Daily Archives: April 24, 2020

"Clearly, Fomalhaut b was doing things a bona fide planet should not be doing," Gspr said.

The last straw for Fomalhaut b was when researchers looked at Hubble images from 2014, which revealed the object had vanished altogether. Though there could be reasons why an exoplanet fades, they certainly dont just disappear.

This led researchers to conclude that Fomalhaut b was nothing more than a planetary mirage namely, an energetic cloud of debris blasted from a collision between two large icy objects. Then, as the cloud dispersed, the faux-planet Fomalhaut b dissolved into nothingness. Based on the evolving shape and location of the debris, the researchers estimate the original colliding bodies were each likely a mix of ice and dust measuring about 125 miles (200 kilometers) across.

Unfortunately, Hubble seems to have been late for the main event, as the researchers think the crash happened right before the telescope began observing the system in 2004. But just detecting the results of such a violent cosmic event is exciting, they say. According to the researchers calculations, such a massive collision may only happen once every 200,000 years in a given system.

Astronomers hope to further study the Fomalhaut system with the upcoming the James Webb Space Telescope during its first year of operations. The future observations will hopefully answer questions about Fomalhauts asteroid belt, as well as about any legitimate planets actually orbiting the star.

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Hubble watches a suspected exoplanet disappear before its very eyes - Astronomy Magazine

A nova is a dramatic episode in the life of a binary pair of stars. Its an explosion of bright light that can last weeks or even months. And though theyre not exactly rarethere are about 10 each year in the Milky Wayastronomers have never watched one from start to finish.

Until now.

A nova occurs in a close binary star system, when one of the stars has gone through its red giant phase. That star leaves behind a remnant white dwarf. When the white dwarf and its partner become close enough, the massive gravitational pull of the white dwarf draws material, mostly hydrogen, from the other star.

That hydrogen accretes onto the surface of the white dwarf, forming a thin atmosphere. The white dwarf heats the hydrogen, and eventually the gas pressure is extremely high, and fusion is ignited. Not just any fusion: rapid, runaway fusion.

When the rapid fusion ignites, we can see the light, and the new hydrogen atmosphere is expelled away from the white dwarf, into space. In the past, astronomers thought these new bright lights were new stars, and the name nova stuck. Astronomers now call these types of nova classical novae. (There are also recurrent novae, when the process repeats itself.)

Suddenly there was a star on our records that wasnt there the day before.

This is an enormously energetic event, that produces not only visible light, but gamma rays and x-rays too. The end result is that some stars that could only be seen through a telescope can be seen with the naked eye during a nova.

All of this is widely accepted in astronomy and astrophysics. But much of it is theoretical. Recently, astronomers using the BRITE (BRIght Target Explorer) Constellation of nanosatellites were fortunate enough to observe the entire process from start to finish, confirming the theory.

BRITE is a constellation of nanosatellites designed to investigate stellar structure and evolution of the brightest stars in the sky and their interaction with the local environment, according to the website. They operate in Low-Earth Orbit and have few restrictions on the parts of the sky that they can observe. BRITE is a coordinated project between Austrian, Polish, and Canadian researchers.

This first-ever observation of a nova was pure chance. BRITE had spent several weeks observing 18 stars for several weeks in the Carina constellation. One day, a new star appeared. BRITE Operations Manager Rainer Kuschnig found the nova during a daily inspection. Suddenly there was a star on our records that wasnt there the day before, he said in a press release. Id never seen anything like it in all the years of the mission!

Professor Werner Weiss is from the Department of Astrophysics at the University of Vienna. In a press release, he emphasized the significance of this observation. But what causes a previously unimpressive star to explode? This was a problem that has not been solved satisfactorily until now, he said. The explosion of Nova V906 in the constellation Carina is giving researchers some answers and has confirmed some of the theoretical concept behind novae.

It is fantastic that for the first time a nova could be observed by our satellites even before its actual eruption and until many weeks later.

V906 Carinae was first spotted by the All-Sky Automated Survey for Supernovae. Fortunately, it appeared in an area of the sky that had been under observation by BRITE for weeks, so the data documenting the nova is in BRITE data. It is fantastic that for the first time a nova could be observed by our satellites even before its actual eruption and until many weeks later, says Prof. Otto Koudelka, project manager of the BRITE Austria (TUGSAT-1) satellite at TU Graz.

V906 Carinae is about 13,000 light years away, so the event is already history. After all, this nova is so far away from us that its light takes about 13,000 years to reach the earth, explains Weiss.

The BRITE team reported their findings in a new paper. The paper is titled Direct evidence for shock-powered optical emission in a nova. Its published in the journal Nature Astronomy. First author is Elias Aydi from Michigan State University.

This fortunate circumstance was decisive in ensuring that the nova event could be recorded with unprecedented precision, explains Prof. Konstanze Zwintz, head of the BRITE Science Team, from the Institute for Astro- and Particle Physics at the University of Innsbruck. Zwintz immediately realised that we had access to observation material that was unique worldwide, according to a press release.

Novae like V906 Carinae are thermonuclear explosions on the surface of white dwarf stars. For a long time, astrophysicists thought that a novas luminosity is powered by continual nuclear burning after the initial burst of runaway fusion. But the data from BRITE suggests something different.

In the new paper, the authors show that shocks play a larger role than thought. The authors say that shocks internal to the nova ejecta may dominate the nova emission. These shocks may also be involved in other events like supernovae, stellar mergers, and tidal disruption events, according to the authors. But up until now, theres been a lack of observational evidence.

Here we report simultaneous space-based optical and ?-ray observations of the 2018 nova V906 Carinae (ASASSN-18fv), revealing a remarkable series of distinct correlated flares in both bands, the researchers write. Since those flares occur at the same time, it implies a common origin in shocks.

During the flares, the nova luminosity doubles, implying that the bulk of the luminosity is shock powered. So rather than continual nuclear burning, novae are driven by shocks. Our data, spanning the spectrum from radio to gamma-ray, provide direct evidence that shocks can power substantial luminosity in classical novae and other optical transients.

In broader terms, shocks have been shown to play some role in events like novae. But that understanding is largely based on studying timescales and luminosities. This study is the first direct observation of such shocks, and is likely only the beginning of observing and understanding the role that shocks play.

In the conclusion of their paper the authors write Our observations of nova V906 Car definitively demonstrate that substantial luminosity can be producedand emerge at optical wavelengthsby heavily absorbed, energetic shocks in explosive transients.

They go on to say that With modern time-domain surveys such as ASAS-SN, the Zwicky Transient Facility (ZTF) and the Vera C. Rubin Observatory, we will be discovering moreand higher luminositytransients than ever before. The novae in our galactic backyard will remain critical for testing the physical drivers powering these distant, exotic events.

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Astronomers Watch a Nova Go From Start to Finish for the First Time - Universe Today

Little is more enticing than the prospect of seeing alien worlds around other starsand perhaps one day even closely studying their atmosphere and mapping their surface. Such observations are exceedingly difficult, of course. Although more than 4,000 exoplanets are now known, the vast majority of them are too distant and dim for our best telescopes to discern against the glare of their host star. Exoplanets near our solar system provide easier imaging opportunities, however. And no worlds are nearer to us than those thought to orbit the cool, faint red dwarf Proxima Centaurithe closest star to our sun at 4.2 light-years away.

In 2016 astronomers discovered the first known planet in this system: the roughly Earth-sized Proxima b. But because of its star-hugging 11-day orbit around Proxima Centauri, Proxima b is a poor candidate for imaging. Proxima c, by contrast, offers much better chances. Announced in 2019, based on somewhat circumstantial evidence, the planet remains unconfirmed. If real, it is estimated to be several times more massive than Eartha so-called super Earth or mini Neptuneand to orbit Proxima Centauri at about 1.5 times the span between Earth and the sun. Its size and distance from its star make the world a tempting target for current and near-future exoplanet-imaging projects. Now, in a new preprint paper accepted for publication in the journal Astronomy & Astrophysics, some astronomers say they mightjust might have managed to see Proxima c for the first time.

This planet is extremely interesting because Proxima is a star very close to the sun, says Raffaele Gratton of the Astronomical Observatory of Padova in Italy, who is the studys lead author. The idea was that since this planet is [far] from the star, it is possible that it can be observed in direct imaging. We found a reasonable candidate that looks like we have really detected the planet.

Last year Gratton and his team were first alerted to the possibility of imaging the planet by Mario Damasso of the Astrophysical Observatory of Turin in Italy, who was the lead author of the original paper on Proxima cs possible discovery. Damasso and his colleagues had presented evidence for Proxima cs existence based on its stars telltale wobbling, which they inferred was caused by the pull of an unseen orbiting planet. Confirming a worlds existence in this way requires seeing the same wobble occur againand againin a process that often takes many months or even years. Damasso wondered if there might be another way. Thus, he asked Gratton and his team to look through data from the SPHERE (Spectro-Polarimetric High-Contrast Exoplanet Research) instrument on the European Southern Observatorys Very Large Telescope (VLT) in Chile to see if they could actually see the planet. As soon as our paper on Proxima c was considered for publication, I contacted [Gratton] to discuss the possibility of pushing SPHERE to its limits, Damasso says. The [planetary] system is potentially so cool that it is worthy to try other techniques.

If you squint a bit while staring at the SPHERE data, a picture of the mysterious planet seems to swim into view. By focusing on Proxima cs predicted position and separation from its star within multiple, stacked infrared images from SPHERE, Gratton and his colleagues were able to pick out 19 potential appearances of the planet across several years of routine observations. Of these candidate detections, one stood out as being particularly enticing: it appeared in the images about six times brighter than their noisethat is, unwanted light from artifacts or background stars. Its a possible candidate that has a low probability of being a false alarm, says Emily Rickman of the Geneva Observatory, who is a co-author of the paper.

If that detection is genuine, it poses intriguing questions. The object believed to be the planet would be at least seven times the mass of Earthlarge enough to place it firmly beyond the super Earth category. This would definitely be some kind of mini Neptune, says Sara Seager, a professor of planetary science at the Massachusetts Institute of Technology, who was not involved in the new paper. The object also appears to be 10 to 100 times brighter than a planet of its mass should be. This luminosity, the study authors reason, couldarise from a large amount of dust surrounding the planet, perhaps in a vast ring system that is three to four times larger than that of Saturn. To some, that situation seems too strange to be true.

It would be a huge ring system around a relatively old star, says astrophysicist Bruce Macintosh of Stanford University, who also was not part of the work. Its certainly possible for things like this to exist. But for your first detection of something like this to have that massive ring system, youd have to postulate a universe in which most Neptune-sized planets have massive ring systems enormously bigger than Saturns. And that seems like an unlikely universe to live in.

If genuine, this detectionthis imagewould have profound implications for our understanding of our nearest neighboring planetary system. It would give us definitive proof of the existence of Proxima c and also provide the angle at which the planet orbits its star, relative to our ownsomething that watching a stars wobbles alone cannot provide. The detection would also all but ensure that we could soon study the planets atmosphere with a new generation of powerful observatories, such as the upcoming European Extremely Large Telescope (E-ELT) and NASAs Wide-Field Infrared Survey Telescope (WFIRST).

Perhaps more importantly, pinning down Proxima c would also likely reveal the orbital angle of Proxima b, because planets would be expected to orbit in the same plane like those in our solar system do. This information, coupled with the wobbles Proxima b raises on its star, would tell us that world must be somewhere between 1.5 and 1.8 times the mass of Earth, which would let us refine theories about its characteristics. Such a mass would strongly point to the fact [that Proxima b] is rocky, says Elizabeth Tasker, an exoplanet scientist at the Japan Aerospace Exploration Agency, who was not involved in the study. In addition to our knowledge that Proxima b orbits in its stars habitable zone, where liquid water and thus life as we know it can exist, proof that the world is rocky would catapult it to the top of any astrobiologists list of promising exoplanets.

Such spectacular possibilities, however, call for steely-eyed skepticism. Indeed, the new papers authors acknowledge there is a decent chance their image is not actually a planet at all but rather just random noise in the data. They also note that the apparent motion of their putative planet conflicts with earlier estimates of Proxima cs position, based on observations of its star made by the European Space Agencys Gaia spacecraft. Thus, other astronomers are treating the potential finding with a considerable amount of caution. Its tough for me to conclude that [this] is a decisive detection, says Thayne Currie, an exoplanet scientist at NASAs Ames Research Center, who was also not part of the work.

Unfortunately, the ongoing global shutdown in response to the COVID-19 pandemic means that the result cannot be checked for the time being, because most of the worlds observatoriesincluding the VLTare not operational. It could be [confirmed or refuted] tomorrow, but the observatories are closed, says astronomer Guillem Anglada-Escud, who led the discovery of Proxima b in 2016 and was not involved in the new study. Time is running out for an immediate follow-up: in July Proxima Centauri will pass out of view behind our sun until February 2021.

So for now, the prospect of Proxima c having been seen for the first time remains an enticing but elusive possibility. Even if it proves to be a miragean astronomical false alarmthis potential detection is unlikely to dampen enthusiasm for further studies. Other teams will try again with upcoming instruments, more advanced than SPHERE, operating on supersized telescopes such as the E-ELT. But if the detection is real, which Gratton says he is two thirds confident about, it would be a historic initial glimpse of a planet orbiting the closest start to our own. If this is true, its very exciting, says Anglada-Escud.

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Astronomers May Have Captured the First Ever Image of Nearby Exoplanet Proxima C - Scientific American

When life events knock you down, looking to the stars may give you a new perspective. It reminds you how small we are and how easy it is to find a diversion with your old friend, the camera.

It doesnt take a lot of expensive equipment to take good photos of the heavens. Astrophotography can involve equipment as simple as a DSLR (digital single-lens reflex) camera with an ISO (International Organization for Standardization) rating of at least 1600 (the higher the number, the more sensitive to light it is).

Besides the camera, your equipment should include a sturdy tripod and a lens with an aperture (f-stop) opening of f/2.8 or higher.. The lower the f-stop the more light flows into the camera.

The size of the lens is also important. If you want a wide view with lots of foreground and more sky you should choose a 14 mm, 16 mm, 20 mm or 35 mm lens. If you want to take pictures of the moon, you will need a lens in the range of 200 mm to 600 mm.

Now find your location and attach your camera to the tripod. Switch off your automatic settings and find either the bulb or manual setting, which allows you to leave open the shutter for long exposures. The manual setting on most cameras will allow exposures of up to 30 seconds. Adjust your aperture to the maximum opening (the smaller numbers). Also, turn off the autofocus feature.

This 20-second exposure at iso-800 shows the difficulty with residential light pollution.

(Mark Boster/Los Angeles Times)

Your training wheels are gone now that youve turned off the automatic settings, and you can begin to experiment with your cameras manual adjustments. Start by manually focusing your lens to infinity and setting the ISO to 1600.

If your camera allows, adjust your shutter speed for an exposure of 15 to 30 seconds. Remember that Earth is rotating, so stars can appear to be streaking with exposures of 30 seconds.

Adjust your cameras image quality setting to RAW mode, which enables the highest-quality picture. Processing the pictures in RAW mode using Adobe Photoshop, Adobe Lightroom or other post-production tools provides better color and contrast control.

There are apps for everything, including astrophotography. Raul Roa, an avid astrophotographer, suggests the Planets app, which gives precise locations and times for viewing Polaris, the Milky Way and other celestial objects. Roa also uses the Sun Surveyor app, which shows where and when the Milky Way will rise, which is useful in planning your trips or locations.

Stan Honda, another former news photographer-turned-astrophotographer, offers his favorite apps: SkySafari, PhotoPills and Stellarium, all of which give you an idea of what you can see right now.

Before heading out to photograph the night sky, check the Weather page in the Times or online for the phases of the moon. Look for when the moon will be full, when it rises and when it sets.

Roa likes chasing the moon, he said, because it is something primordial. I look up and just think of what or who might be out there. Most of us will never get a chance to step off the Earth, so looking up and dreaming is the next best thing for me.

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Astronomy tips: How to photograph the moon, stars, and sky - Los Angeles Times

In another first, scientists at the LIGO and Virgo gravitational wave detectors announced a signal unlike anything theyve ever seen before. While many black hole mergers have been detected thanks to LIGO and Virgos international network for detectors, this particular signal (GW190412) was the first where the two black holes had distinctly different masses.

The event was observed by both LIGO and Virgo on April 12th, 2019, early in the detectors third observation run (O3). According to the study that describes the find, which recently appeared online and the LIGO website, GW190412 took place about 1.9 to 2.9 billion light-years from Earth. It involved the merger of two black holes weighting approximately 8 and 30 Solar masses, respectively.

The event is unique in the history of gravitational wave astronomy since all binaries observed previously by the LIGO and Virgo detectors consisted of two roughly similar masses. Analyses revealthat the merger happened at a distance of 1.9 to 2.9 billion light-years from Earth. The new unequal mass system is a unique discovery since all binaries observed previously by the LIGO and Virgo detectors consisted of two roughly similar masses.

This sharp difference in mass allowed the LIGO/Virgo scientists to verify something predicted by Einsteins General Theory of Relativity, which has so far remained untested. Frank Ohme is the leader of the Independent Max Planck Research Group aka. the Binary Merger Observations and Numerical Relativity at the Albert Einstein Institute (AEI). As he stated in a recent AEI press release:

For the very first time we have heard in GW190412 the unmistakable gravitational-wave hum of a higher harmonic, similar to overtones of musical instruments. In systems with unequal masses like GW190412 our first observation of this type these overtones in the gravitational-wave signal are much louder than in our usual observations. This is why we couldnt hear them before, but in GW190412, we finally can.

These observations once again confirms the theory of General Relativity (GR), which states that massive objects alter the curvature of space time and cause ripples aka. gravitational waves when they merge. The theory also predicts that binary systems where two objects are vastly different in terms of mass will introduce higher harmonics into the waveform.

When the LIGO and Virgo collaborations examined the signal produced by GW190412, they observed this very phenomenon at work for the first time in history. In short, the fundamental frequency of the GWs were two or three times higher than what has been observed with all other events that have been detected so far.

Says Roberto Cotesta, a PhD student in the Astrophysical and Cosmological Relativity division at the AEI in Potsdam:

The black holes at the heart of GW190412 have 8 and 30 times the mass of our Sun, respectively. This is the first binary black-hole system we have observed for which the difference between the masses of the two black holes is so large! This big mass difference means that we can more precisely measure several properties of the system: its distance to us, the angle we look at it, and how fast the heavy black hole spins around its axis.

Another benefit of this latest detection is that it allowed the team to measure the systems astrophysical properties with greater precision. In short, unequal masses imprint themselves on a GW signal, which in turn allows scientists to more precisely measure properties like the mass and spin of the merging objects, as well as the distance to the source and angle of observation.

Essential to this was the accurate models of GWs produced from coalescing black holes, which were provided by researchers from the Albert Einstein Institute. For the first time, these models included both the precession of the black-holes spins and multipole moments beyond the dominant quadrupole which were crucial to measuring their properties and carrying out tests of GR.

The Institutes high-performance Minerva and Hypatia computer clusters at AEI Potsdam and Holodeck at AEI Hannover also played a significant role in the analysis of the signal. According to Alessandra Buonanno, the director of the Astrophysical and Cosmological Relativity division at the AEI, this type of unique signal is something that the two previous observations runs failed to detect. As she said:

During O1 and O2, we have observed the tip of the iceberg of the binary population composed of stellar-mass black holes. Thanks to the improved sensitivity, GW190412 has begun to reveal us a more diverse, submerged population, characterized by mass asymmetry as large as 4 and black holes spinning at about 40% the possible maximum value allowed by general relativity.

Another reason why this kind of observation was not possible before has to do with the recent upgrades made at all the detectors in the LIGO/Virgo international network. This includes a new technique where the quantum-mechanical properties of the lasers used by LIGO and Vigro are squeezed to enhance the sensitivity of the detectors.

This technique was pioneered by researchers at the German-British GEO600 detector in South Hanover, Germany designed and operated by scientists from the Max Planck Institute and multiple European universities. The technique has improved the sensitivity of the GEO600 detector by a factor of two and the AEI is leading the global effort to maximize the effectiveness of the light squeezing technique further.

When the first GW event was detected by scientists at LIGO in February of 2016, it signaled a new age in astronomy. In just over four years, improvements made to individual detectors and international collaborations have ushered in an era where events are being detected every week.

With every new detection, we are learning more about the exotic physics that power our Universe. Be sure to check out this simulation of what the GW190412 merger looked like, courtesy of the Albert Einstein Institute:

Further Reading: Albert Einstein Institute, LSC

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Astronomers Detected a Black Hole Merger With Very Different Mass Objects - Universe Today

This is a piece of the puzzle that gets stacked on top of other points below. Do you need a telescope to start stargazing? Not necessarily. Though you can't see everything with the naked eye. So, it depends on what you're looking for. If you want to view deep-space objects, youre going to need a telescope. If youre looking at planets, youll be able to see a lot of them with the naked eye. Venus, Mars, Saturn, and Jupiter are all easily visible. However, even a pair of binoculars will give you a more impressive view.

However, there are tools available beyond telescopes and binoculars. "The first thing I did when I started is to subscribe to the national magazines," Sreenivasan said. "The two largest ones are Sky and Telescopeand Astronomy." Though, he notes you can read them online as well. They have details about what you can see in the night sky over the coming weeks. (Of course, Thrillist also has details on many space events throughout the year.)

Additionally, there are apps that use augmented reality to show you what's in the sky and help you track down objects you want to see. Some of the most popular apps include Sky View, Sky Safari, Star Walk, and Night Sky. "Also, invest in a star atlas," Sreenivasan said. "There are several out there like Sky & Telescopes Pocket Sky Atlas.Thats one a lot of beginners use, and I still use it myself when I travel. Its just a set of star maps. Its a pretty small book, but its a pretty good book."

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Everything You Need to Know to Take up Stargazing - Thrillist

Want to stargaze with astrophysicists and mingle with astronauts? Now's your chance.

The Intrepid Sea, Air & Space Museum is holding its first-ever Virtual Astronomy Live on Friday, April 24 from 23:30pm. Thisevent commemorates 30 years of the Hubble Space Telescope, the first major optical telescope to be launched into space.

Your guides make up (a-hem) a star-studded lineup: Among the attendees are former astronaut and NASA chiefGeneralCharles F. Bolden Jr, former astronaut ProfessorMike Massimino, engineer and former astronaut Nicole Stott, astrophysicistFrank Summers and others.Virtual Astronomy Live will beled by Summer Ash, arocket scientist and astrophysicist, and Summer Ash, andJohn Das Galloway, creator of the Kerbal Space Academy and host for NASASpaceflight.com.

Visit kerbalspaceacademy.comto take a peek.The proswill discussthe wonders of the cosmos, and they will also talk aboutwhat it takes to live in spaceit turns out there are some similarities between workingin isolation on the International Space Station and trying to keep it professional on Zoomwhileparenting at home.

The fact is, there's so much cool stuff online that will engage, entertain and educate your family while you're at home. From taking actual Hogwarts classes, to streaming virtual storytimes, to working out with these fun online fitness classes for kids, you canmake staying in more fun than a barrel of monkeys.

So order food from the bestfamily restaurants in NYCdoing delivery, and make the most of this time in.

-Disney's free drawing classes teach you how to sketch your favorite princesses- Tour the real-life locations of Harry Potter's world with Google Earth- Celebrate the 100th birthday of Denos Wonder Wheel with a free coloring book- New York's kiddie salons share advice on how to cut your child's hair at home- Best family restaurants in NYC doing delivery

Sign up to receive great Time Out New York Kids deals in your inbox each day.

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This Free Virtual Astronomy Livestream from the Intrepid Is Out of This World! - Time Out New York Kids

In 2016, astronomers working for the European Southern Observatory (ESO) confirmed the existence of a terrestrial planet around Earths closest stellar neighbor Proxima Centauri. The discovery of this nearby extrasolar planet (Proxima b) caused no shortage of excitement because, in addition to being similar in size to Earth, it was found to orbit within the stars habitable zone (HZ).

Thanks to an INAF-led team, a second exoplanet (a super-Earth) was found early this year around Proxima Centauri using the Radial Velocity Method. Based on the separation between the two planets, another INAF-led team attempted to observe this planet using the Direct Imaging Method. While not entirely successful, their observations raise the possibility that this planet has a system of rings around it, much like Saturn.

For the sake of their study, which recently appeared in the journal Astronomy & Astrophysics, the team relied on data obtained by the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument on the ESOs Very Large Telescope (VLT). This extreme adaptive optics system and coronagraphic facility is dedicated to the characterization of exoplanet systems at optical and near-infrared wavelengths.

For years, SPHERE has been revealing the existence of protoplanetary disks around distant stars, something that is extremely difficult to do using conventional optics. However, this particular set of data was gathered during the four-year SpHere INfrared survey for Exoplanets (SHINE) survey, where SPHERE was used to image 600 nearby stars in the near-infrared spectrum.

Relying on SPHEREs high contrast and high angular resolution, the purpose of this survey was to characterize new planetary systems and explore how they formed. One such system was Proxima Centauri, a low-mass M-type (red dwarf) star located just 4.25 light-years from our Solar System. At the time of the survey, which ran from to , the existence of Proxima c was not yet known.

Like Proxima b, Proxima c was discovered using the Radial Velocity (aka. Doppler Spectroscopy) method. This consists of measuring a stars movement back and forth (or wobble) to determine if it is being acted on by the gravitational influence of a system of planets. However, the team was confident that if Proxima c was producing a large enough signal in infrared, SPHERE would have detected it.

As the team which was led by Raffael Gratton of the Astronomical Observatory of Padova explained their methods in their study:

We searched for a counterpart in SPHERE images acquired during four years through the SHINE survey. In order to account for the expected large orbital motion of the planet, we used a method that assumes the circular orbit obtained from radial velocities and exploits the sequence of observations acquired close to quadrature in the orbit. We checked this with a more general approach that considers keplerian motion, K-stacker.

Unfortunately, the SPHERE data did not reveal any clear detections of Proxima c. What they did find was a candidate signal that had a strong signal to noise ratio and that the orientation of its orbital plane fit well with a previous image taken using the Atacama Large Millimeter/submillimeter Arrays (ALMA).

However, they also noted that its position and orbital motion (aka. astrometric signal) were not consistent with what was observed by the ESAs Gaia mission. Last, but not least, they found that the candidate had an unexpectedly high apparent brightness (aka. flux) a planet orbiting a red dwarf star. Because of this, the team could not say with any confidence whether or not what they observed was indeed Proxima c.

However, this last item raised another possibility that the team had to consider, that the unusual brightness may be the result of a circumplanetary material. In other words, they theorize that the brightness could be caused by a ring system around Proxima c, which would be radiating additional light in the infrared spectrum and contributing to the total brightness. As they explain:

In this case we envision either a conspicuous ring system, or dust production by collisions within a swarm of satellites, or evaporation of dust boosting the planet luminosity. This would be unusual for extrasolar planets, with Fomalhaut b, for which there is no dynamical mass determination, as the only other possible example.

This makes Proxima c a prime target for follow-up studies using radial velocity measurements, near-infrared imaging, and other methods. In addition, next-generation telescopes like the Thirty Meter Telescope (TMT), the Giant Magellan Telescope (GMT), and the ESOs Extremely Large Telescope (ELT), will be well-suited to conduct direct imaging surveys of this system to detect Proxima c.

Whats more, if astronomers manage to confirm that the candidate seen here was Proxima c, then Breakthrough Starshot is likely to want to get in on the action! For years, this organization has been working towards the goal of sending a gram-scale wafercraft to the Alpha Centauri system by means of directed-energy propulsion. Ever since the discovery of Proxima b, there has been talk about making a flyby of Proxima Centauri as well.

Not only would this spacecraft be able to get a close-up look of Proxima b, it could also swing by Proxima c and get some snapshots of the planet and its (possible) ring system. Regardless, if the teams findings are confirmed, it will be the first time direct imaging of a planet discovered from radial velocity measurements was made and the second time where reflections from circumplanetary material occurred (after Fomalhaut b).

In any case, these results could have significant implications for future studies and the characterization of Proxima Centauri.

Further Reading: arXiv

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Astronomers Might Have Imaged a Second Planet Around Nearby Proxima Centauri - and it Might Have a Huge Set of Rings - Universe Today

During the warm evenings and clear skies of recent weeks, you may have noticed a brilliant, shining beacon towards the west, far brighter than anything else in the night sky other than the Moon, and wondered what it was.

That bright Evening Star is actually a planet, Venus, and from the Northern Hemisphere it will be visible in the evening sky all through the rest of April and into May. In fact, it will reach its absolute brightest on 28 April yes, it will get even brighter than it already is, if only slightly!

So, why is it so bright? Is it because, like Mars or Jupiter when they are at their brightest, Venus is at its closest point to Earth? Well, not quite. At its closest, Venus comes within 42 million kilometres of our planet during what we call inferior conjunction, when it lies directly between us and the Sun. However, we cant observe it during inferior conjunction, partly because of the Suns glare hiding it, and also because at inferior conjunction we are looking at Venus night-time hemisphere the dayside is facing the Sun instead, so we would not see the illuminated part of the planet.

Instead, we see Venus at its brightest when its close to a point called maximum elongation. To picture what this is, imagine being able to look down on the Solar System from high above the plane of the orbits of the planets. With this birds eye view, you are able to see the planets traverse their (almost) circular orbits. Now, focus on the orbits of the second and third planets, Venus and Earth, and imagine Venus at inferior conjunction with Earth.

Because Venus is closer to the Sun, its orbit is smaller and it moves around the Sun faster than Earth does (one orbit for Venus takes 225 Earth days, as opposed to our 365 days). So soon enough it reaches a position in its orbit relative to Earth where it appears to the side of the Sun from our point of view. The further to the side of the Sun that Venus moves, the easier it is to see it. Its greatest distance to the side of the Sun is called maximum elongation, and as we can see, Venus is quite a distance from the Sun in the sky. For example, on 28 April, when Venus is about 70 million kilometres from Earth, it sets below the western horizon four hours after the Sun does.

During the time around maximum elongation, we dont see all of Venus illuminated by the Sun, but only a portion of it. Indeed, if you turn a pair of binoculars (at minimum they would need to be 10 x 50 binoculars) or a telescope towards Venus during mid-April, you should see it with a crescent phase, much like the Moon, with only 37 per cent of its visible disc is illuminated by the Sun. By 28 April, as Venus continues on its orbit around the Sun and our viewing angle begins to change, this has reduced to 26 per cent.

Yet despite only a small percentage of the visible part of Venus being illuminated, it can still shine so brightly because its atmosphere is composed of thick clouds of carbon dioxide and sulphuric acid that completely enshroud Venus and which are incredibly reflective. Venus has an albedo of 0.7, which means that it reflects about 70 per cent of the sunlight that falls on it.

So, thats why Venus is shining so brightly at the moment, and it makes for wonderful viewing in the evening sky. In particular, look out for the thin crescent of the Moon near Venus on the evening of 26 April if you have a DSLR camera and a steady tripod, perhaps try shooting some pictures of the two close by?

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Beginners' astronomy: That bright light you can see in the western sky? That's Venus - Astronomy Now Online