Tag: astronomy

Conflict in Hubble constant increases with new data from Hubble and Gaia

8:52 am

The uncertainty of science: New data from the Hubble Space Telescope and Gaia continues to measure a different Hubble constant for the expansion rate of the universe, when compared with data from the Planck space telescope.

Using Hubble and newly released data from Gaia, Riess’ team measured the present rate of expansion to be 73.5 kilometers (45.6 miles) per second per megaparsec. This means that for every 3.3 million light-years farther away a galaxy is from us, it appears to be moving 73.5 kilometers per second faster. However, the Planck results predict the universe should be expanding today at only 67.0 kilometers (41.6 miles) per second per megaparsec. As the teams’ measurements have become more and more precise, the chasm between them has continued to widen, and is now about 4 times the size of their combined uncertainty.

The problem really is very simple: We haven’t the faintest idea what is going on. We have some data, but we also have enormous gaps in our knowledge of the cosmos. Moreover, most of our cosmological data is reliant on too many assumptions that could be wrong, or simply in error. And the errors can be tiny and still throw the results off by large amounts.

The one thing that good science and skepticism teaches is humbleness. Do not be too sure of your conclusions. The universe is a large and complex place. It likes to throw curve balls at us, and if we swing too soon we will certainly miss.

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Astronomers dispute existence of galaxy without dark matter

10:40 am

The uncertainty of science: A new analysis by astronomers disputes the conclusion of different astronomers earlier this year that they had found a galaxy that lacked any dark matter.

The original paper from March based its stunning claim of a dark-matter-free galaxy on the way clusters of stars moved through the thin, diffuse galaxy called NGC1052–DF2: They appeared to move at exactly the speed Einstein’s equations of general relativity would predict based on the visible matter (so, slower than they would if the galaxy held dark matter).

This new paper on arXiv suggested otherwise: First, the authors pointed out that NGC1052–DF2 was already discovered way back in 1976 and has previously been referred to by three different names: KKSG04, PGC3097693 and [KKS2000]04.

Then, using those names and then finding all the available data on the galaxy, the researchers argued that the researchers from the March paper simply mismeasured the distance between that galaxy and Earth. This means the galaxy is probably much closer to us than the original researchers thought.

Astronomers calculate the mass of galaxies based on the objects’ brightness and distance. If the galaxy examined in the paper is closer to Earth than previously thought, then its dimness means it’s also much less massive than researchers thought. And at the newly calculated, lighter mass, all the other features of the galaxy make a lot more sense, the researchers in the new paper said. Its globular clusters aren’t moving slowly because they’re in some strange dark matter-desert; instead, they’re moving at the regular speed for a very lightweight galaxy, the arXiv authors said.

To put it bluntly, the astronomers don’t have enough solid data to decide this issue one way or the other. Moreover, the dispute indicates once again that the whole dark matter theory itself is based on very limited data with large margins of error. It might be the best theory we’ve got to explain the data we have, but no good scientist takes it too seriously. We just don’t know enough yet.

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Kepler on verge of death

10:04 am

The Kepler space telescope is now almost out of fuel, and scientists have ceased science observations to devote the telescope’s last days downloading its last 51 days of data.

The telescope lasted far longer than planned, and discovered thousands of exoplanets. Its archives will be producing new discoveries for decades. And a new exoplanet space telescope, TESS, is already in orbit to take over.

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Searchers find fragment of asteroid that hit Earth June 2nd

10:00 am

Researchers and local park volunteers in Botswana’s Central Kalahari Game Reserve on July 8 announced the discovery of a fragment from an asteroid that hit the Earth June 2 only eight hours after it was discovered.

“The biggest uncertainty we faced was to determine where exactly the meteorites fell,” says Peter Jenniskens a subject expert of the SETI Institute in California, who traveled to Botswana to assist in the search. He teamed up with Oliver Moses of the University of Botswana’s Okavango Research Institute (ORI), to gather security surveillance videos in Rakops and Maun to get better constraints on the position and altitude of the fireball’s explosion. Team member Tim Cooper of the Astronomical Society of Southern Africa calibrated videos to the south.

After disruption, the asteroid fragments scattered over a wide area, blown by the wind while falling down. Calculations of the landing area were done independently by the NASA-sponsored group headed by Jenniskens, as well as by Esko Lyytinen and Jarmo Moilanen of the Finnish Fireball Network. These calculations were defining the fall area well enough to warrant the deployment of a search expedition.

The first meteorite was found after five days of walking and scouring a landscape of sand, thick tall grass, shrubs and thorn bushes by a team of geoscientists from the Botswana International University of Science and Technology (BUIST), the Botswana Geoscience Institute (BGI) and from ORI, guided by Jenniskens. The Botswana Department of Wildlife and National Parks granted access and deployed their park rangers to provide protection and participate in the search. BUIST student Lesedi Seitshiro was first to spot the stone.

This is only the second time in history that a small asteroid observed in space was recovered following its impact on Earth.

I have amateur astronomer friends who attempted to do this exact thing, here in Tucson. We actually went out one day hunting for a meteorite they had tracked, but were unsuccessful in finding anything. To have had success we would have likely required more search time and a better constraint on the asteroid’s landing zone.

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Galaxies collide!

7:07 am

Using data from then space telescope Gaia, astronomers have identified evidence that 8 to 10 billion years ago the Milky Way collided with a dwarf galaxy.

The astronomers propose that around 8 billion to 10 billion years ago, an unknown dwarf galaxy smashed into our own Milky Way. The dwarf did not survive the impact: It quickly fell apart, and the wreckage is now all around us.

“The collision ripped the dwarf to shreds, leaving its stars moving in very radial orbits” that are long and narrow like needles, said Vasily Belokurov of the University of Cambridge and the Center for Computational Astrophysics at the Flatiron Institute in New York City. The stars’ paths take them “very close to the center of our galaxy. This is a telltale sign that the dwarf galaxy came in on a really eccentric orbit and its fate was sealed.”

It is thought that this dwarf galaxy was quite large for a dwarf galaxy.

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A star that shoots cosmic rays

7:02 am

New data from the space telescope NuSTAR suggests that the giant star Eta Carina, expected to be a supernova sometime in the future, emits cosmic rays, some of which reach the Earth.

The cosmic rays are produced by shock waves resulting from the clash between the intense solar winds of the system’s two stars.

Go to the link to see a truly beautiful image of this star system. You will immediately see that it is a system exploding.

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James Webb Space Telescope delayed again, with budget rising

11:30 am

Based the conclusions [pdf] of an Independent Review Board (IRB), NASA has once again delayed the launch of the James Webb Space Telescope, now set for 2021, while increasing its construction budget from $8 billion to almost $9 billion.

In its report, the IRB found that technical issues, including human errors, have greatly impacted the development schedule.

The agency previously had estimated an earlier launch date, but awaited findings from the IRB before making a final determination and considered data from Webb’s Standing Review Board. The agency established the new launch date estimate [March 30, 2021] to accommodate changes in the schedule due to environmental testing and work performance challenges by Northrop Grumman on the spacecraft’s sunshield and propulsion system. The telescope’s new total lifecycle cost, to support the revised launch date, is estimated at $9.66 billion; its new development cost estimate is $8.8 billion.

It is important to remember that Webb was originally supposed to cost $1 billion, and launch in 2011. It is now a decade behind schedule, with a cost almost ten times higher.

It really does appear like SLS and Webb are in a race to see who can get launched last. And right now, the race is neck and neck.

I should add that if the launch gets delayed much more, NASA will have further problems with the launch rocket. The Ariane 5 rocket, designated as the launch vehicle, is being retired around 2021. Beyond that date there might be problems using one.

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New observations of interstellar Oumuamua give it comet-like properties

11:10 am

The uncertainty of science: New observations of interstellar object Oumuamua suggest that it is a comet, not an asteroid.

[B]y combining data from the NASA/ESA Hubble Space Telescope, the Canada-France-Hawaii Telescope, ESO’s Very Large Telescope and the Gemini South Telescope, an international team of astronomers has found that the object is moving faster than predicted. The measured gain in speed is tiny and `Oumuamua is still slowing down because of the pull of the Sun — just not as fast as predicted by celestial mechanics.

The team, led by Marco Micheli (European Space Agency) explored several scenarios to explain the faster-than-predicted speed of this peculiar interstellar visitor. The most likely explanation is that `Oumuamua is venting material from its surface due to solar heating — a behaviour known as outgassing. The thrust from this ejected material is thought to provide the small but steady push that is sending `Oumuamua hurtling out of the Solar System faster than expected — as of 1 June, it is travelling with about 114 000 kilometres per hour.

Such outgassing is a typical behaviour for comets and contradicts the previous classification of `Oumuamua as an interstellar asteroid. “We think this is a tiny, weird comet,” comments Marco Micheli. “We can see in the data that its boost is getting smaller the farther away it travels from the Sun, which is typical for comets.”

If I was to speculate wildly, I could also wonder if maybe the aliens on board have decided they needed to get the heck out of here as fast as possible, and have fired their thrusters to make that happen.

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Grease in space

9:16 am

Based on observed data and lab recreations, astronomers have found that much of the galaxy’s interstellar dust is made of grease-like carbon molecules.

Organic matter of different kinds contains carbon, an element considered essential for life. There is though real uncertainty over its abundance, and only half the carbon expected is found between the stars in its pure form. The rest is chemically bound in two main forms, grease-like (aliphatic) and mothball-like (aromatic).

The UNSW / Ege team used a laboratory to create material with the same properties as interstellar dust. They mimicked the process by which organic molecules are synthesised in the outflows of carbon stars, by expanding a carbon-containing plasma into a vacuum at low temperature. The material was collected and then analysed by a combination of techniques. Using magnetic resonance and spectroscopy (splitting light into its constituent wavelengths) they were able to determine how strongly the material absorbed light with a certain infrared wavelength, a marker for aliphatic carbon.

“Combining our lab results with observations from astronomical observatories allows us to measure the amount of aliphatic carbon between us and the stars”, explained Professor Tim Schmidt, from the Australian Research Council Centre of Excellence in Exciton Science in the School of Chemistry at UNSW Sydney.

The researchers found that there are about 100 greasy carbon atoms for every million hydrogen atoms, accounting for between a quarter and a half of the available carbon. In the Milky Way Galaxy, this amounts to about 10 billion trillion trillion tonnes of greasy matter, or enough for 40 trillion trillion trillion packs of butter.

I guarantee that these results have a large margin of error. I also guarantee that they contain a significant element of truth.

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Hawaii’s Supreme Court to review TMT’s permit, again

8:36 am

Hawaii’s Supreme Court is set to review, for the second time, the construction permit for the Thirty Meter Telescope.

Much of the arguments centered around whether it was a conflict of interest for a hearings officer who made a key recommendation in favor of the project to be a member of a Hawaii astronomy center. The state allowed retired judge Riki May Amano to preside over contested-case hearings for the contentious project despite complaints from telescope opponents who decried her paid membership to the Imiloa Astronomy Center.

The Big Island center is connected to the University of Hawaii, which is the permit applicant.

Opponents appealed to the Supreme Court after Amano recommended granting the permit and the state land board approved it. “She should have never presided over the case,” Richard Wurdeman, an attorney representing telescope opponents, told the justices. He noted the center included exhibits about the project planned for the Big Island’s Mauna Kea, Hawaii’s tallest mountain.

The details don’t really matter. Nor will the decision. The protesters will simply find another petty issue if they lose, and will appeal again. Their goal, apparently supported covertly by Hawaii’s Democratic government, is to delay, delay, and delay, until the consortium building TMT is forced to abandon Hawaii.

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The mysterious dust surrounding Tabby’s Star

8:44 am

New studies of Tabby’s Star suggest that the dust clouds that cause it to fluctuate in brightness in apparently random ways are unusual and baffling in their own right.

[I]t appears that the dimming of Tabby’s star comes not from large objects such as swarms of asteroids, comets, or alien solar collectors, but from drifting bands of dust particles. But like any good mystery, it’s not quite that simple.

Each of the four dimming events observed in 2017 affected red and blue light differently, suggesting that they involved dust particles of different sizes. And the long-term brightness changes appear to be associated with much larger grains. “So the dust cloud is extremely complex,” Bodman says. “Each dip is a different kind of dust … What we’re seeing is different parts of the [dust] cloud as they pass in front of the star.”

A first guess, probably wrong, is that the four dimming events were caused by dust streams orbiting the star at different distances, each a different patchy ring around the star made up of slightly different materials.

And if you accept my guess as right, I also have bridge in Brooklyn I want to sell you. Real cheap too!

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More Earthlike exoplanets!

9:13 am

Astronomers using data from Kepler have discovered two stars, both with multiple orbiting Earth-sized planets. One has three planets all almost exactly the mass of Earth.

The first exoplanetary system is located in the star K2-239, characterized by these researchers as a red dwarf type M3V from observations made with the Gran Telescopio Canarias (GTC), at the Roque de los Muchachos Observatory (Garafía, La Palma). It is located in the constellation of the Sextant at 50 parsecs from the Sun (at about 160 light years). It has a compact system of at least three rocky planets of similar size to the Earth (1.1, 1.0 and 1.1 Earth radii) that orbit the star every 5.2, 7.8 and 10.1 days, respectively.

The other red dwarf star called K2-240 has two super-Earth-like planets about twice the size of our planet. Although the atmospheric temperature of red dwarf stars, around which these planets revolve, is 3,450 and 3,800 K respectively, almost half the temperature of our Sun, these researchers estimate that all planets discovered will have temperatures superficial tens of degrees higher than those of the planet Earth due to the strong radiation they receive in these close orbits to their stars.

Knowing more about the surface environments of these very Earthlike exoplanets, as hostile as they might be to life, would teach us a great deal about our own planet and its birth and evolution.

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More problems for James Webb Space Telescope?

9:45 am

The impending release of an independent NASA review of the state of the James Webb Space Telescope project suggests that the project is faced with additional issues.

NASA is in the process of evaluating the report from the Independent Review Board chaired by Tom Young to assess the status of the James Webb Space Telescope (JWST). Established in March, the Board was due to submit its report on May 31. NASA said today that the Board has completed its work and briefed NASA. The report will be released later this month after NASA determines the impact on cost and schedule.

Thomas Zurbuchen, NASA Associate Administrator for the Science Mission Directorate, created the Webb Independent Review Board (WIRB) on March 27, the same day he announced another delay in the telescope’s launch. WIRB held its first meeting the next week.

For many years, JWST appeared to be on track for launch in October 2018 after a 2011 restructuring that followed a series of earlier cost overruns and schedule delays. Congress capped the development cost (not operations) at $8 billion in law. Pursuant to the 2005 NASA Authorization Act, if a program exceeds 30 percent of its baseline estimated cost, NASA must notify Congress and no money may be spent on it after 18 months from the time of that notification unless Congress reauthorizes it.

The project will not die, Congress will simply extend it with lots more money. That is how big NASA projects really function, to take as long as possible so that they can continue their real goal of providing pork barrel jobs in congressional districts.

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No giant planet needed in Kuiper Belt to shape orbits of outer known planets

9:27 am

Using computer models astronomers have found that the tiny objects in the Kuiper Belt could be sufficient, instead of one giant undiscovered planet, to provide the gravity necessary to explain the orbits of the solar system’s outer planets.

They call theorized giant planet “Planet Nine,” which seems silly since Pluto really still fills that role. Nonetheless, this work also might explain the process that flung some surprisingly large objects so far out into the Kuiper Belt.

They ran supercomputer simulations of how bodies might interact in the outer Solar System far beyond Pluto, in the icy region known as the Kuiper belt. They found that a flock of Moon-sized worlds could do many of the same things as Planet Nine.

Over millions of years, the collective gravity of these smaller worlds would nudge the orbits of distant objects. The worlds would jostle one another like bumper cars and, occasionally, cause an object to move into a very distant orbit. Their simulations suggest that more-massive objects would be flung into the most distant orbits — as some observations have suggested.

We must also remind ourselves that this conclusion is based on a computer model, and is filled with uncertainty. We also do not yet have a full census of objects in the Kuiper Belt, which means this model required many assumptions.

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Globular clusters not as old as universe?

9:04 am

The uncertainty of science: A new computer model, based on binary star systems found in globular clusters, now estimates that those clusters are far younger than previously believed.

Comprised of hundreds of thousands of stars densely packed into a tight ball, globular clusters had been thought to be almost as old as the Universe itself – but thanks to newly developed research models it has been shown that they could be as young as 9 billion years old rather than 13 billion. The discovery brings into question current theories on how galaxies, including the Milky Way, were formed – with between 150-180 clusters thought to exist in the Milky Way alone – as globular clusters had previously been thought to be almost as old as the Universe itself.

Designed to reconsider the evolution of stars, the new Binary Population and Spectral Synthesis (BPASS) models take the details of binary star evolution within the globular cluster into account and are used to explore the colours of light from old binary star populations – as well as the traces of chemical elements seen in their spectra. The evolutionary process sees two stars interacting in a binary system, where one star expands into a giant whilst the gravitational force of the smaller star strips away the atmosphere, comprising hydrogen and helium amongst other elements, of the giant. These stars are thought to be formed as the same time as the globular cluster itself.

Through using the BPASS models and calculating the age of the binary star systems the researchers were able to demonstrate that the globular cluster of which they are part was not as ancient as other models had suggested.

All this study really does is demonstrate again that we really don’t know enough to make a very accurate estimate of the ages of globular clusters. They are very old, but determining precisely how old will require a lot more knowledge.

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Boulder-sized asteroid discovered just before it hit Earth

8:59 am

The Catalina Sky Survey, designed to find asteroid with the potential of hitting the Earth, discovered a boulder-sized such asteroid this past weekend just hours before it burned up in the atmosphere.

Although there was not enough tracking data to make precise predictions ahead of time, a swath of possible locations was calculated stretching from Southern Africa, across the Indian Ocean, and onto New Guinea. Reports of a bright fireball above Botswana, Africa, early Saturday evening match up with the predicted trajectory for the asteroid. The asteroid entered Earth’s atmosphere at the high speed of 10 miles per second (38,000 mph, or 17 kilometers per second) at about 16:44 UTC (9:44 a.m. PDT, 12:44 p.m. EDT,6:44 p.m. local Botswana time) and disintegrated several miles above the surface, creating a bright fireball that lit up the evening sky. The event was witnessed by a number of observers and was caught on webcam video.

When it was first detected, the asteroid was nearly as far away as the Moon’s orbit, although that was not initially known. The asteroid appeared as a streak in the series of time-exposure images taken by the Catalina telescope . As is the case for all asteroid-hunting projects, the data were quickly sent to the Minor Planet Center in Cambridge, Massachusetts, which calculated a preliminary trajectory indicating the possibility of an Earth impact. The data were in turn sent to the Center for Near-Earth Object Studies (CNEOS) at NASA’s Jet Propulsion Laboratory in Pasadena, California, where the automated Scout system also found a high probability that the asteroid was on an impact trajectory. Automated alerts were sent out to the community of asteroid observers to obtain further observations, and to the Planetary Defense Coordination Office at NASA Headquarters in Washington. However, since the asteroid was determined to be so small and therefore harmless, no further impact alerts were issued by NASA.

The video at the link makes it appear that the asteroid has hit the ground, but that is not what happened.

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Radio telescope in Greenland sees first “light”

10:03 am

Astronomers have successfully initiated operations of a new radio telescope dish, the first ever located in Greenland.

The Greenland Telescope is a 12-meter radio antenna that was originally built as a prototype for the Atacama Large Millimeter/submillimeter Array (ALMA) North America. Once ALMA was operational in Chile, the telescope was repurposed to Greenland to take advantage of the near-ideal conditions of the Arctic to study the Universe at specific radio frequencies, collaborating with the National Radio Astronomy Observatory (NRAO) and MIT Haystack Observatory.

ASIAA led the effort to refurbish and rebuild the antenna to prepare it for the cold climate of Greenland’s ice sheet. In 2016, the telescope was shipped to the Thule Air Base in Greenland, 1,200 km inside the Arctic Circle, where it was reassembled at this coastal site. ASIAA also built receivers for the antenna. “It is extremely challenging to quickly and successfully set up a new telescope in such a cold environment, where temperatures fall below -30 degrees Celsius,” said Ming-Tang Chen from ASIAA and the Greenland Telescope project manager. “This is now one of the closest radio telescopes to the North Pole.”

They have also linked this radio telescope to others across the globe, helping to increase the resolution of any data these radio telescopes gather as a unit.

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Canada exits WFIRST project

9:32 am

Like rats fleeing a sinking ship: The Canadian government has decided not to fund that country’s contribution to NASA’s WFIRST space telescope project, presently expected to cost $3.2 billion total (already over-budget in the design phase) and set to launch sometime in the 2020s (don’t bet on it).

The Canadian instrument would have been focused on studying dark energy, the mysterious force that is theorized to cause the universe’s expansion rate to accelerate over vast distances.

I can understand the skepticism of the Canadian government. Why commit anything to a project that is already over-budget and has unreliable support in the U.S. (Trump tried to ax it, Congress restored it, for now)? The project is also so far in the future it makes more sense to spend this money on astronomy projects that could be built and used now.

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Astronomers identify 25 stars that have or will come within 3 light years of Sun

9:21 am

Using the second data release from Gaia, astronomers have identified 25 stars that have or will come within 3 light years of Sun sometime within fifteen million years.

But the authors are confident that the 25 stars represent only a sliver of the actual encounters that have occurred over this time period. “They’re still just scratching the surface,” Mamajek agrees. That’s because the Gaia satellite eliminates low-mass stars (which are simply too faint to see at the moment) and high-mass stars (which are often so bright they saturate the satellite’s detectors) — thus limiting the data to stars that range between 0.5 and 1.3 times the mass of the Sun.

As such, the team suspects that they have only spotted 15% of all the encounters that likely pummel our solar system. “It’s a good first step, but one should not look at this as the final word,” Mamajek adds.

In reading their paper (available here), they identify three stars come come within a light year, therefore disturbing the theorized Oort Cloud of comets thought to exist at this distance from the Sun. One, Gliese 710, will do so in 1.3 million years..

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New tests prove EM drive doesn’t work

11:26 am

Two different alternative concepts that proposed methods for creating thrust in space but defied known physics have both been found wanting in new stringent experiments.

The EM drive especially came off badly. Apparently the tiny residual force that remains after building the experiment rigorously and with care is caused not by the EM drive but by the Earth’s magnetic field.

Readers of Behind the Black know that I am a strong skeptic when it comes to flashy new discoveries, whether they are made by famous and well known cosmologists or some guys in their garage. To me, what matters is the data, and its reliability and robustness. The EM drive never passed the smell test. Good science experimentation has now proven this.

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