Monthly Archives: May 2022

Spiral galaxy NGC 4603 containing Cepheids being used for distance measurements. Credit: ESA/Hubble & NASA, J. Maund

The top-ranked scientific justification for building the Hubble Space Telescope was to determine the size and age of the Universe through observations of Cepheid variables in distant galaxies. This scientific goal was so important that it put constraints on the lower limit of the size of Hubbles primary mirror. Cepheids are a special type of variable star with very stable and predictable brightness variations. The period of these variations depends on physical properties of the stars such as their mass and true brightness. This means that astronomers, just by looking at the variability of their light, can find out about the Cepheids physical nature, which then can be used very effectively to determine their distance. For this reason, cosmologists call Cepheids standard candles.

Astronomers have used Hubble to observe Cepheids with extraordinary results. The Cepheids have then been used as stepping-stones to make distance measurements for supernovae, which have, in turn, given a measure for the scale of the Universe. Today we know the age of the Universe to a much higher precision than before Hubble: around 13.7 billion years.

We certainly live in exciting times. Hubble has made enormous progress possible within cosmology. Today we have a much more unified cosmological picture than was possible even five years ago when people were talking of The Cosmology in Crisis. We have seen a dramatic change from misery to glory!

Gustav A. Tammann, Astronomer, University of Basel

Pictured is the supernova of the type Ia star 1994D, in galaxy NGC 4526. The supernova is the bright spot in the lower left corner of the image. Credit: ESA/Hubble

One of Hubbles initial core purposes was to determine the rate of expansion of the Universe, known to astronomers as the Hubble Constant. After eight years of Cepheid observations this work was concluded by finding that the expansion increases by 70 km/second for every 3.26 million light-years you look further out into space.

Hubbles sharp vision means that it can see exploding stars, supernovae that are billions of light years away, and difficult for other telescopes to study. A supernova image from the ground usually blends in with the image of its host galaxy. Hubble can distinguish the light from the two sources and thus measure the supernova directly.

For many years cosmologists have discussed whether the expansion of the Universe would stop in some distant future or continue ever more slowly. From the results of Hubbles supernova studies, it seems clear that the expansion is nowhere near slowing down. In fact, due to some mysterious property of space itself, called dark energy, the expansion is accelerating and will continue forever. This surprising conclusion came from combined measurements of remote supernovae with most of the worlds top-class telescopes, including Hubble. Furthermore, recent supernova results indicate that cosmos did not always accelerate, but began accelerating when the Universe was less than half its current age.

Since Hubbles measurement of the expansion of the Universe, there have been other more precise measurements, such as with the Spitzer Space Telescope. However, these different measurements havent been in agreement, causing a mystery and spawning new theories. New measurements with NASAs Roman Space Telescope or from gravitational waves may help resolve the controversy.

The discovery of the accelerating expansion of the Universe led to three astronomers, Saul Perlmutter, Adam Riess, and Brian Schmidt, being awarded the 2011 Nobel Prize in Physics.

Hubble gave us the distance measurements of the first four supernovae that made us realize something was wrong with our present understanding of the Universe. Even though the definite proof that the Universe is accelerating came later, we could not reconcile our Hubble observations with a Universe where the expansion is slowing down.

Bruno Leibundgut, Astronomer, European Southern Observatory (ESO)

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Astronomy & Astrophysics 101: Measuring the Age and Size of the Universe - SciTechDaily

Messier 5 is a large, bright and beautiful globular cluster, making it a show-stopping object for the late spring. Image: Ronald Brescher.

Messier 5 in Serpens Caput is a dynamic and beautiful globular cluster that can easily be spotted through a pair of binoculars and fruitfully observed through even a moderate-sized telescope. Globular clusters are extremely luminous, spherical conglomerations of up to a million stars crammed into a space spanning between just tens to perhaps 200 light years. This makes them among the most densely packed stellar systems in the Universe. Not only are globulars marvellous objects to observe, but they provide much food for thought as you gaze upon their sheer majesty, with the vast majority of them believed to be nearly as old as the Universe itself.

At this time of the year, the prime-time night sky is brimming with some of the best globulars of all, including mighty Messier 13 in Hercules, Messier 3 in Canes Venatici and a whole sackful in nearby Ophiuchus. The good news is that M5 comfortably holds its own with the fierce competition.

From pristine dark-sky sites, Messier 5 (NGC 5904, magnitude +5.7) is faintly visible with the naked eye, lying 22 arcminutes north-north-west of the star 5 Serpentis (HIP 74975, magnitude +5.4). Remember to look for M5 in Serpens Caput and not Serpens Cauda; the former lies to the south-west of Hercules, while M5s environs border Virgo.

As darkness falls on an early June evening, M5 can be seen at an altitude of around 40 degrees high to the south from mid-northern latitudes, soon destined to transit the southern meridian at around 11.50pm BST.

Messier 5 shows up as an unresolved patch of light through 10 x 50 binoculars, but a telescope as modest as 75 or 80mm (~three inches) in aperture has sufficient revolving power to pick out the clusters more outlying stars. It can also show that M5 is ever-so slightly elliptical in shape, with its concentrated core offset mainly to the east and slightly to the north. Upgrade to a 150200mm (six- to eight-inch) telescope for a truly memorable view; on a steady and transparent night, when you can push the magnification, you should be able to see (resolve) individual stars across a roughly 10 arcminute-sized sphere and more or less all the way down to M5s core.

M5 makes an epic imaging target, especially for long focal length telescopes. Its overall bluish nebulous haze, which expands to between 17 and 23 arcminutes (depending where you look in the literature), is liberally sprinkled with beautifully contrasting golden suns.

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Messier 5's big appeal in early summer's globular feast Astronomy Now - Astronomy Now Online

Students keen to pursue astronomy and physics research can enrol for a seven-week programme hosted by Inter-University Centre for Astronomy and Astrophysics (IUCAA) in Pune. The last date for sending online applications for the VSP is May 31.

Students who have completed their first-year M Sc, either in physics, applied mathematics, astronomy, electronics or scientific computing, are eligible to apply for the Vacation Students Programme (VSP). Besides, third-year bachelors of technology or engineering and those in the third or fourth year of the integrated M Sc programme can also send applications. The last date for sending online applications for the VSP is May 31.

During the programme, students will be mentored by scientists. They can also take part in seminars and pursue projects.

The IUCAA will pay the participating students a stipend of Rs 10,000 along with free on-campus accommodation and travel allowance by train. Enquiries can be sent to aocp@iucaa.in.

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Pune: IUCAA to offer 7-week vacation programme in astronomy, application closes on May 31 - The Indian Express

The Hydrogen Epoch of Reionisation Array in the Northern Cape. (Image credit: SARAO)

South Africas Hydrogen Epoch of Reionisation Array (HERA) telescope has attracted over R74 million direct financial investment since 2013.

This is according to the South African Radio Astronomy Observatory (SARAO), which has undertaken a local impact study of SAs hosting of HERA.

The HERA telescope is an array of 350 antennas situated next to the MeerKAT radio telescope on the site that hosts the Square Kilometre Array in the Northern Cape.

HERA is a US-led project that forms part of a large international collaboration representative of institutions from Europe, SA, the UK and US.

The goal is to observe how the first structures formed in the very early stages of the Universe, as the first stars and galaxies lit up space.

Construction of the telescope began in 2015, with the full array reaching completion in 2021.

SARAO managed the construction of the infrastructure in close collaboration with US institutions. The instrument is now undergoing commissioning and validation of its data.

The findings from the financial assessment of the impact study indicate the total direct investment made towards the HERA project is well over R70 million (R74 090 948), which was invested by the three countries from 2013 to 2021.

This represents the annual direct investment towards HERA from all contributing countries. An increase in the direct financial investment is observed from 2015, which marks the start of construction of the instrument in SA.

The maximum annual direct financial investment occurred in 2018 (R23 409 564; ie, 32% of the total direct financial investment) at the peak of the construction efforts, with the annual direct financial investment tapering off as the project neared completion over the period 2019 to 2021, says SARAO.

It notes the findings from the HERA impact study indicate SA received substantial direct foreign investment for construction of the infrastructure.

Most of the investment towards infrastructure went to the Northern Cape, with materials sourced from local suppliers during construction of the infrastructure.

At a regional level, it was found that Carnarvon benefitted most from the investment when compared to other towns in the province.

The findings demonstrate how international investment in astronomy research infrastructure can stimulate economic development to benefit the region closest to the infrastructure.

With a creative approach and some careful considerations, the smaller, less technically stringent projects can be successfully executed (parts manufactured and supplied, labour sourced and managed) all using the resources available in the Northern Cape, says Ziyaad Halday, SARAO project manager for HERA.

This strategy facilitates employment and spending in sectors that are not the provinces main financial drivers, such as mining and agriculture.

South Africa, through SARAO, has contributed significantly to the HERA collaboration by providing the human resources required for managing the project locally, and employing the workers needed for building, operating and maintaining the infrastructure.

Over the course of seven years, SARAO says the construction of HERA on the telescope site has created employment for 24 individuals, who were mostly recruited from Carnarvon.

It says the co-hosting of astronomy infrastructure such as HERA can have additional benefits for local communities through employment opportunities that arise from construction of the instrument to the maintenance needed following the construction phase.

South Africa has become a destination of choice for the hosting of international astronomy infrastructure, says Dr Bonita de Swardt, SARAO programme manager for strategic partnerships for human capital development and author of the report.

This includes smaller astronomy telescopes, instruments and experiments in astronomy that can be easily plugged into the existing infrastructure on operational sites.

HERA represents only one of these co-hosted instruments for an international collaboration of scientists. The impact study shows how SA can benefit from smaller scale, co-hosted instrumentation through business development, to the employment it can create for people living in some of the most impoverished and rural geographical areas in the country.

On a national level, the impact study found there is growing participation of South African researchers in the HERA collaboration.

This was mainly a result of continuous financial support towards masters and doctoral scholarships, in conjunction with the award of postdoctoral research fellowships supported by SARAOs human capital development programme and collaborating universities, the organisation says.

These initiatives were supported throughout the construction of HERA, which has led to increased participation of researchers based at local universities in the collaboration, ensuring SAs representation in world-class research conducted with this instrument, it concludes.

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HERA telescope shows benefits of radio astronomy in SA - ITWeb

Two First Nations astronomers are working to show Indigenous children they can pursue their astronomy dreams through an Australian National University program.

The ANU last week hosted a week-long program with Indigenous high school students from remote regional NSW and Tasmania to give them first-hand experience of Indigenous astronomy.

Hosted at the Mt Stromlo Observatory in Canberra, the program provided year 10 and 11 students with a chance to work with ANU masters students, Gamilaraay-Yuwaalaraay man Peter Swanton and Gamilaroi astronomer and science communicator Karlie Moon.

Being mentored by professional astronomers, students built smart phone devices to measure the chemical make-up of light and undertook remote observation at Siding Spring Observatory.

Weaved through the program was an exploration of Indigenous interpretations of the night sky to inform navigation, calendars, and predicting the weather.

ASTRO 3D education and outreach manager Delese Brewster was designed to inspire the next-generation of First Nation astronomers, researchers and scientists.

This group is under-represented in astronomy and we need to provide a pipeline that will encourage Aboriginal and Torres Strait Islander students into tertiary study, she said.

Mr Swanton said the program improved visibility for Indigenous children interested in the field.

I never had this when I was going through school, he said.

It felt quite disengaging when I went to high school, as I had no role models.

I never had someone in front of me, that looked like me, that talked like me

Mr Swanton said he enjoyed seeing children take part in the program.

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Indigenous astronomers helping next-gen First Nations scientists reach for the stars - National Indigenous Times

We now know of more than 5,000 exoplanets beyond the solar system. What we really understand about each of these worlds, though, is barely anything at all. Most of them have been seen only indirectly from their shadows as they cross in front of the stars they orbit. The few that researchers have managed to actually take a picture ofthat is, to directly image using light emanating from the planets themselvesappear as little more than monochromatic dots even in the very best current telescopes. And so far all of those directly imaged worlds are among the brightest, largest and least Earth-like exoplanets known.

The far future may be a different matter. How detailed could a picture of a distant exoplanet beespecially one that is small and rocky like Earth? The answer is that someday astronomers could obtain images revealing continents, clouds, oceans, ice caps and even vegetation on some remote Earth-like world orbiting an alien star.

The problem is that the most powerful telescope for this task cant be builtnot exactly, anyway. Instead it must be conjured into existence using the tenets of Einsteins general theory of relativity to transform our sun itself into a star-sized magnifying glass. Albert Einsteins key insightthat gravity can be understood as the curvature of spacetimemeans that stars and other massive objects act as natural gravitational lenses that warp and amplify the light from background objects.

Astronomers today routinely use galaxies and galaxy clusters as gravitational lenses, but the prospect of using this technique for our sun poses so many challenges that few researchers have taken it seriously. Most notably, the approach requires precisely positioning a conventional telescopesomething like Hubble, for instanceat the point where any given targets lens-amplified light comes to a focus. For the sun, those focal points are found at the extreme outskirts of the solar systemat least 14 times farther out than Pluto.

Now a new study by astronomers at Stanford University shows that a simplifying shortcut could exist for the still arduous task of imaging exoplanets using our sun as a cosmic telescope. The study, published in the Astrophysical Journal, suggests astronomers could eventually achieve exoplanet imaging with a resolution 1,000 times greater than that of the Event Horizon Telescope, which has been used to capture the historic first images of supermassive black holes. Its just neat to think of this as kind of the ultimate end game of the process of studying exoplanets, says Bruce Macintosh, a Stanford astrophysicist, who co-authored the paper, or at least the end game short of actually visiting them.

Alex Madurowicz, Macintoshs co-author and graduate student, first fed real satellite images of Earth into a computer model that reduced our world to how it might appear if it was seen from afar through a stellar gravitational lens. In most circumstances, the resulting image would be an Einstein ringa distorted, circular smear produced by the planets light curving around the lensing star. Earlier work by another researcher, Slava Turyshev of NASAs Jet Propulsion Laboratory, had shown that correcting those distortions would require methodically moving a light-gathering conventional telescope back and forth within the focal region at the solar systems edge. The resulting pixel-by-pixel scan of the planets warped projection, somehow choreographed from Earth upward of 80 billion kilometers away, could take thousands of hours and consume enormous amounts of fuel.

Madurowicz and Macintosh realized that this harsh calculus could change, however, given that the sun is slightly oblong rather than perfectly spherical. That minor detail means that if the target exoplanet aligns perfectly with the suns equator as seen from the focal-region telescope, the product is not an Einstein ring but a crossfour asymmetrical copies of the planet around the suns perimeter. Madurowicz found that, by exploiting this asymmetry, the scanning process to reconstruct a target exoplanets undistorted image could be eliminated. You dont have to move [your telescope] around inside the image, he says. You can just stay in one spot.

Turyshev, who was not a part of this latest study, is skeptical that the painstaking process of scanning he first described can actually be eliminated. The idealized technique for image reconstruction that Macintosh and Madurowicz propose, he says, would have to overcome possible interference arising from the brightness of our sun and its seething outer atmosphere, known as the corona. It would be nice if the sun would just be dark, right? Turyshev says. But it is not, of course, and even the best equipment could not fully block a fraction of it from trickling into a telescope, especially one staring directly at our star. Their paper is wonderful, but its a theory, he adds.

Even if the scanning process could be eliminated, there are other limitations to consider as well. Each exoplanet targeted for solar gravitational lensing would likely require its own dedicated Hubble-like space telescope sent to and operated at the solar systems outer limits. For example, for such an observatory to image a second exoplanet just 10 degrees off from its original target, it would need to shift its position around the sun by more than 14 billion kilometers. To use a solar gravitational lens, you need to line up the telescope, the sun and the planet extremely precisely, Madurowicz says. There would be no way for a single telescope to image more than one planet, or one star system with several interesting worlds, at a time.

This limitation is the reason Jean Schneider, an astronomer at the Paris Observatory, has his eye on a different, perhaps more feasible alternative to solar gravitational lensing: the hypertelescope. This broad concept envisions the detection of surface features of exoplanets through the use of space-based fleets of many meter-scale mirrors flying in formation to create virtual telescopes larger than any single one ever could be. Schneider agrees direct images of potential extraterrestrial vegetation would be precious and would provide insights unavailable through any other known method of remote observation.

Aki Roberge, an astrophysicist at NASAs Goddard Space Flight Center, points out that astronomers dont even know if there is another world like our own out there at all. Not just Earth-size, she says, but Earth-like, with oceans, continents, an atmosphere and a biosphere. And direct imaging, it seems, is the only way to really find out.

A proposed observatory recommended in the National Academies of Sciences, Engineering, and Medicines report Pathways to Discovery in Astronomy and Astrophysics for the 2020s, otherwise known as the Astro2020 Decadal Survey, may offer the best near-term hope of giving Roberge and her peers the answers they need. The survey serves as a once-a-decade roadmap guiding U.S. astronomy. And topping its latest roadmap is a concept for a space telescope with a mirror more than six meters wide, something of a super Hubble tuned for gathering optical, infrared and ultraviolet light that is intended for launch as soon as the early 2040s.

According to Astro2020s recommendations, one of the core capabilities of such a telescope would be directly imaging a diversity of exoplanets with the key objective of studying their atmospheres to make better guesses about their environmental conditions. From there, astronomers might determine if the chemical necessities or by-products of life as we know it water, organic compounds, free oxygen, and so onexist on any of the targeted worlds. The fuzzy blobs that might be imaged by this proposed telescope could be the first small step toward truly knowing an exoplanets potential to harbor life. Only after such a mission, most astronomers say, could we make the giant leap of building a hypertelescope or exploiting the solar gravitational lens to get detailed surface images. We have a path to the 2040s. After that, its the Wild West, Roberge says.

Despite the far-out nature of the solar gravitational lens, Turyshev, Macintosh and Madurowicz are of one mind: thinking about its possibilities now is worthwhile. Already, advances in solar sails and other unconventional propulsion technologies offer the possibility of expediting the requisite journey to the solar systems outermost reaches. The challenges remain daunting, but using our star as the ultimate telescope may be closer to reality than anyone now suspects. By anticipating the theoretical and practical limits of the approach, whenor ifit finally lies within our grasp, the question will not have to be Can we do this? but rather What planets should we image?

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Our Sun Could Someday Reveal the Surfaces of Alien Earths - Scientific American

Astronomers have uncovered the first solid evidence that merger events between black holes can deliver a "kick" powerful enough to send a black hole spinning out of its galaxy.

The team, which included Vijay Varma, a physicist at Max Planck Institute for Gravitational Physics, Albert Einstein Institute, Germany, examined gravitational-wave data from the merger event known as GW200129 collected by the LIGO detectors and their European counterpart, Virgo. Through that analysis, the scientists discovered that the black hole created in that collision and merger had been sent hurtling through space at 3 million mph (4.8 million kph) a finding described by one team member as "both surprising and shocking."

"When two black holes collide, they leave behind a more massive, remnant black hole. This process can impart a recoil 'kick' to the remnant black hole," Varma, lead author of a paper detailing the team's work, told Space.com.

Related: 8 ways we know that black holes really do exist

When black holes orbit each other, they emit gravitational waves essentially gravitational radiation that carry away energy and angular momentum as they ripple through the fabric of space. These emissions cause the orbit to shrink, leading to a collision and merger of the black holes.

If the black holes have unequal masses or spins, however, this leads to an asymmetry in the emission of gravitational waves, with them being primarily emitted in one direction. Because the basic laws of physics require that momentum has to be conserved, this asymmetry results in a large kick, causing the remnant black hole to recoil in the opposite direction.

"Black hole mergers also emit gravitational radiation, similar to astrophysical processes that emit electromagnetic radiation light," Varma continued.

These large kicks are expected when the merger's orbital plane precesses, or "wobbles." Orbital precession is observable as a small amplitude modification in the gravitational-wave signal. "This binary black hole system is also the first signal showing strong signs of orbital precession, whereby the orbital plane wobbles," co-author Scott Field, a mathematician at the University of Massachusetts Dartmouth, told Space.com.

Varma added that by analyzing gravitational radiation, astronomers and astrophysicists can learn about black-hole mergers. Additionally, because black holes are influential in the evolution of the galaxies, learning more about these processes could reveal how collections of stars like the Milky Way develop.

This is the first time astronomers have collected strong evidence that such a merger can eject the resulting black hole from its galaxy.

"Unlike previously observed black hole merger events, this is the first one to provide strong evidence for enormous recoil velocity. Large enough, in fact, for the remnant black hole to most likely escape from its host environment," Field said. "While we knew general relativity allowed for such extreme possibilities in principle, we did not know if the universe would produce them. The final black hole's speed is sufficiently large that it most probably exceeds the escape velocity of its host environment."

Field added that this result will have important implications for binary black hole formation scenarios, too. This is because supermassive black holes, like Sagittarius A* (Sgr A*) at the heart of the Milky Way, form through a series of collisions that scientists call hierarchical mergers. Black holes kicked from a galaxy can't partake in this process.

The discovery of mergers lopsided enough to give black holes a powerful kick is now possible thanks to technology that allows for more precise detections of gravitational waves.

"Black hole mergers don't emit any light, so gravitational waves are the only way to observe and learn about them. We would not know about this ejected, rogue black hole without gravitational wave observatories," Field added.

Scientists aren't precisely sure where the gravitational wave event GW200129 originated, so Field points out that the team can't completely sure the black hole was ejected from its galaxy, but this is the probable outcome of it moving at such extreme speeds, according to the researchers.

"If that is indeed the case, it is now roaming around the universe by itself as a rogue black hole," Varma said.

The merger that occurred here may be a miniature version of an even more dramatic event, he noted. "A similar phenomenon happens when supermassive black holes merge, which can happen after a galactic merger," Varma said. "The final supermassive black hole can get displaced from the center of the merged galaxy, or even ejected from it, leaving behind a galaxy without a central black hole."

Although existing gravitational-wave detectors are not quite powerful enough to observe supermassive black hole mergers, the authors added that future space-based detectors like the proposed Laser Interferometer Space Antenna (LISA) mission, might be able to.

"Gravitational-wave astronomy has delivered many high-impact, truly remarkable discoveries over the past five or so years," Field said. "Before the first detection of gravitational waves, the mantra of our field had been that gravitational waves will open a new window on the universe. And this has proven to be true with each and every new LIGO observing run."

The research is described in a paper (opens in new tab) published May 12 in the journal Physical Review Letters.

You can follow Rob Lea on Twitter at @sciencef1rst. Follow us on Twitter @Spacedotcom (opens in new tab) and on Facebook (opens in new tab).

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A black hole formed by a lopsided merger may have gone rogue - Space.com