Showing posts with label irregular galaxies. Show all posts
Showing posts with label irregular galaxies. Show all posts

Monday, July 01, 2024

Gemini North Captures Starburst Galaxy Blazing Bright With Newly Forming Stars

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Starburst Galaxy NGC 4449

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The Milky Way Over Gemini North

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Gemini North Dedication Ceremony



Videos

Cosmoview Episode 83: Gemini North Captures Starburst Galaxy Blazing Bright With Newly Forming Stars
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Cosmoview Episode 83: Gemini North Captures Starburst Galaxy Blazing Bright With Newly Forming Stars

Pan on NGC 4449
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Pan on NGC 4449

Cosmoview Episodio 83: Telescopio de Gemini Norte celebra nuevo aniversario con el confeti cósmico de una devoradora galáctica



Irregular galaxy NGC 4449 exhibits explosive rate of star formation activity due in part to ongoing mergers with nearby dwarf galaxies

A festive array of bright pinks and blues makes for a remarkable sight in this image captured with the Gemini North telescope, one half of the International Gemini Observatory. Resembling a cloud of cosmic confetti, this image is being released in celebration of Gemini North’s 25th anniversary. NGC 4449 is a prime example of starburst activity caused by the interacting and mingling of galaxies as it slowly absorbs its smaller galactic neighbors.

Much of the visible matter in the Universe, the matter that makes up stars, planets — and us — is made inside stars as they complete their cycle of birth, life, and death. They are born from clouds of gas and dust, and when they die their remains are recycled back into the interstellar medium to be used as fuel for the next generation of stars. And in a not-so-distant corner of the Universe, 13 million light-years away in the constellation Canes Venatici, the beginning of this cycle is unfolding at an exceptional rate.

NGC 4449, also known as Caldwell 21, appears to be putting on a cosmic fireworks show in this image, captured with the Gemini North 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. The galaxy’s billowing red clouds and sparkling blue veil are lighting up the sky with the colors of newly forming stars. It’s classified as an irregular Magellanic-type galaxy, reflecting its loose spiral structure and close resemblance to the Large Magellanic Cloud — the prototype of Magellanic galaxies.

Stars have been actively forming within NGC 4449 for several billion years, but currently it is pumping out new stars at a much higher rate than in the past. This unusually explosive and intense star formation activity qualifies it as a starburst galaxy. While starbursts usually occur in the central regions of galaxies, NGC 4449’s star formation is more widespread, evidenced by the fact that the youngest stars are both in the nucleus and in streams surrounding the galaxy.

This ‘global’ starburst activity resembles the Universe’s earliest star-forming galaxies, which grew by merging with and accreting smaller stellar systems. And like its galactic predecessors, NGC 4449’s rapid star formation was likely ignited by interactions with neighboring galaxies. As a member of the M94 Group of galaxies — one of the closest galaxy groups to the Local Group, which hosts the Milky Way — NGC 4449 lies in close proximity to a handful of surrounding smaller galaxies. Astronomers have found evidence of interactions between NGC 4449 and at least two of these satellite galaxies.

One is a very dim dwarf galaxy that is actively being absorbed, as evidenced by a diffuse stream of stars extending to one side of NGC 4449. This ‘stealth’ merger is nearly undetectable by visual inspection owing to its diffuse nature and low stellar mass. However, it possesses a large amount of dark matter, meaning its presence can be detected by the substantial gravitational influence it has on NGC 4449. The other object that provides hints of a past merger is a massive globular star cluster embedded within the outer halo of NGC 4449. This cluster is thought by astronomers to be the surviving nucleus of a former gas-rich satellite galaxy now in the process of being absorbed by NGC 4449.

As NGC 4449 interacts with and absorbs its smaller galactic companions, the tidal interactions between the galaxies compress and shock the gas. The glowing red regions scattered across this image showcase this process, indicating an abundance of ionized hydrogen — a telltale sign of ongoing star formation. A plethora of hot, young blue star clusters are emerging from the galactic ovens, fueled by the dark filaments of cosmic dust lacing throughout the galaxy. At the current rate, the gas supply that feeds NGC 4449’s production of stars will only last for another billion years or so.

This image is being released today in celebration of the Gemini North telescope’s 25th anniversary. On 25 June 1999 a dedication ceremony was held on Maunakea, Hawai‘i, to unveil the new world-class 8.1-meter telescope and reveal its first-light images, which at the time were some of the sharpest infrared images ever obtained by a ground-based telescope. Over the past two and a half decades Gemini North’s large mirror, powerful suite of instruments and advanced adaptive optics have allowed astronomers to peer further and further into the cosmos. From capturing the first direct image of a multi-planet system to testing Einstein’s general theory of relativity — which helped astronomers earn the 2020 Nobel Prize — Gemini North has contributed greatly to humanity’s understanding of the Universe.




More information

NSF NOIRLab (U.S. National Science Foundation National Optical-Infrared Astronomy Research Laboratory), the U.S. center for ground-based optical-infrared astronomy, operates the International Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), Kitt Peak National Observatory (KPNO), Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and Vera C. Rubin Observatory (operated in cooperation with the Department of Energy’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona. The astronomical community is honored to have the opportunity to conduct astronomical research on I’oligam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence that these sites have to the Tohono O’odham Nation, to the Native Hawaiian community, and to the local communities in Chile, respectively.



Links



Contacts:

Josie Fenske
NSF NOIRLab
Email:
josie.fenske@noirlab.edu


Thursday, June 27, 2024

NGC 6822 (Irregular Galaxy)

NGC 6822/M42
Credit: NAOJ

NGC 6822 is an irregular galaxy located toward the constellation Sagittarius. It is in our galactic neighborhood; our Milky Way Galaxy and NGC 6822 are in the same group of galaxies called the Local Group. NGC 6822 is also known as Barnard’s Galaxy because E. E. Barnard, an American astronomer, discovered it.

Many red glowing spots are observable in the galaxy. These are massive star-forming regions similar to the Orion Nebula (M42) in our Milky Way. Massive newborn stars ionize surrounding hydrogen gas with their ultraviolet light, and the ionized gas emits a red glow.

This image was released in the HSC Legacy Archive (HSCLA), a brand-new science archive from Hyper Suprime-Cam (HSC) launched in 2021. Scientists worldwide can use processed, science-ready data from open-use programs through HSCLA for their research.

Distance from Earth: 160 million light-years
Instrument: Hyper Suprime-Cam (HSC)


Relevant Links

Monday, December 25, 2023

NASA's Hubble Presents a Holiday Globe of Stars

Dwarf Irregular Galaxy UGC 8091
Credits: Image: ESA/Hubble, NASA, ESA, Yumi Choi (NSF's NOIRLab), Karoline Gilbert (STScI), Julianne Dalcanton (Center for Computational Astrophysics/Flatiron Inst., UWashington)




The billion stars in galaxy UGC 8091 resemble a sparkling snow globe in this festive Hubble Space Telescope image from NASA and ESA (European Space Agency).

The dwarf galaxy is approximately 7 million light-years from Earth in the constellation Virgo. It is considered an "irregular galaxy" because it does not have an orderly spiral or elliptical appearance. Instead, the stars that make up this celestial gathering look more like a brightly shining tangle of string lights than a galaxy.

Some irregular galaxies may have become tangled by tumultuous internal activity, while others have formed by interactions with neighboring galaxies. The result is a class of galaxies with a diverse array of sizes and shapes, including the diffuse scatter of stars that is this galaxy.

Twelve camera filters were combined to produce this image, with light from the mid-ultraviolet through to the red end of the visible spectrum. The red patches are likely interstellar hydrogen molecules that are glowing because they have been excited by the light from hot, energetic stars. The other sparkles on show in this image are a mix of older stars. An array of distant, diverse galaxies appear in the background, captured by Hubble's sharp view.

The data used in this image were taken by Hubble's Wide Field Camera 3 and the Advanced Camera for Surveys from 2006 to 2021.

Among other things, the observing programs involved in this image sought to investigate the role that dwarf galaxies many billions of years ago had in re-heating the hydrogen that had cooled as the universe expanded after the big bang.

Astronomers are also investigating the composition of dwarf galaxies and their stars to uncover the evolutionary links between these ancient galaxies and more modern galaxies like our own.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble and Webb science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington, D.C.




About This Release

Credits:

Media Contact:

Ray Villard
Space Telescope Science Institute, Baltimore, Maryland

Bethany Downer
ESA/Hubble

Permissions: Content Use Policy

Contact Us: Direct inquiries to the News Team.

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Saturday, November 25, 2023

“Late-type” galaxy?

An irregular galaxy, a narrow streak of stars crossed by faint dust lanes. It is surrounded by a bright glow, appearing like a beam of light in the centre of a dark background. A scatter of small, distant galaxies and a single, bright star surround the galaxy. Credit: ESA/Hubble & NASA, C. Kilpatrick

This Hubble Picture of the Week features NGC 2814, an irregular galaxy that lies about 85 million light years from Earth. In this image, which was captured using Hubble’s Advanced Camera for Surveys (ACS), the galaxy appears to be quite isolated: visually, it looks a little like a loose stroke of bright paint across a dark background. However, looks can be deceiving. NGC 2814 actually has three close (in astronomical terms) galactic neighbours: a side-on spiral galaxy known as NGC 2820; an irregular galaxy named IC 2458; and a face-on non-barred spiral galaxy called NGC 2805. Collectively, the four galaxies make up a galaxy group known as Holmberg 124. In some literature these galaxies are referred to as a group of ‘late-type galaxies’.

The terminology ‘late-type’ refers to spiral and irregular galaxies, whilst ‘early-type’ refers to elliptical galaxies. This rather confusing terminology has led to a common misconception within the astronomy community. It is still quite widely believed that Edwin Hubble inaccurately thought that elliptical galaxies were the evolutionary precursors to spiral and irregular galaxies, and that that is the reason why ellipticals are classed as ‘early-type’ and spirals and irregulars are classed as ‘late-type’. This misconception is due to the Hubble ‘tuning fork’ of galactic classification, which visually shows galaxy types proceeding from elliptical to spiral, in a sequence that could easily be interpreted as a temporal evolution. However, Hubble actually adopted the terms ‘early-type’ and ‘late-type’ from much older astronomical terminology for stellar classifications, and did not mean to state that ellipticals were literally evolutionary precursors to spiral and irregular galaxies. In fact, he explicitly said in his 1927 paper that ‘the nomenclature … [early and late] … refers to position in the sequence, and temporal connotations are made at one’s peril’.

Despite Hubble himself being quite emphatic on this topic, the misunderstanding persists almost a hundred years later, and perhaps provides an instructive example of why it is helpful to classify things with easy-to-interpret terminology from the get-go!



Friday, September 29, 2017

Mapping the nearby Universe

Credit: ESA/Hubble & NASA


The distances to objects in the Universe can differ enormously. The nearest star to us — Proxima Centauri — lies some 4.2 light-years from us, while some incredibly distant galaxies are so far away — 13 billion light-years or more — that they are only visible to us as a result of cosmic tricks of magnification

The subject of this image, a galaxy called ESO 376-16, sits nearly 23 million light-years from Earth — not that great a distance on a cosmic scale. However, given the galaxy’s relative proximity to us, we know surprisingly little about it. Astronomers are still debating about many of the properties of ESO 376-16, including its morphology. Galaxies are divided into types based on their visual appearance and characteristics; spiral galaxies, like the Milky Way, are flattened discs with curved arms sweeping out from a central nucleus, while irregular galaxies lack a distinct structure and look far more chaotic. On the basis of its rather ill-defined morphology, ESO 376-16 is thought to be either a late-type spiral or a dwarf irregular galaxy

Despite its mystique, observations of ESO 376-16 have been useful in several studies, including one made with the NASA/ESA Hubble Space Telescope that aimed to create a 3D map of galaxies lying in the vicinity of Earth. Researchers used Hubble to gauge the distance to galaxies including ESO 376-16 by measuring the luminosities of especially bright red-giant-branch stars sitting within the galaxies. They then used their data to generate and calibrate 3D maps of the distribution of galaxies throughout the nearby cosmos.



Friday, December 02, 2016

Spotlight on IC 3583

Credit: ESA/Hubble & NASA


This delicate blue group of stars — actually an irregular galaxy named IC 3583 — sits some 30 million light-years away in the constellation of Virgo (The Virgin).

It may seem to have no discernable structure, but IC 3583 has been found to have a bar of stars running through its centre. These structures are common throughout the Universe, and are found within the majority of spiral, many irregular, and some lenticular galaxies. Two of our closest cosmic neighbours, the Large and Small Magellanic Clouds, are barred, indicating that they may have once been barred spiral galaxies that were disrupted or torn apart by the gravitational pull of the Milky Way.

Something similar might be happening with IC 3583. This small galaxy is thought to be gravitationally interacting with one of its neighbours, the spiral Messier 90. Together, the duo form a pairing known as Arp 76. It’s still unclear whether these flirtations are the cause of IC 3583’s irregular appearance — but whatever the cause, the galaxy makes for a strikingly delicate sight in this NASA/ESA Hubble Space Telescope image, glimmering in the blackness of space.


Friday, August 12, 2016

A lopsided lynx

Credit: ESA/Hubble & NASA


This galaxy, known as NGC 2337, resides 25 million light-years away in the constellation of Lynx. NGC 2337 is an irregular galaxy, meaning that it — along with a quarter of all galaxies in the Universe — lacks a distinct, regular appearance. The galaxy  was discovered in 1877 by the French astronomer Édouard Stephan who, in the same year, discovered the galactic group Stephan’s Quintet (heic0910i).

Although irregular galaxies may never win a beauty prize when competing with their more symmetrical spiral and elliptical peers, astronomers consider them to be very important. Some irregular galaxies may have once fallen into one of the regular classes of the Hubble sequence, but were warped and deformed by a passing cosmic companion. As such, irregular galaxies provide astronomers with a valuable opportunity to learn more about galactic evolution and interaction.

Despite the disruption, gravitational interactions between galaxies can kickstart star formation activity within the affected galaxies, which may explain the pockets of blue light scattered throughout NGC 2337. These patches and knots of blue signal the presence of young, newly formed, hot stars.



Friday, February 05, 2016

One from many

Credit:ESA/Hubble & NASA
Acknowledgement: Judy Schmidt (
Geckzilla)


This image, taken by the NASA/ESA Hubble Space Telescope, shows a peculiar galaxy known as NGC 1487, lying about 30 million light-years away in the southern constellation of Eridanus.

Rather than viewing a celestial object, it is actually better to think of this as an event. Here, we are witnessing two or more galaxies in the act of merging together to form a single new galaxy. Each progenitor has lost almost all traces of its original appearance, as stars and gas have been thrown hither and thither by gravity in an elaborate cosmic whirl.

Unless one is very much bigger than the other, galaxies are always disrupted by the violence of the merging process. As a result, it is very difficult to determine precisely what the original galaxies looked like and, indeed, how many of them there were. In this case, it is possible that we are seeing the merger of several dwarf galaxies that were previously clumped together in a small group.

Although older yellow and red stars can be seen in the outer regions of the new galaxy, its appearance is dominated by large areas of bright blue stars, illuminating the patches of gas that gave them life. This burst of star formation may well have been triggered by the merger.



Friday, January 22, 2016

Rebel rebel

Credit: ESA/Hubble & NASA
Acknowledgement: Judy Schmidt (Geckzilla)


Most galaxies possess a majestic spiral or elliptical structure. About a quarter of galaxies, though, defy such conventional, rounded aesthetics, instead sporting a messy, indefinable shape. Known as irregular galaxies, this group includes NGC 5408, the galaxy that has been snapped here by the NASA/ESA Hubble Space Telescope.

English polymath John Herschel recorded the existence of NGC 5408 in June 1834. Astronomers had long mistaken NGC 5408 for a planetary nebula, an expelled cloud of material from an aging star. Instead, bucking labels, NGC 5408 turned out to be an entire galaxy, located about 16 million light-years from Earth in the constellation of Centaurus (The Centaur).

In yet another sign of NGC 5408 breaking convention, the galaxy is associated with an object known as an ultraluminous X-ray source, dubbed NGC 5408 X-1, one of the best studied of its class. These rare objects beam out prodigious amounts of energetic X-rays. Astrophysicists believe these sources to be strong candidates for intermediate-mass black holes. This hypothetical type of black hole has significantly less mass than the supermassive black holes found in galactic centres, which can have billions of times the mass of the Sun, but have a good deal more mass than the black holes formed when giant stars collapse.

A version of this image was entered into the Hubble's Hidden Treasures image processing competition by contestant Judy Schmidt.