Starship Asterisk*

Image Credit: Raquel Shida / ESO

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A comet from the outer reaches of the Solar System, nicknamed NEOWISE, was photographed by two ESO staff members — who are also keen astrophotographers — on 8 July 2020 in the skies over the ESO Supernova and ESO Headquarters in Garching, Germany. This rare treat was also accompanied by another night-time phenomena: the very unusual noctilucent clouds — shiny, icy clouds that look remarkably like water ripples in the night sky.

Officially called C/2020 F3, NEOWISE was first discovered by the NASA NEOWISE space mission in March this year. It is expected to dim as the month goes on, but to remain visible to the naked eye throughout July. It will reach its closest point to Earth on 23 July, at a distance of just over 100 million km.

The comet’s spectacular bright tail is caused by heat from the Sun, which is evaporating the outer layers of the icy comet. In fact, NEOWISE has already survived its closest encounter with our Sun, on 3 July 2020. There is still a risk that it will fracture as it slingshots away from the Sun’s heat. If it remains intact, it will journey back to the icy outer regions of our Solar System, and is not expected to return for approximately another 6800 years.

• Alternative views of NEOWISE by astrophotographer Stefan Ströbele (photo 1 | photo 2)
• Another look at the comet by Raquel Shida

Image Credit: ESA/Hubble & NASA, R. Sahai

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Galaxies are well known as the birthplaces of stars and planets thanks to the overwhelmingly large amount of dust and gas within them. Over time, cold gas coalesces into molecular clouds, leading to the further emergence of star-forming regions.

This image taken with the NASA/ESA Hubble Space Telescope depicts a fantastic new class of star-forming nursery, known as Free-floating Evaporating Gaseous Globules, or frEGGs for short. This object, known as J025027.7+600849, is located in the constellation of Cassiopeia.

When a massive new star (or stars) starts to shine while still within the cool molecular cloud from which it formed, its energetic radiation can ionise the cloud’s hydrogen and create a large, hot bubble of ionised gas. Amazingly, located within this bubble of hot gas around a nearby massive star are the frEGGs: dark compact globules of dust and gas, some of which are also giving birth to low-mass stars. The boundary between the cool, dusty frEGG and hot gas bubble is seen as the glowing purple/blue edges in this fascinating image.

Learning more about these odd objects can help astronomers understand how stars like our Sun form under external influences. In fact, our Sun may have even been born in a frEGG!

Ann wrote: ↑Thu Jul 09, 2020 4:36 pm

starsurfer wrote: ↑Thu Jul 09, 2020 3:12 pm NGC 1501
https://www.hansonastronomy.com/ngc1501
Copyright: Mark Hanson
NGC1501.jpg

Fascinating!

Unlike you, starsurfer, I am of course more interested in the bright blue star to the right of the planetary than I am in the planetary itself.

Is that a reflection nebula surrounding that blue star, or is that just a photographic effect?

Ann

bystander wrote: ↑Mon Jul 13, 2020 2:59 pm A frEGGs-cellent Discovery
ESA Hubble Picture of the Week | 2020 Jul 13

Image Credit: ESA/Hubble & NASA, R. Sahai

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Galaxies are well known as the birthplaces of stars and planets thanks to the overwhelmingly large amount of dust and gas within them. Over time, cold gas coalesces into molecular clouds, leading to the further emergence of star-forming regions.

This image taken with the NASA/ESA Hubble Space Telescope depicts a fantastic new class of star-forming nursery, known as Free-floating Evaporating Gaseous Globules, or frEGGs for short. This object, known as J025027.7+600849, is located in the constellation of Cassiopeia.

When a massive new star (or stars) starts to shine while still within the cool molecular cloud from which it formed, its energetic radiation can ionise the cloud’s hydrogen and create a large, hot bubble of ionised gas. Amazingly, located within this bubble of hot gas around a nearby massive star are the frEGGs: dark compact globules of dust and gas, some of which are also giving birth to low-mass stars. The boundary between the cool, dusty frEGG and hot gas bubble is seen as the glowing purple/blue edges in this fascinating image.

Learning more about these odd objects can help astronomers understand how stars like our Sun form under external influences. In fact, our Sun may have even been born in a frEGG!

Image Credit: ESA/Hubble & NASA, M. Gregg

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A notable feature of most spiral galaxies is the multitude of arching spiral arms that seemingly spin out from the galaxy’s centre. In this image, taken with the NASA/ESA Hubble Space Telescope, the stunning silvery-blue spiral arms of the galaxy NGC 4848 are observed in immense detail. Not only do we see the inner section of the spiral arms containing hundreds of thousands of young, bright, blue stars, but Hubble has also captured the extremely faint wispy tails of the outer spiral arms.

This wispy barred spiral galaxy was first discovered in 1865 by the German astronomer Heinrich Louis d’Arrest. In his career, Heinrich also notably discovered the asteroid 76 Freia and many other galaxies and he also contributed to the discovery of Neptune.

If you are situated in the Northern Hemisphere with a large telescope, you might just be able to observe the ghost-like appearance of this faint galaxy within faint constellation of Coma Berenices (Berenice’s Hair).

Image Credit: ESO/ Petr Horalek

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This outstanding picture taken in Chile’s Atacama Desert shows the Sun setting behind three of the four unit telescopes of ESO's Very Large Telescope (VLT). The prime observing conditions are due to the location of the observatory. At an altitude of 2600m, ESO’s Paranal Observatory is hosted in one of the driest areas in the world, with incredibly clear skies.

Taken only a dozen minutes after sunset, stars already scatter across the cloudless sky in this image. The bright star Sirius is visible, while the famous constellation of Orion, the hunter, hovers over the dome of the unit telescope in the foreground. As the darkness deepens, the starry skies will be revealed in more and more detail, until the conditions are perfect for world-leading science observations.

Susanna Kohler wrote:

You’re looking at a frozen, hollow shell of ice roughly 20 cm in diameter and 3 cm thick. In a new laboratory study, scientists Kathryn Harriss and Mark Burchell (University of Kent, UK) have studied what happens when a shell like this is shot with a small, high-speed projectile, causing the ice shell to explode into pieces. You can watch a slow motion video of their experiment below!

This process simulates the possible high-speed collisions and catastrophic disruptions of icy bodies — like the frozen moons of Saturn and Jupiter — in the early solar system. By exploring how a hollow ice sphere responds to impact, Harriss and Burchell hope to better understand the relative roles of a body’s core and its surface layers in determining what happens during a catastrophic disruption. Which is more important in a collision: an icy object’s crust or its core? Check out the original article, linked below, for more information on what the authors learned.

• Planetary Science Journal 1(1):19 (2020 June) DOI: 10.3847/PSJ/ab8f34

Credit: Yuri Beletsky (LCO)/ESO/ALMA

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The bright sky above Chile’s Chajnantor plateau is sliced in two by the vast, vibrant ripple of the Milky Way. Here in the southern hemisphere, the magnificently rich centre of our galaxy is often directly overhead, its brilliant cloudy length stretching from horizon to horizon. Beneath its glow, a cluster of white antennas peers keenly up at the sky, illuminated by a bright yellow light that indicates to technicians whether or not it is safe to approach.

These telescopes are part of the Atacama Large Millimeter/submillimeter Array (ALMA), a giant interferometer made up of 66 individual antennas. These antennas work together over distances of up to 16 kilometres to study the Universe in remarkable detail. ALMA is designed to “see” light invisible to the human eye — at wavelengths of around a millimetre, between infrared light and radio waves. Such light comes from the coldest and most distant places in the Universe — such as vast clouds of gas and dust in interstellar space, and the most ancient galaxies — allowing ALMA to explore how stars and planets form and evolve.

Although these wavelengths can reveal never-before-seen objects and processes, (sub)millimetre astronomy has its difficulties. This light is heavily absorbed by water vapour in the Earth’s atmosphere, and thus struggles to reach the ground. In order to do this kind of astronomy, telescopes must be built on very high, dry sites; the Chajnantor plateau, located at an altitude of over 5000 metres in the Chilean Andes, is therefore an ideal location for ALMA.

Image Credit: ESA/Hubble & NASA, L. Girardi

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Looking its best ever is the star cluster NGC 2203, here imaged by the NASA/ESA Hubble Space Telescope. Aside from its dazzling good looks, this cluster of stars contains lots of astronomical treats that have helped astronomers puzzle together the lifetimes of stars.

A main sequence star, like our Sun, is the term applied to a star during the longest period of its life, when it burns fuel steadily. Our Sun’s fuel will run out in approximately 6 billion years, and it will then move on to the next stage of its life when it will turn into a red giant. Astronomers studying NGC 2203, which contains stars that are roughly twice as massive as our Sun, found that their rotation might be a factor as to why some of the stars stay longer than usual in this main-sequence phase of their life.

This is the best resolution obtained of the star cluster to date.

bystander wrote: ↑Mon Jul 27, 2020 4:17 pm Stellar Sweet Shop
ESA Hubble Picture of the Week | 2020 Jul 27

Image Credit: ESA/Hubble & NASA, L. Girardi

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Looking its best ever is the star cluster NGC 2203, here imaged by the NASA/ESA Hubble Space Telescope. Aside from its dazzling good looks, this cluster of stars contains lots of astronomical treats that have helped astronomers puzzle together the lifetimes of stars.

A main sequence star, like our Sun, is the term applied to a star during the longest period of its life, when it burns fuel steadily. Our Sun’s fuel will run out in approximately 6 billion years, and it will then move on to the next stage of its life when it will turn into a red giant. Astronomers studying NGC 2203, which contains stars that are roughly twice as massive as our Sun, found that their rotation might be a factor as to why some of the stars stay longer than usual in this main-sequence phase of their life.

This is the best resolution obtained of the star cluster to date.