Starship Asterisk*

VLT reveals dark, reddish and highly-elongated object

Artist’s Impression of the Interstellar Asteroid `Oumuamua Credit: ESO/M. Kornmesser

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For the first time ever astronomers have studied an asteroid that has entered the Solar System from interstellar space. Observations from ESO’s Very Large Telescope in Chile and other observatories around the world show that this unique object was traveling through space for millions of years before its chance encounter with our star system. It appears to be a dark, reddish, highly-elongated rocky or high-metal-content object. The new results appear in the journal Nature on 20 November 2017.

On 19 October 2017, the Pan-STARRS 1 telescope in Hawai`i picked up a faint point of light moving across the sky. It initially looked like a typical fast-moving small asteroid, but additional observations over the next couple of days allowed its orbit to be computed fairly accurately. The orbit calculations revealed beyond any doubt that this body did not originate from inside the Solar System, like all other asteroids or comets ever observed, but instead had come from interstellar space. Although originally classified as a comet, observations from ESO and elsewhere revealed no signs of cometary activity after it passed closest to the Sun in September 2017. The object was reclassified as an interstellar asteroid and named 1I/2017 U1 (`Oumuamua) [1]. ...

ESO’s Very Large Telescope was immediately called into action to measure the object’s orbit, brightness and colour more accurately than smaller telescopes could achieve. Speed was vital as `Oumuamua was rapidly fading as it headed away from the Sun and past the Earth’s orbit, on its way out of the Solar System. There were more surprises to come.

Combining the images from the FORS instrument on the VLT using four different filters with those of other large telescopes, the team of astronomers led by Karen Meech (Institute for Astronomy, Hawai`i, USA) found that `Oumuamua varies dramatically in brightness by a factor of ten as it spins on its axis every 7.3 hours. ...

Gemini Observatory provided key observations in characterizing an object visiting from outside our solar system, ‘Oumuamua. After the object was discovered by Pan-STARRS1 on Haleakala, both Gemini telescopes dropped everything to observe ‘Oumuamua for three nights as it quickly dimmed from view. Researchers found that despite its interstellar origin, the object is similar in composition to some objects in our Solar System but its shape is unlike anything found around our Sun. ...

https://en.wikipedia.org/wiki/Monolith_(Space_Odyssey) wrote:

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<<In Arthur C. Clarke's Space Odyssey, monoliths are machines built by an unseen extraterrestrial species. All the monoliths are black, extremely flat, non-reflective rectangular solids whose dimensions are in the precise ratio of 1 : 4 : 9. The monoliths come in several different sizes: TMA-0 and TMA-1 are both about 11 feet long and TMA-2 is two kilometres long on its longest axis, whereas the monolith on Europa is considerably larger. While it is unclear what the composition of the monoliths is, they clearly have mass, which is about the only observation that can be made. In the novel 2010, the crewmen of the spaceship Alexei Leonov measure the mass of TMA-2 and they find that it has a density slightly higher than that of air.

The extraterrestrial species that built the monoliths is never described in much detail, but some knowledge of its existence is given to Dave Bowman after he is transported by the stargate to the "cosmic zoo", as detailed in the novels 2001: A Space Odyssey and 2010: Odyssey Two. The existence of this species is only hypothesized by the rest of humanity, but it is obvious because the monolith was immediately identified as an artifact of non-human origin.

The extraterrestrial species that built the monoliths developed intergalactic travel millions or perhaps billions of years before the present time. In the novels, Clarke refers to them as the "Firstborn" since they were quite possibly the first sapient species to possess a significant capability of interstellar travel. Members of this species explored the universe in the search of knowledge, and especially knowledge about other intelligent species. While these early explorers discovered that life was quite common, they observed that intelligent life was often stunted in its development, or else died out prematurely. Hence, they set about fostering it. The Firstborn were in many ways physically different from human beings, though from another point-of-view they were fundamentally the same: they were creatures made of "flesh and blood", and hence like human beings they were mortal.>>

Click to play embedded YouTube video.

Astronomers recently scrambled to observe an intriguing asteroid that zipped through the solar system on a steep trajectory from interstellar space—the first confirmed object from another star.

Astronomers recently scrambled to observe an intriguing asteroid that zipped through the solar system on a steep trajectory from interstellar space-the first confirmed object from another star.

Now, new data reveal the interstellar interloper to be a rocky, cigar-shaped object with a somewhat reddish hue. The asteroid, named 'Oumuamua by its discoverers, is up to one-quarter mile (400 meters) long and highly-elongated-perhaps 10 times as long as it is wide. That aspect ratio is greater than that of any asteroid or comet observed in our solar system to date. While its elongated shape is quite surprising, and unlike asteroids seen in our solar system, it may provide new clues into how other solar systems formed. ...

• Nature (online 20 Nov 2017) DOI: 10.1038/nature25020

BDanielMayfield wrote: This is an astonishing shape, to say the least. Sure wish it had been detected sooner, so that we'd have more than just an artistic guess as to its appearance.

Two conjectures come to mind: (1) It is a shard or chip off some larger body. (2) It is a humongous crystal.

rstevenson wrote:A different artist's interpretation...
itcamefromspace.jpg

Chris Peterson wrote:

BDanielMayfield wrote: This is an astonishing shape, to say the least. Sure wish it had been detected sooner, so that we'd have more than just an artistic guess as to its appearance.

Two conjectures come to mind: (1) It is a shard or chip off some larger body. (2) It is a humongous crystal.

Consider also that the model could be wrong. Reconstructing the shape of a body from just its temporal reflection profile is generally impossible. There is no closed solution. So what you actually get is a probabilistic reconstruction. Yes, there's a good chance that the conclusion is close to reality, but it isn't certain.

More than three weeks ago on October 18, 2017, the first interstellar object (ISO) discovery was made. Initially designated as a comet by the Minor Planet Center, C/2017 U1, the ISO now known as 1I/’Oumuamua was soon discovered not to behave in any way like a comet should, which raised questions about its origins. Initially, the object was thought to originate far outside the solar system in a region known as the Oort cloud where it can have extreme orbits that take them careening through the inner solar system at speeds exceeding 60 km/s. What made the apparition of 1I/’Oumuamua different is that its speed was too high to have a solar system origin. As it was passing within perihelion distance, 1I was moving at 87.7 km/s, about 4.2 km/s too fast for it to be bound to the sun. ...

Asteroids have been observed indirectly around other stars, but this was the first opportunity to study a piece from another solar system while it still was in the confines of ours at an unprecedented level of detail. Photometric colors and spectra telling the chemical composition of the surface of 1I were taken, and study revealed that it has a reddish color and probably came from the inner part of its original system where its host star’s heat played an important role in the formation of asteroids and planets. Additionally, the object’s rotation was studied revealing that the object was shaped like a skinny potato. ...

• arXiv.org > astro-ph > arXiv:1711.04927 > 14 Nov 2017 (v1), 03 Dec 2017 (v3)

We report on g, r and i band observations of the Interstellar Object 'Oumuamua (1I) taken on 2017 October 29 from 04:28 to 08:40 UTC by the Apache Point Observatory (APO) 3.5m telescope's ARCTIC camera. We find that 1I's colors are g−r=0.41±0.24 and r−i=0.23±0.25, consistent with the visible spectra of Masiero (2017), Ye et al. (2017) and Fitzsimmons et al. (2017), and most comparable to the population of Solar System C/D asteroids, Trojans, or comets. We find no evidence of any cometary activity at a heliocentric distance of 1.46 au, approximately 1.5 months after 1I's closest approach distance to the Sun. Significant brightness variability was seen in the r observations, with the object becoming notably brighter towards the end of the run. By combining our APO photometric time series data with the Discovery Channel Telescope (DCT) data of Knight et al. (2017), taken 20 h later on 2017 October 30, we construct an almost complete light curve with a most probable lightcurve period of P≃4 h. Our results imply a double peaked rotation period of 8.1 ± 0.02 h, with a peak-to-peak amplitude of 1.5 - 2.1 mags. Assuming that 1I's shape can be approximated by an ellipsoid, the amplitude constraint implies that 1I has an axial ratio of 3.5 to 10.3, which is strikingly elongated. Assuming that 1I is rotating above its critical break up limit, our results are compatible with 1I having having modest cohesive strength and may have obtained its elongated shape during a tidal disruption event before being ejected from its home system. Astrometry useful for constraining 1I's orbit was also obtained and published in Weaver et al. (2017).

BDanielMayfield wrote:What exactly does "an axial ratio of 3.5 to 10.3" mean? Is this a range of possibility from 1:3.5 to 1:10.3, or is this a width to length ratio of 3.5:10.3, which would only be about 1:2.94?

Chris Peterson wrote:

BDanielMayfield wrote:What exactly does "an axial ratio of 3.5 to 10.3" mean? Is this a range of possibility from 1:3.5 to 1:10.3, or is this a width to length ratio of 3.5:10.3, which would only be about 1:2.94?

Asteroid shape is commonly simplified to three axial measurements, and the ratio between them (x:y:z). I think in this case they're treating two of those as the same, so basically, this is what we might think of as the length to width ratio for something that is a symmetrical prolate solid. The range given means that this body may be no more elongated than many asteroids we have already observed in our system, or it may be more elongated than anything we've seen before. Big error bars.

Breakthrough Listen, the global astronomical program searching for evidence of civilizations beyond Earth, announced that it is currently focusing its observational efforts on ‘Oumuamua, the mysterious interloper recently spotted moving rapidly through the solar system. ...

Researchers working on long-distance space transportation have previously suggested that a cigar or needle shape is the most likely architecture for an interstellar spacecraft, since this would minimize friction and damage from interstellar gas and dust. While a natural origin is more likely, there is currently no consensus on what that origin might have been, and Breakthrough Listen is well positioned to explore the possibility that ‘Oumuamua could be an artifact.

Listen’s observation campaign will begin on Wednesday, December 13 at 3:00 pm ET. Using the Robert C. Byrd Green Bank Telescope, it will continue to observe ‘Oumuamua across four radio bands, from 1 to 12 GHz. Its first phase of observations will last a total of 10 hours, divided into four “epochs” based on the object’s period of rotation. ...

No evidence of artificial signals emanating from the object so far detected by the Green Bank Telescope, but monitoring and analysis continue. Initial data are available for public inspection in the Breakthrough Listen archive.

bystander wrote:Breakthrough Listen Releases Initial Results and Data from Observations of 'Oumuamua
Breakthrough Initiative | 2017 Dec 14

No evidence of artificial signals emanating from the object so far detected by the Green Bank Telescope, but monitoring and analysis continue. Initial data are available for public inspection in the Breakthrough Listen archive.

daddyo wrote:Just watched the above NASA video and noticed the scientist saying there are no other known asteroids shaped like this in the Solar System. Given that there's been over 100,000 asteroids observed (https://en.wikipedia.org/wiki/Asteroid# ... ed_methods) and assuming many have had their shapes estimated, that would mean there is something very special about this object.

Does anyone know the true number of shape estimated asteroids?

Chris Peterson wrote:

daddyo wrote:Just watched the above NASA video and noticed the scientist saying there are no other known asteroids shaped like this in the Solar System. Given that there's been over 100,000 asteroids observed (https://en.wikipedia.org/wiki/Asteroid# ... ed_methods) and assuming many have had their shapes estimated, that would mean there is something very special about this object.

Does anyone know the true number of shape estimated asteroids?

Keep in mind that the aspect ratio seen here is very speculative. The actual value is probably less, as low as 1:3 (or even a bit less than that), which makes it consistent with a large number of asteroids.

A study of the asteroid’s photometry, led by Michele Bannister (Queen’s University Belfast, UK), used the Gemini-North telescope in Hawaii and the William Herschel Telescope in Spain to explore the asteroid’s shape and color. Bannister and collaborators refined the estimate of the asteroid’s shape to be at least 5.3 times as long as it is wide, which requires this body to have significant internal cohesion to hold together as it tumbles. Their measured color for ‘Oumuamua is largely neutral.

bystander wrote:Update on an Interstellar Asteroid
NOVA | American Astronomical Society | 2018 Jan 19

viewtopic.php?p=279207#p279207

What Does This Visitor Imply?
missing planets
The presence of ‘Oumuamua implies a vast and cool, still undetected population of planets. [Laughlin & Batygin, 2017]
Gregory Laughlin of Yale University and Konstantin Batygin of Caltech (and Planet Nine fame) explore some of the consequences of ‘Oumuamua’s parameters. They argue that its current passage, if it’s not a fluke, suggests the presence of an enormous number (10²⁷) of such objects in our galaxy alone — enough to account for two Earth-masses of material for every star in the galaxy. Flinging asteroids like ‘Oumuamua out into interstellar space isn’t easy, though; the necessary multi-body interaction requires the system to contain a giant and long-period planet like our Neptune or Jupiter. Taken together, this information suggests that every star in the galaxy may host a Neptune-like planet at a Neptune-like distance.

BDanielMayfield wrote: That excellent update also included this gem:

They argue that its current passage, if it’s not a fluke, suggests the presence of an enormous number (10²⁷) of such objects in our galaxy alone — enough to account for two Earth-masses of material for every star in the galaxy.

The way 'Oumuamua tumbles suggests it was involved in a collision (BBC)

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That is the conclusion of new Belfast research that has examined in detail the light bouncing off the cigar-shaped asteroid from outside our Solar System.

"At some point or another it's been in a collision," says Dr Wes Fraser from Queen's University.

His team's latest study is featured in Sunday's Sky At Night episode on the BBC and published in Nature Astronomy.

It is yet another intriguing finding about this strange object that has fascinated scientists since its discovery back in October. ...

The hunt is now on for more 'Oumuamua-like objects. Extrapolating from this one discovery, there ought to be some 10,000 of them passing through our Solar System inside the orbit of Neptune. ...

• Nature Astronomy (online 09 Feb 2018) DOI: 10.1038/s41550-018-0398-z
  arXiv.org > astro-ph > arXiv:1711.11530 > 30 Nov 2017

Artist’s impression of ‘Oumuamua. Credit: ESO / M. Kornmesser

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New research finds that 'Oumuamua, the rocky object identified as the first confirmed interstellar asteroid, very likely came from a binary star system. ...

A binary star system, unlike our Sun, is one with two stars orbiting a common centre.

For the new study ... Jackson and his co-authors set about testing how efficient binary star systems are at ejecting objects. They also looked at how common these star systems are in the galaxy.

They found that rocky objects like ‘Oumuamua are far more likely to come from binary than single star systems. They were also able to determine that rocky objects are ejected from binary systems in comparable numbers to icy objects. ...

Once they determined that binary systems are very efficient at ejecting rocky objects, and that a sufficient number of them exist, they were satisfied that 'Oumuamua very likely came from a binary system. They also concluded that it probably came from a system with a relatively hot, high mass star since such a system would have a greater number of rocky objects closer in. ...

• Monthly Notices of the RAS: Letters (online 19 Mar 2018) DOI: 10.1093/mnrasl/sly033
  arXiv.org > astro-ph > arXiv:1712.04435 > 12 Dec 2017

Click to play embedded YouTube video.

A telescope in outback Western Australia has been used to listen to a mysterious cigar-shaped object that entered our Solar System late last year.

The unusual object—known as ‘Oumuamua—came from another solar system, prompting speculation it could be an alien spacecraft.

“So astronomers went back through observations from the Murchison Widefield Array (MWA) telescope to check for radio transmissions coming from the object between the frequencies of 72 and 102MHz —similar to the frequency range in which FM radio is broadcast.

While they did not find any signs of intelligent life, the research helped expand the search for extra-terrestrial intelligence (SETI) from distant stars to objects closer to home. ...

“We didn’t set out to observe this object with the MWA but because we can see such a large fraction of the sky at once, when something like this happens, we’re able to go back through the data and analyse it after the fact,” Professor Tingay said. ...

• Astrophysical Journal 857(1):11 (10 Apr 2018) DOI: 10.3847/1538-4357/aab359
  arXiv.org > astro-ph > arXiv:1802.09276 > 26 Feb 2018

https://en.wikipedia.org/wiki/Fetch_(game) wrote:

Click to play embedded YouTube video.

<<Arizona State psychology professor Michael McBeath has proposed a simple model to explain how dogs play Fetch. By mounting a camera on the head of a dog, he found that the dog changed its speed and direction in order to keep the frisbee's image in a constant position on its retina. This approach, called the Linear Optical Trajectory, makes the frisbee appear to move in a linear path at a constant speed. McBeath had previously noticed this interception strategy in professional baseball players pursuing fly balls. Tim Pennings, a mathematics professor at Hope College, has found that dogs are somehow able to calculate the optimal path to a ball thrown in the water. While playing Fetch with his Welsh Corgi, he noticed that the dog ran along the beach for a certain distance before jumping into the water. Because the dog is faster on land, this technique minimizes the total retrieval time. He showed that the dog is able to calculate the optimal point to jump into the water with statistical significance, a problem Pennings must resort to calculus to solve.>>