University of Denmark has
found a neutron star with a spin rate of an almost unimaginable 716 rotations per second, putting it in a tie for the fastest spinning astronomical object known.
"We were studying thermonuclear explosions from this system and then found remarkable oscillations, suggesting a neutron star spinning around its centre axis at an astounding 716 times per second," said Gaurava K. Jaisawal, first author on the study, which was published last week in the
Astrophysical Journal. "If future observations confirm this, the 4U 1820-30 neutron star would be one of the fastest-spinning objects ever observed in the universe, matched only by another neutron star called PSR J1748-2446."
So those are our cool discoveries in outer space for today. And now, I suppose that we should reluctantly turn our attention back to the planet we live on. If you live in the United States, please please
please vote tomorrow. If you live elsewhere, you might direct a prayer to whatever deity you happen to favor. I know I've been a disbeliever for a good long while, but hell, at this point we need all the help we can get.
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