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Star birth is a messy and chaotic event. Some of the process remains well hidden behind clouds of gas and dust that make up star-forming regions. However, part of it happens in wavelengths of light we can detect, such as visible light and infrared. It’s an intricate process that the Webb telescope (JWST) can study in detail.

Recently this infrared-sensitive space observatory zeroed in on a portion of a star-forming region called NGC 604 in the Triangulum galaxy and returned a pair of amazing images. The telescope’s Near-infrared Camera (NIRCam) image shows gas bubbles, and tendrils and wisps of glowing material lit up by more than 200 hot, young massive stars. Some of those stars are probably at least 100 times the mass of the Sun. Finding so many of them in such a small area of space is a rare occurrence.

JWST’s mid-infrared instrument (MIRI) identified glowing clouds of gas and dust in NGC 604 and a collection of red supergiant stars in the surrounding galaxy region. They’re cool and ancient, and most are hundreds of times the diameter of the Sun.

JWST Reveals the Chemistry of a Star-forming Region

As cool as these images look, the chemistry they reveal is amazing. Orange-colored streaks in the NIRCam image indicate the presence of polycyclic hydrocarbons (PAHs). These carbon-based molecules play a big role in star- and planet-forming processes. Here on Earth they’re pretty commonly found in coal, oil, gasoline, and as a by-product of burning these substances. Obviously, coal, gasoline, and burning garbage don’t exist in outer space. However, pure PAHs do, and they’re a good tracer of star formation. So, it’s not a surprise to find them in this particular nebula.

Deep red regions in the nebula are pockets of molecular hydrogen. That’s the basic building block of stars. In other places, hot young stars have ionized hydrogen gas, which appears white in the image. The MIRI images also show the distribution of cool gas and dust throughout the nebula, and blue tendrils identify the presence of more PAHs.

The view of NGC 604 from JWST's MIRI instrument. Notice the difference in view from NIRCam. Each part of the infrared spectrum reveals different features in the clouds of gas and dust. Credit: NASA, ESA, CSA, STScI
The view of NGC 604 from JWST’s MIRI instrument. Notice the difference in view from NIRCam. Each part of the infrared spectrum reveals different features in the clouds of gas and dust. Credit: NASA, ESA, CSA, STScI

Dynamics of Star Birth

The chaotic part of star birth comes as hot young stars are born. They directly affect the stellar nursery by emitting copious amounts of ultraviolet radiation into space. That ionizes (heats) the surrounding birth clouds and causes them to glow. The stellar newborns also blow hot stellar winds like gas bubbles out around them. That carves out caverns in the dusty birth cloud and creates those tendrils.

The creation of stars gobbles up immense amounts of gas and dust. The most massive stars, like the ones seen in these images, basically clear out the region. That also shuts down (or severely stunts) future star formation. Eventually, the process of stellar creation will play itself out here, leaving behind clusters of massive, hot young stars, along with smaller more sun-like stars and even a few brown dwarfs.

bout the NGC 604 Star-forming Region

NGC 604 is a pretty typical star birth creche, similar to the Orion Nebula in our own Milky Way Galaxy. It’s fairly extensive—it measures about 1,300 light-years across (much larger than the Orion star-birth complex) and lies about 2.7 million light-years away from us. The cloud has been making baby stars for at least 3.5 million years. Compare that to the Orion Nebula, which is about 1,400 light-years away from us and has been cranking out stars for about 3 million years. Its brightest stars lie in the Trapezium at the heart of the
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The Inner and Outer Milky Way Aren’t the Same Thickness, and that’s Surprising

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At first glance, the universe and night sky seem largely unchanging. The reality is very different, even now, a gas cloud is charging toward the Milky Way Galaxy and is expected to crash into us in 27 million years. A team of astronomers hoping to locate the exact position of the expected impact site have been unsuccessful but have accidentally measured the thickness of the Milky Way! Analysing radio data, they have been able to deduce the thickness of the inner and outer regions and discovered a dramatic difference between the two. 

The team of astronomers from the US National Science Foundation’s Green Bank Observatory were attempting to study the Smith Cloud. This high velocity cloud of hydrogen gas is located in the constellation Aquila at a distance of somewhere between 36,000 and 45,000 light years. Previous studies from the Green Bank Observatory have shown the cloud contains at least 1 million times the mass of the Sun and measures 9,800 light years long by 3,300 light years wide. 

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A false-color image of the Smith Cloud made with data from the Green Bank Telescope (GBT). New analysis indicates that it is wrapped in a dark matter halo. Credit: NRAO/AUI/NSF

The plan was simple enough, to observe the spot where the cloud is currently interacting with the Milky Way. The observation is tricky enough though as the cloud is on the far side of the Milky Way and there is a lot of stuff in the way! The team, led by Toney Minter used the 20m Green Bank Telescope to search for dust and emissions from hydroxyl molecules (composed of a hydrogen and oxygen molecule.)  What the team expected to see was a difference in composition in the region of the Milky Way interacted with the cloud which, should have very little dust and hydroxyl molecules. Clouds in the Milky Way tend to have both so a difference should be detectable. 

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The Robert C. Byrd Green Bank Telescope. Credit: Jay Young.

Minter was candidly open about the study joking ‘I knew there was a low probability that I’d find what I was looking for—and I didn’t,. But this is all part of the scientific process. You learn from what you DO and DON’T find.’

Disappointingly the team did not detect any differences in composition but what they did find was equally as interesting. The study revealed information about the Milky Way itself and the structure of its inner regions. Minter and his team had to look through the Milky Way’s inner regions for their study and what they were able to determine was the thickness of the layer of molecules in the inner Galaxy. The information enabled them to deduce the scale height of the clouds of molecular gas in the inner Milky Way. The results showed that the layer of molecules in the inner region measured 330 light years thick while those in the outer parts measured twice as much, around 660 light years.

The discovery still leaves questions unanswered. The observation certainly shows the difference in thickness between the inner and outer regions but it doesn’t give any clue as to what is driving the difference. Further observations are now required to follow up on this discovery to try and model the underlying process. Of course one other question remains unanswered and that is the nature and mechanics of the Smith Cloud and how it will impact our own Galaxy. Far from being disappointed though, Minter stated ‘That’s why astronomy is exciting, our knowledge is always evolving’

Source : While Aiming for
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Catching Comet 13P Olbers This Summer

Comet 13P Olbers by William R. Brooks

A little known periodic comet graces northern hemisphere summer skies.

Short summer nights present a tough dilemma for nighttime astronomy: to stay up late, or wake up early? Summer 2024 gives you at least one reason to opt for the former, as periodic Comet 13P/Olbers graces the evening sky.

The History of the Comet

The comet was first spotted on the night of March 6th, 1815 by astronomer Heinrich Olbers (of Olbers’ Paradox fame) observing from Bremen, Germany. The orbit was later described by Carl Gauss and Friedrich Bessel as just shy of 74 years, about five years off of the present value.

A sketch of Comet 13P Olbers from 1887 by William Robert Brooks. Credit: Public Domain

The Comet’s Orbit

Comet 13P/Olbers is on a 69 year orbit, which takes it from a perihelion 1.175 Astronomical Units (AU) from the Sun just outside of the Earth’s orbit, out to an aphelion of 32.5 AU out beyond the orbit of Neptune.

Perihelion for the comet occurs June 30th, 2024 at 1.175 AU from the Sun and 1.919 AU from the Earth.

The orbit of Comet 13P Olbers. Credit: NASA/JPL

Synopsis of the Current Apparition

In 2024, Comet 13P Olbers loiters low to the west this summer for northern observers at dusk. This is because it’s approaching Earth along our line of sight. The comet will seem to hang about 20-30 degrees above the horizon on summer evenings for mid-latitude northern hemisphere observers.

June 15
The location of the comet in the evening sky in mid-June. Credit: Stellarium

Here’s our look at what to expect from the comet month-by-month. Unless otherwise noted, ‘Passes near’ means a closest approach of less than one angular degree:


17-The orbital path of the comet is edge on as seen from our point of view, and the comet may exhibit a spiky anti-tail.

19-Passes into the constellation of the Lynx.

28-Passes near the +4.3 magnitude star 31 Lyncis.

The celestial path of the comet
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Starliner Has Five Leaks

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Many space fans have been following the successful launch of the Boeing Starliner, another commercial organisation aiming to make space more accessible. It successfully reached the International Space Station, delivering Butch Wilmore and Suni Williams into orbit but it wasn’t without a hitch. Three of its thrusters experienced problems and there were ‘five small leaks on the service module.’ The crew and ground teams are working through safety checks of power and habitability. To ensure a safe return of the astronauts NASA has extended the mission by four days to 18th June. 

Boeing Starliner is a reusable (partly) spacecraft designed to transport crews to low Earth orbit. NASA is the lead customer so, once certification has been achieved, will be used to deliver astronauts regularly to the ISS. It consists of a crew capsule that can be used ten times and an expendable service module. Measuring 4.6 metres in diameter it is slightly larger than the Apollo Command module that was a part of the historic Armstrong, Aldrin and Collins mission to the Moon.

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The Apollo 10 command/service module nicknamed “Charlie Brown” orbiting the Moon as seen from the lunar module. Credit: NASA

The Boeing Starliner launch marked its first crewed trip into orbit, with the objective of data collection for certification by NASA for regular crewed missions to ISS. The tests are numerous and include; running the spacecraft in minimal power mode (for when docked to ISS), checking suitability to support crew on its own in the event of an emergency, performing habitability studies for a four person crew and a multitude of other system checks. The module has been docked to ISS since 6th June.

Teething problems for any new module are always expected but when the word ‘leak’ pops up it is most definitely a cause for concern. In the case of Starliner, five small leaks have been detected in the service module helium manifolds. When Starliner launched, the ground team already knew there was one leak in the propulsion system but now, four more have been detected! The flight engineers initially suspected a flaw in a manifold seal or possibly even faulty installation but now, with the four additional leaks they’re trying to understand if there is a common problem.

The leaks are not the only problem that has been experienced. As Starliner approached ISS, it relied upon precise pulses from the 28 reaction control thrusters. During this critical phase of the docking process, five of them failed. More accurately, the spacecraft control software deduced they were not working and deselected them. The first docking window was missed as a result but the crew were able to test and restart four of the five engines allowing them to safely dock. Engineers are still looking into the thruster problem but are confidence it will allow the safe return of the astronauts. 

International Space Station. Credit: NASA

As for the helium leak, flight engineers have examined the leak rate and confirmed that Starliner has sufficient margin to support a return trip to Earth. With Starliner docked to the ISS the manifolds are all closed preventing any helium loss until the return trip which takes just seven hours. Even with the manifolds open and the rate of leak there is sufficient helium to support 70 hours of flight time.

Ground support teams are continuing to work through the problems and the return plan. They will explore tolerances and possible operational mitigations for the remainder of the mission. As the
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