Starship Asterisk*

bystander wrote: ↑Mon Sep 26, 2022 2:16 pm Hubble Spies a Stately Spiral Galaxy
ESA Hubble Picture of the Week | 2022 Sep 26

Image Credit: ESA/Hubble & NASA, J. Greene

---

The stately sweeping spiral arms of the spiral galaxy NGC 5495 are revealed by the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 (WFC3) in this image. NGC 5495, which lies around 300 million light-years from Earth in the constellation Hydra, is a Seyfert galaxy, a type of galaxy with a particularly bright central region. These luminous cores — known to astronomers as active galactic nuclei — are dominated by the light emitted by dust and gas falling into a supermassive black hole.

This image is drawn from a series of observations captured by astronomers studying supermassive black holes lurking in the hearts of other galaxies. Studying the central regions of galaxies can be challenging: as well as the light created by matter falling into supermassive black holes, areas of star formation and the light from existing stars all contribute to the brightness of galactic cores. Hubble’s crystal-clear vision helped astronomers disentangle the various sources of light at the core of NGC 5495, allowing them to precisely weigh its supermassive black hole.

As well as NGC 5495, two stellar interlopers are visible in this image. One is just outside the centre of NGC 5495, and the other is very prominent alongside the galaxy. While they share the same location on the sky, these objects are much closer to home than NGC 5495: they are stars from our own Milky Way. The bright stars are surrounded by criss-cross diffraction spikes, optical artefacts created by the internal structure of Hubble interacting with starlight.

starsurfer wrote: ↑Wed Sep 28, 2022 9:35 am Sagittarius B1
https://www.eso.org/public/images/potw2235a/
Copyright: ESO/Nogueras-Lara et al

Click to view full size image

Image Credit: ESA/Hubble & NASA, J. Greene

---

The stately sweeping spiral arms of the spiral galaxy NGC 5495 are revealed by the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 (WFC3) in this image. NGC 5495, which lies around 300 million light-years from Earth in the constellation Hydra, is a Seyfert galaxy, a type of galaxy with a particularly bright central region. These luminous cores — known to astronomers as active galactic nuclei — are dominated by the light emitted by dust and gas falling into a supermassive black hole.

This image is drawn from a series of observations captured by astronomers studying supermassive black holes lurking in the hearts of other galaxies. Studying the central regions of galaxies can be challenging: as well as the light created by matter falling into supermassive black holes, areas of star formation and the light from existing stars all contribute to the brightness of galactic cores. Hubble’s crystal-clear vision helped astronomers disentangle the various sources of light at the core of NGC 5495, allowing them to precisely weigh its supermassive black hole.

As well as NGC 5495, two stellar interlopers are visible in this image. One is just outside the centre of NGC 5495, and the other is very prominent alongside the galaxy. While they share the same location on the sky, these objects are much closer to home than NGC 5495: they are stars from our own Milky Way. The bright stars are surrounded by criss-cross diffraction spikes, optical artefacts created by the internal structure of Hubble interacting with starlight.

Image Credit: ESO/Stefano Bagnulo et al.

---

The arrow in this Picture of the Week marks the asteroid Didymos as seen on the night of September 25/26 with ESO’s Very Large Telescope (VLT) in Chile. Didymos has a smaller 160-metre-long moon called Dimorphos (not seen here), and on 26 September at 23:14 UTC a NASA probe is set to crash into this moon as part of the Double Asteroid Redirection Test (DART). Our VLT, like many other telescopes around the world, will be watching.

The purpose of the mission is to see if a future potentially dangerous asteroid could be deflected from its trajectory using this method. The material following the crash will also hopefully provide us with more information about the composition of asteroids – the original building blocks of our planet.

At ESO’s Paranal Observatory in Chile, all four 8.2-metre telescopes of the VLT will observe the aftermath of the impact with different instruments. The resulting data will allow astronomers to study the composition and motion of the ejected material, the structure of the asteroid’s surface and its internal properties.

The results of this experiment may provide a method of protecting our planet from hazardous asteroids but will also deepen our understanding of asteroids and hence the formation of our Solar System. To learn more about the important scientific data that will be obtained by the VLT, read our latest blog post.

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

---

A bright young star is surrounded by a shroud of thick gas and dust in this image from the NASA/ESA Hubble Space Telescope. Hubble’s Wide Field Camera 3 (WFC3) inspected a young stellar object, over 9000 light years away in the constellation Taurus, to help astronomers understand the earliest stages in the lives of massive stars. This object — which is known to astronomers as IRAS 05506+2414 — is thought to be an example of an explosive event caused by the disruption of a massive young star system. If so, it would only be the second such example known.

Usually the swirling discs of material surrounding a young star are funnelled into twin outflows of gas and dust from the star. In the case of IRAS 05506+2414, however, a fan-like spray of material travelling at velocities of up to 350 kilometres per second is spreading outwards from the centre of this image.

Astronomers turned to Hubble’s Wide Field Camera 3 to measure the distance to IRAS 05506+2414. While it is possible to measure the velocity of material speeding outwards from the star, astronomers cannot tell how far from Earth the star actually is from a single observation. However, by measuring the distance that the outflow travels between successive images, they will be able to infer the distance to IRAS 05506+2414. This will allow astronomers to determine how bright the star is and how much energy it is emitting, and hence to estimate its mass — all vital information that will help to understand the origin of this bright young star’s unusual outflow.

Image Credit: Zdeněk Bardon/ESO

---

Click to play embedded YouTube video.

ESO: Documentary ‘MUSE, The Cosmic Time Machine’

Is this tangle of cords and hoses a machine from the movie The Matrix? You can stay calm: even though the sign says “danger”, what may look like a threatening machine is actually the Multi Unit Spectroscopic Explorer (MUSE) instrument on ESO’s Very Large Telescope (VLT) at Paranal Observatory. MUSE is one of the largest instruments at the VLT and is connected to one of its four 8.2 m telescopes, Yepun.

The power of MUSE is that it can take thousands of images at many different colours in one go or, in other words, to take lots of spectra within a large portion of the sky at once. This means that astronomers can observe a galaxy and get the spectral information about all regions of that galaxy. From the spectra, astronomers can determine, for instance, the chemical composition of the galaxy, key in understanding how elements such as the ones that make up us came to be.

MUSE is highly sophisticated: it comprises 24 spectrographs working together, and it took over nine years to construct, assemble and test it. One can thus truly say that MUSE is a one of its kind and a revolutionary instrument.

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

---

A glittering multitude of stars in the globular cluster Terzan 4 fill this image from the NASA/ESA Hubble Space Telescope. Globular clusters are collections of stars bound together by their mutual gravitational attraction, and can contain millions of individual stars. As this image shows, the heart of a globular cluster such as Terzan 4 is a densely packed, crowded field of stars — which makes for spectacular images!

The launch of Hubble in 1990 revolutionised the study of globular clusters. The individual stars in these dense crowds are almost impossible to distinguish from one another with ground-based telescopes, but can be picked apart using space telescopes. Astronomers have taken advantage of Hubble’s crystal-clear vision to study the stars making up globular clusters, as well as how these systems change over time.

This particular observation comes from astronomers using Hubble to explore Terzan 4 and other globular clusters to understand the shape, density, age, and structure of globular clusters close to the centre of the Milky Way. Unlike globular clusters elsewhere in the sky, these globular clusters have evaded detailed observation because of the clouds of gas and dust swirling around the galactic core. These clouds blot out starlight in a process that astronomers refer to as ‘extinction’, and complicate astronomical observations.

Astronomers took advantage of the sensitivity of two of Hubble’s instruments — the Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3) — to overcome the impact of extinction on Terzan 4. By combining Hubble imagery with sophisticated data processing, astronomers were able to determine the ages of galactic globular clusters to within a billion years — a relatively accurate measurement in astronomical terms!

Image Credit: ESO/VPHAS+ team.
Acknowledgement: Cambridge Astronomical Survey Unit

---

The dark clouds in this image, taken from ESO’s Paranal Observatory in Chile, almost resemble something supernatural, like the wispy trails of ghosts in the sky. But there is no need to call the ghostbusters! These clouds, known as Barnard 92 (right) and Barnard 93 (left) are dark nebulae: they look pitch black because the dense gas and dust they contain block out the background light, creating these hazy ghostlike features.

These nebulae are stellar nurseries, where new stars are born out of the collapsing dense gas and dust. This whole region of space imaged here is actually part of a much larger stellar complex, called the Small Sagittarius Star Cloud (or Messier 24, catalogued by Charles Messier in 1764). This area is so rich in stars that it is clearly visible to the naked eye during dark nights, in the constellation of Sagittarius.

This image was taken with an enormous 268 million pixel camera called OmegaCAM on the VLT Survey Telescope (VST). OmegaCAM is designed for capturing wide fields like this image, where you could impressively fit four full Moons. This image is part of the VST Photometric Hα Survey of the Southern Galactic Plane and Bulge (VPHAS+), which has mapped diffuse nebulae as well as both young and evolved stars in our galaxy.