Category Archives: Education

Astronomy, Education, Space Science

ESO: Dormant black hole discovered outside our galaxy

A new paper from the European Southern Observatory (ESO):

‘Black hole police’ discover a dormant black hole outside our galaxy

This artist’s impression shows what the binary system VFTS 243 might look like if we were observing it up close. The system, which is located in the Tarantula Nebula in the Large Magellanic Cloud, is composed of a hot, blue star with 25 times the Sun’s mass and a black hole, which is at least nine times the mass of the Sun. The sizes of the two binary components are not to scale: in reality, the blue star is about 200 000 times larger than the black hole.  Note that the ‘lensing’ effect around the black hole is shown for illustration purposes only, to make this dark object more noticeable in the image. The inclination of the system means that, when looking at it from Earth, we cannot observe the black hole eclipsing the star.

A team of international experts, renowned for debunking several black hole discoveries, have found a stellar-mass black hole in the Large Magellanic Cloud, a neighbour galaxy to our own.

“For the first time, our team got together to report on a black hole discovery, instead of rejecting one,”

says study leader Tomer Shenar. Moreover, they found that the star that gave rise to the black hole vanished without any sign of a powerful explosion. The discovery was made thanks to six years of observations obtained with the European Southern Observatory’s (ESO’s) Very Large Telescope (VLT).

“We identified a ‘needle in a haystack’,”

says Shenar who started the study at KU Leuven in Belgium [1] and is now a Marie-Curie Fellow at Amsterdam University, the Netherlands. Though other similar black hole candidates have been proposed, the team claims this is the first ‘dormant’ stellar-mass black hole to be unambiguously detected outside our galaxy.

Stellar-mass black holes are formed when massive stars reach the end of their lives and collapse under their own gravity. In a binary, a system of two stars revolving around each other, this process leaves behind a black hole in orbit with a luminous companion star. The black hole is ‘dormant’ if it does not emit high levels of X-ray radiation, which is how such black holes are typically detected.

“It is incredible that we hardly know of any dormant black holes, given how common astronomers believe them to be”,

explains co-author Pablo Marchant of KU Leuven. The newly found black hole is at least nine times the mass of our Sun, and orbits a hot, blue star weighing 25 times the Sun’s mass.

Glowing brightly about 160 000 light-years away, the Tarantula Nebula is the most spectacular feature of the Large Magellanic Cloud, a satellite galaxy to our Milky Way. This image from VLT Survey Telescope at ESO’s Paranal Observatory in Chile shows the region and its rich surroundings in great detail. It reveals a cosmic landscape of star clusters, glowing gas clouds and the scattered remains of supernova explosions.

Dormant black holes are particularly hard to spot since they do not interact much with their surroundings.

“For more than two years now, we have been looking for such black-hole-binary systems,”

says co-author Julia Bodensteiner, a research fellow at ESO in Germany.

“I was very excited when I heard about VFTS 243, which in my opinion is the most convincing candidate reported to date.” [2]

To find VFTS 243, the collaboration searched nearly 1000 massive stars in the Tarantula Nebula region of the Large Magellanic Cloud, looking for the ones that could have black holes as companions. Identifying these companions as black holes is extremely difficult, as so many alternative possibilities exist.

“As a researcher who has debunked potential black holes in recent years, I was extremely skeptical regarding this discovery,”

says Shenar. The skepticism was shared by co-author Kareem El-Badry of the Center for Astrophysics | Harvard & Smithsonian in the USA, whom Shenar calls the “black hole destroyer”.

“When Tomer asked me to double check his findings, I had my doubts. But I could not find a plausible explanation for the data that did not involve a black hole,”

explains El-Badry.

This composite image shows the star-forming region 30 Doradus, also known as the Tarantula Nebula. The background image, taken in the infrared, is itself a composite: it was captured by the HAWK-I instrument on ESO’s Very Large Telescope (VLT) and the Visible and Infrared Survey Telescope for Astronomy (VISTA), shows bright stars and light, pinkish clouds of hot gas. The bright red-yellow streaks that have been superimposed on the image come from radio observations taken by the Atacama Large Millimeter/submillimeter Array (ALMA), revealing regions of cold, dense gas which have the potential to collapse and form stars. The unique web-like structure of the gas clouds led astronomers to the nebula’s spidery nickname.

The discovery also allows the team a unique view into the processes that accompany the formation of black holes. Astronomers believe that a stellar-mass black hole forms as the core of a dying massive star collapses, but it remains uncertain whether or not this is accompanied by a powerful supernova explosion.

“The star that formed the black hole in VFTS 243 appears to have collapsed entirely, with no sign of a previous explosion,” explains Shenar. “Evidence for this ‘direct-collapse’ scenario has been emerging recently, but our study arguably provides one of the most direct indications. This has enormous implications for the origin of black-hole mergers in the cosmos.“

The black hole in VFTS 243 was found using six years of observations of the Tarantula Nebula by the Fibre Large Array Multi Element Spectrograph (FLAMES) instrument on ESO’s VLT [3].

Despite the nickname ‘black hole police’, the team actively encourages scrutiny, and hopes that their work, published today in Nature Astronomy, will enable the discovery of other stellar-mass black holes orbiting massive stars, thousands of which are predicted to exist in Milky Way and in the Magellanic Clouds.

“Of course I expect others in the field to pore over our analysis carefully, and to try to cook up alternative models,” concludes El-Badry. “It’s a very exciting project to be involved in.”

Notes

[1] The work was conducted in the team lead by Hugues Sana at KU Leuven’s Institute of Astronomy.

[2] A separate study led by Laurent Mahy, involving many of the same team members and accepted for publication in Astronomy & Astrophysics, reports on another promising stellar-mass black hole candidate, in the HD 130298 system in our own Milky Way galaxy.

[3] The observations used in the study cover about six years: they consist of data from the VLT FLAMES Tarantula Survey (led by Chris Evans, United Kingdom Astronomy Technology Centre, STFC, Royal Observatory, Edinburgh; now at the European Space Agency) obtained from 2008 and 2009, and additional data from the Tarantula Massive Binary Monitoring programme (led by Hugues Sana, KU Leuven), obtained between 2012 and 2014.

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Astronomy, Education, Space participation

Night sky highlights for July 2022

** What’s Up: July 2022 Skywatching Tips from NASA – NASA JPL

What are some skywatching highlights in July 2022? The naked-eye planets of dawn – Venus, Mars, Jupiter, and Saturn – dominate the sky, appearing more spread out each morning. Next, if you’re feeling the July heat, note the origin of “the dog days” of summer has to do with the bright star Sirius. Finally, if you can find a certain teapot-shaped pattern of stars in the evening, you’ll be looking toward the center of the Milky Way.

0:00 Intro
0:11 Morning planet lineup
0:40 Sirius and the “dog days” of summer
1:50 The Teapot and Milky Way core
3:11 July Moon phases

Additional information about topics covered in this episode of What’s Up, along with still images from the video, and the video transcript, are available at https://solarsystem.nasa.gov/skywatch….

[ Update July.5.2022 : BBC was late in posting the video See Mars in the night sky, July 2022 | BBC Sky at Night Magazine

** What to see in the night sky: July 2022 – BBC Sky at Night Magazine

What can you see in the night sky tonight? Astronomers Pete Lawrence and Paul Abel reveal July’s top night-sky highlights.

]

** Tonight’s Sky: July – Space Telescope Science Institute – Tonight’s Sky

In July, find the Scorpius constellation to identify the reddish supergiant Antares, which will lead you to discover a trio of globular star clusters. Keep watching for space-based views of these densely packed, spherical collections of ancient stars, as well as three nebulas: the Swan Nebula, the Lagoon Nebula, and the Trifid Nebula.

** What’s in the Night Sky July 2022 #WITNS | Milky Way core | Supermoon | Noctilucent Clouds – Alyn Wallace

00:00 Intro
01:40 Squarespace
02:40 Northern Hemisphere Night Sky
05:30 Southern Hemisphere Night Sky
07:24 Close Approaches
08:06 Full Moon
08:37 Meteor Showers
09:44 #WITNS Winners

** Sky & Telescope’s Sky Tour Podcast – July 2022 – Sky & Telescope Youtube

Our monthly Sky Tour #astronomy #podcast provides an informative and entertaining 10-minute guided tour of the nighttime sky. Listen to July’s episode for #stargazing tips and learn about the #stars of #summer.

See also

** Night Sky Notebook July 2022 – Peter Detterline

** See also:

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Astronomy, Education

ESO: Violent star formation mapped in Tarantula Nebula

The latest report from the European Southern Observatory (ESO):

The Tarantula’s cosmic web:
Astronomers map violent star formation
in nebula outside our galaxy

This composite image shows the star-forming region 30 Doradus, also known as the Tarantula Nebula. The background image, taken in the infrared, is itself a composite: it was captured by the HAWK-I instrument on ESO’s Very Large Telescope (VLT) and the Visible and Infrared Survey Telescope for Astronomy (VISTA), shows bright stars and light, pinkish clouds of hot gas. The bright red-yellow streaks that have been superimposed on the image come from radio observations taken by the Atacama Large Millimeter/submillimeter Array (ALMA), revealing regions of cold, dense gas which have the potential to collapse and form stars. The unique web-like structure of the gas clouds led astronomers to the nebula’s spidery nickname.

Astronomers have unveiled intricate details of the star-forming region 30 Doradus, also known as the Tarantula Nebula, using new observations from the Atacama Large Millimeter/submillimeter Array (ALMA). In a high-resolution image released today by the European Southern Observatory (ESO) and including ALMA data, we see the nebula in a new light, with wispy gas clouds that provide insight into how massive stars shape this region.

“These fragments may be the remains of once-larger clouds that have been shredded by the enormous energy being released by young and massive stars, a process dubbed feedback,”

says Tony Wong, who led the research on 30 Doradus presented today at the American Astronomical Society (AAS) meeting and published in The Astrophysical Journal. Astronomers originally thought the gas in these areas would be too sparse and too overwhelmed by this turbulent feedback for gravity to pull it together to form new stars. But the new data also reveal much denser filaments where gravity’s role is still significant.

“Our results imply that even in the presence of very strong feedback, gravity can exert a strong influence and lead to a continuation of star formation,”

adds Wong, who is a professor at the University of Illinois at Urbana-Champaign, USA.

Located in the Large Magellanic Cloud, a satellite galaxy of our own Milky Way, the Tarantula Nebula is one of the brightest and most active star-forming regions in our galactic neighbourhood, lying about 170 000 light-years away from Earth. At its heart are some of the most massive stars known, a few with more than 150 times the mass of our Sun, making the region perfect for studying how gas clouds collapse under gravity to form new stars.

“What makes 30 Doradus unique is that it is close enough for us to study in detail how stars are forming, and yet its properties are similar to those found in very distant galaxies, when the Universe was young,”

said Guido De Marchi, a scientist at the European Space Agency (ESA) and a co-author of the paper presenting the new research.

“Thanks to 30 Doradus, we can study how stars used to form 10 billion years ago when most stars were born.”

This image shows the star-forming region 30 Doradus, also known as the Tarantula Nebula, in radio wavelengths, as observed by the Atacama Large Millimeter/submillimeter Array (ALMA). The bright red-yellow streaks reveal regions of cold, dense gas which have the potential to collapse and form stars. The unique web-like structure of the gas clouds is characteristic of the Tarantula Nebula.

While most of the previous studies of the Tarantula Nebula have focused on its centre, astronomers have long known that massive star formation is happening elsewhere too. To better understand this process, the team conducted high-resolution observations covering a large region of the nebula. Using ALMA, they measured the emission of light from carbon monoxide gas. This allowed them to map the large, cold gas clouds in the nebula that collapse to give birth to new stars — and how they change as huge amounts of energy are released by those young stars.

“We were expecting to find that parts of the cloud closest to the young massive stars would show the clearest signs of gravity being overwhelmed by feedback,” says Wong. “We found instead that gravity is still important in these feedback-exposed regions — at least for parts of the cloud that are sufficiently dense.”

In the image released today by ESO, we see the new ALMA data overlaid on a previous infrared image of the same region that shows bright stars and light pinkish clouds of hot gas, taken with ESO’s Very Large Telescope (VLT) and ESO’s Visible and Infrared Survey Telescope for Astronomy (VISTA). The composition shows the distinct, web-like shape of the Tarantula Nebula’s gas clouds that gave rise to its spidery name. The new ALMA data comprise the bright red-yellow streaks in the image: very cold and dense gas that could one day collapse and form stars.

This infrared image shows the star-forming region 30 Doradus, also known as the Tarantula Nebula, highlighting its bright stars and light, pinkish clouds of hot gas. The image is a composite: it was captured by the HAWK-I instrument on ESO’s Very Large Telescope (VLT) and the Visible and Infrared Survey Telescope for Astronomy (VISTA).

The new research contains detailed clues about how gravity behaves in the Tarantula Nebula’s star-forming regions, but the work is far from finished.

“There is still much more to do with this fantastic data set, and we are releasing it publicly to encourage other researchers to conduct new investigations,”

Wong concludes.

Links

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Astronomy, Education, SpaceCasts

Night sky highlights for June 2022

** What’s Up: June 2022 Skywatching Tips from NASA – NASA JPL

What are some skywatching highlights in June 2022? The morning quartet of Jupiter, Saturn, Venus, and Mars continues to shine, though they will spread farther apart over the next couple of months. Globular cluster M13, aka the Hercules Cluster, is best observed with a telescope, but binoculars will reveal it as a fuzzy spot. And the constellation Lyra is easily located thanks to its brightest star, Vega.

0:00 Intro
0:11 Morning planets spread out
0:44 Globular Cluster M13
2:20 Find the Constellation Lyra
3:42 June Moon phases

Additional information about topics covered in this episode of What’s Up, along with still images from the video, and the video transcript, are available at https://solarsystem.nasa.gov/skywatch….

** Tonight’s Sky: June – Space Telescope Science Institute – Tonight’s Sky

Though the nights are shorter in June, they are filled with fine sights. Look for the Hercules constellation, which will lead you to a globular star cluster with hundreds of thousands of densely packed stars. You can also spot Draco the dragon, which will point you to the Cat’s Eye Nebula. Keep watching for space-based views of globular star clusters and the nebula.

About this Series: “Tonight’s Sky” is a monthly video of constellations you can observe in the night sky. The series is produced by the Space Telescope Science Institute, home of science operations for the Hubble Space Telescope, in partnership with NASA’s Universe of Learning. This is a recurring show, and you can find more episodes—and other astronomy videos—at TONIGHT’S SKY

** What to see in the night sky: June 2022 – BBC Sky at Night Magazine

What can you see in the night sky tonight? Pete Lawrence and Paul Abel reveal their pick of June 2022’s night-sky highlights.

** What’s in the Night Sky June 2022 #WITNS | 5 Planet Alignment | Supermoon | Noctilucent Clouds – Alyn Wallace

00:00 Intro
01:04 Northern Hemisphere Night Sky
03:36 Southern Hemisphere Night Sky
05:37 Full Moon
06:02 Squarespace
06:51 Noctilucent Clouds
09:25 #WITNS Winners

** Night Sky Notebook June 2022 – Peter Detterline

** See also:

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Stellaris: People of the Stars

Activism, Education, Space films and videos

“The Magic of Inspiration” – A documentary film

Alvin Remmers, whom I met while he was making a video series focused on the NewSpace industry and community, tells me about a new documentary film he is producing and directing. The Magic of Inspiration aims to

… unleash the potential of young women and cultivate their aspirations for careers in STEM-related fields. Firm in the belief that “If you can see it, you can be it”, the film is bursting at the seams with role models who have the ability to launch dreams into careers. 

We are profiling women who will provide a look behind the curtain at their remarkable careers, the paths they took to get there and the challenges and joys they derive from their vocations. Our  goal is to develop a more diverse and capable workforce. 

We also will profile organizations and institutions dedicated to developing the curiosity in young people necessary to begin to imagine themselves solving today’s puzzles and influencing tomorrow’s outcomes.

The Magic of Inspiration – a documentary intended to inspire girls and young women to pursue STEM careers.

Alvin says the website, themagic.film, “contains brief info about the film, the reasons for making it, the film’s intended audiences and profiles of the filmmakers“.

Sign up here for updates on the making of the movie.