No, the James Webb Space Telescope Didn't Find the 'Oldest Galaxy' Ever – CNET
If you’ve been following the astronomy community on Twitter or, perhaps, Captain America himself, you’ve likely come across a story about the James Webb Space Telescope’s latest find: the “oldest galaxy we’ve ever seen.”
This is exactly what we were promised from the James Webb Space Telescope. Only a week ago, the world’s collective jaw hit the floor when the first stunning images were revealed. Now the telescope is getting a proper start on its myriad science programs, but researchers have already had access to a ton of data collected during JWST’s commissioning phase and released early to researchers across the globe.
That’s how we ended up finding “the oldest galaxy” so quickly. Scientists pored through a particular dataset looking for far-off galaxies and found a candidate they’ve dubbed GL-z13, a call-back to the current confirmed record holder, GNz11.
There’s more work to be done to confirm GL-z13 is actually the new record holder – some of which will require more time pointing Webb at the galaxy – but even so, several publications have already crowned this galaxy the universal champion.
So how did we get here? And is this “the oldest galaxy” ever seen?
Over the last 24 hours, two different research groups uploaded papers (one here, the other here) to arXiv detailing their search for very distant galaxies in the James Webb data.
The website “arXiv” (I pronounce it “ark-siv” because I am a heathen, but others assure me it’s pronounced “archive”) is a preprint repository, a place for scientists to drop studies so they can be quickly disseminated to peers. It’s a great place to quickly get new research out into the world, particularly for astronomy and astrophysics, with the caveat being that the findings have not typically been peer-reviewed – an important checkpoint for validating the study and its methods.
Hubble and James Webb Space Telescope Images Compared: See the Difference
I don’t want to poop the party for GL-z13, but I do want to exercise just a teensy bit of caution. In communicating findings with such certainty, there’s potential for readers to lose trust in scientists if it turns out GL-z13 is something else entirely. Several astronomers I spoke with believe the data is quite compelling and the galaxy likely does reside a long (loooong) way away, but until there’s confirmation, GL-z13 can’t take the title of “oldest galaxy.”
And to some, even that title itself is a bit misleading.
You see, GL-Z13 isn’t really “the oldest galaxy ever” – it comes from a time when the universe was barely 330 million years old. The light from that galaxy? Well, yes, it’s super old. It has traveled a long time to reach the JWST. But the galaxy itself, if confirmed, is probably the youngest galaxy ever seen, according to Nick Seymour, an astrophysicist at Curtin University in Western Australia.
“At 330 million years after the Big Bang, it can’t be more than 100 million years old at best,” Seymour said. “Hence, this really is a baby galaxy at the dawn of time.”
Getting excited about record-breaking space feats is a given. As a science journalist, I do this practically every day. But in reporting on new discoveries, it’s important to convey uncertainty. In headlines, in social posts, in the way we discuss scientific progress. We have to set the correct benchmark and leave in that uncertainty. The tale of GL-z13 is a wonderful one, and it’s only just beginning. Astronomers now have to study it a whole lot more to make sure the distances are correct.
“There’s obviously a lot of follow-up work to do, but it really is sort of a glimpse of where things are going with James Webb,” said Michael Brown, an astrophysicist at Monash University.
It was only in April, before Webb was scouring the cosmos, that astronomers announced they may have discovered the most distant galaxy yet, HD1. That galaxy is believed to be from a time when the universe was about 330 million years old. Brown noted at the time it was worth being cautious about handing over the title to HD1 because the data might point to a galaxy billions of light-years closer to Earth. To confirm its distance, just like with GL-z13, we need more observations.
Know what telescope might be able to do that? You guessed it: JWST.
We’re fascinated by records being broken, but perhaps the most interesting point from all of this is that if Webb works as well as expected (and it seems to work better than even scientists dreamed), the title for “oldest galaxy” will change hands as much as WWE’s 24/7 Hardcore Championship. We’ll be finding new galaxies from even further back in time at a pace we couldn’t dream of.
If that’s the case, I expect it won’t be too long before the record tumbles.
Updated July 22: Headline changed, added context to oldest galaxy paragraph.
Look up: 5 planets will align in Tuesday's night sky – CBC.ca
Tonight, just after sunset, skywatchers across B.C. will be in for an eye-popping show.
Five planets — Mars, Uranus, Venus, Mercury and Jupiter — will be lined up in an arc and visible on the western horizon from almost anywhere on Earth.
“I like to call it, essentially, a cosmic coincidence,” said Andrew Ferreira, a public relations representative with the Vancouver branch of the Royal Astronomical Society of Canada.
“It’s purely just a coincidence that, you know, five planets happened to line up more or less from our perspective.”
In an interview with CBC, Ferreira said the best time to view the phenomenon will be just after the sun drops below the horizon. Keeping watch just after sunset is best, because as the night sky moves, “it’s essentially going to keep panning these planets down below the horizon.”
Ferreira’s suggestion is to spot the half-moon in the sky and trace a visual line down from there to see Mars. Below that will be Uranus and Venus. Below Venus will be Mercury, and closest to the horizon will be Jupiter.
Ferreira said Venus will outshine Uranus, but Uranus will be visible as a “greenish-blueish glow.” Mercury, he said, will be very faint but visible through binoculars, and people in downtown Vancouver or other urban centres might not be able to see Jupiter because of its low position on the horizon.
Getting away from city lights and buildings increases the chances for clearer viewing. Ferreira said giving your eyes a few minutes to adjust to the sky is also a good idea.
Great conditions for viewing
Of course, people hoping to catch the planetary procession will also benefit from clear skies overhead. And there’s good news on that front.
“The forecast for almost the entire province is looking great for a night-sky viewing,” said CBC meteorologist Johanna Wagstaffe.
“We have a high pressure system in place for B.C. which is bringing cloudless skies for almost everyone. The exceptions are a few high clouds that may sneak in tonight to northern B.C.”
“It may get a little chilly though with no clouds to keep the daytime heat in, so bundle up when you look up tonight.”
Alignments happen once or twice each year
As for the rarity of planetary alignments, Ferreira said ones like tonight happen once or twice each year. But an alignment of all the planets in the solar system, minus Earth, “that’s something like once every 200 or 300 years,” he said. “So it kind of depends on the objects and how many of them are lined up.”
Rare or not, Ferreira said events like tonight are always a joy, even for avid skywatchers like himself.
“It’s exciting being able to tell people about it — to get other people excited about what we do,” he said.
“I always tell people that astronomy is the easiest science to do because all you need is your eyes and the ground. You lie on your back and you look up and you know you’re doing astronomy.”
NASA’S JWST measures the temperature of a rocky exoplanet
An international team of researchers has used the NASA/ESA/CSA James Webb Space Telescope to measure the temperature of the rocky exoplanet TRAPPIST-1 b. The measurement is based on the planet’s thermal emission: heat energy given off in the form of infrared light detected by Webb’s Mid-Infrared Instrument (MIRI). The result indicates that the planet’s dayside has a temperature of about 500 kelvins (roughly 230°C), and suggests that it has no significant atmosphere. This is the first detection of any form of light emitted by an exoplanet as small and as cool as the rocky planets in our own solar system. The result marks an important step in determining whether planets orbiting small active stars like TRAPPIST-1 can sustain atmospheres needed to support life. It also bodes well for Webb’s ability to characterise temperate, Earth-sized exoplanets using MIRI.
“These observations really take advantage of Webb’s mid-infrared capability,” said Thomas Greene, an astrophysicist at NASA’s Ames Research Center and lead author on the study published today in the journal Nature. “No previous telescopes have had the sensitivity to measure such dim mid-infrared light.”
Rocky planets orbiting ultra cool red dwarfs
In early 2017, astronomers reported the discovery of seven rocky planets orbiting an ultracool red dwarf star (or M dwarf) 40 light-years from Earth. What is remarkable about the planets is their similarity in size and mass to the inner, rocky planets of our own solar system. Although they all orbit much closer to their star than any of our planets orbit the Sun – all could fit comfortably within the orbit of Mercury – they receive comparable amounts of energy from their tiny star.
TRAPPIST-1 b, the innermost planet, has an orbital distance about one hundredth that of Earth’s and receives about four times the amount of energy that Earth gets from the Sun. Although it is not within the system’s habitable zone, observations of the planet can provide important information about its sibling planets, as well as those of other M-dwarf systems.
“There are ten times as many of these stars in the Milky Way as there are stars like the Sun, and they are twice as likely to have rocky planets as stars like the Sun,” explained Greene. “But they are also very active – they are very bright when they’re young and they give off flares and X-rays that can wipe out an atmosphere.”
Co-author Elsa Ducrot from CEA in France, who was on the team that conducted the initial studies of the TRAPPIST-1 system, added, “It’s easier to characterise terrestrial planets around smaller, cooler stars. If we want to understand habitability around M stars, the TRAPPIST-1 system is a great laboratory. These are the best targets we have for looking at the atmospheres of rocky planets.”
Detecting an atmosphere (or not)
Previous observations of TRAPPIST-1 b with the NASA/ESA Hubble Space Telescope, as well as NASA’s Spitzer Space Telescope, found no evidence for a puffy atmosphere, but were not able to rule out a dense one.
One way to reduce the uncertainty is to measure the planet’s temperature. “This planet is tidally locked, with one side facing the star at all times and the other in permanent darkness,” said Pierre-Olivier Lagage from CEA, a co-author on the paper. “If it has an atmosphere to circulate and redistribute the heat, the dayside will be cooler than if there is no atmosphere.”
The team used a technique called secondary eclipse photometry, in which MIRI measured the change in brightness from the system as the planet moved behind the star. Although TRAPPIST-1 b is not hot enough to give off its own visible light, it does have an infrared glow. By subtracting the brightness of the star on its own (during the secondary eclipse) from the brightness of the star and planet combined, they were able to successfully calculate how much infrared light is being given off by the planet.
Measuring minuscule changes in brightness
Webb’s detection of a secondary eclipse is itself a major milestone. With the star more than 1,000 times brighter than the planet, the change in brightness is less than 0.1%.
“There was also some fear that we’d miss the eclipse. The planets all tug on each other, so the orbits are not perfect,” said Taylor Bell, the post-doctoral researcher at the Bay Area Environmental Research Institute who analysed the data. “But it was just amazing: The time of the eclipse that we saw in the data matched the predicted time within a couple of minutes.”
Analysis of data from five separate secondary eclipse observations indicates that TRAPPIST-1 b has a dayside temperature of about 500 kelvins, or roughly 230°C. The team thinks the most likely interpretation is that the planet does not have an atmosphere.
“We compared the results to computer models showing what the temperature should be in different scenarios,” explained Ducrot. “The results are almost perfectly consistent with a blackbody made of bare rock and no atmosphere to circulate the heat. We also didn’t see any signs of light being absorbed by carbon dioxide, which would be apparent in these measurements.”
This research was conducted as part of Guaranteed Time Observation (GTO) program 1177, which is one of eight approved GTO and General Observer (GO) programs designed to help fully characterise the TRAPPIST-1 system. Additional secondary eclipse observations of TRAPPIST-1 b are currently in progress, and now that they know how good the data can be, the team hopes to eventually capture a full phase curve showing the change in brightness over the entire orbit. This will allow them to see how the temperature changes from the day to the nightside and confirm if the planet has an atmosphere or not.
“There was one target that I dreamed of having,” said Lagage, who worked on the development of the MIRI instrument for more than two decades. “And it was this one. This is the first time we can detect the emission from a rocky, temperate planet. It’s a really important step in the story of discovering exoplanets.”
Uncrewed Russian spacecraft that leaked coolant lands safely
A Russian space capsule safely returned to Earth without a crew Tuesday, months after it suffered a coolant leak in orbit.
The Soyuz MS-22 leaked coolant in December while attached to the International Space Station. Russian space officials blamed the leak on a tiny meteoroid that punctured the craft’s external radiator. They launched an empty replacement capsule last month to serve as a lifeboat for the crew.
The damaged capsule safely landed Tuesday under a striped parachute in the steppes of Kazakhstan, touching down as scheduled at 5:45 p.m. (7:45 a.m. EDT) 147 kilometres (91 miles) southeast of Zhezkazgan under clear blue skies.
Space officials determined it would be too risky to bring NASA’s Frank Rubio and Russia’s Sergey Prokopyev and Dmitri Petelin back in the Soyuz in March as originally planned, as cabin temperatures would spike with no coolant, potentially damaging computers and other equipment, and exposing the suited-up crew to excessive heat.
The three launched in September for what should have been a six-month mission on the International Space Station. They now are scheduled to return to Earth in September in a new Soyuz that arrived at the space outpost last month with no one on board, meaning the trio will spend a year in orbit.
Also on the station are NASA astronauts Stephen Bowen and Woody Hoburg, the United Arab Emirates’ Sultan Alneyadi, and Russia’s Andrey Fedyaev.
A similar coolant leak was spotted in February on the Russian Progress MS-21 cargo ship docked at the space outpost, raising suspicions of a manufacturing flaw. Russian state space corporation Roscosmos ruled out any defects after a check and concluded that both incidents resulted from hits by meteoroids.
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