Search Results for: nebula

The subject of this week’s Hubble Picture of the Week is a reflection nebula, identified as GN 04.32.8. Reflection nebulae are clouds of dust in space that don’t emit their own light, as other nebulae do. Instead, the light from nearby stars hits and scatters off their dust, lighting them up. Because of the way the light scatters, many reflection nebulae tend to appear blue, GN 04.32.8 included. GN 04.32.8 is a small part of the stellar nursery known as the Taurus Molecular Cloud. At only roughly 480 light-years from Earth in the constellation Taurus, it’s one of the best locations for studying newly forming stars. This reflection nebula is illuminated by the system of three bright stars in the centre of this image, mainly the variable star V1025 Tauri in the very centre. One of those stars overlaps with part of the nebula: this is another variable star that is named HP Tauri, but is classified as a T Tauri star, for its similarity to yet another variable star elsewhere in the Taurus Molecular Complex. T Tauri stars are very active, chaotic stars at an early stage of their evolution, so it’s no surprise that they appear in a prolific stellar nursery like this one! The three stars are also named HP Tau, HP Tau G2 and HP Tau G3; they’re believed to be gravitationally bound to each other, forming a triple system. Eagle-eyed viewers might notice the small, squashed, orange spot, just left of centre below the clouds of the nebula, that’s crossed by a dark line. This is a newly-formed protostar, hidden in a protoplanetary disc that obstructs some of its light. Because the disc is edge-on to us, it’s an ideal candidate for study. Astronomers are using Hubble here to examine it closely, seeking to learn about the kinds of exoplanets that might be formed in discs like it. [Image Description: A long, smoky, greyish-blue cloud in the centre of the image curves in an arc around three bright stars, each with long cross-shaped diffraction spikes. The cloud is lit more brightly on the inner side facing the stars, and fades into the dark background on the outer side. A few other stars and points of light surround the cloud: one small star below it has a dark band crossing its centre.]

In this NASA/ESA Hubble Space Telescope Picture of the Week, Hubble has once again lifted the veil on a famous — and frequently photographed — supernova remnant: the Veil Nebula. This nebula is the remnant of a star roughly 20 times as massive as the Sun that exploded about 10 000 years ago. Situated about 2400 light-years away in the constellation Cygnus, this photogenic nebula made an appearance as the Picture of the Week previously in 2021. This view combines images taken in three different filters by Hubble’s Wide Field Camera 3 instrument, highlighting emission from hydrogen, sulphur and oxygen atoms. This image shows just a small fraction of the Veil Nebula; if you could see the entire nebula without the aid of a telescope, it would be as wide as six full Moons placed side by side. Look in the sidebar of this page to see this image superimposed on its location in the sky, and try zooming out to compare the size of the full nebula! Although this image captures the Veil Nebula at just a single point in time, it will help researchers understand how the supernova remnant has evolved over decades. Combining this snapshot with Hubble observations from 1994 will reveal the motion of individual knots and filaments of gas over that span of time, enhancing our understanding of this stunning nebula. [Image Description: A colourful, glowing nebula that reaches beyond the top and bottom of the image. It is made of translucent clouds of gas: wispy and thin with hard edges in some places, and puffy and opaque in others. Blue, red and yellow colours mix together, showing light emitted by different types of atoms in the hot gas. Bright and pointlike stars are scattered across the nebula. The background is black.]

Displaying wispy layers of red, orange and yellow, the nebula encasing NGC 2040 resembles a vibrant rose in this image captured by the Gemini South telescope, one half of the International Gemini Observatory, which is supported in part by the U.S. National Science Foundation and operated by NSF NOIRLab. This nebulous flower showcases the dramatic story of stellar life, death and rebirth.

This NASA/ESA Hubble Space Telescope Picture of the Week features the galaxy LEDA 22057, which is located about 650 million light-years away in the constellation Gemini. Like the subject of last week’s Picture of the Week, LEDA 22057 is the site of a supernova explosion. This particular supernova, named SN 2024PI, was discovered by an automated survey in January 2024. The survey covers the entire northern half of the night sky every two days and has catalogued more than 10 000 supernovae. The supernova is visible in this image: located just down and to the right of the galactic nucleus, the pale blue dot of SN 2024PI stands out against the galaxy’s ghostly spiral arms. This image was taken about a month and a half after the supernova was discovered, so the supernova is seen here many times fainter than its maximum brilliance. SN 2024PI is classified as a Type Ia supernova. This type of supernova requires a remarkable object called a white dwarf, the crystallised core of a star with a mass less than about eight times the mass of the Sun. When a star of this size uses up the supply of hydrogen in its core, it balloons into a red giant, becoming cool, puffy and luminous. Over time, pulsations and stellar winds cause the star to shed its outer layers, leaving behind a white dwarf and a colourful planetary nebula. White dwarfs can have surface temperatures higher than 100 000 degrees and are extremely dense, packing roughly the mass of the Sun into a sphere the size of Earth.  While nearly all of the stars in the Milky Way will one day evolve into white dwarfs — this is the fate that awaits the Sun some five billion years in the future — not all of them will explode as Type Ia supernovae. For that to happen, the white dwarf must be a member of a binary star system. When a white dwarf syphons material from a stellar partner, the white dwarf can become too massive to support itself. The resulting burst of runaway nuclear fusion destroys the white dwarf in a supernova explosion that can be seen many galaxies away. [Image Description: A spiral galaxy with two thin, slowly-curving arms, one fainter than the other, coming off the tips of a bright, oval-shaped core region. The disc of the galaxy is also oval-shaped and filled with fuzzy dust under the arms. It has some bright spots where stars are concentrated, especially along the arms. The core has a white glow in the centre and thick bands of gas around it. A supernova is visible as a pale blue dot near the core.]

What kind of astronomical object is this? It doesn’t look quite like the kinds of galaxies, nebulae, star clusters or galaxy clusters which Hubble normally brings us images of. In fact, this is a spiral galaxy, named UGC 10043 — we just happen to be seeing it directly from the side! Located roughly 150 million light-years from Earth in the constellation Serpens, UGC 10043 is one of the somewhat rare spiral galaxies that are seen edge-on. From this point of view, we see the galaxy’s disc as a sharp line through space, overlain with a prominent dust lane. This dust is spread across the spiral arms of UGC 10043, but it looks very thick and cloudy when viewed from the side. You can even see the lights of some active star-forming regions in the arms, shining out from behind the dust. Strikingly, we can also see that the centre of the galaxy sports a glowing, almost egg-shaped ‘bulge’, rising far above and below the disc. All spiral galaxies have a bulge like this one as part of their structure, containing stars that orbit the galactic centre on paths above and below the whirling disc; it’s a feature that isn’t normally obvious in pictures of galaxies. The unusually large size of this bulge compared to the galaxy’s disc is possibly thanks to UGC 10043 siphoning material from a nearby dwarf galaxy. This may also be why the disc is warped, bending up at one end and down at the other. Like most of the full-colour Hubble images released by ESA/Hubble, this image is a composite, made up of several individual snapshots taken by Hubble at different times and capturing different wavelengths of light. You can see the exact images used in the sidebar on this page. A notable aspect of this image is that the two sets of Hubble data used were collected 23 years apart, in 2000 and 2023! Hubble’s longevity doesn’t just afford us the ability to produce new and better images of old targets; it also provides a long-term archive of data which only becomes more and more useful to astronomers. [Image Description: A spiral galaxy seen directly from the side, such that its disc looks like a narrow diagonal band across the image. A band of dark dust covers the disc in the centre most of the way out to the ends, and the disc glows around that. In the centre a whitish circle of light bulges out above and below the disc. The tips of the disc are a bit bent. The background is black and mostly empty.] Links Pan of UGC 10043

This Hubble Picture of the Week features the galaxy LEDA 857074, located in the constellation Eridanus. LEDA 857074 is a barred spiral galaxy, with partially broken spiral arms. It also has a particularly bright spot right in its bar: this is a supernova snapped by Hubble, named SN 2022ADQZ, and quite relevant to this Picture of the Week. The NASA/ESA Hubble Space Telescope has observed a vast range of celestial objects, from galaxies, to nebulae, to star clusters, to planets in the Solar System and beyond. Observing programmes usually seek to gather data so that astronomers can answer a specific question. Naturally, this means most scheduled observations target an object that astronomers have already researched. Some are famous, like the Crab Nebula or the globular cluster Omega Centauri; others might not be so well known to the public, but still be featured in hundreds of scientific papers, such as the Spider Galaxy or NGC 4753. Not so with this galaxy: LEDA 857074 is named in fewer than five papers, one of which is the Lyon-Meudon Extragalactic Database itself. Virtually no data have been recorded about it, other than its position: since its discovery, it simply hasn’t been studied. So how did it attract the gaze of the legendary Hubble? The supernova is the answer — SN 2022ADQZ was detected by an automated survey in late 2022, and led to Hubble being pointed at its host galaxy, LEDA 857074, in early 2023. Astronomers have catalogued millions of galaxies, so while today tens of thousands of supernovae are detected annually, the chance that one is spotted in any particular galaxy is slim. We also do not know how actively LEDA 857074 is forming stars, and therefore how often it might host a supernova. This galaxy is therefore an unlikely and lucky target of Hubble, thanks to this supernova shining a spotlight on it! It now joins the ranks of many more famous celestial objects, with its own Hubble image. [Image Description: A close-in view of a barred spiral galaxy. The bright, glowing bar crosses the centre of the galaxy, with blurred spiral arms curving away from its ends and continuing out of view. It’s surrounded by bright points of light that indicate stars and galaxies. The galaxy also hosts a bright supernova in its central bar.] Links Pan of LEDA 857074

In this week’s Hubble Picture of the Week we are treated to a wonderfully detailed snapshot of NGC 3430. A spiral galaxy, it lies 100 million light-years from Earth in the constellation Leo Minor. Several other galaxies are located relatively nearby to this one, just out of frame; one is close enough that gravitational interaction is driving some star formation in NGC 3430.  That NGC 3430 is such a fine example of a galactic spiral may be why it ended up as part of the sample that Edwin Hubble used to define his classification of galaxies. Namesake of the Hubble Space Telescope, in 1926 he authored a paper which classified some four hundred galaxies by their appearance — as either spiral, barred spiral, lenticular, elliptical or irregular. This straightforward typology proved immensely influential, and the modern, more detailed schemes that astronomers use today are still based on it. NGC 3430 itself is an SAc galaxy, a spiral lacking a central bar with open, clearly-defined arms. At the time of Hubble’s paper, the study of galaxies in their own right was in its infancy. With the benefit of Henrietta Leavitt’s work on Cepheid variable stars, Hubble had only a couple of years before settled the debate about whether these ‘nebulae’, as they were called then, were situated within our galaxy or were distant and independent. He himself referred to ‘extragalactic nebulae’ in his paper, indicating that they lay beyond the Milky Way galaxy. Once it became clear that these distant objects were very different from actual nebulae, the favoured term for a while was the quite poetic ‘island universe’. While NGC 3430 may look as if it still deserves this moniker, today we simply call it and the objects like it a ‘galaxy’. [Image Description: A spiral galaxy with three prominent arms wrapping around it, and plenty of extra gas and dark dust between the arms. There are shining blue points throughout the arms and some patches of gas out beyond the galaxy’s edge, where stars are forming. The centre of the galaxy also shines brightly. It is on a dark background where some small orange dots mark distant galaxies.]

An international team of astronomers has used more than 500 images from the NASA/ESA Hubble Space Telescope spanning two decades to detect seven fast-moving stars in the innermost region of Omega Centauri, the largest and brightest globular cluster in the sky. These stars provide compelling new evidence for the presence of an intermediate-mass black hole. Omega Centauri is visible from Earth with the naked eye and is one of the favourite celestial objects for stargazers in the southern hemisphere. Although the cluster is 17 700 light-years away, lying just above the plane of the Milky Way, it appears almost as large as the full Moon when seen from a dark rural area. The exact classification of Omega Centauri has evolved through time, as our ability to study it has improved. It was first listed in Ptolemy’s catalogue nearly two thousand years ago as a single star. Edmond Halley reported it as a nebula in 1677, and in the 1830s the English astronomer John Herschel was the first to recognise it as a globular cluster. Omega Centauri consists of roughly 10 million stars that are gravitationally bound. [Image Description: A globular cluster, appearing as a highly dense and numerous collection of shining stars. Some appear a bit larger and brighter than others, with the majority of stars appearing blue and orange. They are scattered mostly uniformly, but in the centre they crowd together more and more densely, and merge into a stronger glow at the cluster’s core.]

This Hubble Picture of the Week depicts the spiral galaxy ESO 422-41, which lies about 34 million light-years from Earth in the constellation Columba. The patchy, star-filled structure of the galaxy’s spiral arms and the glow from its dense core are laid out in intricate detail here by Hubble’s Advanced Camera for Surveys. Images of this galaxy have, however, a decades-long history. The name ESO 422-41 comes from its identification in the European Southern Observatory (B) Atlas of the Southern Sky. In the times before automated sky surveys with space observatories such as ESA’s Gaia, many stars, galaxies and nebulae were discovered by means of large photographic surveys. Astronomers used the most advanced large telescopes of the time to produce hundreds of photographs, covering an area of the sky. They later studied the resulting photographs, attempting to catalogue all the new astronomical objects revealed. In the 1970s a new telescope at ESO’s La Silla facility in Chile performed such a survey of the southern sky, which still had not been examined in as much depth as the sky in the north. At the time, the premier technology for recording images was glass plates treated with chemicals. The resulting collection of photographic plates became the ESO (B) Atlas of the Southern Sky. Astronomers at ESO and in Uppsala, Sweden collaborated to study the plates, recording hundreds of galaxies — ESO 422-41 being just one of those — star clusters, and nebulae. Many were new to astronomy. Astronomical sky surveying has since transitioned through digital, computer-aided surveys such as the Sloan Digital Sky Survey and the Legacy Surveys, to surveys made by space telescopes including Gaia and the Wide-Field Infrared Survey Explorer. Even so, photographic sky surveys contributed immensely to astronomical knowledge for decades, and the archives of glass plates serve as an important historical reference for large swathes of the sky. Some are still actively used today, for instance to study variable stars through time. And the objects that these surveys revealed, including ESO 422-41, can now be studied in depth by telescopes such as Hubble.  [Image Description: A spiral galaxy, with a brightly shining core and two large arms. The arms are broad, faint overall and quite patchy, and feature several small bright spots where stars are forming. A few foreground stars with small diffraction spikes can be seen in front of the galaxy.]Links Pan video: ESO 422-41