This image taken with the NASA/ESA Hubble Space Telescope depicts the open star cluster NGC 330, which lies around 180,000 light-years away inside the Small Magellanic Cloud. The cluster – which is in the constellation Tucana (the Toucan) – contains a multitude of stars, many of which are scattered across this striking image.
Because star clusters form from a single primordial cloud of gas and dust, all the stars they contain are roughly the same age. This makes them useful natural laboratories for astronomers to learn how stars form and evolve. This image uses observations from Hubble’s Wide Field Camera 3 and incorporates data from two very different astronomical investigations. The first aimed to understand why stars in star clusters appear to evolve differently from stars elsewhere, a peculiarity first observed with Hubble. The second aimed to determine how large stars can be before they become doomed to end their lives in cataclysmic supernova explosions.
Hubble images show us something new about the universe. This image, however, also contains clues about the inner workings of Hubble itself. The crisscross patterns surrounding the stars in this image, known as diffraction spikes, were created when starlight interacted with the four thin vanes supporting Hubble’s secondary mirror.
Text credit: European Space Agency (ESA) Image credit: ESA/Hubble & NASA, J. Kalirai, A. Milone
This image, taken with Hubble’s Wide Field Camera 3, features the spiral galaxy NGC 4680. Two other galaxies, at the far right and bottom center of the image, flank NGC 4680. NGC 4680 enjoyed a wave of attention in 1997, as it played host to a supernova explosion known as SN 1997bp. Australian amateur astronomer Robert Evans identified the supernova and has identified an extraordinary 42 supernova explosions.
NGC 4680 is actually a rather tricky galaxy to classify. It is sometimes referred to as a spiral galaxy, but it is also sometimes classified as a lenticular galaxy. Lenticular galaxies fall somewhere in between spiral galaxies and elliptical galaxies. While NGC 4680 does have distinguishable spiral arms, they are not clearly defined, and the tip of one arm appears very diffuse. Galaxies are not static, and their morphologies (and therefore their classifications) vary throughout their lifetimes. Spiral galaxies are thought to evolve into elliptical galaxies, most likely by merging with one another, causing them to lose their distinctive spiral structures.
Text credit: European Space Agency (ESA) Image credit: ESA/Hubble & NASA, A. Riess et al.
Interview with Giovanni Cresci (Inaf) on the new instrument just approved by Eso for the Vlt, Mavis. It will cost about 12 million euros (8 already funded), will make adaptive optics in the visible and will allow the telescope to reach the sensitivity and resolution of the next generation giant telescopes, remaining at the forefront of astronomical research.
With the signing of the agreement with Ex (announced today , Tuesday, June 1), the project Mavis – a new innovative tool designed for the VLT – enters the so-called Phase B . The design of the instrument then begins in view of the next stage, the Preliminary Design Review . What characteristics must an instrument have to be considered worthy of being included in a system that – between the individual Vlt telescopes and the Vlti network – already boasts at least fifteen others? Media Inaf went to ask Giovanni Cresci , co-project scientist of Mavis and researcher of INAF of Arcetri.
With the start of Phase B , it starts to get serious. However, there are still many steps to be taken. What are the timelines?
«I would say that the most important date to keep in mind is when the instrument will have to be operational at the telescope: this is what interests astronomers and also those who want to see the results in terms of the instrument’s performance. We are talking about 2028, date in line – among other things – with the implementation of the first instruments of the Extremely large telescope ( Elt ), the 30-meter ESO telescope that will soon be built in Chile ».
Why does he emphasize this alignment?
«It is an interesting combination because on the one hand we will have Mavis, which will obtain images with very high angular resolution in the visible, and on the other Elt, which will reach the same resolution in the infrared. A unique synergy can be established between the two ».
About seven years to go from concept to realization. Is it likely as a time frame?
«Our schedule foresees that it is, even if unexpected events and delays can always happen. Until now, however, despite the pandemic – which has greatly limited the possibility of interaction and work in the laboratories – we have managed to stay on time and conclude Phase A with excellent results. The Mavis consortium is mainly composed of some INAF offices in Italy and various Australian institutes, plus a contribution from the Laboratoire d’Astrophysique de Marseille (Lam): we work with time differences of ten hours and the fact of not being able to see each other in person he weighed a lot ».
Before looking closely at the division of roles between partners, however, let’s take a step back. What is Mavis?
“Mavis is an instrument that will make multi-conjugated adaptive optics in the visible: it will use 8 laser guide stars and 3 natural guide stars to make a correction of the turbulence introduced by the Earth’s atmosphere on a very large field of 30 × 30 arc seconds – rather than correcting a very small field of view as the tools available today do. Moreover, it will do so at optical wavelengths ».
Which is totally new, right?
“Exact. A few years ago we began to do adaptive optics also to optical wavelengths but limiting ourselves to a small source in the center of the field, while this instrument will allow to do so on a large field. Mavis will allow its imager to obtain images at a resolution three times better than that of the Hubble Space Telescope. In addition, it is also equipped with an integral field spectrograph, which will provide a spectrum with a resolution of approximately 20 milliarcoseconds for each point of a field of 6 × 6 arc seconds. It is a revolutionary instrument which, thanks to its angular resolution and sensitivity, will allow us to do astronomy as we have never done so far ».
Will the full-field spectrograph be better than Muse ?
“It will be different and somewhat complementary to Muse – which is a spectrograph that covers a very large field, 1 × 1 arc minutes. With Mavis we will be able to study the regions at the center of galaxies or globular clusters where the sources have a very high density and cannot be solved individually with Muse ».
What other adaptive optics tools are currently present at the Vlt?
«The adaptive tools in the visible are Sphere and Muse, and they have two main limitations: they work on very small fields and they need a very bright star to guide the adaptive optics system. Mavis will overcome these limits, and will be able to see about an order of magnitude more sources than those currently observable in the visible. For example, at the Galactic Pole , where there are fewer stars, Muse can only see 5 percent of the sources. With Mavis, on the other hand, we will be able to reach 50 percent ».
What are the main risks and the main technological challenges in making Mavis?
«As I said before, this is the first time that multi-conjugated adaptive optics have been done in the visible – usually in infrared. This is our great technological challenge. However, we think that the techniques developed up to now in the infrared are mature enough to allow such an extension. It is difficult, but we can also count on what the Vlt already offers us ».
“The idea is to use an infrastructure already present in one of the four telescopes, which has a deformable secondary mirror with 1170 actuators and four laser guide stars working for Muse.”
The four stars, however, are not enough, according to what he told me before.
“No, we need eight stars. Our solution is to divide the laser beam of each one in two: instead of having four lasers we will have eight with a reduced power ».
How much money has been allocated for this tool?
“Thus, the workforce is provided by the partners, who will receive approximately 150 nights of guaranteed observation time. Inaf will therefore have about 45 percent of these nights. As for the hardware, Eso will finance us with eight million euros, which however are not enough to complete the tool. We need about 10 million plus two in contingency – for the unexpected. We are working to find the missing sum ».
How do you plan to do?
«First of all, by participating in European and Australian calls for funding and grants , or by identifying a new partner who wants to join the consortium by bringing the money that is missing to be able to implement the instrument. We think we can do it quickly, given that we already have the bulk of the sum ».
What led to the signing of this agreement today?
«We had to pass a first review at the end of the so-called Phase A , in which Eso verified that the design of the instrument met the needs that the institution had for it. Before signing, we also had to negotiate the technical and scientific requirements of Mavis to make explicit the objectives to be achieved ».
How will the work be divided between the partners?
“Most of the effort is shared between INAF and a consortium of Australian institutes. As for Inaf, we will mainly deal with adaptive optics and instrument software, while the Australians will focus on wavefront sensors for lasers and postfocal instrumentation: imager and spectrograph. Lam instead will mainly deal with the postprocessing of raw data, in particular with the reconstruction of the point spread function . Finally, there is Eso, who will take care of inserting the instrument into the telescope and interfacing with the other instruments ».
All these parts, therefore, will be developed separately. In which laboratory will the integration take place?
“In Australia, at the Stromlo Observatory . And finally in Chile for integration with the telescope ».
In Italy, however, in which laboratories will you work?
«In the laboratories of the Inaf headquarters in Padua».
If you were to identify an emblematic scientific case to which Mavis will contribute, what would you say?
«So, it is a bit difficult, because this instrument will deal with numerous and very different scientific cases: from the Solar System to the most distant galaxies. Kind of like Hubble did , and in fact Mavis sets out to be a bit of Hubble’s replacement when it can’t work anymore. However, I can mention something particularly interesting: First, we want to create the deepest image ever made of the universe. With 10 hours of integration it will be possible to observe galaxies even fainter than those seen in the Hubble Ultra Deep Field, the deepest picture of the universe we have so far. It will also be possible to investigate the origin of supermassive black holes, whose primordial seeds should reside at the center of low-mass objects such as globular clusters or dwarf galaxies. Before Mavis, we did not have the angular resolution necessary to do astrometry at this level of precision ».
So, if everything goes as it should, will Mavis have nothing to envy to a space telescope like Hubble despite being on Earth?
“Exactly. In fact, it should be more sensitive and be able to see finer details. In fact, with this adaptive optics system, the damaging effect of the Earth’s atmosphere should be overcome. But, above all, it will be interesting that Mavis will be the optical counterpart of what we will do in the infrared with the great telescopes of the future like Elt ».
As if to say that it will give a new life to Vlt allowing it to stay on track alongside the telescopes of the future.
What is your role in Mavis?
«As regards the scientific part, we have two project scientists : one for the Australian part and one for Inaf, which is me. I am mainly concerned with ensuring that the characteristics of the instrument are the optimal ones for doing the science that is required. For the scientific part, then, there is also a representative for each site that participates in the construction of the instrument. In the case of Inaf, therefore, the offices of Arcetri, Rome and Padua. In identifying scientific cases for Mavis, Italy played the lion’s share: when there was a call from Eso for the presentation of scientific proposals, more than half of the proposed projects had Italian principal investigators ».
Besides being involved in many projects of telescope instruments, you use them to do science. What do you do?
«I deal with the evolution of galaxies – especially chemical evolution – from the local universe to the more distant one. I am also involved in the co-evolution between the central black hole and the host galaxy. Also for the scientific progress of these two areas Mavis will be a revolutionary tool. As he said, I also deal a lot with instrumentation: I think it is interesting for us scientists to understand what is the whole process that is needed to build and optimize the instruments, and allow them to obtain the results we are looking for from them ».
Does knowing the tools in depth also allow us to think about more adequate scientific cases?
“Of course. And also to better understand what problems can arise in the data and how to solve any oddities or artifacts that can only be understood by knowing the instrument in depth ».
Featured image: Rendering of the Mavis tool. Credits: Eso / Mavis consortium / L. Calçada
The lives of planetary nebulae are often chaotic, from the death of their parent star to the scattering of its contents far out into space. Captured here by the NASA/ESA Hubble Space Telescope, ESO 455-10 is one such planetary nebula, located in the constellation of Scorpius (The Scorpion).
The oblate shells of ESO 455-10, previously held tightly together as layers of its central star, not only give this planetary nebula its unique appearance, but also offer information about the nebula. Seen in a field of stars, the distinct asymmetrical arc of material over the north side of the nebula is a clear sign of interactions between ESO 455-10 and the interstellar medium.
The interstellar medium is the material — consisting of matter and radiation — between star systems and galaxies. The star at the centre of ESO 455-10 allows Hubble to see the interaction with the gas and dust of the nebula, the surrounding interstellar medium, and the light from the star itself. Planetary nebulae are thought to be crucial in galactic enrichment as they distribute their elements, particularly the heavier metal elements produced inside a star, into the interstellar medium which will in time form the next generation of stars.
About the Object
Name: ESO 455-10Type: Milky Way : Nebula : Type : Planetary Constellation: Scorpius Category: Nebulae
Featured image Credit: ESA/Hubble & NASA, L. Stanghellini
The NASA/ESA Hubble Space Telescope has observed the supernova remnant named 1E 0102.2-7219. Researchers are using Hubble’s imagery of the remnant object to wind back the clock on the expanding remains of this exploded star in the hope of understanding the supernova event that caused it 1700 years ago.
The featured star that exploded long ago belongs to the Small Magellanic Cloud, a satellite galaxy of our Milky Way located roughly 200 000 light-years away. The doomed star left behind an expanding, gaseous corpse — a supernova remnant — known as 1E 0102.2-7219.
Because the gaseous knots in this supernova remnant are moving at different speeds and directions from the supernova explosion, those moving toward Earth are colored blue in this composition and the ones moving away are shown in red. This new Hubble image shows these ribbons of gas speeding away from the explosion site at an average speed of 3.2 million kilometers per hour. At that speed, you could travel to the Moon and back in 15 minutes.
Researchers have studied the Hubble archive looking for visible-light images of the supernova remnant and they have analysed the data to calculate a more accurate estimate of the age and centre of the supernova blast.
According to their new estimates , light from this blast arrived at Earth 1700 years ago, during the decline of the Roman Empire. This supernova would only have been visible to inhabitants of Earth’s southern hemisphere. Unfortunately, there are no known records of this titanic event. Earlier studies proposed explosion dates of 2000 and 1000 years ago, but this new analysis is believed to be more robust.
To pinpoint when the explosion occurred, researchers studied the tadpole-shaped, oxygen-rich clumps of ejecta flung out by this supernova blast. Ionised oxygen is an excellent tracer because it glows brightest in visible light. By using Hubble’s powerful resolution to identify the 22 fastest moving ejecta clumps, or knots, the researchers determined that these targets were the least likely to have been slowed down by passage through interstellar material. They then traced the knots’ motion backward until the ejecta coalesced at one point, identifying the explosion site. Once that was known, they could calculate how long it took the speedy knots to travel from the explosion centre to their current location.
Hubble also measured the speed of a suspected neutron star — the crushed core of the doomed star — that was ejected from the blast. Based on the researchers’ estimates, itmust be moving at more than 3 million kilometres per hour from the centre of the explosion to have arrived at its current position. The suspected neutron star was identified in observations with the European Southern Observatory’s Very Large Telescope in Chile, in combination with data from NASA’s Chandra X-ray Observatory.
 The international team of astronomers who carried out this study consists of J. Banovetz, D. Milisavljevic, N. Sravan, R. A. Fesen, D. J. Patnaude, P. P. Plucinsky, W. P. Blair, K. E. Weil, J. A. Morse, R. Margutti, and M. R. Drout.
The Hubble Space Telescope observations involved in this study are associated with programmes 6052 (Morse), 12001 (Green), 12858 (Madore), and 13378 (Milisavljevic).
These results have been presented at the 237th American Astronomical Society virtual meeting on 14 January 2021 and will be published in the Astrophysical Journal.
First discovered in 1798 by German-English astronomer William Hershel, NGC 613 is a galaxy which lies in the southern constellation of Sculptor 67 million light-years away.
Featured here in a new image from the NASA/ESA Hubble Space Telescope, NGC 613 is a lovely example of a barred spiral galaxy. It is easily distinguishable as such because of its well defined central bar and long arms, which spiral loosely around its nucleus. As revealed by surveys, about two thirds of spiral galaxies, including our own Milky Way galaxy, contain a bar.
Recent studies have shown that bars are more common in galaxies now than they were in the past, which gives us important clues about galaxy formation and evolution.
About the Object
Name: NGC 613Type: Local Universe : Galaxy : Type : Spiral, Distance : 65 million light years, Constellation: Sculptor, Category: Galaxies
Combining signals from multiple observations of neutron stars has allowed researchers to better understand the properties of ultra-dense matter and constrain the Hubble constant, which describes how fast the Universe is expanding, according to a new study.
Neutron stars are the collapsed cores of massive stars and have greater densities than an atomic nucleus. However, little is known about the properties of matter under such conditions, which cannot be reached in Earth-bound laboratories.
To study matter at these extremes, researchers turn to cosmic collisions – binary neutron star mergers. When neutron stars collide, they release both electromagnetic radiation and gravitational waves. Observations of these distinct signals from the same event, known as multi-messenger astronomy, can be used to study the state of immensely dense neutron star material and the expansion rate of the Universe.
Tim Dietrich and colleagues developed an analytical framework that combined messengers from two neutron star mergers – the gravitational wave event GW170817 and its accompanying electromagnetic signals, and the gravitational wave-only event GW1904215. Combining these events with independent electromagnetic measurements of isolated neutron stars and calculations from nuclear physics theory, Dietrich et al. constrained the neutron star equation of state, which relates the mass and radius of each neutron star.
The approach also provides a measurement of the Hubble constant; they find a value which is most consistent with previous measurements of the cosmic microwave background.
References: Tim Dietrich, Michael W. Coughlin, Peter T. H. Pang, Mattia Bulla, Jack Heinzel, Lina Issa, Ingo Tews, Sarah Antier, “Multimessenger constraints on the neutron-star equation of state and the Hubble constant”, Science 18 Dec 2020: Vol. 370, Issue 6523, pp. 1450-1453 DOI: 10.1126/science.abb4317 https://science.sciencemag.org/content/370/6523/1450
This illustration shows a distant galaxy with an active quasar at its center. A quasar emits exceptionally large amounts of energy generated by a supermassive black hole fueled by infalling matter. Using the unique capabilities of Hubble, astronomers have discovered that blistering radiation pressure from the vicinity of the black hole pushes material away from the galaxy’s center at a fraction of the speed of light. The “quasar winds” are propelling hundreds of solar masses of material each year. This affects the entire galaxy as the material snowplows into surrounding gas and dust.
Even though the Universe is constantly changing, most processes are too slow to be observed within a human lifespan. However, the Stingray Nebula is now offering scientists a special opportunity to observe a system’s evolution in real time.
Images captured by Hubble in 2016, when compared to Hubble images taken in 1996, show a nebula that has drastically dimmed in brightness and changed shape. Bright blue shells of gas near the centre of the nebula have all but disappeared, and the wavy edges that earned this nebula its aquatic-themed name are virtually gone. The young nebula no longer pops against the black velvet background of the distant Universe.
Researchers discovered unprecedented changes in the light emitted by glowing gas — nitrogen, hydrogen and oxygen — that is being blasted off by the dying star at the centre of the nebula. The oxygen emission, in particular, dropped in brightness by a factor of nearly 1000.
“In most studies, the nebula usually gets bigger,” said Bruce Balick of the University of Washington, USA, who led the new research. “Here, it’s fundamentally changing its shape and getting fainter, and doing so on an unprecedented timescale.”
“Because of Hubble’s optical stability, we are very, very confident that this nebula is changing in brightness,” said team member Martin Guerrero of the Instituto de Astrofísica de Andalucía in Granada, Spain. “That easy to see since, unlike the nebula, all of the other stars in the Hubble image – including a distant companion star – stayed constant in brightness.”
The researchers note that while speculating on causes for this surprising finding, it’s important to explore the properties of the dying star at the centre of the Stingray nebula, which influences the structure and brightness of the nebula.
A 2016 study by Nicole Reindl of the University of Leicester, UK, and a team of international researchers, also using Hubble data, noted that the star at the centre of the Stingray nebula, SAO 244567, is special in its own right.
Observations from 1971 to 2002 showed the temperature of the star skyrocketing to almost ten times hotter than the surface of our Sun. Reindl speculates the temperature jump was caused by a brief flash of helium fusion that occurred outside the core of the central star. After that the star began to cool again, returning to its previous stage of stellar evolution.
The team studying the rapid fading of the Stingray nebula can only speculate at this time what’s in store for the future of this young nebula.
Video 1: This video morphs archival data from the NASA/ESA Hubble Space Telescope to reveal that the nebula Hen 3-1357, nicknamed the Stingray nebula, has faded precipitously over just the past two decades. Witnessing such a swift rate of change in a planetary nebula is exceedingly rare, say researchers. These images captured by Hubble in 1996, when compared to Hubble images taken in 2016, show a nebula that has drastically dimmed in brightness and changed shape. Bright blue shells of gas near the centre of the nebula have all but disappeared, and the wavy edges that earned this nebula its aquatic-themed name are virtually gone. The young nebula no longer pops against the black velvet background of the distant Universe. Credit: NASA, ESA, B. Balick (University of Washington), M. Guerrero (Instituto de Astrofísica de Andalucía), and G. Ramos-Larios (Universidad de Guadalajara), M. Kornmesser (ESA/Hubble)
Video 2: This video zooms into the nebula Hen 3-1357, nicknamed the Stingray nebula, which has faded precipitously over just the past two decades. Witnessing such a swift rate of change in a planetary nebula is exceedingly rare, say researchers. Credit: ESA/Hubble, Digitized Sky Survey, Nick Risinger (skysurvey.org) Music: Astral Electronic
References: Bruce Balick, Martín A. Guerrero, Gerardo Ramos-Larios, “The Fall of the Youngest Planetary Nebula, Hen 3-1357”, ArXiv, pp. 1-5, 2020. https://arxiv.org/abs/2009.01701v1