Space Cat


Joined September 2020

The Hubble Space Telescope is currently offline.

On Sunday 13 June, the telescope’s payload computer went offline, and engineers here on Earth are currently performing operations to get it up and running again.

The payload computer, as you might expect, is vital to Hubble’s continued science operations. It’s the ‘brains’ of the instrument, coordinating and controlling the various instruments with which Hubble is equipped. It also monitors the telescope for issues.

Initially, NASA engineers speculated that the cause of the halt was a degrading memory module. An attempt to restart the computer failed, so, on Wednesday 16 June, the Hubble operations team attempted to switch to a backup memory module.

This, too, proved futile.

“The command to initiate the backup module failed to complete,” NASA explained in a blog post.

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In January 1861 John Tyndall, a physicist at London’s Royal Institution, submitted a paper to the Philosophical Transactions of the Royal Society of London. The paper bore the title “On the absorption and radiation of heat by gases and vapours, and on the physical connexion of radiation, absorption, and conduction.” After testing the heat-retaining properties of several gases, Tyndall had concluded that some were capable of trapping heat, and thus he became one of the first physicists to recognize and describe that basis for the greenhouse effect. A month after its submission, the paper was read aloud at a meeting of the society, and several months after that, a revised version of the paper was in print.

That path from submission to revision and publication will sound familiar to modern scientists. However, Tyndall’s experience with the Philosophical Transactions—in particular, with its refereeing system—was quite different from what authors experience today. Tracing “On the absorption and radiation of heat” through the Royal Society’s editorial process highlights how one of the world’s most established refereeing systems worked in the 1860s. Rather than relying on anonymous referee reports to improve their papers, authors engaged in extensive personal exchanges with their reviewers. Such a collegial approach gradually lost favor but recently has undergone something of a resurgence.

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Why does this galaxy have such a long tail? In this stunning vista, based on image data from the Hubble Legacy Archive, distant galaxies form a dramatic backdrop for disrupted spiral galaxy Arp 188, the Tadpole Galaxy. The cosmic tadpole is a mere 420 million light-years distant toward the northern constellation of the Dragon (Draco). Its eye-catching tail is about 280 thousand light-years long and features massive, bright blue star clusters. One story goes that a more compact intruder galaxy crossed in front of Arp 188 - from right to left in this view - and was slung around behind the Tadpole by their gravitational attraction. During the close encounter, tidal forces drew out the spiral galaxy’s stars, gas, and dust forming the spectacular tail. The intruder galaxy itself, estimated to lie about 300 thousand light-years behind the Tadpole, can be seen through foreground spiral arms at the upper right. Following its terrestrial namesake, the Tadpole Galaxy will likely lose its tail as it grows older, the tail’s star clusters forming smaller satellites of the large spiral galaxy.

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I have little doubt in my mind that as this gets closer to the Sun, it will begin displaying the coma and tail typical of every other object yet seen in its orbit. It almost feels premature to ascribe any sort of theoretical slope to it with how little precedent there is for objects like this, but if Hale-Bopp is any indication with its slope of 20 at large distances, then 2014 UN271 could possibly reach magnitude 13 in early 2031 - but I wouldn’t count on much brighter than 16 or 17 just yet. Either way, that’s impressively bright, and this object should make an exceptional target of study in the next couple of decades to accompany how exceptional an object it looks to be.

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Today the Sun reaches its northernmost point in planet Earth’s sky. Called a solstice, many cultures mark this date as a change of seasons – from spring to summer in Earth’s Northern Hemisphere and from fall to winter in Earth’s Southern Hemisphere. Precisely, the single time of solstice occurs today for some parts of the world, but tomorrow for other regions. The featured image was taken during the week of the 2008 summer solstice at Stonehenge in United Kingdom, and captures a picturesque sunrise involving fog, trees, clouds, stones placed about 4,500 years ago, and a 4.5 billion year old large glowing orb. Even given the precession of the Earth’s rotational axis over the millennia, the Sun continues to rise over Stonehenge in an astronomically significant way.

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The Hubble Space Telescope, which has been peering into the universe for more than 30 years, has been down for the past few days, NASA said Friday.

The problem is a payload computer that stopped working last Sunday, the US space agency said.

It insisted the telescope itself and scientific instruments that accompany it are “in good health.”

“The payload computer’s purpose is to control and coordinate the science instruments and monitor them for health and safety purposes,” NASA said.

An attempt to restart it on Monday failed.

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The most accurate distance measurement yet of ultra-diffuse galaxy (UDG) NGC1052-DF2 (DF2) confirms beyond any shadow of a doubt that it is lacking in dark matter. The newly measured distance of 22.1 +/-1.2 megaparsecs was obtained by an international team of researchers led by Zili Shen and Pieter van Dokkum of Yale University and Shany Danieli, a NASA Hubble Fellow at the Institute for Advanced Study.

“Determining an accurate distance to DF2 has been key in supporting our earlier results,” stated Danieli. “The new measurement reported in this study has crucial implications for estimating the physical properties of the galaxy, thus confirming its lack of dark matter.”

The results, published in Astrophysical Journal Letters on June 9, 2021, are based on 40 orbits of NASA’s Hubble Space Telescope, with imaging by the Advanced Camera for Surveys and a ‘tip of the red giant branch’ (TRGB) analysis, the gold standard for such refined measurements. In 2019, the team published results measuring the distance to neighboring UDG NGC1052-DF4 (DF4) based on 12 Hubble orbits and TRGB analysis, which provided compelling evidence of missing dark matter. This preferred method expands on the team’s 2018 studies that relied on “surface brightness fluctuations” to gage distance. Both galaxies were discovered with the Dragonfly Telephoto Array at the New Mexico Skies observatory.

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NGC 6888, also known as the Crescent Nebula, is a about 25 light-years across blown by winds from its central, bright, massive star. A triumvirate of astroimagers ( Joe, Glenn, Russell) created this sharp portrait of the cosmic bubble. Their telescopic collaboration collected over 30 hours of narrow band image data isolating light from hydrogen and oxygen atoms. The oxygen atoms produce the blue-green hue that seems to enshroud the detailed folds and filaments. Visible within the nebula, NGC 6888’s central star is classified as a Wolf-Rayet star (WR 136). The star is shedding its outer envelope in a strong stellar wind, ejecting the equivalent of the Sun’s mass every 10,000 years. The nebula’s complex structures are likely the result of this strong wind interacting with material ejected in an earlier phase. Burning fuel at a prodigious rate and near the end of its stellar life this star should ultimately go out with a bang in a spectacular supernova explosion. Found in the nebula rich constellation Cygnus, NGC 6888 is about 5,000 light-years away.

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Astronomers say they’ve put to bed the mystery of why one of the most familiar stars in the night sky suddenly dimmed just over a year ago.

Betelgeuse, a red supergiant in the constellation of Orion, abruptly darkened in late 2019, early 2020.

The behaviour led many to speculate that it might be about to explode.

But a team using the Very Large Telescope (VLT) in Chile say the cause was almost certainly a giant dust cloud between us and the star.

Even if you can’t name many points in the sky, you’ll definitely know Betelgeuse by sight. It’s the orange dot in the top-left corner of Orion - or bottom-right, if you’re viewing the constellation in the Southern Hemisphere.

Close to Earth, relatively speaking, at a distance of about 550 light-years, Betelgeuse is what’s known as a semi-regular variable star. It naturally brightens and darkens over a period of roughly 400 days.

But what happened 18 months ago was out of the ordinary. The loss of brightness was far greater than anything previously recorded.

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If Scorpius looked this good to the unaided eye, humans might remember it better. Scorpius more typically appears as a few bright stars in a well-known but rarely pointed out zodiacal constellation. To get a spectacular image like this, though, one needs a good camera, a dark sky, and some sophisticated image processing. The resulting digitally-enhanced image shows many breathtaking features. Diagonal across the image right is part of the plane of our Milky Way Galaxy. Visible there are vast clouds of bright stars and long filaments of dark and intricate dust. Rising vertically on the image left are dark dust bands known as the Dark River. Several of the bright stars on the left are part of Scorpius’ head and claws, and include the bright star Antares. Numerous red emission nebulas, blue reflection nebulas, and dark filaments became visible as the deep 17-hour expo image developed. Scorpius appears prominently in southern skies after sunset during the middle of the year.

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The spin of the Milky Way’s galactic bar, which is made up of billions of clustered stars, has slowed by about a quarter since its formation, according to a new study by researchers at University College London (UCL) and the University of Oxford.

For 30 years, astrophysicists have predicted such a slowdown, but this is the first time it has been measured.

The researchers say it gives a new type of insight into the nature of dark matter, which acts like a counterweight slowing the spin.

In the study, published in the Monthly Notices of the Royal Astronomical Society, researchers analysed Gaia space telescope observations of a large group of stars, the Hercules stream, which are in resonance with the bar—that is, they revolve around the galaxy at the same rate as the bar’s spin.

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A galactic powerhouse. This image shows the spiral galaxy NGC 3254, observed using Hubble’s Wide Field Camera 3 (WFC3).

What does the largest moon in the Solar System look like? Jupiter’s moon Ganymede, larger than even Mercury and Pluto, has an icy surface speckled with bright young craters overlying a mixture of older, darker, more cratered terrain laced with grooves and ridges. The cause of the grooved terrain remains a topic of research, with a leading hypothesis relating it to shifting ice plates. Ganymede is thought to have an ocean layer that contains more water than Earth – and might contain life. Like Earth’s Moon, Ganymede keeps the same face towards its central planet, in this case Jupiter. The featured image was captured last week by NASA’s robotic Juno spacecraft as it passed only about 1000 kilometers above the immense moon. The close pass reduced Juno’s orbital period around Jupiter from 53 days to 43 days. Juno continues to study the giant planet’s high gravity, unusual magnetic field, and complex cloud structures.

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Cosmonaut Valeri Polyakov looks out a window of Mir space station in this photo taken from Space Shuttle Discovery on February 6, 1995.

This June 2020 image from the Hubble Space Telescope shows the galaxy cluster MACS J0416. This is one of six galaxy clusters being studied by the Hubble Frontier Fields program, which produced the deepest images of gravitational lensing ever made. Scientists used intracluster light (visible in blue) to study the distribution of dark matter within the cluster.

Image Credit: NASA, ESA and M. Montes (University of New South Wales)

China has released new images from its Zhurong rover, which began wheeling its way around Mars in late May. One of the photos is a lovely selfie of Zhurong posed next to its landing platform. The “touring group photo,” as the China National Space Administration calls it in a blog post, was taken with a small wireless camera that the rover placed on the surface before scooting back to line up for the shot like an excited parent.

Zhurong also took a photo of the landing platform by itself, showing the ramp the rover drove down, the Chinese flag, and if you look closely to the left of the flag, the mascots for the Beijing Winter Olympics.

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Jupiter in infrared light.

One definition for goulash, according to the Merriam-Webster dictionary, is a mixture of heterogeneous elements, or jumble. This 2017 image of galaxy Arp 299 is just that.

Arp 299 is a system located about 140 million light-years from Earth, containing two galaxies that are merging, which has created a partially blended mix of stars from each galaxy.

Data from the Chandra X-Ray Observatory reveals 25 bright X-ray sources sprinkled throughout the Arp 299 concoction. Fourteen of these sources are such strong emitters of X-rays that astronomers categorize them as “ultra-luminous X-ray sources,” or ULXs.

This composite image of Arp 299 contains X-ray data from Chandra (pink), higher-energy X-ray data from NuSTAR (purple), and optical data from the Hubble Space Telescope (white and faint brown). Arp 299 also emits copious amounts of infrared light that have been detected by observatories such as the Spitzer Space Telescope.

Image Credit: X-ray: NASA/CXC/Univ of Crete/K. Anastasopoulou et al, NASA/NuSTAR/GSFC/A. Ptak et al; Optical: NASA/STScI

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