An alien star passed through our Solar System just 70,000 years ago, astronomers have discovered.
No other star is known to have approached this close to us.
An international team of researchers says it came five times closer than our current nearest neighbour - Proxima Centauri.
The object, a red dwarf known as Scholz’s star, cruised through the outer reaches of the Solar System - a region known as the Oort Cloud.
Scholz’s star was not alone; it was accompanied on its travels by an object known as a brown dwarf. These are essentially failed stars that lacked the necessary mass to get fusion going in their cores.
The findings are published in Astrophysical Journal Letters.
Observations of the dim star’s trajectory suggest that 70,000 years ago this cosmic infiltrator passed within 0.8 light years of the Sun. By comparison, Proxima Centauri is 4.2 light years away.
In the paper, astronomers led by Eric Mamajek at the University of Rochester, New York, say they are 98% certain that Scholz’s star travelled through what is known as the “outer Oort Cloud” - a region at the edge of the Solar System filled with trillions of comets a mile or more across.
This region is like a spherical shell around the Solar System and may extend out to as much as 100,000 Astronomical Units, or AU (one AU is the distance between the Earth and the Sun).
The Oort Cloud is thought to give rise to long-period comets that can swing past the Sun when their orbits are disturbed.
To determine the trajectory of the star, the researchers needed two pieces of information: the change in distance from the Sun to the star (its radial velocity) and the star’s motion across the sky (its tangential velocity).
Scholz’s star currently lies 20 light years away - making it a fairly nearby system. But it showed very slow tangential motion for a star this close. This indicated that it was either moving away from us or towards a future close encounter with the Solar System.
The radial velocity measurements confirmed that the binary star system was actually speeding away from us. By tracing its movements back in time, they found its close shave with the Sun occurred some 70,000 years ago.
Grand theft Oort-o?
A star passing through the Oort Cloud could potentially play gravitational havoc with the orbits of comets there, sending them on trajectories into the inner Solar System. But Dr Mamajek believes the effects of Scholz’s star on our cosmic neighbourhood were “negligible”.
“There are trillions of comets in the Oort cloud and likely some of them were perturbed by this object,” he told BBC News.
“But so far it seems unlikely that this star actually triggered a significant ‘comet shower’.”
The effect of a passing star on the Oort Cloud is a function of the star’s mass, speed and proximity. The worst case scenario for stirring up comets would be a slow-moving, massive star that came close to the Sun.
Scholz’s star came relatively close, but the binary system (the red dwarf and its brown dwarf companion) has a low mass and it was speeding by. These factors conspired to make its effect on the Oort Cloud very small.
While this is the closest flyby detected so far, Dr Mamajek thinks it’s not uncommon for alien stars to buzz the Sun. He says a star probably passes through the Oort Cloud every 100,000 years, or so.
But he suggests an approach as close - or closer - than that made by Scholz’s star is somewhat rarer. Dr Mamajek said mathematical simulations show such an event occurs on average about once every nine million years.
“So it is a bit of a strange coincidence that we happen to have caught one that passed so close within the past 100,000 years or so,” he said.
Completely non-anime related at all, do you have any fic recs for Star Trek? I saw that you like Bones and he is my absolute fave (so salty about SO MUCH), but I don't know if you read Trek fic. Thanks!
I’m not much of a Spock/Kirk shipper (in that I like other pairings more, even if I see the massive amounts of potential in KS), so this list is pretty much Bones-centric, whoops.
whats good mckirk fic to read ?? any authors i should know about ?? like, the Really Good Stuff™
okay my Top Tip for fic reading is to click the pairing, and then filter it by kudos or hits, that way you get the most popular fics. the only major mckirk authors i can think of is canistakahari and ceres_libera. aside from them, these are all great fics, and my all time faves are bolded
We on earth marvel, and rightfully so, at the daily return of our single sun. But from a planet orbiting a star in a distant globular cluster… A still more glorious dawn awaits. Not a sunrise - but a galaxy rise. A morning filled with 400 billion suns; the rising of the Milky Way.
“ Scientists say they have extraordinary new evidence to support a Big Bang Theory for the origin of the Universe. Researchers believe they have found the signal left in the sky by the super-rapid expansion of space that must have occurred just fractions of a second after everything came into being. It takes the form of a distinctive twist in the oldest light detectable with telescopes. The work will be scrutinised carefully, but already there is talk of a Nobel. "This is spectacular,” commented Prof Marc Kamionkowski, from Johns Hopkins University. “I’ve seen the research; the arguments are persuasive, and the scientists involved are among the most careful and conservative people I know,” he told BBC News. The breakthrough was announced by an American team working on a project known as BICEP2. This has been using a telescope at the South Pole to make detailed observations of a small patch of sky. The aim has been to try to find a residual marker for “inflation” - the idea that the cosmos experienced an exponential growth spurt in its first trillionth, of a trillionth of a trillionth of a second.
Theory holds that this would have taken the infant Universe from something unimaginably small to something about the size of a marble. Space has continued to expand for the nearly 14 billion years since. Inflation was first proposed in the early 1980s to explain some aspects of Big Bang Theory that appeared to not quite add up, such as why deep space looks broadly the same on all sides of the sky. The contention was that a very rapid expansion early on could have smoothed out any unevenness. But inflation came with a very specific prediction - that it would be associated with waves of gravitational energy, and that these ripples in the fabric of space would leave an indelible mark on the oldest light in the sky - the famous Cosmic Microwave Background. The BICEP2 team says it has now identified that signal. Scientists call it B-mode polarisation. It is a characteristic twist in the directional properties of the CMB. Only the gravitational waves moving through the Universe in its inflationary phase could have produced such a marker. It is a true “smoking gun”. Speaking at the press conference to announce the results, Prof John Kovac of the Harvard-Smithsonian Center for Astrophysics, and a leader of the BICEP2 collaboration, said: “This is opening a window on what we believe to be a new regime of physics - the physics of what happened in the first unbelievably tiny fraction of a second in the Universe.” ‘Completely astounded’ The signal is reported to be quite a bit stronger than many scientists had dared hope. This simplifies matters, say experts. It means the more exotic models for how inflation worked are no longer tenable. The results also constrain the energies involved - at 10,000 trillion gigaelectronvolts. This is consistent with ideas for what is termed “