February 20, 2016

Lonely Galaxy

Lonely Galaxy NGC 1569

Astronomers have long puzzled over why a small, nearby, isolated galaxy is pumping out new stars faster than any galaxy in our local neighborhood.

Now NASA's Hubble Space Telescope has helped astronomers solve the mystery of the loner starburst galaxy, called NGC 1569, by showing that it is one and a half times farther away than astronomers thought.

The extra distance places the galaxy in the middle of a group of about 10 galaxies centered on the spiral galaxy IC 342. Gravitational interactions among the group's galaxies may be compressing gas in NGC 1569 and igniting the star-birthing frenzy.

The farther distance not only means that the galaxy is intrinsically brighter, but also that it is producing stars two times faster than first thought. The galaxy is forming stars at a rate more than 100 times higher than in the Milky Way. This high star-formation rate has been almost continuous for the past 100 million years.

Discovered by William Herschel in 1788, NGC 1569 is home to three of the most massive star clusters ever discovered in the local universe. Each cluster contains more than a million stars.

Image Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), and A. Aloisi (STScI/ESA)
Explanation from: http://www.nasa.gov/multimedia/imagegallery/image_feature_1255.html

Wide-field view of the Gum 15 star formation region

Gum 15 star formation region

This relatively unknown wide-field view captures the spectacular celestial landscape around the central object Gum 15. Among many other objects the star cluster NGC 2671 is visible a little to the lower left of centre and at the lower right of the image some of the filaments forming part of the Vela Supernova Remnant can be seen. This view was created from images forming part of the Digitized Sky Survey 2.

Image Credit: ESO/Digitized Sky Survey 2, Davide De Martin
Explanation from: http://www.eso.org/public/images/eso1420c/

Volcán de Fuego Eruption

Sierra Madre, Guatemala
November 12, 2014

Image Credit & Copyright: Andy Shepard

February 19, 2016

The Jellyfish Nebula

Jellyfish Nebula

Lying in the constellation of Gemini, IC 443 is a galactic supernova remnant, a star that could have exploded as many as 30,000 years ago. Its globular appearance has earned the celestial structure the moniker the Jellyfish Nebula

Image Credit & Copyright: Patrick Gilliland
Explanation by: Royal Observatory Greenwich

Globular Cluster Messier 5

Globular Cluster Messier 5

The globular cluster Messier 5, shown here in this NASA/ESA Hubble Space Telescope image, is one of the oldest belonging to the Milky Way. The majority of its stars formed more than 12 billion years ago, but there are some unexpected newcomers on the scene, adding some vitality to this aging population.

Stars in globular clusters form in the same stellar nursery and grow old together. The most massive stars age quickly, exhausting their fuel supply in less than a million years, and end their lives in spectacular supernovae explosions. This process should have left the ancient cluster Messier 5 with only old, low-mass stars, which, as they have aged and cooled, have become red giants, while the oldest stars have evolved even further into blue horizontal branch stars.

Yet astronomers have spotted many young, blue stars in this cluster, hiding amongst the much more luminous ancient stars. Astronomers think that these laggard youngsters, called blue stragglers, were created either by stellar collisions or by the transfer of mass between binary stars. Such events are easy to imagine in densely populated globular clusters, in which up to a few million stars are tightly packed together.

Messier 5 lies at a distance of about 25 000 light-years in the constellation of Serpens (The Snake). This image was taken with Wide Field Channel of Hubble’s Advanced Camera for Surveys. The picture was created from images taken through a blue filter (F435W, coloured blue), a red filter (F625W, coloured green) and a near-infrared filter (F814W, coloured red). The total exposure times per filter were 750 s, 400 s and 567 s, respectively. The field of view is about 2.6 arcminutes across.

Image Credit: ESA/Hubble & NASA
Explanation from: https://www.spacetelescope.org/images/potw1118a/

Lightning over Grand Canyon

Lightning over Grand Canyon

Grand Canyon, Arizona, USA
August 30, 2013

Image Credit & Copyright: Rex Features and Rolf Maeder

February 18, 2016

Hubble Directly Measures Rotation of Cloudy 'Super-Jupiter'

Companion Super-Jupiter 2M1207b
Companion Super-Jupiter 2M1207b
Brown Dwarf 2M1207A
Brown Dwarf 2M1207A
Artist's View of a Super-Jupiter around a Brown Dwarf (2M1207)
Artist's View of a Super-Jupiter around a Brown Dwarf (2M1207)
Astronomers using NASA's Hubble Space Telescope have measured the rotation rate of an extreme exoplanet by observing the varied brightness in its atmosphere. This is the first measurement of the rotation of a massive exoplanet using direct imaging.

"The result is very exciting," said Daniel Apai of the University of Arizona in Tucson, leader of the Hubble investigation. "It gives us a unique technique to explore the atmospheres of exoplanets and to measure their rotation rates."

The planet, called 2M1207b, is about four times more massive than Jupiter and is dubbed a "super-Jupiter." It is a companion to a failed star known as a brown dwarf, orbiting the object at a distance of 5 billion miles. By contrast, Jupiter is approximately 500 million miles from the sun. The brown dwarf is known as 2M1207. The system resides 170 light-years away from Earth.

Hubble's image stability, high resolution, and high-contrast imaging capabilities allowed astronomers to precisely measure the planet's brightness changes as it spins. The researchers attribute the brightness variation to complex clouds patterns in the planet's atmosphere. The new Hubble measurements not only verify the presence of these clouds, but also show that the cloud layers are patchy and colorless.

Astronomers first observed the massive exoplanet 10 years ago with Hubble. The observations revealed that the exoplanet's atmosphere is hot enough to have "rain" clouds made of silicates: vaporized rock that cools down to form tiny particles with sizes similar to those in cigarette smoke. Deeper into the atmosphere, iron droplets are forming and falling like rain, eventually evaporating as they enter the lower levels of the atmosphere.

"So at higher altitudes it rains glass, and at lower altitudes it rains iron," said Yifan Zhou of the University of Arizona, lead author on the research paper. "The atmospheric temperatures are between about 2,200 to 2,600 degrees Fahrenheit."

The super-Jupiter is so hot that it appears brightest in infrared light. Astronomers used Hubble's Wide Field Camera 3 to analyze the exoplanet in infrared light to explore the object's cloud cover and measure its rotation rate. The planet is hot because it is only about 10 million years old and is still contracting and cooling. For comparison, Jupiter in our solar system is about 4.5 billion years old.

The planet, however, will not maintain these sizzling temperatures. Over the next few billion years, the object will cool and fade dramatically. As its temperature decreases, the iron and silicate clouds will also form lower and lower in the atmosphere and will eventually disappear from view.

Zhou and his team have also determined that the super-Jupiter completes one rotation approximately every 10 hours, spinning at about the same fast rate as Jupiter.

This super-Jupiter is only about five to seven times less massive than its brown-dwarf host. By contrast, our sun is about 1,000 times more massive than Jupiter. "So this is a very good clue that the 2M1207 system we studied formed differently than our own solar system," Zhou explained. The planets orbiting our sun formed inside a circumstellar disk through accretion. But the super-Jupiter and its companion may have formed throughout the gravitational collapse of a pair of separate disks.

"Our study demonstrates that Hubble and its successor, NASA's James Webb Space Telescope, will be able to derive cloud maps for exoplanets, based on the light we receive from them," Apai said. Indeed, this super-Jupiter is an ideal target for the Webb telescope, an infrared space observatory scheduled to launch in 2018. Webb will help astronomers better determine the exoplanet's atmospheric composition and derive detailed maps from brightness changes with the new technique demonstrated with the Hubble observations.

Image Credit: NASA, ESA, G. Bacon (STScI), Y. Zhou
Explanation from: http://hubblesite.org/newscenter/archive/releases/2016/05/full/

Volcán de Colima Eruption

Volcan de Colima Eruption

Colima, Mexico
December 13, 2015

Image Credit & Copyright: Sergio Tapiro

Coronal Mass Ejection: January 4, 2002

Coronal Mass Ejection

Another treatment of a fiery Coronal Mass Ejection (CME) with stunning, bright details in the ejected material. In this composite image, an EIT image of the Sun in extreme UV light, taken on January 4, 2002, was enlarged and superimposed on LASCO C2. In coronagraph images, direct sunlight is blocked by an occulter (covered by the Sun here) to reveal the surrounding faint corona.

Image Credit: NASA/SOHO
Explanation from: http://sohowww.nascom.nasa.gov/bestofsoho/images/suncombo2.html

February 17, 2016

Earth and Galactic Center of the Milky Way Galaxy seen from the International Space Station

milky way from iss

NASA astronaut Reid Wiseman captured this image from the International Space Station and published it on September 28, 2014, writing, "The Milky Way steals the show from Sahara sands that make the Earth glow orange."

ISS, Orbit of the Earth
September 28, 2014

Image Credit: NASA/Reid Wiseman

Centaurus A

Centaurus A

The NASA/ESA Hubble Space Telescope has produced a close-up view of the galaxy Centaurus A. Hubble’s out-of-this-world location and world-class Wide Field Camera 3 instrument reveal a dramatic picture of a dynamic galaxy in flux.

Centaurus A, also known as NGC 5128, is well known for its dramatic dusty lanes of dark material. Hubble’s observations, using its most advanced instrument, the Wide Field Camera 3, are the most detailed ever made of this galaxy. They have been combined here in a multi-wavelength image that reveals never-before-seen detail in the dusty portion of the galaxy.

As well as features in the visible spectrum, this composite shows ultraviolet light from young stars, and near-infrared light, which lets us glimpse some of the detail otherwise obscured by the dust.

The dark dust lane that crosses Centaurus A does not show an absence of stars, but rather a relative lack of starlight, as the opaque clouds block the visible light from reaching us. Hubble’s Wide Field Camera 3 has focussed on these dusty regions, which span from corner to corner in this image. Wider views from ground-based telescopes show this stripe crossing the entire galaxy.

Interesting features such as the warped shape of its disc of gas and dust (outside the view) hint that at some point in the past, Centaurus A collided and merged with another galaxy. The shockwaves of this event caused hydrogen gas to coalesce and sparked intense areas of star formation, as seen in its outlying regions and in red patches visible in this Hubble close-up.

The galaxy’s compact nucleus contains a highly active supermassive black hole at its centre. Powerful relativistic jets release vast amounts of radio and X-ray radiation — although these are invisible here as Hubble’s instruments are designed to study optical, ultraviolet and infrared wavelengths.

At just over 11 million light-years distant, Centaurus A is relatively nearby in astronomical terms. However, it is not only close, it is also bright. This makes it a very attractive target for amateur astronomers in the southern hemisphere, where it is visible. Stargazers can see the galaxy through binoculars, while larger amateur telescopes begin to unveil the distinctive dusty lanes.

However it is only with the capabilities of the Hubble Space Telescope that many of the features in this image become visible: as well as providing unparalleled clarity and resolution, Hubble’s position in orbit means that it can see ultraviolet wavelengths which are blocked by the atmosphere and so invisible from the ground.

Image Credit: NASA, ESA, and the Hubble Heritage (STScI/AURA)
Explanation from: http://www.spacetelescope.org/news/heic1110/

Supercell over Texas

Supercell Texas

Booker, Texas, USA
June 3, 2013

Image Credit & Copyright: Marko Korošec

February 16, 2016

A cloud of ash above Calbuco Volcano

A cloud of ash above Calbuco Volcano

Puerto Varas, Chile
April 22, 2015

Image Credit: Diego Main

First Detection of Super-Earth Atmosphere

55 Cancri eSuper-Earth

For the first time astronomers were able to analyse the atmosphere of an exoplanet in the class known as super-Earths. Using data gathered with the NASA/ESA Hubble Space Telescope and new analysis techniques, the exoplanet 55 Cancri e is revealed to have a dry atmosphere without any indications of water vapour. The results, to be published in the Astrophysical Journal, indicate that the atmosphere consists mainly of hydrogen and helium.

The international team, led by scientists from University College London (UCL) in the UK, took observations of the nearby exoplanet 55 Cancri e, a super-Earth with a mass of eight Earth-masses. It is located in the planetary system of 55 Cancri, a star about 40 light-years from Earth.

Using observations made with the Wide Field Camera 3 (WFC3) on board the NASA/ESA Hubble Space Telescope, the scientists were able to analyse the atmosphere of this exoplanet. This makes it the first detection of gases in the atmosphere of a super-Earth. The results allowed the team to examine the atmosphere of 55 Cancri e in detail and revealed the presence of hydrogen and helium, but no water vapour. These results were only made possible by exploiting a newly-developed processing technique.

This is a very exciting result because it’s the first time that we have been able to find the spectral fingerprints that show the gases present in the atmosphere of a super-Earth,” explains Angelos Tsiaras, a PhD student at UCL, who developed the analysis technique along with his colleagues Ingo Waldmann and Marco Rocchetto. “The observations of 55 Cancri e’s atmosphere suggest that the planet has managed to cling on to a significant amount of hydrogen and helium from the nebula from which it originally formed.

Super-Earths like 55 Cancri e are thought to be the most common type of planet in our galaxy. They acquired the name ‘super-Earth’ because they have a mass larger than that of the Earth but are still much smaller than the gas giants in the Solar System. The WFC3 instrument on Hubble has already been used to probe the atmospheres of two other super-Earths, but no spectral features were found in those previous studies.

55 Cancri e, however, is an unusual super-Earth as it orbits very close to its parent star. A year on the exoplanet lasts for only 18 hours and temperatures on the surface are thought to reach around 2000 degrees Celsius. Because the exoplanet is orbiting its bright parent star at such a small distance, the team was able to use new analysis techniques to extract information about the planet, during its transits in front of the host star.

Observations were made by scanning the WFC3 very quickly across the star to create a number of spectra. By combining these observations and processing them through analytic software, the researchers were able to retrieve the spectrum of 55 Cancri e embedded in the light of its parent star.

This result gives a first insight into the atmosphere of a super-Earth. We now have clues as to what the planet is currently like and how it might have formed and evolved, and this has important implications for 55 Cancri e and other super-Earths,” said Giovanna Tinetti, also from UCL, UK.

Intriguingly, the data also contain hints of the presence of hydrogen cyanide, a marker for carbon-rich atmospheres.

Such an amount of hydrogen cyanide would indicate an atmosphere with a very high ratio of carbon to oxygen,” said Olivia Venot, KU Leuven, who developed an atmospheric chemical model of 55 Cancri e that supported the analysis of the observations.

If the presence of hydrogen cyanide and other molecules is confirmed in a few years time by the next generation of infrared telescopes, it would support the theory that this planet is indeed carbon rich and a very exotic place,” concludes Jonathan Tennyson, UCL. “Although hydrogen cyanide, or prussic acid, is highly poisonous, so it is perhaps not a planet I would like to live on!

Image Credit: ESA/Hubble, M. Kornmesser
Explanation from: http://www.spacetelescope.org/news/heic1603/

Anticyclonic Tornado in Colorado


An anticyclonic tornado is a tornado which rotates in a clockwise direction in the Northern Hemisphere and a counterclockwise direction in the Southern Hemisphere. The term is a naming convention denoting the anomaly from normal rotation which is cyclonic in upwards of 98 percent of tornadoes. Many, but not all, anticyclonic tornadoes are smaller and weaker than cyclonic tornadoes, forming from a different process.

Most strong tornadoes (the classic conception of a tornado) form in the inflow and updraft area bordering the updraft-downdraft interface (which is also near the mesoscale "triple point") zone of supercell thunderstorms. The thunderstorm itself is rotating, with a rotating updraft known as a mesocyclone, and then a smaller area of rotation at lower altitude the tornadocyclone (or low-level mesocyclone) which produces or enables the smaller rotation that is a tornado. All of these may be, but aren't always, quasi-vertically aligned continuing from the ground to the mid-upper levels of the storm. All of these cyclones and scaling all the way up to large extratropical (low-pressure systems) and tropical cyclones rotate cyclonically.

Rotation in these synoptic scale systems stems partly from the Coriolis effect, however, thunderstorms and tornadoes are too small to be significantly affected. The common property here is an area of lower pressure, thus surrounding air flows into the area of less dense air forming cyclonic rotation. The rotation of the thunderstorm itself is induced mostly by vertical wind shear.

Various processes can produce an anticyclonic tornado. Most often they are satellite tornadoes of larger tornadoes which are directly associated with the tornadocyclone and mesocyclone. Occasionally anticyclonic tornadoes occur as an anticyclonic companion (mesoanticyclone) to a mesocyclone within a single storm.

Anticyclonic tornadoes can occur as the primary tornado with a mesocyclone and under a rotating wall cloud. Also, anticyclonic supercells (with mesoanticyclone), which usually are storms that split and move to the left of the parent storm motion, though very rarely spawning tornadoes, spawn anticyclonic tornadoes. There is an increased incidence of anticyclonic tornadoes associated with tropical cyclones, and mesovortices within bow echoes may spawn anticyclonic tornadoes. The first anticyclonic tornado associated with a mesoanticyclone was spotted on WSR-88D weather radar in Sunnyvale, California May 4, 1998. The tornado was an F-2 on the Fujita Scale.

Simla, Colorado, USA
June 5, 2015

Image Credit: James Smart
Explanation from: https://en.wikipedia.org/wiki/Anticyclonic_tornado

The open star cluster Messier 7

The open star cluster Messier 7

This image from the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile, shows the bright star cluster Messier 7, also known as NGC 6475. Easily spotted by the naked eye in the direction of the tail of the constellation of Scorpius (The Scorpion), this cluster is one of the most prominent open clusters of stars in the sky and an important research target.

Image Credit: ESO
Explanation from: https://www.eso.org/public/images/eso1406a/

February 15, 2016

The Stephan's Quintet Galaxy Group

Stephan's Quintet Galaxy Group

A clash among members of a famous galaxy quintet reveals an assortment of stars across a wide color range, from young, blue stars to aging, red stars.

This portrait of Stephan's Quintet, also known as Hickson Compact Group 92, was taken by the new Wide Field Camera 3 (WFC3) aboard NASA's Hubble Space Telescope. Stephan's Quintet, as the name implies, is a group of five galaxies. The name, however, is a bit of a misnomer. Studies have shown that group member NGC 7320, at upper left, is actually a foreground galaxy about seven times closer to Earth than the rest of the group.

Three of the galaxies have distorted shapes, elongated spiral arms, and long, gaseous tidal tails containing myriad star clusters, proof of their close encounters. These interactions have sparked a frenzy of star birth in the central pair of galaxies. This drama is being played out against a rich backdrop of faraway galaxies.

The image, taken in visible and near-infrared light, showcases WFC3's broad wavelength range.

The colors trace the ages of the stellar populations, showing that star birth occurred at different epochs, stretching over hundreds of millions of years. The camera's infrared vision also peers through curtains of dust to see groupings of stars that cannot be seen in visible light.

NGC 7319, at top right, is a barred spiral with distinct spiral arms that follow nearly 180 degrees back to the bar. The blue specks in the spiral arm at the top of NGC 7319 and the red dots just above and to the right of the core are clusters of many thousands of stars. Most of the quintet is too far away even for Hubble to resolve individual stars.

Continuing clockwise, the next galaxy appears to have two cores, but it is actually two galaxies, NGC 7318A and NGC 7318B. Encircling the galaxies are young, bright blue star clusters and pinkish clouds of glowing hydrogen where infant stars are being born. These stars are less than 10 million years old and have not yet blown away their natal cloud. Far away from the galaxies, at right, is a patch of intergalactic space where many star clusters are forming.

NGC 7317, at bottom left, is a normal-looking elliptical galaxy that is less affected by the interactions.

Sharply contrasting with these galaxies is the dwarf galaxy NGC 7320 at upper left. Bursts of star formation are occurring in the galaxy's disk, as seen by the blue and pink dots. In this galaxy, Hubble can resolve individual stars, evidence that NGC 7320 is closer to Earth.

NGC 7320 is 40 million light-years from Earth. The other members of the quintet reside 290 million light-years away in the constellation Pegasus.

These farther members are markedly redder than the foreground galaxy, suggesting that older stars reside in their cores. The stars' light also may be further reddened by dust stirred up in the encounters.

Spied by Edouard M. Stephan in 1877, Stephan's Quintet is the first compact group ever discovered.

WFC3 observed the quintet in July and August 2009. The composite image was made by using filters that isolate light from the blue, green, and infrared portions of the spectrum, as well as emission from ionized hydrogen.

Image Credit: NASA, ESA, and the Hubble SM4 ERO Team
Explanation from: http://hubblesite.org/newscenter/archive/releases/2009/25/image/x/

Cosmic dust clouds in Messier 78

Messier 78

This image of the region surrounding the reflection nebula Messier 78, just to the north of Orion’s belt, shows clouds of cosmic dust threaded through the nebula like a string of pearls. The submillimetre-wavelength observations, made with the Atacama Pathfinder Experiment (APEX) telescope and shown here in orange, use the heat glow of interstellar dust grains to show astronomers where new stars are being formed. They are overlaid on a view of the region in visible light.

Image Credit: ESO/APEX (MPIfR/ESO/OSO)/T. Stanke et al./Igor Chekalin/Digitized Sky Survey 2
Explanation from: http://www.eso.org/public/images/eso1219a/

2015 Total Solar Eclipse

2015 Total Solar Eclipse

The total solar eclipse of 20th March 2015 seen from Svalbard - one of only two habitable locations that were able to witness totality – just 16 seconds after it began. The image shows totality about 100m above the large valley of Sassendalen situated on the only permanently inhabited island of the Norwegian archipelago. Venus can also be seen in the photograph, as a bright spot in the upper left of the image.

Spitsbergen, Svalbard, Norway
March 20, 2015

Image Credit & Copyright: Luc Jamet
Explanation by: Royal Observatory Greenwich

February 14, 2016

Globular Cluster: Messier 10

Globular Cluster Messier 10

Like many of the most famous objects in the sky, globular cluster Messier 10 was of little interest to its discoverer: Charles Messier, the 18th century French astronomer, catalogued over 100 galaxies and clusters, but was primarily interested in comets. Through the telescopes available at the time, comets, nebulae, globular clusters and galaxies appeared just as faint, diffuse blobs and could easily be confused for one another.

Only by carefully observing their motion — or lack of it — were astronomers able to distinguish them: comets move slowly relative to the stars in the background, while other more distant astronomical objects do not move at all.

Messier’s decision to catalogue all the objects that he could find and that were not comets, was a pragmatic solution which would have a huge impact on astronomy. His catalogue of just over 100 objects includes many of the most famous objects in the night sky. Messier 10, seen here in an image from the NASA/ESA Hubble Space Telescope, is one of them. Messier described it in the very first edition of his catalogue, which was published in 1774 and included the first 45 objects he identified.

Messier 10 is a ball of stars that lies about 15 000 light-years from Earth, in the constellation of Ophiuchus (The Serpent Bearer). Approximately 80 light-years across, it should therefore appear about two thirds the size of the Moon in the night sky. However, its outer regions are extremely diffuse, and even the comparatively bright core is too dim to see with the naked eye.

Hubble, which has no problems seeing faint objects, has observed the brightest part of the centre of the cluster in this image, a region which is about 13 light-years across.

This image is made up of observations made in visible and infrared light using Hubble’s Advanced Camera for Surveys. The observations were carried out as part of a major Hubble survey of globular clusters in the Milky Way.

Image Credit: ESA/Hubble & NASA
Explanation from: https://www.spacetelescope.org/images/potw1225a/

Young star lights up reflection nebula IC 2631

Reflection Nebula IC 2631

A newly formed star lights up the surrounding cosmic clouds in this new image from ESO’s La Silla Observatory in Chile. Dust particles in the vast clouds that surround the star HD 97300 diffuse its light, like a car headlight in enveloping fog, and create the reflection nebula IC 2631. Although HD 97300 is in the spotlight for now, the very dust that makes it so hard to miss heralds the birth of additional, potentially scene-stealing, future stars.

The glowing region in this new image from the MPG/ESO 2.2-metre telescope is a reflection nebula known as IC 2631. These objects are clouds of cosmic dust that reflect light from a nearby star into space, creating a stunning light show like the one captured here. IC 2631 is the brightest nebula in the Chamaeleon Complex, a large region of gas and dust clouds that harbours numerous newborn and still-forming stars. The complex lies about 500 light-years away in the southern constellation of Chamaeleon.

IC 2631 is illuminated by the star HD 97300, one of the youngest — as well as most massive and brightest — stars in its neighbourhood. This region is full of star-making material, which is made evident by the presence of dark nebulae noticeable above and below IC 2631 in this picture. Dark nebulae are so dense with gas and dust that they prevent the passage of background starlight.

Despite its dominating presence, the heft of HD 97300 should be kept in perspective. It is a T Tauri star, the youngest visible stage for relatively small stars. As these stars mature and reach adulthood they will lose mass and shrink. But during the T Tauri phase these stars have not yet contracted to the more modest size that they will maintain for billions of years as main sequence stars.

These fledging stars already have surface temperatures similar to their main sequence phase and accordingly, because T Tauri-phase objects are essentially jumbo versions of their later selves, they look brighter in their oversized youth than in maturity. They have not yet started to fuse hydrogen into helium in their cores, like normal main sequence stars, but are just starting to flex their thermal muscles by generating heat from contraction.

Reflection nebula, like the one spawned by HD 97300, merely scatter starlight back out into space. Starlight that is more energetic, such as the ultraviolet radiation pouring forth from very hot new stars, can ionise nearby gas, making it emit light of its own. These emission nebulae indicate the presence of hotter and more powerful stars, which in their maturity can be observed across thousands of light-years. HD 97300 is not so powerful, and its moment in the spotlight is destined not to last.

Image Credit: ESO
Explanation from: https://www.eso.org/public/news/eso1605/

The Sunflower Galaxy (Messier 63)

The Sunflower Galaxy (Messier 63)

The arrangement of the spiral arms in the galaxy Messier 63, seen here in an image from the NASA/ESA Hubble Space Telescope, recall the pattern at the center of a sunflower. So the nickname for this cosmic object — the Sunflower Galaxy — is no coincidence.

Discovered by Pierre Mechain in 1779, the galaxy later made it as the 63rd entry into fellow French astronomer Charles Messier’s famous catalogue, published in 1781. The two astronomers spotted the Sunflower Galaxy’s glow in the small, northern constellation Canes Venatici (the Hunting Dogs). We now know this galaxy is about 27 million light-years away and belongs to the M51 Group — a group of galaxies, named after its brightest member, Messier 51, another spiral-shaped galaxy dubbed the Whirlpool Galaxy.

Galactic arms, sunflowers and whirlpools are only a few examples of nature’s apparent preference for spirals. For galaxies like Messier 63 the winding arms shine bright because of the presence of recently formed, blue–white giant stars and clusters, readily seen in this Hubble image.

Image Credit: ESA/Hubble & NASA
Explanation from: https://www.nasa.gov/image-feature/goddard/hubbles-galactic-sunflower/