Discovered: An Earth-sized temperate planet only 11 light-years away

Image: Planet Ross 128 b

This artist’s impression shows the temperate planet Ross 128 b, with its red dwarf parent star in the background. Image Credit: European Southern Observatory

A team working with ESO’s High Accuracy Radial velocity Planet Searcher (HARPS) at the La Silla Observatory in Chile has found that the red dwarf star Ross 128 is orbited by a low-mass exoplanet every 9.9 days. This Earth-sized world is expected to be temperate, with a surface temperature that may also be close to that of the Earth. Ross 128 is the “quietest” nearby star to host such a temperate exoplanet.

“This discovery is based on more than a decade of HARPS intensive monitoring together with state-of-the-art data reduction and analysis techniques. Only HARPS has demonstrated such a precision and it remains the best planet hunter of its kind, 15 years after it began operations,” explains Nicola Astudillo-Defru (Geneva Observatory – University of Geneva, Switzerland), who co-authored the discovery paper.

Red dwarfs are some of the coolest, faintest — and most common — stars in the Universe. This makes them very good targets in the search for exoplanets and so they are increasingly being studied. In fact, lead author Xavier Bonfils (Institut de Planétologie et d’Astrophysique de Grenoble – Université Grenoble-Alpes/CNRS, Grenoble, France), named their HARPS program The shortcut to happiness, as it is easier to detect small cool siblings of Earth around these stars, than around stars more similar to the Sun.

Many red dwarf stars, including Proxima Centauri, are subject to flares that occasionally bathe their orbiting planets in deadly ultraviolet and X-ray radiation. However, it seems that Ross 128 is a much quieter star, and so its planets may be the closest known comfortable abode for possible life.

Although it is currently 11 light-years from Earth, Ross 128 is moving towards us and is expected to become our nearest stellar neighbor in just 79,000 years — a blink of the eye in cosmic terms. Ross 128 b will by then take the crown from Proxima b and become the closest exoplanet to Earth!

With the data from HARPS, the team found that Ross 128 b orbits 20 times closer than the Earth orbits the Sun. Despite this proximity, Ross 128 b receives only 1.38 times more irradiation than the Earth. As a result, Ross 128 b’s equilibrium temperature is estimated to lie between -60°C and 20°C, thanks to the cool and faint nature of its small red dwarf host star, which has just over half the surface temperature of the Sun. While the scientists involved in this discovery consider Ross 128b to be a temperate planet, uncertainty remains as to whether the planet lies inside, outside, or on the cusp of the habitable zone, where liquid water may exist on a planet’s surface.

Astronomers are now detecting more and more temperate exoplanets, and the next stage will be to study their atmospheres, composition and chemistry in more detail. Vitally, the detection of biomarkers such as oxygen in the very closest exoplanet atmospheres will be a huge next step, which ESO’s Extremely Large Telescope (ELT) is in prime position to take.

“New facilities at ESO will first play a critical role in building the census of Earth-mass planets amenable to characterization. In particular, NIRPS, the infrared arm of HARPS, will boost our efficiency in observing red dwarfs, which emit most of their radiation in the infrared. And then, the ELT will provide the opportunity to observe and characterize a large fraction of these planets,” concludes Xavier Bonfils.

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November 13: Monthly Membership Meeting

Artist's Concept: Nuclear Rocket at Mars. Credit: NASA

Artist’s Concept: Nuclear Rocket at Mars. Credit: NASA

The Cuyahoga Astronomical Association (CAA) will host its monthly meeting at 7:30 PM, Monday, November 13 in the Cleveland Metroparks’ Rocky River Nature Center, North Olmsted. Our speaker, Dr. Stanley Borowski, a Senior Engineer at NASA’s Glenn Research Center, Cleveland, will discuss the use of nuclear rocket engines in space exploration. The program is free and open to the public, no reservations required.

Following the program, the club’s monthly membership meeting will convene.

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First observation of gravitational wave source, a kilonova: the merger of two neutron stars

Photo: Kilonova observed. Credit: NASA and ESA. Acknowledgment: A.J. Levan (U. Warwick), N.R. Tanvir (U. Leicester), and A. Fruchter and O. Fox (STScI)

On 17 August 2017, the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo Interferometer both detected gravitational waves from the collision between two neutron stars. Within 12 hours observatories had identified the source of the event within the lenticular galaxy NGC 4993, shown in this image gathered with the NASA/ESA Hubble Space Telescope. The associated stellar flare, a kilonova, is clearly visible in the Hubble observations. This is the first time the optical counterpart of a gravitational wave event was observed. Hubble observed the kilonova gradually fading over the course of six days, as shown in these observations taken in between 22 and 28 August. Credit: NASA and ESA. Acknowledgment: A.J. Levan (U. Warwick), N.R. Tanvir (U. Leicester), and A. Fruchter and O. Fox (STScI)

On 17 August 2017 the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo Interferometerboth alerted astronomical observers all over the globe about the detection of a gravitational wave event named GW170817. About two seconds after the detection of the gravitational wave, ESA’s INTEGRAL telescope and NASA’s Fermi Gamma-ray Space Telescope observed a short gamma-ray burst in the same direction.

In the night following the initial discovery, a fleet of telescopes started their hunt to locate the source of the event. Astronomers found it in the lenticular galaxy NGC 4993, about 130 million light-years away. A point of light was shining where nothing was visible before and this set off one of the largest multi-telescope observing campaigns ever — among these telescopes was the NASA/ESA Hubble Space Telescope.

Several different teams of scientists used Hubble over the two weeks following the gravitational wave event alert to observe NGC 4993. Using Hubble’s high-resolution imaging capabilities they managed to get the first observational proof for a kilonova, the visible counterpart of the merging of two extremely dense objects — most likely two neutron stars. Such mergers were first suggested more than 30 years ago but this marks the first firm observation of such an event. The distance to the merger makes the source both the closest gravitational wave event detected so far and also one of the closest gamma-ray burst sources ever seen.

“Once I saw that there had been a trigger from LIGO and Virgo at the same time as a gamma-ray burst I was blown away,” recalls Andrew Levan of the University of Warwick, who led the Hubble team that obtained the first observations. “When I realised that it looked like neutron stars were involved, I was even more amazed. We’ve been waiting a long time for an opportunity like this!”

Hubble captured images of the galaxy in visible and infrared light, witnessing a new bright object within NGC 4993 that was brighter than a nova but fainter than a supernova. The images showed that the object faded noticeably over the six days of the Hubble observations. Using Hubble’s spectroscopic capabilities the teams also found indications of material being ejected by the kilonova as fast as one-fifth of the speed of light.

“It was surprising just how closely the behaviour of the kilonova matched the predictions,” said Nial Tanvir, professor at the University of Leicester and leader of another Hubble observing team. “It looked nothing like known supernovae, which this object could have been, and so confidence was soon very high that this was the real deal.”

Connecting kilonovae and short gamma-ray bursts to neutron star mergers has so far been difficult, but the multitude of detailed observations following the detection of the gravitational wave event GW170817 has now finally verified these connections.

“The spectrum of the kilonova looked exactly like how theoretical physicists had predicted the outcome of the merger of two neutron stars would appear,” says Levan. “It ties this object to the gravitational wave source beyond all reasonable doubt.”

The infrared spectra taken with Hubble also showed several broad bumps and wiggles that signal the formation of some of the heaviest elements in nature. These observations may help solve another long-standing question in astronomy: the origin of heavy chemical elements, like gold and platinum. In the merger of two neutron stars, the conditions appear just right for their production.

The implications of these observations are immense. As Tanvir explains: “This discovery has opened up a new approach to astronomical research, where we combine information from both electromagnetic light and from gravitational waves. We call this multi-messenger astronomy — but until now it has just been a dream!”

Levan concludes: “Now, astronomers won’t just look at the light from an object, as we’ve done for hundreds of years, but also listen to it. Gravitational waves provide us with complementary information from objects which are very hard to study using only electromagnetic waves. So pairing gravitational waves with electromagnetic radiation will help astronomers understand some of the most extreme events in the Universe.”

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October 9: Monthly Membership Meeting

New Horizons Spacecraft - Artist's depiction of the spacecraft as it passed through the Pluto/Charon system in July 2015. Image Credit: NASA

New Horizons Spacecraft – Artist’s depiction of the spacecraft as it passed through the Pluto/Charon system in July 2015. Image Credit: NASA

The Monthly Membership Meeting of the Cuyahoga Astronomical Association (CAA) will take place on Monday, October 9, beginning at 7:30 PM. An astronomy presentation is first, followed by a social break, and wrapped up with the club’s business meeting.

The night’s program will be a presentation by CAA member Kai Getrost entitled “New Horizons’ Next Target: The Kuiper Belt.” Getrost enjoyed the adventure of a lifetime, traveling to Argentina as part of a 50-team effort to observe and record data on a rare Kuiper Belt object occultation. A distant object, selected as the next object for study by the New Horizons spacecraft, passed in front of a star; data collected from the event has given astronomers a better understanding of the distance and movement of their target.

Free and open to the public, the program and meeting will take place at the at the Rocky River Nature Center; 24000 Valley Parkway; North Olmsted, Ohio, in the Cleveland Metroparks.

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CAA’s 2017 OTAA Convention

by Bill Murmann, CAA President

I’d like to thank members who joined us and brought food to share and who helped with our Annual Convention and potluck picnic Saturday (Sept. 16) at Letha House Park.  And thanks to our officers and board members-at-large who brought supplies and helped with the picnic — especially Treasurer Ron Palcic who handled ticket sales for our raffle.

We had nice weather and pretty decent night skies for observing, though we had some haze around the horizon and dewy conditions later in the evening.

Special thanks goes to Rich Whisler who did all the grilling for our meal, and to Marianne Wadsworth and Gail Korylak who organized the food line on three tables.  Thanks also to Marianne, and Nancy Whisler who helped clean up.

And thanks to Observatory Director Jay Reynolds who held observatory training and brought a slide show about our solar eclipse program that helped draw an estimated 10,000 guests to Edgewater Park.

I think everyone, including visitors from the Black River and Mahoning Valley astronomy clubs, enjoyed the food and socializing.

Jay Reynolds, Bruce Lane, Dave Watkins, and I were the last to leave at 12:45 AM after listening to groups of coyotes howling in the distance off to the east and the west.

Finally, our sincere appreciation to the following donors who generously provided items for our raffle:

Orion Telescopes & Binoculars
TeleVue
Meade Instrument Corporation
Sky & Telescope Magazine
Knightware, LLC
Bob’s Knobs

Next year’s Annual Convention and picnic will be on Saturday, September 8, 2018.

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Monday, September 11: Monthly Membership Meeting

Image: Artist's concept of Cassini spacecraft at Saturn. Credit: NASA/JPL-Caltech

In this still from the short film Cassini’s Grand Finale, the spacecraft is shown diving between Saturn and the planet’s innermost ring. Credit: NASA/JPL-Caltech

The Cuyahoga Astronomical Association (CAA) will host its monthly meeting at 7:30 PM, Monday, September 11 in the Cleveland Metroparks’ Rocky River Nature Center, North Olmsted. The speaker will be Jay Reynolds who will discuss NASA’s Cassini Mission to Saturn and its finale, set to occur September 15. The program is free and open to the public, no reservations required.

The Cassini spacecraft will make its final approach to the giant planet Saturn this Friday, ending an extremely productive seven-year mission. This encounter will be like no other. This time, Cassini will dive into the planet’s atmosphere, sending science data for as long as its small thrusters can keep the spacecraft’s antenna pointed at Earth. Soon after, Cassini will burn up and disintegrate like a meteor.

In addition to being a research astronomer who teaches at Cleveland State University, Reynolds is CAA’s observatory director. He frequently appears on Cleveland television, hosting a show about astronomy on WKYC, Channel 3.

Following the program, the club’s monthly membership meeting will convene.

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Public observing night at Letha House September 9

Photo: Saturn, by Rochus Hess

Saturn. Credit: Rochus Hess

The Cuyahoga Astronomical Association (CAA) will host a public star party this Saturday (Sept. 9) from 8:00 to 10:00 PM at the Medina County Park District’s at Letha House Park (West). The club’s observatory will be open and CAA members will offer viewing through their personally-owned telescopes.

The weather forecast is looking good for Saturday.  If skies are clear, Jupiter, Saturn, and Neptune will be visible at dusk. Later, Uranus, Saturn, and Neptune will be visible.
The waning Gibbous Moon will clear the horizon at 10:15.  When the sky grows dark enough, and before moonrise, there about 30 Messier objects visible. Messier objects include such things as brighter star clusters, nebulas, and galaxies.
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