Starry spectacle

NGC 685

A spiral galaxy seen directly on. It glows strongly at its centre and has a short horizontal bar. Two spiral arms extend from this bar, but they are broad and irregularly-shaped. They are filled with tiny blue dots - stars - and glowing pink clouds - star-forming nebulae. The arms break apart into many strands at the edge of the disc. Beyond this is a dark background.

A galaxy ablaze with young stars is the subject of today’s NASA/ESA Hubble Space Telescope Picture of the Week. This galaxy is called NGC 685 and is situated about 64 million light-years away in the constellation Eridanus (The River). NGC 685 is classified as a barred spiral because its feathery spiral arms sprout from the ends of a bar of stars at the galaxy’s centre. The Milky Way is also a barred spiral, but our galaxy is a little less than twice the size of NGC 685.

Astronomers used Hubble to study NGC 685 for two observing programmes, both of which focus on star formation. It’s no surprise that NGC 685 was chosen for these programmes: numerous patches of young blue stars highlight the galaxy’s spiral arms. Many of these star clusters are cocooned in pink gas clouds, which are called H II (pronounced ‘H-two’) regions. An H II region is a gas cloud that glows for a short time when particularly hot and massive stars are born. An especially eye-catching H II region peeks out at the bottom edge of the image. Despite the dozens of star-forming regions evident in this image, NGC 685 converts an amount of gas equivalent to less than half the mass of the Sun into stars each year.

The Hubble data collected for the two observing programmes will allow astronomers to catalogue 50 000 H II regions and 100 000 star clusters in nearby galaxies. By combining Hubble’s sensitive visible and ultraviolet observations with infrared data from the NASA/ESA/CSA James Webb Space Telescope and radio data from the Atacama Large Millimeter/submillimeter Array, researchers will peer into the depths of dusty stellar nurseries and illuminate the stars forming there.

Source: ESA/Hubble/potw

---

Sidewinding Young Stellar Jets Spied by Gemini South

The sinuous young stellar jet, MHO 2147, meanders lazily across a field of stars in this image captured from Chile by the international Gemini Observatory, a Program of NSF's NOIRLab. The stellar jet is the outflow from a young star that is embedded in an infrared dark cloud. Astronomers suspect its sidewinding appearance is caused by the gravitational attraction of companion stars. These crystal-clear observations were made using the Gemini South telescope’s adaptive optics system, which helps astronomers counteract the blurring effects of atmospheric turbulence. Credit: International Gemini Observatory/NOIRLab/NSF/AURA. Acknowledgments: PI: L. Ferrero (Universidad Nacional de Córdoba). Download  Large JPEG

The knotted young stellar jet, MHO 1502, is captured in this image from Chile by the international Gemini Observatory, a Program of NSF's NOIRLab. The stellar jet is embedded in an area of star formation known as an HII region. The bipolar jet is composed of a chain of knots, suggesting that its source, thought to be two stars, has been intermittently emitting material. These crystal-clear observations were made using the Gemini South telescope’s adaptive optics system, which helps astronomers counteract the blurring effects of atmospheric turbulence. Credit: International Gemini Observatory/NOIRLab/NSF/AURA. Acknowledgments: PI: L. Ferrero (Universidad Nacional de Córdoba). Download  Large JPEG

Young stellar jet MHO 2147 (wider crop). The sinuous young stellar jet, MHO 2147, meanders lazily across a field of stars in this image captured from Chile by the international Gemini Observatory, a Program of NSF's NOIRLab. The stellar jet is the outflow from a young star that is embedded in an infrared dark cloud. Astronomers suspect its sidewinding appearance is caused by the gravitational attraction of companion stars. These crystal-clear observations were made using the Gemini South telescope’s adaptive optics system, which helps astronomers counteract the blurring effects of atmospheric turbulence. Credit: International Gemini Observatory/NOIRLab/NSF/AURA. Acknowledgments: PI: L. Ferrero (Universidad Nacional de Córdoba). Download  JPEG

CosmoView Episode 40: Sidewinding Young Stellar Jets Spied by Gemini South. Sinuous stellar jets meander lazily across a field of stars in new images captured from Chile by the international Gemini Observatory, a Program of NSF's NOIRLab. The gently curving stellar jets are the outflow from young stars, and astronomers suspect their sidewinding appearances are caused by the gravitational attraction of companion stars. These crystal-clear observations were made using the Gemini South telescope’s adaptive optics system, which helps astronomers counteract the blurring effects of atmospheric turbulence. Credit: Images and videos: International Gemini Observatory/NOIRLab/NSF/AURA. Image processing: T.A. Rector (University of Alaska Anchorage/NSF’s NOIRLab), M. Zamani (NSF’s NOIRLab) & D. de Martin (NSF’s NOIRLab). Music: Stellardrone - Billions and Billions.

Crystal-clear images of meandering bipolar stellar jets from young stars captured with adaptive optics.

Sinuous stellar jets meander lazily across a field of stars in new images captured from Chile by the international Gemini Observatory, a Program of NSF's NOIRLab. The gently curving stellar jets are the outflow from young stars, and astronomers suspect their sidewinding appearances are caused by the gravitational attraction of companion stars. These crystal-clear observations were made using the Gemini South telescope’s adaptive optics system, which helps astronomers counteract the blurring effects of atmospheric turbulence.

Young stellar jets are a common by-product of star formation and are thought to be caused by the interplay between the magnetic fields of rotating young stars and the disks of gas surrounding them. These interactions eject twin torrents of ionized gas in opposite directions, such as those pictured in two images captured by astronomers using the Gemini South telescope on Cerro Pachón on the edge of the Chilean Andes. Gemini South is one half of the international Gemini Observatory, a Program of NSF's NOIRLab, that comprises twin 8.1-meter optical/infrared telescopes on two of the best observing sites on the planet. Its counterpart, Gemini North, is located near the summit of Maunakea in Hawai‘i.

The jet in the first image, named MHO 2147, is roughly 10,000 light-years from Earth, and lies in the galactic plane of the Milky Way, close to the boundary between the constellations Sagittarius and Ophiuchus. MHO 2147 snakes across a starry backdrop in the image — an appropriately serpentine appearance for an object close to Ophiuchus. Like many of the 88 modern astronomical constellations, Ophiuchus has mythological roots — in ancient Greece it represented a variety of gods and heroes grappling with a serpent. MHO 1502, the jet pictured in the second image, is located in the constellation of Vela, approximately 2000 light-years away.

Most stellar jets are straight but some can be wandering or knotted. The shape of the uneven jets is thought to be related to a characteristic of the object or objects that created them. In the case of the two bipolar jets MHO 2147 and MHO 1502, the stars which created them are obscured from view

In the case of MHO 2147, this young central star, which has the catchy identifier IRAS 17527-2439, is embedded in an infrared dark cloud — a cold, dense region of gas that is opaque at the infrared wavelengths represented in this image [1]. The sinuous shape of MHO 2147 is caused because the direction of the jet has changed over time, tracing out a gentle curve on either side of the central star. These almost unbroken curves suggest that MHO 2147 has been sculpted by continuous emission from its central source. Astronomers found that the changing direction (precession) of the jet may be due to the gravitational influence of nearby stars acting on the central star. Their observations suggest that IRAS 17527-2439 could belong to a triple star system separated by more than 300 billion kilometers (almost 200 billion miles).

MHO 1502, on the other hand, is embedded in a totally different environment — an area of star formation known as an HII region. The bipolar jet is composed of a chain of knots, suggesting that its source, thought to be two stars, has been intermittently emitting material.

These detailed images were captured by the Gemini South Adaptive Optics Imager (GSAOI), an instrument on the 8.1-meter-diameter Gemini South telescope. Gemini South is perched on the summit of Cerro Pachón, where dry air and negligible cloud cover provide one of the best observing sites on the planet. Even atop Cerro Pachón, however, atmospheric turbulence causes the stars to blur and twinkle. 

GSAOI works with GeMs, the Gemini Multi-Conjugate Adaptive Optics System, to cancel out this blurring effect using a technique called adaptive optics. By monitoring the twinkling of natural and artificial guide stars up to 800 times a second, GeMs can determine how atmospheric turbulence is distorting Gemini South’s observations [2]. A computer uses this information to minutely adjust the shape of deformable mirrors, canceling out the distortions caused by turbulence. In this case, the sharp adaptive optics images have made it possible to recognize more details in each knot of the young stellar jets than in previous studies.

Source: Gemini Observatory

---

Notes

[1] Astronomical objects can appear very different at different wavelengths. For example, the dust surrounding newborn stars blocks visible light but is transparent at infrared wavelengths. Something similar also happens here on Earth — doctors can see right through you with an X-ray machine even though human bodies are not transparent at visible wavelengths. Astronomers therefore study the Universe across the electromagnetic spectrum to learn as much as possible about the Universe.

[2] Adaptive optics systems on telescopes often make use of "natural guide stars" which are bright stars that lie close to the target of an astronomical observation. Their brightness makes it easy to measure how atmospheric turbulence is distorting their appearance. Gemini South also uses artificial guide stars produced by shining powerful lasers into the upper atmosphere. 

Links

• Research paper 
• Photos of Gemini South
• Videos of Gemini South

Contacts

Leticia Ferrero
Universidad Nacional de Córdoba
Tel: ​+54 9 351 4331063/4/5 int: 105
Email:lvferrero@unc.edu.ar

Amanda Kocz
NSF’s NOIRLab Communications
Tel: +1 520 318 8591
Email:amanda.kocz@noirlab.edu

---

Purple Haze

DG121
Credit: ESO

This week’s picture of the week features DG121, an HII region — a cloud of ionised hydrogen — located in the constellation of Puppis (the Stern).

HII regions, a type of emission nebulae, are created when young, massive stars release enough ultraviolet energy to ionise the surrounding gas clouds. These regions tend to have irregular structures and lack sharp boundaries, giving them their hazy, yet photogenic, appearance. The brightest star in the DG121 region, seen near the centre in this picture, is HD 60068. 

This spectacular image was taken with the FORS 2 (FOcal Reducer and low dispersion Spectrograph 2) instrument on ESO’s Very Large Telescope in the Chilean Atacama Desert. This instrument has been described by astronomers as "the Swiss army knife of instruments at Paranal", because of its ability to study many different astronomical objects in many different ways.

 Source: ESO/potw

---

Caught “Pink-Handed”

Gum 26

Credit: ESO

The Milky Way contains many regions of starbirth — areas where new stars are springing to life within collapsing clumps of gas and dust. One such region, named Gum 26, is shown here as imaged by the FORS instrument on ESO’s Very Large Telescope in Chile.

Gum 26 is located roughly 20,000 light-years away in the southern constellation of Vela (The Sails). It is something known as an HII region or  emission nebula, where the intense ultraviolet radiation streaming from newly-formed stars ionises the surrounding hydrogen gas, causing it to emit a faint pinkish glow. By catching new stars “pink-handed” in this manner, astronomers can learn more about the conditions under which stars arise, and study how they influence their cosmic environment. 

This image was created as part of the ESO Cosmic Gems programme, an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes, for the purposes of education and public outreach. The programme makes use of telescope time that cannot be used for science observations. All data collected may also be suitable for scientific purposes, and are made available to astronomers through ESO’s science archive.

Source:  ESO/potw

---

Anatomy of a Cosmic Seagull

PR Image eso1913a

The Rosy Glow of a Cosmic Seagull

 

PR Image eso1913b

The Seagull Nebula on the borders of the constellations of Monoceros and Canis Major

 

PR Image eso1913c

Wide-field view of the entire Seagull Nebula (IC 2177)

---

Videos

PR Video eso1913a

ESOcast 205 Light: The Rosy Glow of a Cosmic Seagull

PR Video eso1913b

Panning across the Cosmic Seagull

PR Video eso1913c

Zooming into the Cosmic Seagull

PR Video eso1913d

3D animation of the Seagull Nebula

---

ESO’s VST captures a celestial gull in flight

Colourful and wispy, this intriguing collection of objects is known as the Seagull Nebula, named for its resemblance to a gull in flight. Made up of dust, hydrogen, helium and traces of heavier elements, this region is the hot and energetic birthplace of new stars. The remarkable detail captured here by ESO’s VLT Survey Telescope (VST) reveals the individual astronomical objects that make up the celestial bird, as well as the finer features within them. The VST is one of the largest survey telescopes in the world observing the sky in visible light.

The main components of the Seagull are three large clouds of gas, the most distinctive being Sharpless 2-296, which forms the “wings”. Spanning about 100 light-years from one wingtip to the other, Sh2-296 displays glowing material and dark dust lanes weaving amid bright stars. It is a beautiful example of an emission nebula, in this case an HII region, indicating active formation of new stars, which can be seen peppering this image.

It is the radiation emanating from these young stars that gives the clouds their fantastical colours and makes them so eye-catching, by ionising the surrounding gas and causing it to glow. This radiation is also the main factor that determines the clouds’ shapes, by exerting pressure on the surrounding material and sculpting it into the whimsical morphologies we see. Since each nebula has a unique distribution of stars and may, like this one, be a composite of multiple clouds, they come in a variety of shapes, firing astronomers’ imaginations and evoking comparisons to animals or familiar objects.

This diversity of shapes is exemplified by the contrast between Sh2-296 and Sh2-292. The latter, seen here just below the “wings”, is a more compact cloud that forms the seagull’s “head”. Its most prominent feature is a huge, extremely luminous star called HD 53367 that is 20 times more massive than the Sun, and which we see as the seagull’s piercing “eye”. Sh2-292 is both an emission nebula and a reflection nebula; much of its light is emitted by ionised gas surrounding its nascent stars, but a significant amount is also reflected from stars outside it.

The dark swathes that interrupt the clouds’ homogeneity and give them texture are dust lanes – paths of much denser material that hide some of the luminous gas behind them. Nebulae like this one have densities of a few hundred atoms per cubic centimetre, much less than the best artificial vacuums on Earth. Nonetheless, nebulae are still much denser than the gas outside them, which has an average density of about 1 atom per cubic centimetre.

The Seagull lies along the border between the constellations of Canis Major (The Great Dog) and Monoceros (The Unicorn), at a distance of about 3700 light-years in one arm of the Milky Way. Spiral galaxies can contain thousands of these clouds, almost all of which are concentrated along their whirling arms.

Several smaller clouds are also counted as part of the Seagull Nebula, including Sh2-297, which is a small, knotty addition to the tip of the gull’s upper “wing”, Sh2-292 and Sh2-295. These objects are all included in the Sharpless Catalogue, a list of over 300 clouds of glowing gas compiled by American astronomer Stewart Sharpless.

This image was taken using the VLT Survey Telescope (VST), one of the largest survey telescopes in the world observing the sky in visible light. The VST is designed to photograph large areas of the sky quickly and deeply.

Can you spot the seagull in this photo? We challenge our readers to let their imagination run free and outline the bird in our photo as they see it. Share your photos with the outline of the bird using the hashtag #SpotTheSeagull.

---

More Information

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It has 16 Member States: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile and with Australia as a Strategic Partner. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. Also at Paranal ESO will host and operate the Cherenkov Telescope Array South, the world’s largest and most sensitive gamma-ray observatory. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largestastronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.

---

Contact:

Mariya Lyubenova
ESO Head of Media Relations Team
Garching bei München, Germany
Tel: +49 89 3200 6188
Email: pio@eso.org

Source: ESO/News

---

Off to a strong start

Lagoon Nebula/M 8

Credit: ESO

If you had a brand new state-of-the-art telescope facility, what would you look at first? Researchers at the SPECULOOS Southern Observatory — which comprises four small telescopes, each with a 1-metre primary mirror — chose to view the Lagoon Nebula. This magnificent picture is the result, and is one of the SPECULOOS’ first ever observations. The nebula is a cloud of dust and gas in our galaxy where new stars are being born, and is found roughly 5000 light-years from us.

This striking image is made even more impressive by the fact that the SPECULOOS isn’t actually designed to study nebulae. The name says it all — SPECULOOS, the Search for habitable Planets EClipsing ULtra-cOOl Stars. In other words, the primary mission of this telescope facility is to find Earth-like planets orbiting faint nearby stars. The candidates it discovers will be passed over to larger telescopes, such as ESO’s forthcoming Extremely Large Telescope (ELT), to be studied in more detail.

SPECULOOS is located at ESO’s Paranal Observatory in the Atacama Desert of Chile, taking full advantage of the location’s dark skies, ideal atmospheric conditions, and the support systems ESO has there, from telescope infrastructure to staff accommodation. It will have a partner, the SPECULOOS Northern Observatory, in the Canary Islands, which will hunt for planets in the northern skies not visible from Chile. Together they promise to vastly expand our knowledge of the exoplanets in our neighbourhood.

Source: ESO/Potw

---

Bubbles of Brand New Stars

PR Image eso1903a

Bubbles of Brand New Stars 

 

PR Image eso1903b

Jumbo Jets 

 

PR Image eso1903c

Digitized Sky Survey image around the HII region LHA 120-N 180B 

 

PR Image eso1903d

The HII region LHA 120-N 180B in the constellation Mensa

 

PR Image eso1903e

Jet Infographic

---

Videos

PR Video eso1903a
ESOcast 193 Light: Bubbles of Brand New Stars 

PR Video eso1903b

Zooming in on the HII Region LHA 120-N 180B

PR Video eso1903c

Panning across N180

---

This dazzling region of newly-forming stars in the Large Magellanic Cloud (LMC) was captured by the Multi Unit Spectroscopic Explorer instrument (MUSE) on ESO’s Very Large Telescope. The relatively small amount of dust in the LMC and MUSE’s acute vision allowed intricate details of the region to be picked out in visible light.

This region of the Large Magellanic Cloud (LMC) glows in striking colours in this image captured by the Multi Unit Spectroscopic Explorer (MUSE) instrument on ESO’s Very Large Telescope (VLT). The region, known as LHA 120-N 180B — N180 B for short — is a type of nebula known as an H II region (pronounced “H two”), and is a fertile source of new stars.

The LMC is a satellite galaxy of the Milky Way, visible mainly from the Southern Hemisphere. At only around 160 000 light-years away from the Earth, it is practically on our doorstep. As well as being close to home, the LMC’s single spiral arm appears nearly face-on, allowing us to inspect regions such as N180 B with ease.

H II regions are interstellar clouds of ionised hydrogen — the bare nuclei of hydrogen atoms. These regions are stellar nurseries — and the newly formed massive stars are responsible for the ionisation of the surrounding gas, which makes for a spectacular sight. N180 B’s distinctive shape is made up of a gargantuan bubble of ionised hydrogen surrounded by four smaller bubbles.

Deep within this glowing cloud, MUSE has spotted a jet emitted by a fledgling star — a massive young stellar object with a mass 12 times greater than our Sun. The jet — named Herbig–Haro 1177, or HH 1177 for short — is shown in detail in this accompanying image. This is the first time such a jet has been observed in visible light outside the Milky Way, as they are usually obscured by their dusty surroundings. However, the relatively dust-free environment of the LMC allows HH 1177 to be observed at visible wavelengths. At nearly 33 light-years in length, it is one of the longest such jets ever observed.

HH 1177 tells us about the early lives of stars. The beam is highly collimated; it barely spreads out as it travels. Jets like this are associated with the accretion discs of their star, and can shed light on how fledgling stars gather matter. Astronomers have found that both high- and low-mass stars launch collimated jets like HH 1177 via similar mechanisms — hinting that massive stars can form in the same way as their low-mass counterparts.

MUSE has recently been vastly improved by the addition of the Adaptive Optics Facility , the Wide Field Mode of which saw first light in 2017. Adaptive optics is the process by which ESO’s telescopes compensate for the blurring effects of the atmosphere — turning twinkling stars into sharp, high-resolution images. Since obtaining these data, the addition of the Narrow Field Mode, has given MUSE vision nearly as sharp as that of the NASA/ESA Hubble Space Telescope — giving it the potential to explore the Universe in greater detail than ever before.

---

More Information

This research was presented in a paper entitled “An optical parsec-scale jet from a massive young star in the Large Magellanic Cloud” which appeared in the journal Nature.

The research team was composed of A. F. McLeod (who conducted this research while at the University of Canterbury, New Zealand and is now affiliated with the Department of Astronomy, University of California, Berkeley, and the Department of Physics and Astronomy, Texas Tech University, USA), M. Reiter (Department of Astronomy, University of Michigan, Ann Arbor, USA), R. Kuiper (Institute of Astronomy and Astrophysics, University of Tübingen, Germany), P. D. Klaassen (UK Astronomy Technology Centre, Royal Observatory Edinburgh, UK) and C. J, Evans (UK Astronomy Technology Centre, Royal Observatory Edinburgh, UK).

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It has 16 Member States: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile and with Australia as a Strategic Partner. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”

---

Links

• Link to the research paper
• More information on MUSE
• More information on the VLT

---

Contacts 

Anna McLeod

Postdoctoral Research Fellow — Texas Tech University & University of California Berkeley

Tel: +1 80 6834 2588

Email: anna.mcleod@ttu.edu

Calum Turner

ESO Public Information Officer

Garching bei München, Germany

Tel: +49 89 3200 6670

Email: pio@eso.org

Source: ESO/News

---

Stellar Nursery Blooms into View

PR Image eso1740a

Stellar Nursery Blooms into View

PR Image eso1740b

The star formation region NGC 6559 in the constellation of Sagittarius

PR Image eso1740c

The rich surroundings of Sharpless 29

---

Videos

PR Video eso1740a

ESOcast 142 Light: Stellar Nursery Blooms into View (4K UHD)

PR Video eso1740b

Zooming in on the star-forming region Sharpless 29

PR Video eso1740c

Panning across the VST’s view of Sharpless 29

---

The OmegaCAM camera on ESO’s VLT Survey Telescope has captured this glittering view of the stellar nursery called Sharpless 29. Many astronomical phenomena can be seen in this giant image, including cosmic dust and gas clouds that reflect, absorb, and re-emit the light of hot young stars within the nebula.

The region of sky pictured is listed in the Sharpless catalogue of H II regions: interstellar clouds of ionised gas, rife with star formation. Also known as Sh 2-29, Sharpless 29 is located about 5500 light-years away in the constellation of Sagittarius (The Archer), next door to the larger Lagoon Nebula. It contains many astronomical wonders, including the highly active star formation site of NGC 6559, the nebula at the centre of the image.

This central nebula is Sharpless 29’s most striking feature. Though just a few light-years across, it showcases the havoc that stars can wreak when they form within an interstellar cloud. The hot young stars in this image are no more than two million years old and are blasting out streams of high-energy radiation. This energy heats up the surrounding dust and gas, while their stellar winds dramatically erode and sculpt their birthplace. In fact, the nebula contains a prominent cavity that was carved out by an energetic binary star system. This cavity is expanding, causing the interstellar material to pile up and create the reddish arc-shaped border.

When interstellar dust and gas are bombarded with ultraviolet light from hot young stars, the energy causes them to shine brilliantly. The diffuse red glow permeating this image comes from the emission of hydrogen gas, while the shimmering blue light is caused by reflection and scattering off small dust particles. As well as emission and reflection, absorption takes place in this region. Patches of dust block out the light as it travels towards us, preventing us from seeing the stars behind it, and smaller tendrils of dust create the dark filamentary structures within the clouds.

The rich and diverse environment of Sharpless 29 offers astronomers a smorgasbord of physical properties to study. The triggered formation of stars, the influence of the young stars upon dust and gas, and the disturbance of magnetic fields can all be observed and examined in this single area.

But young, massive stars live fast and die young. They will eventually explosively end their lives in a supernova, leaving behind rich debris of gas and dust. In tens of millions of years, this will be swept away and only an open cluster of stars will remain.

Sharpless 29 was observed with ESO’s OmegaCAM on the VLT Survey Telescope (VST) at Cerro Paranal in Chile. OmegaCAM produces images that cover an area of sky more than 300 times greater than the largest field of view imager of the NASA/ESA Hubble Space Telescope, and can observe over a wide range of wavelengths from the ultraviolet to the infrared. Its hallmark feature is its ability to capture the very red spectral line H-alpha, created when the electron inside a hydrogen atom loses energy, a prominent occurrence in a nebula like Sharpless 29.

---

More Information

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile and by Australia as a strategic partner. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.

---

Links

• Photos of OmegaCAM
• Photos of VST

---

Contacts

Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591

Email: rhook@eso.org

Source: ESO

Starbursts in NGC 5398

NGC 5398

Credit: ESA/Hubble & NASA

This NASA/ESA Hubble Space Telescope picture shows NGC 5398, a barred spiral galaxy located about 55 million light-years away

The galaxy is famous for containing an especially extensive HII region, a large cloud composed of ionised hydrogen (or HII, pronounced “H-two”, with H being the chemical symbol for hydrogen and the “II” indicating that the atoms have lost an electron to become ionised). NGC 5398’s cloud is named Tol 89 and sits at the lower left end of the galaxy’s central “bar” of stars, a structure that cuts through the galactic core and funnels material inwards to maintain the star formation occurring there.

Tol 86 is conspicuous in being the only large massive star forming complex in the entire galaxy, with an extension of roughly 5000 times 4000 light-years; it contains at least seven young and massive star clusters. The two brightest clumps within Tol 89, which astronomers have named simply “A” and “B”, appear to have undergone two bursts of star-forming activity — “starbursts” — roughly 4 million and less than 3 million years ago respectively. Tol 89-A is thought to contain a number of particularly bright and massive stars known as Wolf-Rayet stars, which are known for their high temperatures and extreme stellar winds.

Source: ESA/Hubble/Potw

Galactic David and Goliath

PR Image heic1712a

NGC 1512 and NGC 1510

 

PR Image heic1712b

Wide-field view of NGC 1510 and NGC 1512 (ground-based view)

---

Videos

 

PR Video heic1712a

Zooming onto the galaxies NGC 1512 and NGC 1510

PR Video heic1712b

Pan across NGC 1512 and NGC 1510

---

The gravitational dance between two galaxies in our local neighbourhood has led to intriguing visual features in both as witnessed in this new NASA/ESA Hubble Space Telescope image. The tiny NGC 1510 and its colossal neighbour NGC 1512 are at the beginning of a lengthy merger, a crucial process in galaxy evolution. Despite its diminutive size, NGC 1510 has had a significant effect on NGC 1512’s structure and amount of star formation.

Galaxies come in a range of shapes and sizes, and astronomers use this fact to classify them based on their appearance. NGC 1512, the large galaxy to the left in this image, is classified as a barred spiral, named after the bar composed of stars, gas and dust slicing through its centre. The tiny NGC 1510 to the right, on the other hand, is a dwarf galaxy. Despite their very different sizes, each galaxy affects the other through gravity, causing slow changes in their appearances.

The bar in NGC 1512 acts as a cosmic funnel, channelling the raw materials required for star formation from the outer ring into the heart of the galaxy. This pipeline of gas and dust in NGC 1512 fuels intense star birth in the bright, blue, shimmering inner disc known as a circumnuclear starburst ring, which spans 2400 light-years.

Both the bar and the starburst ring are thought to be at least in part the result of the cosmic scuffle between the two galaxies — a merger that has been going on for 400 million years.

NGC 1512, which has been observed by Hubble in the past, is also home to a second, more serene, star-forming region in its outer ring. This ring is dotted with dozens of HII regions, where large swathes of hydrogen gas are subject to intense radiation from nearby, newly formed stars. This radiation causes the gas to glow and creates the bright knots of light seen throughout the ring.

Remarkably, NGC 1512 extends even further than we can see in this image — beyond the outer ring — displaying malformed, tendril-like spiral arms enveloping NGC 1510. These huge arms are thought to be warped by strong gravitational interactions with NGC 1510 and the accretion of material from it. But these interactions are not just affecting NGC 1512; they have also taken their toll on the smaller of the pair.

The constant tidal tugging from its neighbour has swirled up the gas and dust in NGC 1510 and kick-started star formation that is even more intense than in NGC 1512. This causes the galaxy to glow with the blue hue that is indicative of hot new stars.

NGC 1510 is not the only galaxy to have experienced the massive gravitational tidal forces of NGC 1512. Observations made in 2015 showed that the outer regions of the spiral arms of NGC 1512 were indeed once part of a separate, older galaxy. This galaxy was ripped apart and absorbed by NGC 1512, just as it is doing now to NGC 1510.

Together, the pair demonstrate how interactions between galaxies, even if they are of very different sizes, can have a significant influence on their structures, changing the dynamics of their constituent gas and dust and even triggering starbursts. Such interactions between galaxies, and galaxy mergers in particular, play a key role in galactic evolution.

---

Links

• Images of Hubble
• Press release on NGC 1512 (2001)

---

Contact

Mathias Jäger
ESA/Hubble, Public Information Officer
Garching, Germany
Tel: +49 176 62397500
Email: mjaeger@partner.eso.org

Source: ESA/Hubble/News

A Tale of Three Stellar Cities

PR Image eso1723a

The Orion Nebula and cluster from the VLT Survey Telescope

PR Image eso1723b

The jewel in Orion’s sword

PR Image eso1723c 

The Orion Nebula showing three populations of young stars

---

Videos

PR Video eso1723a

ESOcast 118 Light: A Tale of Three Stellar Cities (4K UHD)

PR Video eso1723b

Zooming in on the Orion Nebula 

PR Video eso1723c

Panning across the Orion Nebula

---

Using new observations from ESO’s VLT Survey Telescope, astronomers have discovered three different populations of young stars within the Orion Nebula Cluster. This unexpected discovery adds very valuable new insights for the understanding of how such clusters form. It suggests that star formation might proceed in bursts, where each burst occurs on a much faster time-scale than previously thought.

OmegaCAM — the wide-field optical camera on ESO’s VLT Survey Telescope (VST) — has captured the spectacular Orion Nebula and its associated cluster of young stars in great detail, producing a beautiful new image. This object is one of the closest stellar nurseries for both low and high-mass stars, at a distance of about 1350 light-years [1].

But this is more than just a pretty picture. A team led by ESO astronomer Giacomo Beccari has used these data of unparallelled quality to precisely measure the brightness and colours of all the stars in the Orion Nebula Cluster. These measurements allowed the astronomers to determine the mass and ages of the stars. To their surprise, the data revealed three different sequences of potentially different ages.

“Looking at the data for the first time was one of those ‘Wow!’ moments that happen only once or twice in an astronomer's lifetime,” says Beccari, lead ­author of the paper presenting the results. “The incredible quality of the OmegaCAM images revealed without any doubt that we were seeing three distinct populations of stars in the central parts of Orion.”

Monika Petr-Gotzens, co-author and also based at ESO Garching, continues, “This is an important result. What we are witnessing is that the stars of a cluster at the beginning of their lives didn’t form altogether simultaneously. This may mean that our understanding of how stars form in clusters needs to be modified.”

The astronomers looked carefully at the possibility that instead of indicating different ages, the different brightnesses and colours of some of the stars were due to hidden companion stars, which would make the stars appear brighter and redder than they really were. But this idea would imply quite unusual properties of the pairs, which have never before been observed. Other measurements of the stars, such as their rotation speeds and spectra, also indicated that they must have different ages [2].

“Although we cannot yet formally disprove the possibility that these stars are binaries, it seems much more natural to accept that what we see are three generations of stars that formed in succession, within less than three million years,” concludes Beccari.

The new results strongly suggest that star formation in the Orion Nebula Cluster is proceeding in bursts, and more quickly than had been previously thought.

---

Notes

[1] The Orion Nebula has been studied by many of ESO’s telescopes, including images in visible light from the MPG/ESO 2.2-metre telescope (eso1103) and infrared images from VISTA (eso1701) and the HAWK-I instrument on the Very Large Telescope (eso1625).

[2] The group also found that each of the three different generations rotate at different speeds — the youngest stars rotate the fastest, and the oldest stars rotate the slowest. In this scenario, the stars would have formed in quick succession, within a time frame of three million years.

---

More Information

This research was presented in a paper entitled “A Tale of Three Cities: OmegaCAM discovers multiple sequences in the color­ magnitude diagram of the Orion Nebula Cluster,” by G. Beccari and colleagues, to appear in the journal Astronomy & Astrophysics.

The team is composed of G. Beccari, M.G. Petr-Gotzens and H.M.J. Boffin (ESO, Garching bei München, Germany), M. Romaniello (ESO; Excellence Cluster Universe, Garching bei München, Germany), D. Fedele (INAF-Osservatorio Astrofisico di Arcetri, Firenze, Italy), G. Carraro (Dipartimento di Fisica e Astronomia Galileo Galilei, Padova, Italy), G. De Marchi (Science Support Office, European Space Research and Technology Centre (ESA/ESTEC), The Netherlands), W.J. de Wit (ESO, Santiago, Chile), J.E. Drew (School of Physics, University of Hertfordshire, UK), V.M. Kalari (Departamento de Astronomía, Universidad de Chile, Santiago, Chile), C.F. Manara (ESA/ESTEC), E.L. Martin (Centro de Astrobiologia (CSIC-INTA), Madrid, Spain), S. Mieske (ESO, Chile), N. Panagia (Space Telescope Science Institute, USA); L. Testi (ESO, Garching); J.S. Vink (Armagh Observatory, UK); J.R. Walsh (ESO, Garching); and N.J. Wright (School of Physics, University of Hertfordshire; Astrophysics Group, Keele University, UK).

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.

---

Links

• Research paper
• Photos of the VLT Survey Telescope

---

Contacts

Giacomo Beccari

ESO

Garching bei München, Germany

Tel: +49 89 3200 6195

Email: gbeccari@eso.org

Richard Hook

ESO Public Information Officer

Garching bei München, Germany

Tel: +49 89 3200 6655

Cell: +49 151 1537 3591

Email: rhook@eso.org

Souce: ESO/News

A stormy stellar nursery

A stormy stellar nursery

Copyright: ESA/Hubble & NASA; CC BY 4.0

Hi-res image

This shot from the NASA/ESA Hubble Space Telescope shows a maelstrom of glowing gas and dark dust within one of the Milky Way’s satellite galaxies, the Large Magellanic Cloud.

The stormy scene shows a stellar nursery known as N159, measuring over 150 light-years across. It is known as a HII region, meaning it is rich in ionised hydrogen. Indeed, it contains many hot young stars that are emitting intense ultraviolet light, which causes nearby hydrogen gas to glow. Torrential stellar winds are also carving out ridges, arcs and filaments from the surrounding material.

At the heart of this cosmic cloud lies the Papillon Nebula, a butterfly-shaped region of nebulosity dominating the left of the scene. This compact nebula likely contains massive stars in the very early stages of formation. Its shape earned it the name (papillon being French for butterfly) and was first resolved by Hubble in 1999.

N159 is located over 160 000 light-years away. It resides just south of the Tarantula Nebula, another massive star-forming complex within the Large Magellanic Cloud.

This image was first released as a Hubble picture of the week on 5 September 2016.

Source: ESA/Space in Images

Intense radiation and winds emitted by massive stars regulate star formation in galaxies

Fig. 1: Edge-on (top) and face-on (bottom) slices through the center of the simulation box for density and temperature (left two panels), projections of the total gas density (3rd panel) and the density of the different forms of hydrogen, ionized, atomic and molecular, (bluish panels) and an image of the resulting emission in the Hα line (right). The locations of the star clusters are indicated with white circles.
The images are for a simulation with all three feedback processes included, and a giant region of ionized hydrogen created by the ionizing radiation can be seen in the ionized hydrogen (H⁺) and Hα images. © MPA

Only a small fraction of the stars that form in the Milky Way are much more massive than our Sun and explode as supernovae type II at the end of their lifetimes. Still, these high-mass stars influence the surrounding interstellar medium (ISM) much more than their small number might suggest, both by their intense radiation and powerful winds (“pre-supernova feedback”) and through their violent supernova explosions (“supernova feedback”). Scientists at the Max Planck Institute for Astrophysics, in the framework of the SILCC collaboration, use complex supercomputer simulations to investigate the detailed impact of the different feedback processes on the ISM with conditions similar to our solar neighborhood. Ionizing radiation from young, massive stars dominates their energy output and can exceed the energy released during supernova explosions by an order of magnitude. Only if the simulation includes this radiative feedback and the momentum input from stellar winds are the results consistent with observations of the ISM and the star formation rate is reduced.

High-mass stars dominate the energy output of newly formed stellar populations. Most of the energy is emitted in the form of radiation, followed by supernova explosions and stellar winds. When the radiation deposits its energy in the ISM, the photoelectric heating of dust and photo-ionization can lead to temperatures of a few thousand degrees and more. The photo-ionizing radiation is also a major source of ionized hydrogen in the ISM and drives the formation of so-called “H II regions”, which consist of hot gas with temperatures of ten thousand degrees around young, massive clusters. Supernovae and to some degree stellar winds are energetic enough to shock-heat the ISM to temperatures of a few million degrees.

The emission of radiation, stellar winds and supernova explosions therefore all have different effects in shaping the structure of the ISM and should be considered in concert. Modern attempts to improve the numerical modelling towards a consistent theory of the ISM and star formation need to take all three processes into account. A successful model should then be able to reproduce the ISM as seen in the Milky Way and the observed relation between the amount of dense molecular gas and star formation in galaxies.

Together with a European team of experts, scientists at MPA have used complex supercomputer simulations to investigate the impact of stellar radiation, stellar winds and supernova explosions on the ISM of a galactic disk. For the first time, the simulations include all three dominant forms of stellar feedback and follow the chemical transitions from ionized over neutral atomic to molecular gas. In the simulations, star clusters form dynamically out of parcels of gas collapsing under their own gravity. The team has investigated the effects of the different forms of feedback from the stars in these clusters on the structure of the surrounding ISM and the resulting star formation rate (SFR) in the simulations (see Fig. 1).

Photoionization heating is the dominant energy source in the ISM, it exceeds the energy input from supernovae by one and from winds by two orders of magnitude. All the different photochemical processes started by radiation can individually impart more energy into the ISM than supernovae as a whole. This radiation, however, is not a constant source; the star cluster luminosities are highly variable with time because they are dominated by extremely massive stars that shine very brightly but have lifetimes of only a few million years.

Fig. 2: The surface density of the Star Formation Rate (SFR) measured in the simulation (blue) and derived via various SFR calibrations of observations (other colours) as a function of time. Please note the logarithmic scale. The offset between the true and the observed SFR can be up to an order of magnitude. © MPA 

The time variability of the cluster luminosities has important consequences for SFR measurements (Fig. 2). The observed SFR only matches the true SFR when very massive stars are present in the clusters. Less massive stars do not produce enough ionizing radiation and measurements of the so-called “Hα-line” then underestimate the SFR by up to an order of magnitude; and this result is independent of the calibration used.

Observationally, the amount of star formation within a patch inside a galaxy is closely related to the amount of molecular gas that is present there. The ratio of these two quantities is called the depletion time, and it is universally found to be around 2 billion years. The simulation with radiation naturally exhibits a similar depletion time, while the other simulations fail to do so (Fig. 3).

Fig. 3: The simulations predict the effect of supernova feedback (blue) in the combination with stellar winds (green) and stellar radiation (red) on the star formation rate and the mass in molecular gas. Stellar winds reduce the amount of newly forming stars but do not affect the molecular gas (blue to green). Additional stellar radiation destroys molecular gas but does not change the star formation rate (green to red). Observed galaxies lie in the grey shaded area. The timescales by which all molecular gas would be converted into stars (depletion time - the ratio of star formation rate to molecular gas mass) are indicated by the dotted lines. For galaxies this timescale is around 2 billion years in good agreement with simulations including stellar winds, radiation and supernova explosions. © MPA 

The “pre-supernova feedback” by both radiation and winds also influences the third process by significantly reducing the environmental density of supernova explosion sites. For a simulation with supernova feedback only, 80% of all supernovae go off in gas with mean densities below 100 particles per cubic centimeter. If winds are included in the simulation, this density is reduced by a factor of more than 10, and with radiation by another factor of 100. Exploding at lower environmental densities the supernova can cause more “damage” to the ISM and even drive gas out of the galaxy.

The presence of radiative feedback significantly affects also the mass fractions of the different chemical states of hydrogen. The photoionization by star clusters ionizes the gas in the ISM. This ionized gas then cools radiatively and produces gas in the warm phase, at the same time leading to a substantial reduction of the fraction of gas in the hot phase compared to simulations without radiation. This process is essential to match the observed fractions of the warm and hot phases.

The simulations thus indicate that “pre-supernova feedback” can regulate star formation and the abundance of molecular, neutral and warm ionized gas. “Supernova feedback” determines large-scale turbulent structure of the ISM, its hot gas volume filling fraction and the driving of outflows.

To understand which physical processes produce the ISM and star formation observed in galaxies, it is crucial to run complex simulations that include all important ingredients, which are at work simultaneously in complex star forming regions. The simulations of the SILCC collaboration are therefore an important step forward in this endeavor.

Thomas Peters and Thorsten Naab for the SILCC collaboration

Notes:

The SILCC project (Simulating the Life Cycle of molecular Clouds) is a supercomputing initiative of a group of European scientists to investigate the formation of molecular clouds, star formation and the impact of massive stars on parental cloud dispersal and the driving of galactic outflows. The team consists of Stefanie Walch, Dominik Derigs, Annika Franeck & Daniel Seifried (University of Cologne), Andrea Gatto, Philipp Girichidis, Thorsten Naab, Anabele Pardi & Thomas Peters (Max-Planck-Institute for Astrophysics), Simon Glover & Ralf Klessen (University of Heidelberg), Christian Baczynski (University of St Andrews), Richard Wunsch (Astronomical Institute of the Czech Academy of Sciences), Paul Clark (Cardiff University). Computations are performed at the Leibnitz Supercomputing Centre and the Max Planck Computing and Data Facility.

Authors

Peters, Thomas
Postdoc
Phone: 2195
Email: tpeters@mpa-garching.mpg.de

Naab, Thorsten
Scientific Staff
Phone: 2295
Email: tnaab@mpa-garching.mpg.de


Links: personal homepage (the institute is not responsible for the contents of personal homepages)

Original Publication

Peters, Thomas; Naab, Thorsten; Walch, Stefanie; Glover, Simon C. O.; Girichidis, Philipp; Pellegrini, Eric; Klessen, Ralf S.; Wünsch, Richard; Gatto, Andrea; Baczynski, Christian.

The SILCC project - IV. Impact of dissociating and ionizing radiation on the interstellar medium and Hα emission as a tracer of the star formation rate

MNRAS 2017, 466, 3293

Source / DOI

Source: Max Planck Institute for Astrophysics