Tag: astronomy

Water and carbon monoxide detected in exoplanet’s atmosphere

9:54 am

Astronomers, using both the Hubble Space Telescope and the ground-based Gemini Telescope, have detected water and carbon monoxide in the atmosphere of an exoplanet 320 light years away.

Previously hydrogen, helium, hydrogen cyanide, iron, and magnesium have been detected in the atmospheres of a variety of exoplanets. In other cases scientists found exoplanets that were devoid of water.

This detection of water and carbon monoxide is a first for these two materials, and is somewhat significant as it is the first detection that suggests an exoplanet atmosphere that might have similarities to Earth.

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First exoplanet detected in another galaxy?

8:32 am

The uncertainty of science: Using the Chandra X-ray Observatory, astronomers think they may have detected the first exoplanet ever found in another galaxy, the Whirlpool Galaxy, 28 million light years away.

This new result is based on transits, events in which the passage of a planet in front of a star blocks some of the star’s light and produces a characteristic dip. Astronomers using both ground-based and space-based telescopes — like those on NASA’s Kepler and TESS missions — have searched for dips in optical light, electromagnetic radiation humans can see, enabling the discovery of thousands of planets.

Di Stefano and colleagues have instead searched for dips in the brightness of X-rays received from X-ray bright binaries. These luminous systems typically contain a neutron star or black hole pulling in gas from a closely orbiting companion star. The material near the neutron star or black hole becomes superheated and glows in X-rays.

Because the region producing bright X-rays is small, a planet passing in front of it could block most or all of the X-rays, making the transit easier to spot because the X-rays can completely disappear. This could allow exoplanets to be detected at much greater distances than current optical light transit studies, which must be able to detect tiny decreases in light because the planet only blocks a tiny fraction of the star.

The team used this method to detect the exoplanet candidate in a binary system called M51-ULS-1, located in M51. This binary system contains a black hole or neutron star orbiting a companion star with a mass about 20 times that of the Sun. The X-ray transit they found using Chandra data lasted about three hours, during which the X-ray emission decreased to zero. Based on this and other information, the researchers estimate the exoplanet candidate in M51-ULS-1 would be roughly the size of Saturn, and orbit the neutron star or black hole at about twice the distance of Saturn from the Sun.

While this is a tantalizing study, more data would be needed to verify the interpretation as an extragalactic exoplanet. One challenge is that the planet candidate’s large orbit means it would not cross in front of its binary partner again for about 70 years, thwarting any attempts for a confirming observation for decades. [emphasis mine]

As the press release says, this data is tantalizing, but it is really insufficient to prove that an exoplanet has been found. What is known is that for some reason the X-ray emissions from the X-ray binary system disappeared for about three hours. An exoplanet could be one explanation. So could many other things.

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Next Ariane 5 launch postponed

11:39 am

Arianespace today announced that it has postponed its next Ariane 5 launch of two communications satellites, scheduled for October 22nd, because of issues with ground equipment.

Though there appear to be no issues with the rocket, this delay could effect the launch of the James Webb Space Telescope in December on another Ariane 5 rocket. Arianespace has said that it wants to complete this launch first, to make sure the fixes it completed on the rocket’s fairing are truly working.

It was those problems that shut down all Ariane 5 launches for almost a full year.

No new launch date has been set. Normally, ground equipment issues cause short delays, so we should be hopeful all will be fixed quickly and this launch will be quickly rescheduled and take off without problems.

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Early solar system had gap separating its inner and outer regions

9:29 am

New research looking at the make-up of asteroids now suggests that the early solar system had a gap that separated the formation of planets between its inner and outer regions.

Earlier data had suggested that asteroids come in two fundamentally different groups. This new research, looking the magnetic field strength of these two groups, has confirmed this distinction, and provided additional information about the formation process of each.

Surprisingly, they found that their field strength was stronger than that of the closer-in noncarbonaceous meteorites they previously measured. As young planetary systems are taking shape, scientists expect that the strength of the magnetic field should decay with distance from the sun.

In contrast, Borlina and his colleagues found the far-out chondrules had a stronger magnetic field, of about 100 microteslas, compared to a field of 50 microteslas in the closer chondrules. For reference, the Earth’s magnetic field today is around 50 microteslas.

A planetary system’s magnetic field is a measure of its accretion rate, or the amount of gas and dust it can draw into its center over time. Based on the carbonaceous chondrules’ magnetic field, the solar system’s outer region must have been accreting much more mass than the inner region.

In other words, the accretion of planets in the outer region was faster and producing larger objects, while the inner region was slower and producing smaller objects. The data also suggests that gap existed about 4.5 billion years ago, at about the location of the asteroid belt. All in all, this scenario matches the solar system we see today.

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Webb telescope finally arrives at launch site in French Guiana

2:54 pm

Webb deployment

After almost twenty years of construction (a decade behind schedule) and a cost of $10 billion, ($9.5 billion over budget), the James Webb Space Telescope today arrived at the processing facility at Arianespace’s French Guiana spaceport, where it will be prepared for a December 18, 2021 launch on an Ariane 5 rocket.

Once launched the telescope, which is not a replacement for Hubble because it observes in the infrared (not optical) and is optimized for deep space cosmology, will take two weeks to reach its orbital position about a million miles from Earth, as shown in the graphic.

Let us all cross our fingers and toes that it all works as designed, for if it doesn’t this will be the biggest failure ever in the history of NASA.

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As expected, Pluto’s atmosphere is freezing as its orbit takes it from the Sun

10:48 am

Data from ground-based telescopes has now confirmed that Pluto’s nitrogen atmosphere has begun it annual winter freeze out as the planet’s somewhat elliptical 248-year-long orbit takes it away from the Sun.

For about 25 years, Pluto has been moving farther and farther away from the sun, so its surface temperature has been going down. And with these recent observations, the researchers found evidence showing that Pluto’s atmosphere is actually refreezing back onto its surface as the dwarf planet gets colder and colder. Pluto is so far from the sun that, as time goes on, it will get distinctly farther away (and colder) before getting closer to the sun in other regions of its immense orbit.

The astronomers were able to detect this refreezing by observing the planet as it eclipsed a star in 2018.

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New Horizons discovers two binary asteroids in Kuiper Belt

10:32 am

Overview map
Click for full map.

As New Horizons traveled from Pluto to the asteroid Arrokoth in 2018, scientists used it to take images of the relatively nearby asteroids that it was passing, and found that two of those asteroids appeared elongated.

[T]he team fit the shapes with a two-body model: two asteroids in a tight orbit. Even though the individual rocks weren’t resolved, the modeling showed that two bodies were better able to explain the elongation, as well as the brightness seen. The model for 2011 JY31 had two 50-km-wide objects nearly 200 km apart, while for 2014 OS393, the model had slightly smaller bodies (30 km across) that orbited each other 150 km apart.

The map, cropped and further annotated by me, shows New Horizons’ path during this time period, with the two binary asteroids indicated in blue.

This data, combined with the double lobe shape of Arrokoth (formerly named Ultima Thule), strongly suggests that it was not unusual for these primitives asteroids in the early solar system to coalesce from comparably sized partners.

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Orbit of biggest comet ever detected refined

10:59 am

Astronomers have now been able to better refine the orbit and size of Comet Bernardinelli-Bernstein, comet with the largest nucleus ever detected.

A new analysis, led by Bernardinelli and Bernstein themselves, found that the comet nucleus is around 150 km wide, based on its brightness. If so, that makes it the largest comet ever discovered, by quite a margin. Most are only a few kilometers to several dozen kilometers wide, while some particularly big ones, like Hale-Bopp, may be up to 80 km (50 miles) wide. The previous record-holder, Sarabat’s Comet of 1729, has been estimated at about 100 km wide.

The team was also able to calculate the orbit of Comet BB in more detail. This object is on an incredibly long round trip into and out of the solar system – at its most distant point, some 1.5 million years ago, it was about 40,400 AU away. Last time it swung through our neighborhood was about 3.5 million years ago, when it came within 18 AU of the Sun.

But its current inward journey will be its closest so far. Astronomers have already calculated that in 2031, Comet BB will peak at 10.9 AU, almost reaching the orbit of Saturn.

It is presently unclear how bright the comet will be when it reachest its closest point. It will be much farther from the Sun than most bright comets, but its large size may change what is normally expected.

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Galaxies in the early universe don’t fit the theories

9:33 am

The uncertainty of science: New data from both the ALMA telescope in Chile and the Hubble Space Telescope about six massive galaxies in the early universe suggest that there are problems and gaps in the presently accepted theories about the universe’s formation.

Early massive galaxies—those that formed in the three billion years following the Big Bang should have contained large amounts of cold hydrogen gas, the fuel required to make stars. But scientists observing the early Universe with the Atacama Large Millimeter/submillimeter Array (ALMA) and the Hubble Space Telescope have spotted something strange: half a dozen early massive galaxies that ran out of fuel. The results of the research are published today in Nature.

Known as “quenched” galaxies—or galaxies that have shut down star formation—the six galaxies selected for observation from the REsolving QUIEscent Magnified galaxies at high redshift. or the REQUIEM survey, are inconsistent with what astronomers expect of the early Universe.

It was expected that the early universe would have lots of that cold hydrogen for making stars. For some galaxies to lack that gas is inexplicable, and raises questions about the assumptions inherent in the theory of the Big Bang. It doesn’t disprove it, it simply makes it harder to fit the facts to the theory, suggesting — as is always the case — that the reality is far more complicated than the theories of scientists.

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NASA now targets December 18, 2021 for launch of Webb

1:12 pm

NASA today announced that it and the European Space Agency have scheduled the Ariane 5 launch of the James Webb Space Telescope from French Guiana for December 18, 2021.

The agency set the new target launch date in coordination with Arianespace after Webb recently and successfully completed its rigorous testing regimen – a major turning point for the mission. The new date also follows Arianespace successfully launching an Ariane 5 rocket in late July and scheduling a launch that will precede Webb. The July launch was the first for an Ariane 5 since August 2020.

Launching before the end of ’21 will allow NASA to claim that Webb is only be ten years behind schedule, not eleven. The cost overruns however remain astronomical (no pun intended). Initially budgeted at $500 million, Webb is now estimated to have cost $10 billion.

Once launched the telescope will take about six months to slowly move to its Lagrange point location about a million miles from the Earth, in the Earth’s shadow. During that time it will also be steadily deploying its many segmented mirror for infrared observations (an important detail as Webb is not a replacement for Hubble, which does most of its observations in the optical wavelengths).

Should deployment and placement go as planned, Webb will undoubtedly do ground-breaking astronomy, especially in the field of deep space cosmology. If anything should go wrong, any repair mission will take at a minimum five years to mount, if ever.

Keep those fingers and toes crossed!

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Astronomers discover white dwarf stars still burning hydrogen

9:50 am

The uncertainty of science: Using Hubble observations of the white dwarfs in two different globular clusters, astronomers have discovered that — contrary to the consensus opinion — some white dwarf stars are not slowly cooling embers of a dead star, but are still generating nuclear fusion by burning hydrogen in their outer layers.

Using Hubble’s Wide Field Camera 3 the team observed [globular clusters] M3 and M13 at near-ultraviolet wavelengths, allowing them to compare more than 700 white dwarfs in the two clusters. They found that M3 contains standard white dwarfs, which are simply cooling stellar cores. M13, on the other hand, contains two populations of white dwarfs: standard white dwarfs and those which have managed to hold on to an outer envelope of hydrogen, allowing them to burn for longer and hence cool more slowly.

Comparing their results with computer simulations of stellar evolution in M13, the researchers were able to show that roughly 70% of the white dwarfs in M13 are burning hydrogen on their surfaces, slowing down the rate at which they are cooling.

This discovery could have consequences for how astronomers measure the ages of stars in the Milky Way galaxy. The evolution of white dwarfs has previously been modeled as a predictable cooling process. This relatively straightforward relationship between age and temperature has led astronomers to use the white dwarf cooling rate as a natural clock to determine the ages of star clusters, particularly globular and open clusters. However, white dwarfs burning hydrogen could cause these age estimates to be inaccurate by as much as 1 billion years.

In other words, many past age estimates for star clusters could be very wrong, which in turn could mean the general understanding of the evolution of these objects could be very wrong as well.

These results also illustrate a fact that astronomers seem to always forget. The stars in any one category (white dwarfs, red super giants, yellow stars like the Sun, etc.) are not all identical, and thus their life and death processes will not all follow the predicted stages, like clockwork. Things are always far more complicated. Though the predictions might be broadly right, there will be many variations, so many that it will often be difficult to draw a generalized conclusion.

It seems that with white dwarfs astronomers have made this mistake, and now must rethink many of their conclusions.

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The troubled politics of ground-based astronomy

10:54 am

Link here. The article outlines the politics and negotiations now going on during the writing of the next astronomy decadal survey, the document American astronomers have published every decade since the 1960s to provide the science agencies in the federal government guidance on how to spend the taxpayers’ money on the next decade’s astronomy projects.

The focus is on the problems now faced by the two big American ground-based telescopes, the Thirty Meter Telescope (TMT) and the Giant Magellan Telescope (GMT).

The future of the Giant Magellan Telescope (GMT) and the Thirty Meter Telescope (TMT) likely depends on whether the survey recommends that NSF spend what sources put at $1.8 billion to support a recently forged partnership between the projects. If it does, other proposals could lose out, such as a ­continent-spanning radio array and detectors for neutrinos and other cosmic particles.

While some astronomers are pushing for this $1.8 billion bailout to save both, others are arguing the money can be better spent elsewhere. There is also a third option, not mentioned, which would be to abandon one of these telescopes and instead build just one.

The story is focused entirely on ground-based astronomy, which is remarkably very near-sighted for scientists whose job it is to see a far as possible. The future of astronomy is in space, and to not consider that alternative in this discussion means you aren’t considering all your options. For $1.8 billion, using private rockets and competitive construction approaches, I strongly believe a very large optical telescope could be launched that would provide far more cutting edge astronomy than any larger ground-based telescope. Hubble has proven that endlessly for the past thirty years.

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