Tag Archives: astronomy

Strange things at center of Milky Way

Astronomers have discovered an additional four more weird objects orbiting the supermassive black hole, dubbed Sagittarius A* (pronounced A-star) for a total of six, all of which display behavior that is inexplicable.

Part of a new class called G objects, they look compact most of the time and stretch out when their orbits bring them closest to the black hole. Those orbits range from about 100 to 1000 years. “These objects look like gas and behave like stars,” says Andrea Ghez, director of the Galactic Centre Group at the University of California, Los Angeles (UCLA) and co-author of a paper in the journal Nature.

The new discoveries are known simply as G3 to G6. G1 was discovered by Ghez’s research group back in 2005, and G2 by astronomers in Germany in 2012. “The fact that there are now several of these objects observed near the black hole means that they are, most likely, part of a common population,” says co-author Randy Campbell, from the Keck Observatory in Hawaii.

It is not surprising that the intense gravitational field of Sagittarius A* rips these objects into elongated stretched objects as their orbits bring them close to the black hole. What is very very puzzling is their apparent ability to spring back to compact form as their orbits take them away from the black hole.

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A second exoplanet orbiting Proxima Centauri?

Worlds without end: Astronomers think they have found evidence of a second exoplanet orbiting the nearest star, Proxima Centauri.

The planet, a super-Earth called Proxima Centauri c (Proxima c for short), has at least six times more mass than Earth and orbits its star every 5.2 years.

…“Stars like Proxima Centauri are rather restless and continuously present eruptions and spots on their surface, which make the detection of a planetary-induced oscillation very complicated,” says coauthor Fabio Del Sordo (University of Crete and Foundation for Research and Technology-Hellas in Heraklion, Greece). Because the observations span almost two decades, the scientists have confidently ruled out those sources of noise, but they caution that follow-up observations are needed to confirm that the signal comes from a planet.

There is a lot of uncertainty here, requiring an independent confirmation of this result. It would not be surprising if this exoplanet vanished when others took a look, finding it a creation not of a periodic gravitation wobble but of the random fluctuations of the star itself.

If it does exist, it will not likely be a place where life exists. Too far from this very dim red dwarf star to get enough energy. However, as a super-Earth it might someday in the far future be a great mining world.

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Spitzer SpaceTelescope shutdown in a week

After sixteen years in orbit, NASA will shut down the Spitzer Space Telescope on January 22, 2020,

The telescope is still functional in a somewhat limited manner but NASA wishes to save the annual budget of $14 million to operate it. Moreover, it will become redundant and significantly superseded once the infrared James Webb Space Telescope launches and becomes operational next year.

NASA had hoped a private organization would take over Spitzer’s operation, but apparently got no takers.

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First asteroid discovered that circles Sun closer than Venus

Astronomers have detected the first asteroid circling the Sun in an orbit that lies entirely inside Venus’s orbit.

In addition to being the first known asteroid with this orbit, the space rock, called 2020 AV2, has the smallest aphelion, or distance from the sun, of any known natural object in the solar system, excluding Mercury. Moreover, by traveling around the sun in a mere 151 days, 2020 AV2 has the shortest orbital period of any known asteroid, according to The Virtual Telescope Project, an online observatory based in Italy.

The reason this is a first is because it is very hard to find such small objects orbiting closer to the Sun than Earth. The glare of the Sun limits what can be spotted. This fact is also why the scientists are unsure of the size of 2020 AV2.

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More superEarth exoplanets found circling nearby stars

Worlds without end: Among a new bunch of thirteen exoplanets, astronomers have discovered two more superEarth-sized exoplanets circling nearby red dwarf stars.

The two potentially habitable planets are orbiting GJ180 and GJ229A, which are among the nearest stars to our own Sun, making them prime targets for observations by next-generation space- and land-based telescopes. They are both super-Earths with at least 7.5 and 7.9 times our planet’s mass and orbital periods of 106 and 122 days respectively.

The Neptune-mass planet—found orbiting GJ433 at a distance at which surface water is likely to be frozen—is probably the first of its kind that is a realistic candidate for future direct imaging. “GJ 433 d is the nearest, widest, and coldest Neptune-like planet ever detected,” Feng added.

For a lot of reasons it is likely that life as we know it probably does not exist on these planets. Nonetheless, their close proximity makes it possible to study them, and since we have no such planets in our own solar system they can teach us a lot about planetary formation and evolution.

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Arecibo shut temporarily due to earthquakes

The Arecibo Observatory in Puerto Rico has suspended all operations temporarily because of the swarm of earthquakes that have hit the island in the past two weeks.

The strongest of those quakes was a 6.4 temblor early in the morning of Tuesday (Jan. 7). An initial survey conducted by drone after that event found no damage to the massive radio dish or the equipment above it, an Arecibo Observatory representative said here at the 235th meeting of the American Astronomical Society on Tuesday (Jan. 7).

However, safety protocols mean that observatory personnel can’t examine the dish or its accessories until the ground stops shaking, and it’s difficult to predict when that will happen.

The observatory was about to embark on a yearlong refitting to repair damage caused by Hurricane Maria in 2017. They have set January 10th as a tentative reopen date.

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Webb telescope remains on schedule for March 2021 launch

Good news: According to NASA and Northrop Grumman officials, the James Webb Space Telescope remains on schedule for its March 2021 launch by an Ariane 5 rocket.

This might be the first update on Webb in years where no new delays were announced. Instead, the Space Telescope Science Institute in Maryland, which will manage the telescope, is preparing to release in two weeks its first call for research proposals.

Proposals will be due May 1, with the institute making selections later in the summer. …[I]nstitute officials said they expect to receive 1,000 to 1,600 proposals, seeking some fraction of the 6,000 hours of observing time that will be available in that initial round of observations. About 300 proposals will be selected for Cycle 1, which will begin once spacecraft commissioning is complete about six months after launch.

Let us all pray that all goes well during launch and spacecraft deployment.

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TESS finds its first Earth

Worlds without end: TESS has discovered its first Earth-sized planet, orbiting a M dwarf star within the habitable zone.

TOI 700 is a small, cool M dwarf star located just over 100 light-years away in the southern constellation Dorado. It’s roughly 40% of the Sun’s mass and size and about half its surface temperature. The star appears in 11 of the 13 sectors TESS observed during the mission’s first year, and scientists caught multiple transits by its three planets.

The star was originally misclassified in the TESS database as being more similar to our Sun, which meant the planets appeared larger and hotter than they really are. Several researchers, including Alton Spencer, a high school student working with members of the TESS team, identified the error.

“When we corrected the star’s parameters, the sizes of its planets dropped, and we realized the outermost one was about the size of Earth and in the habitable zone,” said Emily Gilbert, a graduate student at the University of Chicago. “Additionally, in 11 months of data we saw no flares from the star, which improves the chances TOI 700 d is habitable and makes it easier to model its atmospheric and surface conditions.”

We could also give this story the subhead “the uncertainty of science.” Note how a revision of the star’s mass changed the planet’s. Though I am sure they have improved their estimate of the star, this error illustrates how easy it is to get a final astronomical conclusion wrong. There are always a lot of assumptions long the way, any one of which could have a margin of error significant enough to change the final result.

In other TESS news, the space telescope has also found an exoplanet orbiting a stellar binary system of two stars.

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Astronomers predict nova outburst later this century

Based on the rate of material spiraling from one star to another in a nearby stellar binary system, astronomers now predict that the two stars will merge sometime between 2067 and 2099, producing a nova that will among the brightest stars in the sky, visible to the naked eye for about a month.

From the press release:

Currently, the faint star V Sagittae, V Sge, in the constellation Sagitta, is barely visible, even in mid-sized telescopes. However, around the year 2083, this innocent star will explode, becoming as bright as Sirius, the brightest star visible in the night sky. During this time of eruption, V Sge will be the most luminous star in the Milky Way galaxy. … “We now have a strong prediction for the future of V Sge,” said Professor Emeritus Bradley E. Schaefer, LSU Department of Physics & Astronomy. “Over the next few decades, the star will brighten rapidly. Around the year 2083, its accretion rate will rise catastrophically, spilling mass at incredibly high rates onto the white dwarf, with this material blazing away. In the final days of this death-spiral, all of the mass from the companion star will fall onto the white dwarf, creating a supermassive wind from the merging star, appearing as bright as Sirius, possibly even as bright as Venus.”

“V Sge is exponentially gaining luminosity with a doubling time scale of 89 years,” said Frank. “This brightening can only result with the rate of mass falling off the normal companion star increasing exponentially, ultimately because the binary orbit is in-spiraling rapidly.”

“In anticipation of this fast decaying of the orbit, the fate of V Sge is sealed,” stated Schaefer. “The critical and simple physics are derived from V Sge having the companion star being much more massive than the white dwarf star, so forcing the rate of mass transfer to rise exponentially. Anticipating the next few decades, V Sge will in-spiral at a rapid pace with increasing brightness. Inevitably, this in-spiral will climax with the majority of the gas in the normal star falling onto the white dwarf, all within the final weeks and days. This falling mass will release a tremendous amount of gravitational potential energy, driving a stellar wind as never before seen, and raise the system luminosity to just short of that of supernovae at peak.”

This explosive event will have peak brightness over a month, with two stars merging into one star. The end result of the merger will produce a single star with a degenerate white dwarf core, a hydrogen-burning layer, surrounded by a vast gas envelope mostly of hydrogen.

The press release has not yet been posted, but the press materials for the announcement can be found here.

If their hypothesis turns out to be true, it will be the first such event ever predicted.

Note that they are not predicting a supernova, an event caused by a variety of ways (all related to the death of a star). This is a less spectacular nova event, though because of its relative nearness will be very bright in our sky.

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Newly discovered repeating fast radio burst breaks rules

The uncertainty of science: Astronomers have discovered the second fast radio burst that also repeats its bursts, and the discovery occurred in a place where such bursts were not expected to occur.

On 19th June 2019, eight telescopes from the European VLBI Network (EVN) simultaneously observed a radio source known as FRB 180916.J0158+65. This source was originally discovered in 2018 by the CHIME telescope in Canada, which enabled the team to conduct a very high resolution observation with the EVN in the direction of FRB 180916.J0158+65. During five hours of observations the researchers detected four bursts, each lasting for less than two thousandths of a second.

…With the precise position of the radio source the team was able to conduct observations with one of the world’s largest optical telescopes, the 8-m Gemini North on Mauna Kea in Hawaii. Examining the environment around the source revealed that the bursts originated from a spiral galaxy named SDSS J015800.28+654253.0, located half a billion light years from Earth. The bursts come from a region of that galaxy where star formation is prominent.

“The found location is radically different from the previously located repeating FRB, but also different from all previously studied FRBs”, explains Kenzie Nimmo, PhD student at the University of Amsterdam. “The differences between repeating and non-repeating fast radio bursts are thus less clear and we think that these events may not be linked to a particular type of galaxy or environment. It may be that FRBs are produced in a large zoo of locations across the Universe and just require some specific conditions to be visible.”

The actual locations of only five such bursts have been identified, so any generalization about their origin or nature seems premature anyway.

The American Astronomical Society (AAS) is having its semi-annual convention right now in Hawaii, which is why we are suddenly having a burst of astronomy-related press announcements.

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New evidence: dark energy might not exist

The uncertainty of science: New evidence once again suggests that the assumptions that resulted in the invention of dark energy in the late 1990s might have been in error, and that dark energy simply might not exist.

New observations and analysis made by a team of astronomers at Yonsei University (Seoul, South Korea), together with their collaborators at Lyon University and KASI, show, however, that this key assumption is most likely in error. The team has performed very high-quality (signal-to-noise ratio ~175) spectroscopic observations to cover most of the reported nearby early-type host galaxies of SN Ia, from which they obtained the most direct and reliable measurements of population ages for these host galaxies. They find a significant correlation between SN luminosity and stellar population age at a 99.5% confidence level. As such, this is the most direct and stringent test ever made for the luminosity evolution of SN Ia. Since SN progenitors in host galaxies are getting younger with redshift (look-back time), this result inevitably indicates a serious systematic bias with redshift in SN cosmology. Taken at face values, the luminosity evolution of SN is significant enough to question the very existence of dark energy. When the luminosity evolution of SN is properly taken into account, the team found that the evidence for the existence of dark energy simply goes away.

…Other cosmological probes, such as CMB (Cosmic Microwave Background) and BAO (Baryonic Acoustic Oscillations), are also known to provide some indirect and “circumstantial” evidence for dark energy, but it was recently suggested that CMB from Planck mission no longer supports the concordance cosmological model which may require new physics. Some investigators have also shown that BAO and other low-redshift cosmological probes can be consistent with a non-accelerating universe without dark energy. In this respect, the present result showing the luminosity evolution mimicking dark energy in SN cosmology is crucial and is very timely.

There was also this story from early December, also raising questions about the existence of dark energy.

Bottom line: The data that suggested dark energy’s existence was always shallow with many assumptions and large margins of uncertainty. This research only underlines that fact, a fact that many cosmologists have frequently tried to sweep under the rug.

Dark energy still might exist, but it behooves scientists to look coldly at the data and always recognize its weaknesses. It appears in terms of dark energy the cosomological community is finally beginning to do so.

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Hubble captures giant galaxy

Giant spiral galaxy imaged by Hubble
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Cool image time! The above image, cropped and reduced to post here, was compiled from images taken by the Hubble Space Telescope in 2018 of one of the largest known spiral galaxies.

One of the most photogenic is the huge spiral galaxy UGC 2885, located 232 million light-years away in the northern constellation, Perseus. It’s a whopper even by galactic standards. The galaxy is 2.5 times wider than our Milky Way and contains 10 times as many stars, about 1 trillion. This galaxy has lived a quiescent life by not colliding with other large galaxies. It has gradually bulked up on intergalactic hydrogen to make new stars at a slow and steady pace over many billions of years. The galaxy has been nicknamed “Rubin’s galaxy,” after astronomer Vera Rubin (1928 – 2016). Rubin used the galaxy to look for invisible dark matter. The galaxy is embedded inside a vast halo of dark matter. The amount of dark matter can be estimated by measuring its gravitational influence on the galaxy’s rotation rate.

This majestic spiral galaxy might earn the nickname the “Godzilla Galaxy” because it may be the largest known in the local universe. The galaxy, UGC 2885, is 2.5 times wider than our Milky Way and contains 10 times as many stars.

But it is a “gentle giant,” say researchers, because it looks like it has been sitting quietly over billions of years, possibly sipping hydrogen from the filamentary structure of intergalactic space. This fuels modest ongoing star birth at half the rate of our Milky Way. In fact, its supermassive central black hole is a sleeping giant, too; because the galaxy does not appear to be feeding on much smaller satellite galaxies, it is starved of infalling gas.

There are mysteries here, many of which we are as yet entirely unaware of yet.

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Betelguese fades a full magnitude

Long term observations of the red giant star Betelguese have found it to have faded a full magnitude in the past few months, dropping it from 6th brightest in the sky to the 21st.

You will see a lot of bad journalism related to this story, hyping the fact that Betelguese is considered one of the top nearby stars to someday in the far future go supernovae. However, the recent change in brightness is unlikely related to this and is nothing unusual, as the star fluctuates regularly.

The current faintness of Betelgeuse appears to arise from the coincidence of the star being near the minimum light of the ~5.9-yr light-cycle as well as near, the deeper than usual, minimum of the ~425-d period.

The star is definitely interesting, because it is so large (if placed in our solar system its surface would be around the orbit of Jupiter) and so defuse, more like a partly filled gasbag. However, the odds of it going supernovae in the near future is quite unlikely.

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Protesters continue to shut down TMT

Mob rule: Though an agreement has been reached between the anti-telescope protesters and the mayor of the Big Island to move a tent blocking the access road to Mauna Kea, the deal also provided that no construction will proceed, even though the consortium that is building the Thirty Meter Telescope (TMT) has gotten legal permission to do so.

They agreed to move the so-called “kupuna tent,” referring to the Hawaiian word for elder, as part of a deal announced by Big Island Mayor Harry Kim.

In exchange, Kim promised protesters there will be no attempts to deliver construction equipment to the telescope site “anytime soon,” according to Kim’s offer letter to Noe Noe Wong-Wilson, one of the protest leaders who is considered a kupuna. “I, Mayor Kim give you my personal assurances that no attempt will be made to move TMT construction equipment up the mountain for a minimum of two months,” his letter said.

Legally Kim doesn’t really have the right to do this, unless Hawaii has decided to completely abandon the rule of law. Then again, Hawaii has decided to abandon the rule of law, as it now lets mobs, not the law, determine who can build where and when.

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The importance of small telescopes to science and civilization

The main cluster of telescopes, on Mount Lemmon
Largest cluster of telescopes on Mount Lemmon, six visible with three just out of view.

On December 11, 2019 I was kindly given a personal tour by Alan Strauss, director of the Mount Lemmon Sky Center, of the telescopes located on the mountaintops of the Santa Catalina Mountains overlooking Tucson. Strauss runs the educational outreach program for the University of Arizona astronomy department and the Steward Observatory, both of which operate the mountaintop facility.

The telescopes, numbering almost a dozen, are in two groups, two telescopes on the peak of Mount Bigelow and the rest clustered on the higher peak of Mount Lemmon. None are very gigantic by today’s standards, with their primary mirrors ranging in size from 20- to 61-inches. For comparison, the largest operating telescope in the world on the Canary Islands is 409 inches across. Hubble has a 94-inch mirror. And the new giant telescopes under design or being built have mirrors ranging from 842 inches (Giant Magellan) to 1,654 inches (European Extremely Large Telescope).

Thus, the small telescopes in the Santa Catalinas generally don’t make the news. They are considered passe and out-of-date, not capable of doing the kind of cutting edge astronomy that all the coolest astronomers hunger for.

Yet, without them, we likely would not have future astronomers. » Read more

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Scientists reject discovery of biggest known black hole

The uncertainty of science: In three new papers published this week astronomers have found that the announced discovery in early December of the biggest super-massive black hole ever found, 70 times the mass of the Sun, does not hold up.

In a recent study (a peer-reviewed study published Nov. 27), a team of scientists reported the discovery of the binary system LB-1, which contains a star and, according to the findings, a black hole companion 70 times the mass of our sun. This was major news, a stellar-mass black holes (black holes formed by the gravitational collapse of a star) are typically less than half that massive. But while the study, led by Jifeng Liu, of the National Astronomical Observatory of China (NAOC) of the Chinese Academy of Sciences, was exciting, it was also wrong.

Three new papers came out this week that reexamined the findings from Liu’s study, and these studies say that LB-1’s black hole isn’t actually all that massive.

The new papers find that a closer look at the data finds that it wasn’t doing what the initial researchers thought.

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Interacting galaxies

Interacting galaxies
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Astronomers using the 8-meter Gemini Telescope on Mauna Kea today released a new image of the Heron galaxy, showing its interaction with a nearby neighbor.

The new image captures the slow and intimate dance of a pair of galaxies some 160 million light-years distant and reveals the sparkle of subsequent star formation fueled by the pair’s interactions.

The two galaxies, astronomers have concluded, have already “collided” at least once. However, galactic collisions can be a lengthy process of successive gravitational encounters, which over time can morph the galaxies into exotic, yet unrecognizable forms. These galaxies, as in all galactic collisions, are engaged in a ghostly dance as the distances between the stars in each galaxy preclude actual stellar collisions and their overall shapes are deformed only by each galaxy’s gravity.

One byproduct of the turbulence caused by the interaction is the coalescence of hydrogen gas into regions of star formation. In this image, these stellar nurseries are revealed in the form of the reddish clumps scattered in a ring-like fashion in the larger galaxy (and a few in the smaller galaxy). Also visible is a dusty ring that is seen in silhouette against the backdrop of the larger galaxy. A similar ring structure is seen in this previous image from the Gemini Observatory, likely the result of another interacting galactic pair.

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New Hubble images of Comet 2I/Borisov

Comet 2I/Borisov taken by Hubble prior to and at its closest approach to Sun
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Scientists today released new images taken by the Hubble Space Telescope of the interstellar object Comet 2I/Borisov. The image on the left was taken prior to the comet’s closest approach to the Sun, while the image on the right was taken during that closest approach. The vertical smeared object to the left in the earlier image is a galaxy that happened to be in the field of view. The blue color of both images is a false color to bring out details.

“Hubble gives us the best upper limit of the size of comet Borisov’s nucleus, which is the really important part of the comet,” said David Jewitt, a UCLA professor of planetary science and astronomy, whose team has captured the best and sharpest look at this first confirmed interstellar comet. “Surprisingly, our Hubble images show that its nucleus is more than 15 times smaller than earlier investigations suggested it might be. Our Hubble images show that the radius is smaller than half-a-kilometer. Knowing the size is potentially useful for beginning to estimate how common such objects may be in the solar system and our galaxy. Borisov is the first known interstellar comet, and we would like to learn how many others there are.”

The first image was taken from a distance of 203 million miles, while the second was taken from 185 million miles. Expect more images in late December, when the comet makes its closest approach to Earth at a distance of 180 million miles.

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TESS captures outburst from comet

Wirtanen outburst

The space telescope TESS, designed to look for exoplanets by imaging one hemisphere of the sky repeatedly over a full year, also successfully captured in those images the full outburst from the comet 46P/Wirtanen that occurred on September 26, 2018.

The animation created from those images is to the right.

According to Farnham, the TESS observations of comet Wirtanen were the first to capture all phases of a natural comet outburst, from beginning to end. He noted that three other previous observations came close to recording the beginning of an outburst event. Observations of a 2007 outburst from comet 17P/Holmes began late, missing several hours of the initial brightening phase of the event. In 2017, observations of an outburst from comet 29P/Schwassmann-Wachmann 1 (SW1) concluded early, due to limitations on pre-scheduled observation time. And, while observations from the UMD-led Deep Impact mission captured an outburst from comet Tempel 1 in unprecedented detail in 2005, the outburst was not natural—created instead by the mission’s impactor module. However, the current observations are the first to capture the dissipation phase in its entirety, Farnham said.

Although Wirtanen came closest to Earth on December 16, 2018, the outburst occurred earlier in its approach, beginning on September 26, 2018. The initial brightening of the outburst occurred in two distinct phases, with an hour-long flash followed by a more gradual second stage that continued to grow brighter for another 8 hours. This second stage was likely caused by the gradual spreading of comet dust from the outburst, which causes the dust cloud to reflect more sunlight overall. After reaching peak brightness, the comet faded gradually over a period of more than two weeks. Because TESS takes detailed, composite images every 30 minutes, the team was able to view each phase in exquisite detail.

The data from TESS is likely going to overwhelm the astronomy community for years.

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New analysis suggests dark energy might not be necessary

The uncertainty of science: A new peer-reviewed paper in a major astronomy science journal suggests that dark energy might not actually exist, and that the evidence for it might simply be because the original data was biased by the Milky Way’s own movement.

What [the scientists in this new paper] found is that the best fit to the data is that the redshift of supernovae is not the same in all directions, but that it depends on the direction. This direction is aligned with the direction in which we move through the cosmic microwave background. And – most importantly – you do not need further redshift to explain the observations.

If what they say is correct, then it is unnecessary to postulate dark energy which means that the expansion of the universe might not speed up after all.

Why didn’t Perlmutter and Riess [the discoverers of dark energy] come to this conclusion? They could not, because the supernovae that they looked were skewed in direction. The ones with low redshift were in the direction of the CMB dipole; and high redshift ones away from it. With a skewed sample like this, you can’t tell if the effect you see is the same in all directions.

The link is to a blog post by a physicist in the field, commenting on the new paper. Below the fold I have embedded a video from that same physicist that does a nice job of illustrating what she wrote.

This paper does not disprove dark energy. It instead illustrates the large uncertainties involved, as well as show solid evidence that the present consensus favoring the existence of dark energy should be questioned.

But then, that’s how real science works. When the data is sketchy or thin, with many assumptions, it is essential that everyone, especially the scientists in the field, question the results. We shall see now if the physics community will do this.

Hat tip to reader Mike Nelson.

» Read more

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Astronomers find record-setting heaviest supermassive black hole

Astronomers have discovered the most massive black hole yet discovered, having a mass 40 billion times the mass of our Sun.

The new data obtained at the USM Wendelstein observatory of the Ludwig-Maximilians-University and with the MUSE instrument at the VLT [Very Large Telescope in Chile] allowed the team to perform a mass estimate based directly on the stellar motions around the core of the galaxy. With a mass of 40 billion solar masses, this is the most massive black hole known today in the local universe. “This is several times larger than expected from indirect measurements, such as the stellar mass or the velocity dispersion of the galaxy,” remarks Roberto Saglia, senior scientist MPE and lecturer at the LMU.

The light profile of the galaxy shows a centre with an extremely low and very diffuse surface brightness, much fainter than in other elliptical galaxies. “The light profile in the inner core is also very flat,” explains USM doctoral student Kianusch Mehrgan, who performed the data analysis. “This means that most of the stars in the centre must have been expelled due to interactions in previous mergers.”

To give some perspective, the mass of the supermassive black hole in the center of the Milky Way, Sagittarius A* (pronounced A-Star), is thought to be about 4.6 million solar masses. This newly discovered supermassive black hole is almost nine thousand times heavier.

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New Horizons confirms solar wind slows at greater solar distances

The New Horizons science team today released data that confirms that, as theorized, the speed of the solar wind decreases as it travels farther from the Sun.

As the solar wind moves farther from the Sun, it encounters an increasing amount of material from interstellar space. When interstellar material is ionized, the solar wind picks up the material and, researchers theorized, slows and heats in response. SWAP [an instrument on New Horizons] has now detected and confirmed this predicted effect.

The SWAP team compared the New Horizons solar wind speed measurements from 21 to 42 astronomical units to the speeds at 1 AU from both the Advanced Composition Explorer (ACE) and Solar TErrestrial RElations Observatory (STEREO) spacecraft. (One AU is equal to the distance between the Sun and Earth.) By 21 AU, it appeared that SWAP could be detecting the slowing of the solar wind in response to picking up interstellar material. However, when New Horizons traveled beyond Pluto, between 33 and 42 AU, the solar wind measured 6-7% slower than at the 1 AU distance, confirming the effect.

The data also suggests that New Horizons could exit the heliosphere and enter interstellar space as early as sometime in the 2020s.

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New image of Comet 2I/Borisov

Comet 2I/Borisov
Click for full image.

Astronomers have taken a new image of the interstellar comet 2I/Borisov. The photograph to the right is that image, with the Earth placed alongside to show scale.

According to van Dokkum the comet’s tail, shown in the new image, is nearly 100,000 miles long, which is 14 times the size of Earth. “It’s humbling to realize how small Earth is next to this visitor from another solar system,” van Dokkum said.

Laughlin noted that 2l/Borisov is evaporating as it gets closer to Earth, releasing gas and fine dust in its tail. “Astronomers are taking advantage of Borisov’s visit, using telescopes such as Keck to obtain information about the building blocks of planets in systems other than our own,” Laughlin said.

The solid nucleus of the comet is only about a mile wide. As it began reacting to the Sun’s warming effect, the comet has taken on a “ghostly” appearance, the researchers said.

The comet will reach its closest point to the Earth, 190 million miles, in early December.

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First detection of extended galactic magnetic field

Whale galaxy with magnetic filaments
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Astronomers have made the first detection in another galaxy of a magnetic field that extends out into the galaxy’s halo.

The image above, based on data from the Jansky radio telescope, illustrates what they found..

The spiral galaxy is seen edge-on, with its disk of stars shown in pink. The filaments, shown in green and blue, extend beyond the disk into the galaxy’s extended halo. Green indicates filaments with their magnetic field pointing roughly toward us and blue with the field pointing away. This phenomenon, with the field alternating in direction, has never before been seen in the halo of a galaxy.

“This is the first time that we have clearly detected what astronomers call large-scale, coherent, magnetic fields far in the halo of a spiral galaxy, with the field lines aligned in the same direction over distances of a thousand light-years. We even see a regular pattern of this organized field changing direction,” said Marita Krause, of the Max-Planck Institute for Radioastronomy in Bonn, Germany.

The galaxy, dubbed the Whale by the astronomers, is about 35 million light years away, and has a diameter of about 80,000 light years, slightly smaller than the Milky Way.

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Astronomers find 19 more galaxies showing lack of dark matter

The uncertainty of science: Astronomers have discovered 19 more dwarf galaxies, now totaling 23, that appear to have significant deficits of dark matter.

Of 324 dwarf galaxies analyzed, 19 appear to be missing similarly large stores of dark matter. Those 19 are all within about 500 million light-years of Earth, and five are in or near other groups of galaxies. In those cases, the researchers note, perhaps their galactic neighbors have somehow siphoned off their dark matter. But the remaining 14 are far from other galaxies. Either these oddballs were born different, or some internal machinations such as exploding stars have upset their balance of dark matter and everyday matter, or baryons.

It may not be a case of missing dark matter, says James Bullock, an astrophysicist at the University of California, Irvine. Instead, maybe these dwarf galaxies have clung to their normal matter — or even stolen some — and so “have too many baryons.” Either way, he says, “this is telling us something about the diversity of galaxy formation…. Exactly what that’s telling us, that’s the trick.”

Since we do not know what dark matter is to begin with, finding galaxies lacking it only makes more difficult to create a theory to explain it. Something causes most galaxies to rotate faster than they should, based on their visible mass. What that is remains an unknown.

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Astronomers think they have pinned down location of Supernova 1987a’s central star

More than three decades after Supernova 1987a erupted, becoming the first supernova in centuries visible to the naked eye, astronomers finally think they have narrowed the location of the neutron star remaining from that supernova.

Astronomers knew the object must exist but had always struggled to identify its location because of a shroud of obscuring dust. Now, a UK-led team thinks the remnant’s hiding place can be pinpointed from the way it’s been heating up that dust.

The researchers refer to the area of interest as “the blob”. “It’s so much hotter than its surroundings, the blob needs some explanation. It really stands out from its neighbouring dust clumps,” Prof Haley Gomez from Cardiff University told BBC News. “We think it’s being heated by the hot neutron star created in the supernova.”

It will still likely be 50 to 100 years before the dust clears enough for the neutron star itself to be visible.

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Upcoming big satellite constellations vex and worry astronomers

Astronomers are expressing increasing distress over the possible negative consequences to their Earth-based telescope observations from the several new giant satellite constellations being launched by SpaceX and others.

[M]any astronomers worry that such ‘megaconstellations’ — which are also planned by other companies that could launch tens of thousands of satellites in the coming years — might interfere with crucial observations of the Universe. They fear that megaconstellations could disrupt radio frequencies used for astronomical observation, create bright streaks in the night sky and increase congestion in orbit, raising the risk of collisions.

The Nature article then details the issues faced by some specific telescopes. Hidden within the article however was this interesting tidbit that admitted the problem for many telescopes is really not significant.

Within the next year or so, SpaceX plans to launch an initial set of 1,584 Starlink satellites into 550-kilometre-high orbits. At a site like Cerro Tololo, Chile, which hosts several major telescopes, six to nine of these satellites would be visible for about an hour before dark and after dawn each night, Seitzer has calculated.

Most telescopes can deal with that, says Olivier Hainaut, an astronomer at the European Southern Observatory (ESO) in Garching, Germany. Even if more companies launch megaconstellations, many astronomers might still be okay, he says. Hainaut has calculated that if 27,000 new satellites are launched, then ESO’s telescopes in Chile would lose about 0.8% of their long-exposure observing time near dusk and dawn. “Normally, we don’t do long exposures during twilight,” he says. “We are pretty sure it won’t be a problem for us.” [emphasis mine]

The article then proceeds with its Chicken-Little spin as if the astronomical world is about to end if something is not done to stop or more tightly control these new satellite constellations.

As indicated by the quote above, it appears however that the threat is overstated. The constellations might reduce observing time slightly on LSST, scheduled for completion in 2022 and designed to take full sky images once every three nights. Also, the satellite radio signals might impact some radio astronomy. In both cases, however, the fears seem exaggerated. Radio frequencies are well regulated, and LSST’s data should easily be able to separate out the satellite tracks from the real astronomical data.

Rather than demand some limits or controls on this new satellite technology, the astronomical community should rise to the occasion and find ways to overcome this new challenge. The most obvious solution is to shift the construction of new telescopes from ground-based to space-based. In fact, this same new satellite technology should make it possible for them to do so, at much less cost and relatively quickly.

But then, astronomers are part of our modern academic community, whose culture is routinely leftist and therefore fascist in philosophy (even though they usually don’t realize it). To them too often the knee-jerk response to any competition is to try to control and squelch it.

We shall see if the astronomers succeed in this case.

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New Horizons team renames “Ultima Thule” to “Arrokoth”

The New Horizons team has renamed the Kuiper Belt object that the spacecraft flew past on January 1, 2019 from its informal nickname of “Ultima Thule” to “Arrokoth,” which means “sky” in Powhatan/Algonquian language.

This official, and very politically correct, name has apparently gotten the stamp of approval from the IAU.

In accordance with IAU naming conventions, the discovery team earned the privilege of selecting a permanent name for the celestial body. The team used this convention to associate the culture of the native peoples who lived in the region where the object was discovered; in this case, both the Hubble Space Telescope (at the Space Telescope Science Institute) and the New Horizons mission (at the Johns Hopkins Applied Physics Laboratory) are operated out of Maryland — a tie to the significance of the Chesapeake Bay region to the Powhatan people.

“We graciously accept this gift from the Powhatan people,” said Lori Glaze, director of NASA’s Planetary Science Division. “Bestowing the name Arrokoth signifies the strength and endurance of the indigenous Algonquian people of the Chesapeake region. Their heritage continues to be a guiding light for all who search for meaning and understanding of the origins of the universe and the celestial connection of humanity.” [emphasis mine]

It is a good name, especially because its pronunciation is straight-forward, unlike the nickname.

The blather from Glaze above, however, is quite disingenuous. The Algonquian people have had literally nothing to do with the modern scientific quest for “meaning and understanding of the origins of the unverse.” They were a stone-age culture, with no written language. It was western civilization that has made their present lives far better. And it was the heritage of western civilization, not “the indigenous Algonquian people” that made the New Horizons’ journey possible. Without the demand for knowledge and truth, as demanded by western civilization, we would still not know that Arrokoth even existed.

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Astronomers discover star fleeing Milky Way at 3.7 million mph

Astronomers have discovered a star that rocketing out of the Milky Way at 3.7 million miles per hour because five million years ago it made a close approach to Sagittarius A* (prounounced “A-star”), the super-massive black at the center of the galaxy.

“The velocity of the discovered star is so high that it will inevitably leave the Galaxy and never return”, said Douglas Boubert from the University of Oxford, a co-author on the study.

Astronomers have wondered about high velocity stars since their discovery only two decades ago. S5-HVS1 is unprecedented due to its high speed and close passage to the Earth, “only” 29 thousand light years away. With this information, astronomers could track its journey back into the centre of the Milky Way, where a 4 million solar mass black hole, known as Sagittarius A*, lurks.

Almost certainly there are many such stars. They are just hard to spot.

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Bennu & Ryugu: Two very old and strange asteroids

Bennu as seen by OSIRIS-REx
Bennu’s equatorial ridge. Click for full image.

This week the science team operating the OSIRIS-REx spacecraft at the asteroid Bennu hosted a joint conference in Tucson, Arizona, with the scientists operating the Hayabusa-2 spacecraft at the asteroid Ryugu. Both gave up-to-date reports on the science so far obtained, as well as outlined upcoming events. I was fortunate enough to attend.

First an overview. Both Bennu and Ryugu are near earth asteroids, with Bennu having an orbit that might even have it hit the Earth in the last quarter of 2100s. Both are very dark, and are rubble piles. Both were thought to be of the carbonaceous chondrite family of asteroids, sometimes referred to as C-type asteroids. This family, making up about 75% of all asteroids, includes a bewildering collection of subtypes (B-types, F-types, G-types, CI, CM, CV, CH, CB, etc), all of which were initially thought to hold a lot of carbon. We now know that only a few of these categories, the CI and CM for example, are carbon rich.

Even so, we actually know very little about these types of asteroids. They are very fragile, so that any that reach the Earth’s surface are not a good selection of what exists. About 90% of the material gets destroyed in the atmosphere, with the remnant generally coming from the innermost core or more robust nodules. We therefore have a biased and limited sample.

It is therefore not surprising that the scientists are finding that neither Bennu nor Ryugu resembles anything else they have ever seen. Both have aspects that resemble certain types of carbonaceous chondrite asteroids, but neither provides a very good fit for anything.
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