Archives For astronomy

Image: Star π1 Gruis

Astronomers using ESO’s Very Large Telescope have directly observed granulation patterns on the surface of a star outside the Solar System — the ageing red giant π1 Gruis. This remarkable new image from the PIONIER instrument reveals the convective cells that make up the surface of this huge star. Each cell covers more than a quarter of the star’s diameter and measures about 120 million kilometers across. Image Credit: ESO


 
Astronomers using ESO’s Very Large Telescope have for the first time directly observed granulation patterns on the surface of a star outside the Solar System — the ageing red giant π1 Gruis. This remarkable new image from the PIONIER instrument reveals the convective cells that make up the surface of this huge star, which has 700 times the diameter of the Sun. Each cell covers more than a quarter of the star’s diameter and measures about 120 million kilometers across. These new results are being published this week in the journal Nature.

Located 530 light-years from Earth in the constellation of Grus (The Crane), π1 Gruis is a cool red giant. It has about the same mass as our Sun, but is 700 times larger and several thousand times as bright. Our Sun will swell to become a similar red giant star in about five billion years.

An international team of astronomers led by Claudia Paladini (ESO) used the PIONIER instrument on European Southern Observatory’s (ESO’s) Very Large Telescope to observe π1 Gruis in greater detail than ever before. They found that the surface of this red giant has just a few convective cells, or granules, that are each about 120 million kilometers across — about a quarter of the star’s diameter. Just one of these granules would extend from the Sun to beyond Venus. The surfaces — known as photospheres — of many giant stars are obscured by dust, which hinders observations. However, in the case of π1 Gruis, although dust is present far from the star, it does not have a significant effect on the new infrared observations.

When π1 Gruis ran out of hydrogen to burn long ago, this ancient star ceased the first stage of its nuclear fusion program. It shrank as it ran out of energy, causing it to heat up to over 100 million degrees. These extreme temperatures fueled the star’s next phase as it began to fuse helium into heavier atoms such as carbon and oxygen. This intensely hot core then expelled the star’s outer layers, causing it to balloon to hundreds of times larger than its original size. The star we see today is a variable red giant. Until now, the surface of one of these stars has never before been imaged in detail.

By comparison, the Sun’s photosphere contains about two million convective cells, with typical diameters of just 1,500 kilometers. The vast size differences in the convective cells of these two stars can be explained in part by their varying surface gravities. π1 Gruis is just 1.5 times the mass of our Sun but much larger, resulting in a much lower surface gravity and just a few, extremely large, granules.

While stars more massive than eight solar masses end their lives in dramatic supernovae explosions, less massive stars like this one gradually expel their outer layers, resulting in beautiful planetary nebulae. Previous studies of π1 Gruis found a shell of material 0.9 light-years away from the central star, thought to have been ejected around 20,000 years ago. This relatively short period in a star’s life lasts just a few tens of thousands of years – compared to the overall lifetime of several billion – and these observations reveal a new method for probing this fleeting red giant phase.

Photo: StarLab Portable Planetarium

StarLab Portable Planetarium


 
We expect we will cancel our scheduled Friday night Observatory event due to cloudy skies and possible snow. There is, however, a special treat awaiting sky-watchers on campus and it’s indoors, you know, where it’s warm!

The portable StarLab planetarium will be set up and open to the public! Free of charge! No tickets required! Folks can just come any time from 7:00 to 9:00 PM. The more the merrier. We will run 20-minute programs in the dome and have a few things planned while people are waiting or as they leave.

The StarLab will be set up in the Gerstacker science building on the Hiram College campus, not far north of the Post Office: 11700 Dean St.; Hiram.

So, come on out and enjoy a fun and informative evening snug inside StarLab. And to everyone we wish a happy holiday season, as well as peace and happiness in the coming new year!

Photo: Mare Imbrium region of Earth's Moon. Credit: James Guilford/Stephens Memorial Observatory

Mare Imbrium and Crater Copernicus. Credit: James Guilford/Stephens Memorial Observatory

We hosted our September Open Night as scheduled on the 30th with Earth’s Moon as our primary subject. The sky was (for once) completely clear of clouds and full of stars when we opened the dome for the 9:00 start. In all, 19 folks from small children to senior citizens attended and enjoyed spectacular views of our nearest neighbor in space. Two or three individuals attempted smart phone photography of the Moon with varying degrees of success. We also observed the Andromeda Galaxy and the Perseus Double Cluster. The image above was made just before we closed up and has been corrected for the telescope’s optical “flipping” of the image. Camera used was a Canon EOS 7D equipped with a 50mm lens and held to the telescope’s massive eyepiece. We will look at the Moon again October 28 when we celebrate the annual International Observe the Moon Night. See you then?

Photo: The partial solar eclipse reaches its maximum at 2:23 PM EDT as viewed from Hiram College, Hiram, Ohio. Photo by James Guilford.

The partial solar eclipse reaches its maximum at 2:23 PM EDT as viewed from Hiram College, Hiram, Ohio

On Monday, August 21 millions gathered along a thin path crossing the United States to watch a total eclipse of the Sun, the first to cross the continent since June 1918. Those with favorable viewing conditions along the path of totality enjoyed a truly amazing sight and experience; a total solar eclipse is truly awe-inspiring. From Northern Ohio, outside of the eclipse path, 80 percent of the solar disk would be covered by the Moon. Public interest in the event was high and so we hosted the Hiram Eclipse Watch

 

Photo: People Watching and Waiting for the Big Event - Credit: James Guilford

Watching and Waiting for the Big Event – Credit: James Guilford

We estimate at least 375 people came to the campus lawn to share nature’s show and enjoy the sight together. Some families brought blankets and had picnic lunch in the shade of trees while waiting for the eclipse to begin. Driven by media reports, demand for Sun-safe eclipse viewing glasses was tremendous. Hiram had 300 eclipse viewers available for free distribution and even with restriction to one viewer per family or group, we ran out of glasses long before the eclipse ended. The offer of free eclipse glasses did, however, encourage some of our attendees to come out to Hiram College and discover there was more to enjoy than a giveaway; the view through our telescopes was tremendous.

Photo: Woman watches eclipse through specially-equipped telescope. Credit: Dave Dreimiller

Woman watches eclipse through specially-equipped telescope. Credit: Dave Dreimiller

Three telescopes offered safe views of the eclipsing Sun three different ways. One scope employed a glass filter with metal compounds that absorbed the Sun’s dangerous radiation and presented an orange-tinted image. The largest telescope present, a six-inch refractor, was outfitted with a modern version of the Herschel Wedge; that telescope focussed unfiltered light into the wedge which, in turn, deflected all but a small amount of light with a green tint and offered tack-sharp viewing of the disappearing Sun, sunspots, and granulation texture in the solar atmosphere. A third instrument was a telescope specifically made to view the Sun only hydrogen alpha (Ha) light. Ideally, an Hscope will show details of the solar atmosphere invisible to those using other methods, and include solar prominences — geysers of plasma arcing high above the Sun — but none were seen this day.

Photo: Girl Watching the Eclipse with Safety Glasses - Credit: Dave Dreimiller

Watching the Eclipse with Safety Glasses – Credit: Dave Dreimiller

People of all description came and went during the event though most stayed until the maximum eclipse had been reached and the Moon began to recede from Sun. Lines of folks waited patiently to see the telescopic views, even attempting smart phone photos; there were many repeat views, observing the progress of the eclipse with each fresh look. We estimate at more than 375 people came to the campus lawn to share nature’s show and enjoy the sight together.

Photo: Solar Telescopes Trained on the Eclipse - Credit: Dave Dreimiller

Solar Telescopes Trained on the Eclipse – Credit: Dave Dreimiller

There was learning, and laughter, and a fine day shared under Sun and Moon. It may not have been a total eclipse for those watching from Hiram College, but it was a total pleasure.

Photo: Sun in process of being eclipsed by Moon. August 21, 2017. Photo by James Guilford.

Before Maximum Eclipse – Credit: James Guilford

Cooperative weather plus plenty of happy and excited people made the afternoon a wonderful occasion sharing a fine day featuring a dance by the Sun and Moon.

Photo: Edge of lunar silhouette shows mountains on Moon. Photo by James Guilford.

Before Maximum – Rough Edge. Look closely along the dark curve of the Moon moving over the Sun and note “bumps” along the edge: the silhouettes of craters and mountains on the Moon.

The (Ravenna) Record-Courier made it front-page news!

Image: The Record-Courier - August 22, 2017 -- Page 1

The Record-Courier – August 22, 2017 — Page 1

Image: Path of the August 21, 2017 Total Solar Eclipse - Courtesy NationalEclipse.com

Path of the August 21, 2017 Total Solar Eclipse – Courtesy NationalEclipse.com


 
Planning is underway for a public event celebrating the upcoming August 21, 2017 solar eclipse. The eclipse will begin at 1:07 PM and end at 3:52 PM Eastern Daylight Time. Maximum eclipse will occur locally at about 2:30 PM EDT. Details are developing but the Hiram Eclipse Watch will take place on the Hiram College campus and will be free and open to the general public — everyone’s invited!

The so-called “American Eclipse” or “National Eclipse” will be a total solar eclipse (Moon covering the entire solar disk) only for those situated on a relatively narrow path stretching from the Pacific Northwest to South Carolina and the Atlantic. For the balance of the Continental United States, the eclipse will be partial — the Moon will cover only part of the Sun. Northern Ohioans will see a bit more than 80 percent of the Sun covered by the Moon reducing the Sun to a brilliant crescent!

We have created and are regularly updating a page on this website dedicated to Hiram’s eclipse event; check there for event details as they develop. We hope to see you August 21 for a fun and memorable experience.

To reach our Eclipse Watch page see the menu at the top of this page, or click here!

Photo: A Bright Meteor - a Fireball - Recorded over Hiram April 23, 2017. Image Credit: NASA/MEO

A Bright Meteor – a Fireball – Recorded over Hiram April 23, 2017. Image Credit: NASA/MEO

 

An exceptionally bright and long-lasting fireball meteor was recorded early Sunday morning by the NASA All-Sky Fireball Network camera situated on the campus of Hiram College. The event took place at 5:09 AM EDT, April 23, the meteor streaking from south to north as it burned up entering Earth’s atmosphere. Several other fireball meteors were also recorded during during the night but this was the brightest of the bunch. A fireball is a meteor that glows brighter than the planet Venus. NASA uses data collected from Hiram’s camera along with that from other systems in the network to learn about micrometeorites and their threat to spacecraft. Fireball Network images and data are available to astronomers and to the general public alike, and are updated daily.  Click here to visit the All-Sky Fireball Network website.

Image: Artist's impression of star system. Credit: ESO/M. Kornmesser/spaceengine.org

This artist’s impression shows the view from the surface of one of the planets in the TRAPPIST-1 system. At least seven planets orbit this ultra cool dwarf star 40 light-years from Earth and they are all roughly the same size as the Earth. They are at the right distances from their star for liquid water to exist on the surfaces of several of them. This artist’s impression is based on the known physical parameters for the planets and stars seen, and uses a vast database of objects in the Universe. Credit: ESO/M. Kornmesser/spaceengine.org

 

Astronomers have found a system of seven Earth-sized planets just 40 light-years away. Using ground and space telescopes, including ESO’s Very Large Telescope, the planets were all detected as they passed in front of their parent star, the ultracool dwarf star known as TRAPPIST-1. According to the paper appearing today in the journal Nature, three of the planets lie in the habitable zone and could harbor oceans of water on their surfaces, increasing the possibility that the star system could play host to life. This system has both the largest number of Earth-sized planets yet found and the largest number of worlds that could support liquid water on their surfaces.

Astronomers using the TRAPPIST–South telescope at ESO’s La Silla Observatory, the Very Large Telescope (VLT) at Paranal and the NASA Spitzer Space Telescope, as well as other telescopes around the world, have now confirmed the existence of at least seven small planets orbiting the cool red dwarf star TRAPPIST-1. All the planets, labelled TRAPPIST-1b, c, d, e, f, g and h in order of increasing distance from their parent star, have sizes similar to Earth.

Dips in the star’s light output caused by each of the seven planets passing in front of it — events known as transits — allowed the astronomers to infer information about their sizes, compositions and orbits. They found that at least the inner six planets are comparable in both size and temperature to the Earth.

Lead author Michaël Gillon of the STAR Institute at the University of Liège in Belgium is delighted by the findings: “This is an amazing planetary system — not only because we have found so many planets, but because they are all surprisingly similar in size to the Earth!”

With just eight percent the mass of the Sun, TRAPPIST-1 is very small in stellar terms — only marginally bigger than the planet Jupiter — and though nearby in the constellation Aquarius (The Water Carrier), it appears very dim. Astronomers expected that such dwarf stars might host many Earth-sized planets in tight orbits, making them promising targets in the hunt for extraterrestrial life, but TRAPPIST-1 is the first such system to be found.

Co-author Amaury Triaud expands: “The energy output from dwarf stars like TRAPPIST-1 is much weaker than that of our Sun. Planets would need to be in far closer orbits than we see in the Solar System if there is to be surface water. Fortunately, it seems that this kind of compact configuration is just what we see around TRAPPIST-1!”

The team determined that all the planets in the system are similar in size to Earth and Venus in the Solar System, or slightly smaller. The density measurements suggest that at least the innermost six are probably rocky in composition.

The planetary orbits are not much larger than that of Jupiter’s Galilean moon system, and much smaller than the orbit of Mercury in the Solar System. However, TRAPPIST-1’s small size and low temperature mean that the energy input to its planets is similar to that received by the inner planets in our Solar System; TRAPPIST-1c, d and f receive similar amounts of energy to Venus, Earth and Mars, respectively.

All seven planets discovered in the system could potentially have liquid water on their surfaces, though their orbital distances make some of them more likely candidates than others. Climate models suggest the innermost planets, TRAPPIST-1b, c and d, are probably too hot to support liquid water, except maybe on a small fraction of their surfaces. The orbital distance of the system’s outermost planet, TRAPPIST-1h, is unconfirmed, though it is likely to be too distant and cold to harbor liquid water — assuming no alternative heating processes are occurring. TRAPPIST-1e, f, and g, however, represent the holy grail for planet-hunting astronomers, as they orbit in the star’s habitable zone and could host oceans of surface water.

These new discoveries make the TRAPPIST-1 system a very important target for future study. The NASA/ESA Hubble Space Telescope is already being used to search for atmospheres around the planets and team member Emmanuël Jehin is excited about the future possibilities: “With the upcoming generation of telescopes, such as ESO’s European Extremely Large Telescope and the NASA/ESA/CSA James Webb Space Telescope, we will soon be able to search for water and perhaps even evidence of life on these worlds.”