Category Archives: Astronomy

The latest report from ESO (European Southern Observatory):

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

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

Surprise: astronomers have found what look like three different generations of baby stars within the Orion Nebula Cluster.
[Higher resolution video]

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

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

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

Monika Petr-Gotzens, co-author and also based at ESO Garching, continues,

“This is an important result. What we are witnessing is that the stars of a cluster at the beginning of their lives didn’t form altogether simultaneously. This may mean that our understanding of how stars form in clusters needs to be modified.”

This video sequence starts with a wide view of the Milky Way and slowly zooms in on the Orion Nebula, one of the brightest nearby regions of active star formation. The final view shows a very detailed new view of the stellar nursery from the VLT Survey Telescope. Credit: ESO, N. Risinger (skysurvey.org), Digitized Sky Survey 2. Music: Johan B. Monell (www.johanmonell.com)

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

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

concludes Beccari.

This pan video shows a richly detailed new view of the Orion Nebula from the VLT Survey Telescope at ESO’s Paranal Observatory in Chile. This star formation region comprises glowing clouds of gas, veins of dark dust and many very young stars. Credit: ESO. Music: Johan B. Monell (www.johanmonell.com)

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

Notes

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

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

This chart shows the location of the Orion Nebula (Messier 42) in the sword of the famous constellation of Orion (the Hunter). This map shows most of the stars visible to the unaided eye under good conditions and the Orion Nebula itself is highlighted with a red circle on the image. This grand star formation region can be seen with the unaided eye and is an impressive sight in moderate-sized amateur telescopes.

Astronomy, Events, Solar Science

Videos: Solar eclipses, syzygy, and citizen solar science

July 22, 2017 TopSpacer 1 Comment

The Planetary Society has released three short videos about the solar eclipse over the US on August 21st:

Bill Nye explains the basics of a solar eclipses, the path of totality, and how to safely view a solar eclipse with National Park Ranger Coral O’Riley.

Bill Nye loves syzygy and Dr. Ashwin Vasavada from JPL talks about a curious eclipse on Mars

Bill Nye explains how to see the Milky Way after a solar eclipse and Dr. Tyler Nordgren shows an ancient eclipse petroglyph.

And here is NASA initiative to involve the public in experimental solar science: Become a Citizen Scientist During Total Solar Eclipse | NASA

Astronomy, Mars

Video: Hubble captures Phobos in motion around Mars

July 20, 2017 TopSpacer 1 Comment

The Hubble Space Telescope makes a cool time-lapse video of the Martian moon Phobos circling the Red Planet:

NASA’s Hubble Sees Martian Moon Orbiting the Red Planet

When the Hubble Space Telescope observed Mars near opposition in May, 2016, a sneaky companion photobombed the picture. Phobos, the Greek personification of fear, is one of two tiny moons orbiting Mars. In 13 exposures over 22 minutes, Hubble captured a timelapse of Phobos moving through its 7-hour 39-minute orbit. Credits: NASA’s Goddard Space Flight Center

The sharp eye of NASA’s Hubble Space Telescope has captured the tiny moon Phobos during its orbital trek around Mars. Because the moon is so small, it appears star-like in the Hubble pictures.

Over the course of 22 minutes, Hubble took 13 separate exposures, allowing astronomers to create a time-lapse video showing the diminutive moon’s orbital path. The Hubble observations were intended to photograph Mars, and the moon’s cameo appearance was a bonus.

A football-shaped object just 16.5 miles by 13.5 miles by 11 miles, Phobos is one of the smallest moons in the solar system. It is so tiny that it would fit comfortably inside the Washington, D.C. Beltway.

The little moon completes an orbit in just 7 hours and 39 minutes, which is faster than Mars rotates. Rising in the Martian west, it runs three laps around the Red Planet in the course of one Martian day, which is about 24 hours and 40 minutes. It is the only natural satellite in the solar system that circles its planet in a time shorter than the parent planet’s day.

About two weeks after the Apollo 11 manned lunar landing on July 20, 1969, NASA’s Mariner 7 flew by the Red Planet and took the first crude close-up snapshot of Phobos. On July 20, 1976 NASA’s Viking 1 lander touched down on the Martian surface. A year later, its parent craft, the Viking 1 orbiter, took the first detailed photograph of Phobos, revealing a gaping crater from an impact that nearly shattered the moon.

Phobos was discovered by Asaph Hall on August 17, 1877 at the U.S. Naval Observatory in Washington, D.C., six days after he found the smaller, outer moon, named Deimos. Hall was deliberately searching for Martian moons.

Both moons are named after the sons of Ares, the Greek god of war, who was known as Mars in Roman mythology. Phobos (panic or fear) and Deimos (terror or dread) accompanied their father into battle.

Close-up photos from Mars-orbiting spacecraft reveal that Phobos is apparently being torn apart by the gravitational pull of Mars. The moon is marred by long, shallow grooves that are probably caused by tidal interactions with its parent planet. Phobos draws nearer to Mars by about 6.5 feet every hundred years. Scientists predict that within 30 to 50 million years, it either will crash into the Red Planet or be torn to pieces and scattered as a ring around Mars.

Orbiting 3,700 miles above the Martian surface, Phobos is closer to its parent planet than any other moon in the solar system. Despite its proximity, observers on Mars would see Phobos at just one-third the width of the full moon as seen from Earth. Conversely, someone standing on Phobos would see Mars dominating the horizon, enveloping a quarter of the sky.

From the surface of Mars, Phobos can be seen eclipsing the sun. However, it is so tiny that it doesn’t completely cover our host star. Transits of Phobos across the sun have been photographed by several Mars-faring spacecraft.

The origin of Phobos and Deimos is still being debated. Scientists concluded that the two moons were made of the same material as asteroids. This composition and their irregular shapes led some astrophysicists to theorize that the Martian moons came from the asteroid belt.

However, because of their stable, nearly circular orbits, other scientists doubt that the moons were born as asteroids. Such orbits are rare for captured objects, which tend to move erratically. An atmosphere could have slowed down Phobos and Deimos and settled them into their current orbits, but the Martian atmosphere is too thin to have circularized the orbits. Also, the moons are not as dense as members of the asteroid belt.

Phobos may be a pile of rubble that is held together by a thin crust. It may have formed as dust and rocks encircling Mars were drawn together by gravity. Or, it may have experienced a more violent birth, where a large body smashing into Mars flung pieces skyward, and those pieces were brought together by gravity. Perhaps an existing moon was destroyed, reduced to the rubble that would become Phobos.

Hubble took the images of Phobos orbiting the Red Planet on May 12, 2016, when Mars was 50 million miles from Earth. This was just a few days before the planet passed closer to Earth in its orbit than it had in the past 11 years.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

While photographing Mars, NASA’s Hubble Space Telescope captured a cameo appearance of the tiny moon Phobos on its trek around the Red Planet. Discovered in 1877, the diminutive, potato-shaped moon is so small that it appears star-like in the Hubble pictures. Phobos orbits Mars in just 7 hours and 39 minutes, which is faster than Mars rotates. The moon’s orbit is very slowly shrinking, meaning it will eventually shatter under Mars’ gravitational pull, or crash onto the planet. Hubble took 13 separate exposures over 22 minutes to create a time-lapse video showing the moon’s orbital path.

For images and more information about Hubble, visit:

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Check out the Space Telescope Live page to see what Hubble is currently observing.

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Astronomy, Exoplanets

Video: “How to Find an Inhabited Exoplanet”

July 11, 2017 TopSpacer 1 Comment

Here is an excellent overview for a general public audience of the question, “How to Find an Inhabited Exoplanet”:

The speaker is David Charbonneau of Harvard University. He gave the presentation at the Space Telescope Science Institute in Baltimore, Maryland for one of their public lectures:

Over the past couple decades, research has uncovered thousands of exoplanets in orbit around other stars. In particular, the NASA Kepler Mission taught us that Earth-sized planets are commonplace throughout the Galaxy. But the big question remains – did life take root on any of these distant worlds? Using upcoming large telescopes, astronomers will examine the atmospheres of Earth-like planets for the telltale chemical fingerprints of life. The search for life in the universe has entered an exciting new phase.

Astronomy

ESO’s Very Large Telescope captures a “Dazzling Spiral with an Active Heart”

July 5, 2017 TopSpacer 1 Comment

A new report from ESO (European Southern Observatory):

Dazzling Spiral with an Active Heart

ESO’s Very Large Telescope (VLT) has captured a magnificent face-on view of the barred spiral galaxy Messier 77. The image does justice to the galaxy’s beauty, showcasing its glittering arms criss-crossed with dust lanes — but it fails to betray Messier 77’s turbulent nature.

This picturesque spiral galaxy appears to be tranquil, but there is more to it than meets the eye. Messier 77 (also known as NGC 1068) is one of the closest active galaxies, which are some of the most energetic and spectacular objects in the Universe. Their nuclei are often bright enough to outshine the whole of the rest of the galaxy. Active galaxies are among the brightest objects in the Universe and emit light at most, if not all, wavelengths, from gamma rays and X-rays all the way to microwaves and radiowaves. Messier 77 is further classified as a Type II Seyfert galaxy, characterised by being particularly bright at infrared wavelengths.

ESO’s Very Large Telescope (VLT) has captured a magnificent face-on view of the barred spiral galaxy Messier 77. But there is more to this galaxy than meets the eye. This ESOcast Light takes a closer look.

This impressive luminosity is caused by intense radiation blasting out from a central engine — the accretion disc surrounding a supermassive black hole. Material that falls towards the black hole is compressed and heated up to incredible temperatures, causing it to radiate a tremendous amount of energy. This accretion disc is thought to be enshrouded by thick doughnut-shaped structure of gas and dust, called a “torus”. Observations of Messier 77 back in 2003 were the first to resolve such a structure using the powerful VLT Interferometer (eso0319).

This video sequence takes the viewer deep into a detailed view of the active galaxy Messier 77 from ESO’s Very Large Telescope in northern Chile. Credit: ESO/Digitized Sky Survey 2

This image of Messier 77 was taken in four different wavelength bands represented by blue, red, violet and pink (hydrogen-alpha) colours. Each wavelength brings out a different quality: for example, the pinkish hydrogen-alpha highlights the hotter and younger stars forming in the spiral arms, while in red are the fine, thread-like filamentary structures in the gas surrounding Messier 77 [1]. A foreground Milky Way star is also seen beside the galaxy centre, displaying tell-tale diffraction spikes. Additionally, many more distant galaxies are visible; sitting at the outskirts of the spiral arms, they appear tiny and delicate compared to the colossal active galaxy.

*This image from the Digitized Sky Survey shows spiral galaxy Messier 77 and its surroundings. Messier 77 appears at the centre and the edge-on galaxy NGC 1055 to the upper-right. [Larger image]*

Located 47 million light-years away in the constellation of Cetus (The Sea Monster), Messier 77 is one of the most remote galaxies of the Messier catalogue. Initially, Messier believed that the highly luminous object he saw through his telescope was a cluster of stars, but as technology progressed its true status as a galaxy was realised. At approximately 100 000 light-years across, Messier 77 is also one of largest galaxies in the Messier catalogue — so massive that its gravity causes other nearby galaxies to twist and become warped (eso1707) [2].

This image was obtained using the FOcal Reducer and low dispersion Spectrograph 2 (FORS2) instrument mounted on Unit Telescope 1 (Antu) of the VLT, located at ESO’s Paranal Observatory in Chile. It hails from ESO’s Cosmic Gems programme, an outreach initiative that produces images of interesting, intriguing or visually attractive objects using ESO telescopes for the purposes of education and outreach.

This video pan shows a new image from ESO’s Very Large Telescope of Messier 77. Also known as NGC 1068, Messier 77 is one of the closest active galaxies, which are some of the most energetic and spectacular objects in the Universe. Credit: ESO

Notes

[1] Similar red filaments are also found in NGC 1275. They are cool, despite being surrounded by a very hot gas at around 50 million degrees Celsius. The filaments are suspended in a magnetic field which maintains their structure and demonstrates how energy from the central black hole is transferred to the surrounding gas.

[2] NGC 1055 is located about 60 million light-years away. It is an edge-on galaxy, in contrast to Messier 77. This Astronomy Picture of the Day portrays both of them together, in a field of view about the size of the Moon (APOD).