Daily Archives: January 9, 2021

Within our galaxy, there are thousands of stars that orbit the center of the Milky Way at high velocities. On occasion, some of them pick up so much speed that they break free of our galaxy and become intergalactic objects. Because of the extreme dynamical and astrophysical processes involved, astronomers are most interested in studying these stars especially those that are able to achieve escape velocity and leave our galaxy.

However, an international team of astronomers led from the National Astronomical Observatories of China (NAOC) recently announced the discovery of 591 high-velocity stars. Based on data provided by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and the ESAs Gaia Observatory, they indicated that 43 of these stars are fast enough to escape the Milky Way someday.

The study waspublished inThe Astrophysical Journal Supplement Serieson Dec. 17th. The study was led by Dr. LI Yinbi, an NAOC astronomer, and included researchers from the Chinese Academy of Sciences (CAS), the Max-Planck Institute for Astronomy (MPIA), the Institute for Advanced Study, the European Southern Observatory (ESO), the ExtantFuture Technology Co., the Institute of Statistical Mathematics in Tokyo, and multiple universities.

In terms of astrophysical studies, high-velocity stars are a relatively recent discovery. The first was observed in 2005, and in the subsequent 15 years, over 550 have been discovered by multiple observatories. From these, astronomers have been able to deduce four subclasses of high-velocity stars, which include: hypervelocity stars, runaway stars, hyper-runaway stars, and fast halo stars.

This latest discovery is especially significant then because it effectively doubles the number of known high-velocity stars, which are quite rare in our galaxy. The 591 high-velocity stars discovered this time doubled the total numberpreviously discovered, bringing the current totalnumber exceeding 1,000, said Dr. Li.

Hypervelocity stars (HVS), the fastest of the bunch, are especially interesting because they have achieved relativistic speeds (a fraction of the speed of light). In fact, astronomers have estimated that with the right kind of gravitational acceleration, hypervelocity stars can reach 1/10th to 1/3rd the speed of light roughly 30,000 to 100,000 km/s (18,640 to 62,130 mi/s).

It is these stars that have the escape velocity needed to leave the Milky Way. Said Prof. LU Youjun from NAOC, a co-author of this paper:

Though rare in the Milky Way, high-velocity stars, with unique kinematics, can provide deep insight into a wide range of Galactic science, from the central supermassive black hole to distant Galactic halo.

Rare is certainly an apt description. According to previous estimates made by astrophysicists, there are likely to be just 1000 HVS in our galaxy (thats 0.0000005 % of the galactic population). But given their speed and the vast distances they travel, tracking these stars and creating a database of their movements could tell us a great deal about a number of cosmic mysteries.

For the sake of their study, the international team relied in part on data provided by LAMOST. In addition to being the largest optical telescope in China, LAMOST has the highest spectral acquisition rate of any telescope in the world and can observe about 4,000 celestial objects in a single exposure. Since it began conducting surveys in 2012, it has established the worlds largest spectra database.

In addition, the team relied on astrometric measurements performed by the Gaia Observatory, which was launched by the European Space Agency (ESA) in 2013. Since then, it has gathered information on the location, proper motion, and velocity of over 1.3 billion celestial objects, making it the largest astrometric database in the world. Both observatories and their massive databases have been invaluable in the detection and study of HVS.

Based on the motion and composition of the objects they observed, the research team identified 591 HVSthat originated in the Milky Ways inner halo. Their low metallicities indicate that the bulk of the stellar halo formed as a consequence of the accretion and tidal disruption of dwarf galaxies, said co-author Prof. Zhao Gang of the CAS School of Astronomy and Space Science.

One of the greatest takeaways from this study the way it demonstrates how combining multiple large surveys can lead to the discovery of rare objects. In the future, astronomers will be able to draw from even larger databases containing survey data provided by next-generation instruments. This data will be especially useful in the study of Dark Matter, the mysterious mass that constitutes 27% of the mass-energy density of the Universe.

By tracking the movement of HVS, astrophysicists will be able to better constrain the shape of the Milky Ways dark matter halo. In addition, they could tell us a great deal about the formation and evolution of the Milky Way itself, as HVS are believed to be the result of galactic mergers and other extreme gravitational forces (i.e. supermassive holes). Having more to study could therefore help astronomers create a history of past galactic mergers.

It has also been ventured that HVS could allow astrophysicists to accurately constrain the mass of our galaxy, something that remains unresolved. On top of all that, previous research has indicated that HVS can carry their planetary systems with them, which could be one of the ways that life is spread throughout the cosmos (intergalactic panspermia).

Further Reading: Chinese Academy of Sciences, The Astrophysical Journal

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Astronomers Discover Hundreds of High-Velocity Stars, Many on Their Way Out of the Milky Way - Universe Today

Since time immemorial, philosophers and scholars have contemplated the beginning of time and even tried to determine when all things began. Its only been in the age of modern astronomy that weve come close to answering that question with a fair degree of certainty. According to the most widely-accepted cosmological models, the Universe began with the Bang Bang roughly 13.8 billion years ago.

Even so, astronomers are still uncertain about what the early Universe looked like since this period coincided with the cosmic Dark Ages. Therefore, astronomers keep pushing the limits of their instruments to see when the earliest galaxies formed. Thanks to new research by an international team of astronomers, the oldest and most distant galaxy observed in our Universe to date (GN-z11) has been identified!

The team, whose research was recently published in the journal Nature Astronomy, was led by Linhua Jiang of the Kavli Institute for Astronomy and Astrophysics and Prof. Nobunari Kashikawa of the University of Tokyo. They were joined by researchers from the Observatories of the Carnegie Institution for Science, the Steward Observatory, the Geneva Observatory, Peking University, and the University of Tokyo.

Simply put, the cosmic Dark Ages began about 370 thousand years after the Big Bang and continued for another 1 billion years. At this time, the only light sources were either the photons released before which is still detectable today as the Cosmic Microwave Background (CMB) and those released by neutral hydrogen atoms. The light of these photons is so shifted due to the expansion of the Universe that they are invisible to us today.

This effect is known as redshift, where the wavelength of light is elongated (or shift towards the red end of the spectrum) as it passes through the ever-expanding cosmos on its way to reach us. For objects moving closer to our galaxy, the effect is reversed, with the wavelength shortening and shifting towards the blue end of the spectrum (aka. blueshift).

For nearly a century, astronomers have used these effects to determine the distance of galaxies and the rate at which the Universe is expanding. In this case, the research team used the Keck I telescope at Maunakea, Hawaii, to measure the redshift of GN-z11 to determine its distance. The results they obtained indicated that it is the farthest (and oldest) galaxy ever observed. As Kashikawa explained in a University of Tokyo press release:

From previous studies, the galaxy GN-z11 seems to be the farthest detectable galaxy from us, at 13.4 billion light years, or 134 nonillion kilometers (thats 134 followed by 30 zeros). But measuring and verifying such a distance is not an easy task.

Specifically, the team examined the carbon emissions lines coming from GN-z11, which were in the ultraviolet range when they left the galaxy and were shifted by a factor of 10 to the infrared (0.2 micrometers) by the time it reached Earth. This level of redshift indicates that this galaxy existed as observed roughly 13.4 billion years ago aka. just 400 million years after the Big Bang.

At this distance, GN-z11 is so far that it defines the very boundary of the observable Universe itself! While this galaxy had been observed in the past (by Hubble), it took the resolving power and spectroscopic capabilities of the Keck Observatory to make accurate measurements. This was performed as part of the Multi-Object Spectrograph for Infrared Exploration (MOSFIRE) survey, which captured the emission lines from GN-z11 in detail.

This allowed the team to produce distance estimates for this galaxy that were improved by a factor of 100 over any measurements that were previously made. Said Kashikawa:

The Hubble Space Telescope detected the signature multiple times in the spectrum of GN-z11. However, even the Hubble cannot resolve ultraviolet emission lines to the degree we needed. So we turned to a more up-to-date ground-based spectrograph, an instrument to measure emission lines, called MOSFIRE, which is mounted to the Keck I telescope in Hawaii.

If subsequent observations can confirm the results of this latest study, then the astronomers can say with certainty that GN-z11 is the farthest galaxy ever observed. Through the study of objects like this one, astronomers hope to be able to shed light on a period of cosmic history when the Universe was just a few hundred millions of years old.

This period coincides with the Universe was beginning to emerge from the Dark Ages, when the first stars and galaxies formed and filled the early Universe with visible light. By studying these, astronomers hope to learn more about how the large-scale structures of the Universe subsequently evolved. This will be assisted by next-generation telescopes like the James Webb Space Telescope (JWST) scheduled to launch on October 31st, 2021.

These instruments will even allow astronomers to be able to study the the Dark Ages itself, a time when the only non-CMB light was the spin line of neutral hydrogen in the far microwave wavelength (21 cm). To be able to probe the very beginnings of the Universe itself and watch as the first stars and galaxies form. What a time an exciting that will be!

The observations that made this research possible were conducted under the time exchange program between the Keck Observatory and the Subaru Telescope on Maunakea, Hawaii.

Further Reading: University of Tokyo, Keck Observatory, Nature Astronomy

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Astronomers set a new Record and Find the Farthest Galaxy. Its Light Took 13.4 Billion Years to Reach us - Universe Today

Astronomy education in Canada is "very, very centred in the European model," said Hilding Neilson, who is Mi'kmaw and a professor in the department of astronomy and astrophysics at the University of Toronto. The way introductory astronomy is generally taught, he explained, "it's just this one linear path from the Romans to, essentially, Neil deGrasse Tyson."

Neilson is trying to change the dominant way of approaching astronomy by incorporating Indigenous astronomies in the classroom. Indigenous astronomies, explained Hilding, are "the astronomies and the knowledges of the peoples of the land."

"Every Nation has their own perspective of the night sky, their own interpretation and knowledge of it," he said.

"Indigenous astronomies speak to a connection to the land and to the people. And that knowledge has been here as long as people have been here."

Neilson teaches his students the Mi'kmaw concept of Two Eyed Seeing which, he explained,involves looking at the world through the lenses of both Western science and Indigenous knowledges.

"With one eye we're only looking through one lens," said Neilson. "When we bring both lenses together, we can build a greater picture."

The origins of astro-colonialism, explained Hilding, stretch back in time. As an example, Hilding cites James Cook's first voyage to the Pacific, in 1769, to observe the transit of Venus across the sun. Cook, Hilding said, had British orders to "discover" the region, and the voyage triggered colonisation in the area.

Today, said Hilding, astro-colonialism can be seen in the location of telescopes. "Modern astrophysics relies on the biggest telescopes in the world to look for the first stars, to look for evidence of dark matter," explained Hilding.

These telescopes, hesaid, are on Indigenous territories "whether that's in Hawaii on Maunakea, the southern United States, Chile, Australia."

The planned construction of the controversial Thirty Meter Telescope (TMT) on Maunakea, Hawaii's tallest mountain, has sparked opposition from many Indigenous people in Hawaii.

In 2015, Canadian astronomers successfully lobbied the federal government to commit $254.5 million in funding toward the project.

Hilding has been outspoken about the issue and about the need for Indigenous consent of telescopes and astronomy facilities on Indigenous lands.

Hilding saidit's complicated because, as an academic, his research relies on having access to telescopes like TMT. "If I want to have a permanent job in academia, I need to write papers, I need to publish journal articles. And that depends on using these facilities."

"If the Thirty Meter Telescope existed, I would have the ability to apply for observations of planets going around other stars, looking for the first stars ever born in our universe, to do science that I cannot think about yet. But at the same time, if we don't have permission or consent, how is that ethical? Do I have to choose between being a good astronomer or respecting Indigenous rights? Is that a fair choice at all?"

"In the end, it's just a matter of: we have to respect Indigenous rights first and worry about thirty meter telescopes later."

Producedand written byZoe Tennant.

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Indigenous astronomies and 'astro-colonialism' - CBC.ca

Stargazers are in for a treat throughout 2021 with a packed year of astronomical dates to enjoy.

There's a calendar full of amazing celestial events to look forward to.

From impressive meteor showers, awe-inspiring supermoons and a close-up look at different planets, 2021 has got plenty on offer to appease even the most discerning of observers.

Many, you won't even need any special equipment to experience either. Just find a dark location with minimal light pollution - if restrictions at the time allow - for a front row seat to some of the best natural phenomenon.

Otherwise, get out in the garden and see what you can see.

Grab your diary and make note of some of the biggest and best astronomy events taking place over the next 12 months - all visible from the UK.

January 24

The planet Mercury is known for its unusual non-circular orbit and it's only visible for a few weeks at a time as it's usually drowned out by the glare of the sun.

And in January and February, it will reach its greatest separation from the sun - known as Mercury at Greatest Eastern Elongation - meaning it will be shining visible in the twilight sky over the UK.

It will reach its optimum point on January 24, and should be visible just after the sun sets. It might be tricky to spot, but there are guides online to help you find where to look.

However in all cases, do not look for Mercury using binoculars until the sun has completely disappeared from the sky due to the risk of permanent sight damage.

March 26

Stargazers won't have to wait too long for the first Super Full Moon of the year - when a full Moon is at its closest point to Earth.

It happens because the planet isn't actually perfectly spherical - and shaped more like an ellipse.

This means that when the moon is closest to the Earth on the same night as a full moon - commonly referred to as a supermoon - it appears as much as 14 percent bigger and 30 per cent brighter in the sky.

The first one of 2021 will be called a Super Worm Moon - because the first or only full moon in March is always known as a Worm Moon, named for the end of winter when worms and other critters typically make their first appearance of the year.

This will be visible in the sky on the night of March 26-27.

April 22 to 23

Those who missed the Quadrantids meteor shower at the start of January will get another chance to catch some shooting stars in the night sky.

April will see the annual Lyrids meteors rain over the UK, which produces around 20 shooting stars an hour at its peak.

The visible meteors are produced by dust particles left behind by comet C/1861 G1 Thatcher, which leave bright trails as they graze the Earths upper atmosphere at 110,000 miles per hour.

However this year, the Lyrids coincide with a nearly-full waxing gibbous moon, which means visibility may be blocked by the glare - but it will still be possible to get a decent view of the brightest meteors in the shower if viewing from a dark location free of light pollution after midnight.

The Lyrids Meteor Shower will peak overnight on April 22 - 23, 2021.

April 27

April's full moon will also be a super moon, given its close proximity to the Earth.

This moon is given the moniker the Pink Moon - but stargazers shouldn't be fooled into thinking it will turn a rosy shade.

It's actually named after early blooming pink wildflowers which typically appear around the time of the full moon in April. And this month, the moon will be near its closest approach to the Earth and may look slightly larger and brighter than usual.

April 19 to May 28 (Peaks May 5-6)

This meteor shower looks more spectacular in the southern hemisphere but can still be seen in the north.

It occurs when the Earth passes through debris left behind by Halley's Comet, with the particles burning as they pass through the upper atmosphere.

Stargazers in the northern hemisphere can expect to see about 30 meteors per hour, peaking on the night between May 5 and 6. It is expected to be at its most active at around 3am with up to 50 meteors visible per hour if weather conditions permit.

May 11

The month of May will herald a phenomenon known as a Micromoon - where coincides with apogee, the point in the Moon's orbit farthest away from Earth.

It's essentially the opposite of a Supermoon, and the Micromoon this month is a Micro New Moon - bringing with it the ideal conditions to stargaze.

Because it is further away, it will look much smaller in the sky - and because it appears smaller it may also seem less bright than usual too.

May 26

The full moon in May is known as the Flower Moon, to signify the abundance of wildflowers that begin to bloom throughout the month.

The third of four super moons this year, it will once again be at its closest point to earth, making it seem much bigger and brighter than usual.

June 10

In June, the moon will partially obscure the sun as it passes by Earth in orbit. From around 10am and lasting till around midday, the moon will block out 20 per cent of the sun at maximum eclipse - which will take place at 11.13am GMT.

The safest way to watch this astronomical phenomenon will be to do so via specially manufactured eclipse glasses, or by making a pinhole camera. Never attempt to view an eclipse with the naked eye.

The solar eclipse will be visible from 10am on June 10, 2021.

July 17 to August 24 (Peaks August 12 - 13)

Possibly the brightest meteor shower of the year for those of us in the UK, the Perseids can dazzle stargazers with as many as 100 shooting stars an hour at the peak.

This celestial phenomenon, described as nature's fireworks, is caused as the planet crosses paths with a debris cloud in the solar system left by the giant Swift-Tuttle comet.

As the bits of rock and dust hit our atmosphere at astronomical speed, they burn up and in some cases cause fireballs streaking across the sky.

It's visible between July 17 and August 24 and peaks every year overnight between August 12 and 13. To spot these meteors, you don't need any special equipment as many are visible to the naked eye, but viewing from a dark location away from light pollution is alway recommended for the best view.

August 2 and 19

Saturn that will move to the direct opposite side of the Earth from the Sun in August, making it the closest it will get to Earth on August 2.

Due to its close proximity it will be brightly illuminated by the sun and will be visible in the sky all night making it the perfect opportunity to catch a closer look of this planetary giant - and the Seeliger effect will make the rings appear brighter than normal

And just a couple of weeks later, on August 19, Jupiter will come into opposition, and will be bigger and brighter than at any point in the rest of the year. You should be able to see its four largest satellites (it has 79 in total) with a good pair of binoculars, appearing as bright dots on either side of the planet.

August 22

This calendar event only happens once every few years - it's where the old adage once in a blue moon comes from.

There are normally only three full moons in each season of the year. But since full moons occur every 29.53days, occasionally a season will contain four full moons. The extra full moon of the season is known as a blue moon.

However this is based on the old definition of what constitutes a blue moon. The modern interpretation defines a blue moon as where there are two full moons in a month.

But going off the original blue moon rules, the seasonal full moon in August - known as the Sturgeon moon, is technically one, too.

September 14

In normal circumstances, there's pretty much no way to see Neptune in the night sky without some sort of special equipment.

But those armed with simple binoculars or a basic small telescope will be able to catch a glimpse of this faraway world in autumn as it moves into opposition with Earth. It will reach opposition on September 14 and will be visible all night.

October 21 to 22

This annual meteor shower is caused when the Earth passes through debris left by Halley's Comet. The Orionids are named after Orion, because the meteors seem to emerge or radiate from the same area in the sky as the constellation.

It's not as active as some of the other meteor showers visible throughout the year, but from adark location, with the moon is out of the way, you might see 10 to 20 meteors per hour at its peak.

The meteors themselves aren't the brightest and are really fast so you'll need to be focused, but they make up for it with some of the longest-lasting bright streaks - known as trains - after it has gone.

October 8 to 9

This meteor shower is typically a modest one, though there have been spectacular exceptions in the past - including a stormy display in 2018.

It's created by the dust debris left by the Comet Giacobini-Zinner and coincides with the head of the constellation known as Draco the Dragon, found in the northern sky.

This year's shower peaks on the night between October 8 and 9 and and is best viewed in the evening at nightfall, unlike most other meteor showers where activity is typically highest after midnight.

November 5

Uranus is normally hidden and out of view to onlookers and you'd struggle to see it with the naked eye even in the most optimum of conditions and with the exact coordinates of where to find it.

But its position in November means that those with binoculars or a small telescope will get a rare opportunity to get a really decent look at the elusive giant, which will not only be big, bright and easy to spot, it will also move slowly in the sky over the course of a month either side of November 5.

November 6 to 30 (peak November 16- 17)

The fast, bright Leonids are associated with Comet Tempel-Tuttle, and named after the Leo constellation.

This year's shower will peak between midnight and dawn on November 16 and 17.

The Leonids are also known for their spectacular meteor storms every 33 years or so, when hundreds and even thousands of shooting stars can be seen - however there's a bit of a wait for the next one, which is not expected until 2034.

A typical shower usually produces about 10 to 20 meteors per hour at its peak, though it's not often to spot as many as this in the UK as some are below the horizon.

November 19

Stargazers in the UK will get the chance to see a lunar eclipse in November.

This time, it will take place in the early morning, beginning at 6am. The moon will start to eclipse at 07.18am, moving partially into the Earth's shadow.

The eclipse will take around an hour and a half to complete, finishing at 07.24am.

December 4 to December 17 (Peak December 13-14)

One of the last major showers of the year, the Geminids are particularly impressive with their multi-coloured firework-like meteors.

While most are white, some are yellow and a handful are green, red and blue thanks to traces of metals like sodium and calcium in the debris that creates them - left behind by the asteroid 3200 Phaethon and offering surprisingly colourful bursts of light.

At its peak, this shower has been known produce more than 100 meteors per hour - and the Geminids in 2021 are predicted to have the highest average rate of the year, making it one to watch out for.

They will peak on the night between December 13 and 14 and best watched from a dark location.

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Super moons, meteor showers and other stargazing and astronomy dates in the UK for 2021 - Manchester Evening News

By Sarah Lindenfeld Hall, Go Ask Mom editor

Morehead Planetarium and Science Center's Teen Science Cafe is this week, and it will focus on answering astronomical questions with Python code

This is part of a regular, now virtual, series, that's designed for teens who want to explore a variety of STEM topics.

This month's program is set for 4:45 p.m. to 6 p.m., Friday, Jan. 8, and will feature Tony Rice, a NASA ambassador who also contributes regularly to WRAL. When writing about astronomy topics for WRAL, he often creates Python scripts to answer specific astronomy questions that range from how often common conjunctions like the "great conjunction" on Dec. 21 happen, how often is there a full moon on Halloween and more.

Rice, according to the event description, will walk participants through some of the code and then will live code, test and get an answer to an astronomy question. These are free, but all attendees must register. More information is on Morehead's website.

(As a reminder, Take the Kids: With renovations complete, Morehead Planetarium reopens this weekend with new exhibits if you're up for an in-person visit.)

The N.C. Museum of Natural Sciences also has regular Teen Science Cafes, and the next one is slated for Jan. 15. The topic is climate change.

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Morehead's Teen Science Cafe to focus on how astronomical questions are answered - WRAL.com