Earth-sized world detected at Proxima Centauri

Astronomers using ESO telescopes and other facilities have found clear evidence of a planet orbiting the nearest star to our own Sun, Proxima Centauri. The long-sought world, designated Proxima b, orbits its cool red parent star every 11 days and has a temperature possibly suitable for liquid water to exist on its surface. This rocky world is a little more massive than the Earth and is the closest exoplanet to us — and it may also be the closest possible abode for life outside the Solar System. A paper describing this milestone finding will be published in the journal Nature on 25 August 2016.

Just over four light-years from the Solar System lies the red dwarf star named Proxima Centauri as it is the closest star to Earth apart from the Sun. This cool star, in the southern hemisphere constellation of Centaurus, is too faint to be seen with the unaided eye and lies near to the much brighter pair of stars known as Alpha Centauri AB.

During the first half of 2016 Proxima Centauri was regularly observed with the HARPS spectrograph on the ESO 3.6-metre telescope at La Silla in Chile and simultaneously monitored by other telescopes around the world. This was the Pale Red Dot Campaign, in which a team of astronomers led by Guillem Anglada-Escudé, from Queen Mary University of London, was looking for the tiny back and forth wobble of the star that would be caused by the gravitational pull of a possible orbiting planet.

As this was a topic with very wide public interest, the progress of the campaign between mid-January and April 2016 was shared publicly as it happened on the Pale Red Dot website and via social media. The reports were accompanied by numerous outreach articles written by specialists around the world.

Guillem Anglada-Escudé explains the background to this unique search: “The first hints of a possible planet were spotted back in 2013, but the detection was not convincing. Since then we have worked hard to get further observations off the ground with help from ESO and others. The recent Pale Red Dot campaign has been about two years in the planning.”
The Pale Red Dot data, when combined with earlier observations made at ESO observatories and elsewhere, revealed the clear signal of a truly exciting result.

At times Proxima Centauri is approaching Earth at about five kilometers per hour — normal human walking pace — and at times receding at the same speed. This regular pattern of changing radial velocities repeats with a period of 11.2 days. Careful analysis of the resulting tiny Doppler shifts showed that they indicated the presence of a planet with a mass at least 1.3 times that of the Earth, orbiting about seven million kilometers from Proxima Centauri — only five percent of the Earth-Sun distance.

Guillem Anglada-Escudé comments on the excitement of the last few months: “I kept checking the consistency of the signal every single day during the 60 nights of the Pale Red Dot Campaign. The first 10 were promising, the first 20 were consistent with expectations, and at 30 days the result was pretty much definitive, so we started drafting the paper!”

Red dwarfs like Proxima Centauri are active stars and can vary in ways that would mimic the presence of a planet. To exclude this possibility the team also monitored the changing brightness of the star very carefully during the campaign using the ASH2 telescope at the San Pedro de Atacama Celestial Explorations Observatory in Chile and the Las Cumbres Observatory telescope network. Radial velocity data taken when the star was flaring were excluded from the final analysis.

Although Proxima b orbits much closer to its star than Mercury does to the Sun in the Solar System, the star itself is far fainter than the Sun. As a result Proxima b lies well within the habitable zone around the star and has an estimated surface temperature that would allow the presence of liquid water. Despite the temperate orbit of Proxima b, the conditions on the surface may be strongly affected by the ultraviolet and X-ray flares from the star — far more intense than the Earth experiences from the Sun.

Two separate papers discuss the habitability of Proxima b and its climate. They find that the existence of liquid water on the planet today cannot be ruled out and, in such case, it may be present over the surface of the planet only in the sunniest regions, either in an area in the hemisphere of the planet facing the star (synchronous rotation) or in a tropical belt (3:2 resonance rotation). Proxima b’s rotation, the strong radiation from its star and the formation history of the planet makes its climate quite different from that of the Earth, and it is unlikely that Proxima b has seasons.

This discovery will be the beginning of extensive further observations, both with current instruments and with the next generation of giant telescopes such as the European Extremely Large Telescope (E-ELT). Proxima b will be a prime target for the hunt for evidence of life elsewhere in the Universe. Indeed, the Alpha Centauri system is also the target of humankind’s first attempt to travel to another star system, the StarShot project.

Guillem Anglada-Escudé concludes: “Many exoplanets have been found and many more will be found, but searching for the closest potential Earth-analog and succeeding has been the experience of a lifetime for all of us. Many people’s stories and efforts have converged on this discovery. The result is also a tribute to all of them. The search for life on Proxima b comes next…”

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Milky Way stars during public star party

Photo: Looking South Along the Lake at Letha House Park, Milky Way Glowing Overhead, the Moon Sinking Low in the West. Photo by Alan Studt.

Looking South Along the Lake at Letha House Park, Milky Way Glowing Overhead. Photo by Alan Studt. Nikon D810: ISO 3200, 13 sec., f/2.8, 14mm.

We had great sky conditions for our August 6 public star party at Letha House Park. We didn’t get an exact count, but I think there were between 75 and 100 guests who came for the program, including Park Ranger Bob who stopped by to say hello.

I had to make a quick count in the dark, but I think we had about 12 telescopes for this Medina County Park District program. Two telescopes were brought by new members who I believe joined one of our star parties for the first time.

Many thanks to Dave Nuti, Chris Christe, Bruce Lane, Jay Reynolds, Nora Mishey, Carl Kudrna, Rich & Nancy Whisler, Bob Wiersma, Alan Studt, Rob Seig, Bob & Mary Deep, and Gale Franko who joined me to help with the program!

Thanks to Jay, who manned the observatory and gave our new 12-inch go-to scope a workout to show the night sky to our numerous  guests.  And thanks also to Nora, who brought delicious homemade cookies and her astronomy Q & A display, and who served as a host in the building to help promote our club and the park district’s programs.

Reported by William Murmann, CAA President

Photo: Summer Milky Way. Photo by Alan Studt.

Summer Milky Way. Photo by Alan Studt. Nikon D810: ISO 5000, 15 sec., f/2.8, 14mm.

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Public Observing Saturday, August 6

The Cuyahoga Astronomical Association’s (CAA’s) observatory at Letha House Park will be open for public observing Saturday, August 6, from 8:30 to 11:00 PM. Visitors will be treated to telescopic views of the Moon (early), Saturn, and as the sky darkens, deep sky objects such as star clusters. Mars may also be viewed but is becoming more distant from Earth and offers less detail to viewers. Click here for our observatory’s web page for information on how to get to the observatory and advice on attending a star party.

The observatory is operated in cooperation with the Medina County Park District (which owns the property). Restroom facilities are available at the park and, in the event of cloudy or inclement weather, an indoor astronomy program will be offered in place of outdoor observing.

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Rescheduled Convention: September 24

The CAA’s annual OTAA Convention event has been rescheduled to take place on September 24, 2016 at Letha House Park West; registration should begin at 3:00 PM. The gathering was to have been held July 30 but a scheduling issue prevented it taking place.

Socializing, a cookout, door prize raffle, astronomy talk, and (weather permitting) star party are planned for the day and night, and members of the CAA and other regional astronomy clubs are invited to attend. In the event of cloudy or inclement weather, all events except for stargazing will take place.

Image: All-Sky Map, September 24, 2016

All-Sky Map, September 24, 2016 – Click to Embiggen

Letha House Park West features an enclosed, heated and air conditioned event building with modern lighting, projection equipment, and restrooms. The CAA maintains its observatory at Letha House Park and that facility will be open during the star party. The parking lot is paved and a large, grassy area adjacent to the lot makes for easy telescope setup. Nighttime skies are good (considering the Northeastern Ohio location) allowing for rewarding observations.

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CANCELED: Annual OTAA Convention

Due to a scheduling conflict involving our Letha House Park venue, our planned July 30, 2016 OTAA Convention has been CANCELED. We are disappointed and upset that this issue developed outside of the CAA’s responsibility but circumstances afford us no alternatives. The officers and members of the Cuyahoga Astronomical Association regret any inconvenience this emergency cancellation may cause.

UPDATE: The event has been rescheduled to take place on September 24, 2016 at Letha House Park West. Announcements concerning the event will be posted soon. 7/29/2016

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Looking deep into the heart of Orion

Photo: This spectacular image of the Orion Nebula star-formation region was obtained from multiple exposures using the HAWK-I infrared camera on ESO’s Very Large Telescope in Chile. This is the deepest view ever of this region and reveals more very faint planetary-mass objects than expected. Credit: ESO/H. Drass et al.

This spectacular image of the Orion Nebula star-formation region was obtained from multiple exposures using the HAWK-I infrared camera on ESO’s Very Large Telescope in Chile. This is the deepest view ever of this region and reveals more very faint planetary-mass objects than expected. Credit: ESO/H. Drass et al.

ESO’s HAWK-I infrared instrument on the Very Large Telescope (VLT) in Chile has been used to peer deeper into the heart of Orion Nebula than ever before. The spectacular picture reveals about ten times as many brown dwarfs and isolated planetary-mass objects than were previously known. This discovery poses challenges for the widely-accepted scenario for Orion’s star formation history.

An international team has made use of the power of the HAWK-I infrared instrument on ESO’s Very Large Telescope (VLT) to produce the deepest and most comprehensive view of the Orion Nebula to date. Not only has this led to an image of spectacular beauty, but it has revealed a great abundance of faint brown dwarfs and isolated planetary-mass objects. The very presence of these low-mass bodies provides an exciting insight into the history of star formation within the nebula itself.

The famous Orion Nebula spans about 24 light-years within the constellation of Orion, and is visible from Earth with the naked eye, as a fuzzy patch in Orion’s sword. Some nebulae, like Orion, are strongly illuminated by ultraviolet radiation from the many hot stars born within them, such that the gas is ionised and glows brightly.

The relative proximity of the Orion Nebula makes it an ideal testbed to better understand the process and history of star formation, and to determine how many stars of different masses form.

Amelia Bayo (Universidad de Valparaíso, Valparaíso, Chile; Max-Planck Institut für Astronomie, Königstuhl, Germany), a co-author of the new paper and member of the research team, explained why this is important: “Understanding how many low-mass objects are found in the Orion Nebula is very important to constrain current theories of star formation. We now realise that the way these very low-mass objects form depends on their environment.”

This new image has caused excitement because it reveals a unexpected wealth of very-low-mass objects, which in turn suggests that the Orion Nebula may be forming proportionally far more low-mass objects than closer and less active star formation regions.

Astronomers count up how many objects of different masses form in regions like the Orion Nebula to try to understand the star-formation process. Before this research the greatest number of objects were found with masses of about one quarter that of our Sun. The discovery of a plethora of new objects with masses far lower than this in the Orion Nebula has now created a second maximum at a much lower mass in the distribution of star counts.

These observations also hint tantalisingly that the number of planet-sized objects might be far greater than previously thought. Whilst the technology to readily observe these objects does not exist yet, ESO’s future European Extremely Large Telescope (E-ELT), scheduled to begin operations in 2024, is designed to pursue this as one of its goals.

Lead scientist Holger Drass (Astronomisches Institut, Ruhr-Universität Bochum, Bochum, Germany; Pontificia Universidad Católica de Chile, Santiago, Chile) enthused: “Our result feels to me like a glimpse into a new era of planet and star formation science. The huge number of free-floating planets at our current observational limit is giving me hope that we will discover a wealth of smaller Earth-sized planets with the E-ELT.”

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After five years, Juno nears its destination

Image: This illustration depicts NASA's Juno spacecraft at Jupiter, with its solar arrays and main antenna pointed toward the distant sun and Earth. Image Credit: NASA/JPL-Caltech

This illustration depicts NASA’s Juno spacecraft at Jupiter, with its solar arrays and main antenna pointed toward the distant sun and Earth. Image Credit: NASA/JPL-Caltech

NASA’s Juno mission, launched nearly five years ago, will soon reach its final destination: the most massive planet in our solar system, Jupiter. On the evening of July 4, at roughly 9 PM PDT (12 AM EDT, July 5), the spacecraft will complete a burn of its main engine, placing it in orbit around the king of planets.

During Juno’s orbit-insertion phase, or JOI, the spacecraft will perform a series of steps in preparation for a main engine burn that will guide it into orbit. At 9:16 PM EDT (July 4), Juno will begin to turn slowly away from the sun and toward its orbit-insertion attitude. Then 72 minutes later, it will make a faster turn into the orbit-insertion attitude.

At 10:41 PM EDT, Juno switches to its low-gain antenna. Fine-tune adjustments are then made to the spacecraft’s attitude. Twenty-two minutes before the main engine burn, at 10:56 PM, the spacecraft spins up from two to five revolutions per minute (RPM) to help stabilize it for the orbit insertion burn.

At 11:18 PM, Juno’s 35-minute main-engine burn will begin. This will slow it enough to be captured by the giant planet’s gravity. The burn will impart a mean change in velocity of 1,212 MPH (542 meters a second) on the spacecraft. It is performed in view of Earth, allowing its progress to be monitored by the mission teams at NASA’s Jet Propulsion Laboratory in Pasadena, California, and Lockheed Martin Space Systems in Denver, via signal reception by Deep Space Network (DSN) antennas in Goldstone, California, and Canberra, Australia.

After the main engine burn early July 5 (Eastern Daylight Time), Juno will be in orbit around Jupiter. The spacecraft will spin down from five to two RPM, turn back toward the sun, and ultimately transmit telemetry via its high-gain antenna. At Jupiter’s current distance of 536.9 million miles from Earth, radio signals will take about 48 minutes to reach the DSN.

Juno starts its tour of Jupiter in a 53.5-day orbit. The spacecraft saves fuel by executing a burn that places it in a capture orbit with a 53.5-day orbit instead of going directly for the 14-day orbit that will occur during the mission’s primary science collection period. The 14-day science orbit phase will begin after the final burn of the mission for Juno’s main engine on October 19.

JPL manages the Juno mission for NASA. The mission’s principal investigator is Scott Bolton of Southwest Research Institute in San Antonio. The mission is part of NASA’s New Frontiers Program, managed at the agency’s Marshall Space Flight Center in Huntsville, Alabama, for NASA’s Science Mission Directorate. Lockheed Martin Space Systems in Denver built the spacecraft.

Learn more about the June mission, and get an up-to-date schedule of events, at:

http://www.nasa.gov/juno

https://solarsystem.nasa.gov/planets/jupiter/junotoolkit

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