When it is deployed to space, the James Webb Space Telescope (JWST) will be the most powerful and advanced telescope ever deployed. As the spiritual and scientific successor to the Hubble, Spitzer, and Kepler Space Telescopes, this space observatory will use its advanced suite of infrared instruments to look back at the early Universe, study the Solar System, and help characterize extra-solar planets.
Unfortunately, after many delays, there’s some good news and bad news about this mission. The good news is that recently, the Independent Review Board (IRB) established by NASA to assess the progress on the JWST unanimously decided that work on the space telescope should continue. The bad news is that NASA has decided to push the launch date back again – this time to March 30th, 2021.
As part of their assessment, the IRB was established in April of 2018 to address a range of factors influencing Webb’s schedule and performance. These included the technical challenges and tasks that need to be tackled by its primary contractor (Northrop Grumman) before the mission can launch. A summary of the report’s recommendations, and NASA’s response, can be read here.
In the report, the IRB identified technical issues, which including human errors, that they claim have greatly impacted the development schedule. As they stated in their Overview:
“The observation that there are no small JWST integration and test problems was not initially recognized by the Webb IRB, and this also may be true of others involved with JWST. It is a most important observation that will be apparent in subsequent Findings and Recommendations. It is caused by the complexity and highly integrated nature of the observatory. Specifically, it implies, as an example, that a very small human error or test anomaly can impact the schedule by months and the cost by tens of millions of dollars.”
The anomaly mentioned in the report refers to the “anomalous readings” that were detected from the telescope during vibration testing back in December 2016. NASA responded to this by giving the project up to 4 months of schedule reserve by extending the launch window. However, in 2017, NASA delayed the launch window again by 5 months, from October 2018 to a between March and June 2019.
This delay was requested by the project team, who indicated that they needed to address lessons learned from the initial folding and deployment of the observatory’s sun shield. In February of 2018, the Government Accountability Office (GAO) issued a report that expressed concerns over further delays and cost overruns. Shortly thereafter, the JWST’s Standing Review Board (SRB) made an independent assessment of the remaining tasks.
In May of 2018, NASA issued a statement indicating that they now estimated that the launch window would be some time in May 2020. However, they chose to await the findings of the IRB and consider the data from the JWST’s Standing Review Board before making the final determination. The new launch date was set to accommodate environmental testing and work performances challenges on the sunshield and propulsion system.
According to the IRB report, this latest delay will also result in a budget overrun. “As a result of the delay, Webb’s total lifecycle cost to support the March 2021 launch date is estimated at $9.66 billion,” they concluded. “The development cost estimate to support the new launch date is $8.8B (up from the $8B development cost estimate established in 2011).”
As Jim Bridenstine, the NASA Administrator, indicated in a message to the NASA workforce on Wednesday about the report:
“Webb is vital to the next generation of research beyond NASA’s Hubble Space Telescope. It’s going to do amazing things – things we’ve never been able to do before – as we peer into other galaxies and see light from the very dawn of time. Despite major challenges, the board and NASA unanimously agree that Webb will achieve mission success with the implementation of the board’s recommendations, many of which already are underway.”
In the end, the IRB, SRB and NASA are all in total agreement that the James Webb Space Telescope is a crucial mission that must be seen through. In addition to shedding light on a number of mysteries of the Universe – ranging from the earliest stars and galaxies in the Universe to exoplanet habitability – the JWST will also complement and enhance the discoveries made by other missions.
“The more we learn more about our universe, the more we realize that Webb is critical to answering questions we didn’t even know how to ask when the spacecraft was first designed. Webb is poised to answer those questions, and is worth the wait. The valuable recommendations of the IRB support our efforts towards mission success; we expect spectacular scientific advances from NASA’s highest science priority.”
The JWST will also be the first telescope of its kind, being larger and more complex than any previous space telescope – so challenges were anticipated from its very inception. In addition, the final phase consists of some of the most challenging work, where the 6.5-meter telescope and science payload element are being joined with the spacecraft element to complete the observatory.
The science team also needs to ensure that the observatory can be folded up to fit inside the Ariane 5 rocket that will launch it into space. They also need to ensure that it will unfold again once it reaches space, deploy its sunshield, mirrors and primary mirror. Beyond that, there are also the technical challenges of building a complex observatory that was created here on Earth, but designed to operate in space.
As a collaborative project between NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA), the JWST is also representative of the new era of international cooperation. As such, no one wishes to see the mission abandoned so close to completion. In the meantime, any delays that allow for extra testing will only ensure success in the long run.
Good luck JWST, we look forward to hearing about your first discoveries!
Once it deploys, the James Webb Space Telescope (JWST) will be the most powerful and technically complex space telescope ever deployed. Using its powerful suite of infrared-optimized instruments, this telescope will be able to study the earliest stars and galaxies in the Universe, extra-solar planets around nearby stars, and the planets, moons and asteroids of our Solar System.
Unfortunately, due to its complexity and the need for more testing, the launch of the JWST has been subject to multiple delays. And as of this morning, NASA announced that the launch JWST has been delayed yet again. According to a statement issued by the agency, the launch window for the JWST is now targeted for sometime around May 2020.
The decision came after an independent assessment by the project’s Standing Review Board (SRB) of the remaining tasks, all of which are part of the final stage of integration and testing before the JWST launches. These tasks consist of integrating the combined optics and science instruments onto the spacecraft element, then testing them to ensure that they will deploy properly and work once they are in space.
This assessment came on the heels of a report issued by the Government Accountability Office (GAO) in February that expressed concerns over further delays and cost overruns. These concerns were based on the fact that it is typically in the final phase when problems are found and schedules revised, and that only 1.5 months of schedule reserved remained (at the time) until the end of the telescope’s launch window – which was scheduled for 2019.
But as acting NASA Administrator Robert Lightfoot stressed, the JWST is still a go:
“Webb is the highest priority project for the agency’s Science Mission Directorate, and the largest international space science project in U.S. history. All the observatory’s flight hardware is now complete, however, the issues brought to light with the spacecraft element are prompting us to take the necessary steps to refocus our efforts on the completion of this ambitious and complex observatory.”
NASA also announced that it is establishing an external Independent Review Board (IRB) chaired by Thomas Young – a highly-respected NASA and industry veteran who has a long history of chairing advisory committees and analyzing organizational and technical issues. The IRB findings, along with the SRB data, will be considered by NASA to set a more specific launch date, and will be presented to Congress this summer.
In the meantime, NASA and the European Space Agency (ESA) will be setting a new launch readiness date for the Ariane 5 rocket that will bring the JWST into space. Once a launch date is set, NASA will also be providing a cost estimate that may exceed the $8 billion budget cap established by Congress in 2011. This too is in keeping with the GAO’s report, which predicted cost overruns.
For those who have been following the JWST’s development, this news should come as no surprise. Due to its complexity and the need for extensive testing, the launch of the JWST has been delayed several times in recent years. In addition, the final phase consists of some of the most challenging work, where the 6.5-meter telescope and science payload element are being joined with the spacecraft element to complete the observatory.
In addition, the science team also needs to ensure that the observatory can be folded up to fit inside the Ariane 5 rocket that will launch it into space. They also need to ensure that it will unfold again once it reaches space, deploying its sunshield, mirrors and primary mirror. Beyond that, there are also the technical challenges of building a complex observatory that was created here on Earth, but designed to operate in space.
Not only does all of this represent a very technically-challenging feet, it is the first time that any space telescope has had to perform it. Already, the JWST has completed an extensive range of tests to ensure that it will reach its orbit roughly 1.6 million km (1 million mi) from Earth. And while delays can be discouraging, they also increase the likelihood of mission success.
As Thomas Zurbuchen, the associate administrator for NASA’s Science Mission Directorate, stated:
“Considering the investment NASA and our international partners have made, we want to proceed systematically through these last tests, with the additional time necessary, to be ready for a May 2020 launch.”
The next step in testing will take several months, and will consist of the spacecraft element undergoing tests to simulate the vibrational, acoustic and thermal environments it will experience during its launch and operations. Once complete, the project engineers will integrate and test the fully assembled observatory and verify that all its components work together properly.
And then (fingers crossed!) this ambitious telescope will finally be ready to take to space and start collecting light. In so doing, scientists from all around the world hope to shed new light on some of the most fundamental questions of science – namely, how did the Universe evolve, is their life in our Solar System beyond Earth, are their habitable worlds beyond our Solar System, and are there other civilizations out there?
Bottom line, NASA remains committed to deploying the James Webb Space Telescope. So even if the answers to these questions are delayed a little, they are still coming!
Once deployed, the James Webb Space Telescope (JWST) will be the most powerful telescope ever built. As the spiritual and scientific successor to the Hubble, Spitzer, and Kepler space telescopes, this space observatory will use its advanced suite of infrared instruments to the look back at the earliest stars and galaxies, study the Solar System in depth, and help characterize extra-solar planets (among other things).
Unfortunately, the launch of the JWST has been subject to multiple delays, with the launch date now set for some time in 2019. Luckily, on Thursday, March 8th, engineers at the Northrop Grumman company headquarters began the final step in the observatory’s integration and testing. Once complete, the JWST will be ready to ship to French Guiana, where it will be launched into space.
This final phase consisted of removing the combined optics and science instruments from their shipping containers – known as the Space Telescope Transporter for Air, Road and Sea (STTARS) – which recently arrived after being testing at NASA’s Johnson Space Center in Houston. This constitutes half the observatory, and includes the telescope’s 6.5 meter (21.3 foot) golden primary mirror.
The science payload was also tested at NASA’s Goddard Space Flight Center last year to ensure it could handle the vibrations associated with space launches and the temperatures and vacuum conditions of space. The other half of the observatory consists of the integrated spacecraft and sunshield, which is in the final phase of assembly at the Northrop Grumman company headquarters.
These will soon undergo a launch environment test to prove that they are ready to be combined with the science payload. Once both halves are finished being integrated, addition testing will be performed to guarantee the fully assembled observatory can operate at the L2 Earth-Sun Lagrange Point. As Eric Smith, the program director for the JWST at NASA Headquarters, said in a recent NASA press statement:
“Extensive and rigorous testing prior to launch has proven effective in ensuring that NASA’s missions achieve their goals in space. Webb is far along into its testing phase and has seen great success with the telescope and science instruments, which will deliver the spectacular results we anticipate.”
These final tests are crucial to ensuring that that the observatory deploys properly and can operate once it is in space. This is largely because of the telescope’s complicated design, which needs to be folded in order to fit inside the Ariane 5 rocket that it will carry it into space. Once it reaches its destination, the telescope will have to unfold again, deploying its sunshield, mirrors and primary mirror.
Not only does all of this represented a very technically-challenging feet, it is the first time that any space telescope has had to perform it. Beyond that, there are also the technical challenges of building a complex observatory that is designed to operate in space. While the JWST’s optics and science instruments were all built at room temperature here on Earth, they had to be designed to operate at cryogenic temperatures.
As such, its mirrors had to be precisely polished and formed that they would achieve the correct shape once they cool in space. Similarly, its sunshield will be operating in a zero gravity environment, but was built and tested here on Earth where the gravity is a hefty 9.8 m/s² (1 g). In short, the James Webb Space Telescope is the largest and most complex space telescope ever built, and is one of NASA’s highest priority science projects.
It is little wonder then why NASA has had to put the JWST through such a highly-rigorous testing process. As Smith put it:
“At NASA, we do the seemingly impossible every day, and it’s our job to do the hardest things humankind can think of for space exploration. The way we achieve success is to test, test and retest, so we understand the complex systems and verify they will work.”
Knowing that the JWST is now embarking on the final phase of its development – and that its engineers are confident it will perform up to task – is certainly good news. Especially in light of a recent report from the US Government Accountability Office (GAO), which stated that more delays were likely and that the project would probably exceed its original budget cap of $8 billion.
As the report indicated, it is the final phase of integration and testing where problems are most likely to be found and schedules revised. However, the report also stated that “Considering the investment NASA has made, and the good performance to date, we want to proceed very systematically through these tests to be ready for a Spring 2019 launch.”
In other words, there is no indication whatsoever that Congress is considering cancelling the project, regardless of further delays or cost overruns. And when the JWST is deployed, it will use its 6.5 meter (21-foot) infrared-optimized telescopes will search to a distance of over 13 billion light years, allow astronomers to study the atmospheres of Solar Planets, exoplanets, and other objects within our Solar System.
So while the JWST may not make its launch window in 2019, we can still expect that it will be taking to space in the near future. And when it does, we can also expect that what it reveals about our Universe will be mind-blowing!
When the James Webb Space Telescope takes to space, some tremendous scientific discoveries are expected to result. As the spiritual and scientific successor to the Hubble, Spitzer, and Kepler Space Telescopes, this space observatory will use its advanced suite of infrared instruments to the look back at the early Universe, study the Solar System, and help characterize extra-solar planets.
Unfortunately, the launch of this mission has been delayed several times now, with the launch date now set for some time in 2019. And based on the amount of work NASA needs to do complete the JWST before launch, the Government Accountability Office (GAO) believes that more delays are coming and believes that the project is likely to exceed the cost cap set by Congress in 2011 at $8 billion.
Part of the problem is that all the remaining schedule reserve – the extra time set aside in the event of delays or unforeseen risks – was recently used to address technical issues. These include the “anomalous readings” detected from the telescope during vibration testing back in December 2016. NASA responded to this by giving the project up to 4 months of schedule reserve by extending the launch window.
However, in 2017, NASA delayed the launch window again by 5 months, from October 2018 to a between March and June 2019. This delay was requested by the project team, who indicated that they needed to address lessons learned from the initial folding and deployment of the observatory’s sunshield. As Eric Smith, the program director for the James Webb Space Telescope at NASA Headquarters, explained to Congress at the time:
“Webb’s spacecraft and sunshield are larger and more complex than most spacecraft. The combination of some integration activities taking longer than initially planned, such as the installation of more than 100 sunshield membrane release devices, factoring in lessons learned from earlier testing, like longer time spans for vibration testing, has meant the integration and testing process is just taking longer. Considering the investment NASA has made, and the good performance to date, we want to proceed very systemmatically through these tests to be ready for a Spring 2019 launch.”
Given the remaining integration and test work that lies ahead, more delays are expected. According to the GAO, it is this phase where problems are most likely to be found and schedules revised. Coupled with the fact that only 1.5 months of schedule reserves remain until the end of the launch window, they anticipate that additional launch delays are likely, which will also require budget increases.
Initially, the budget estimates that were set by Congress indicated that the observatory would cost $1.6 billion and would launch by 2011, with an overall cost cap set at $8 billion. However, NASA has revised the budget multiple times since then (in conjunction with the multiple delays) and estimates that the budget for a 2019 launch window would now be $8.8 billion.
Once deployed, the JWST will be the most powerful space telescope ever built and will serve thousands of astronomers worldwide. As a collaborative project between NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA), it also representative of the new era of international cooperation. But by far, the most impressive thing about this mission is the scientific discoveries it is expected to make.
It’s 6.5 meter (21-foot) infrared-optimized telescopes will search to a distance of over 13 billion light years, allowing it to study the first stars and galaxies that formed. It will also allow astronomers to study the atmospheres of Solar Planets and exoplanets and other objects within our Solar System. As such, and delays and cost overruns in the project are cause for concern.
In the meantime, the project’s Standing Review Board will conduct an independent review in early 2018 to determine if the June 2019 launch window can still be met. With so many experiments and surveys planned for the telescope, it would be no exaggeration to say that a lot is riding on its successful completion and deployment. Best of luck passing review James Webb Space Telescope!
The super-Earth 55 Cancri e (aka. Janssen) is somewhat famous, as exoplanet go. Originally discovered in 2004, this world was one of the few whose discovery predated the Kepler mission. By 2016, it was also the first exoplanet to have its atmosphere successfully characterized. Over the years, several studies have been conducted on this planet that revealed some rather interesting things about its composition and structure.
For example, scientists believed at one time that 55 Cancri e was a “diamond planet“, whereas more recent work based on data from the Spitzer Space Telescope concluded that its surface was covered in lakes of hot lava. However, a new study conducted by scientists from NASA’s Jet Propulsion Laboratory indicates that despite its intense surface heat, 55 Cancri e has an atmosphere that is comparable to Earth’s, only much hotter!
The study, titled “A Case for an Atmosphere on Super-Earth 55 Cancri e“, recently appeared in The Astrophysical Journal. Led by Isabel Angelo (a physics major with UC Berkeley) with the assistance of Renyu Hu – a astronomer and Hubble Fellow with JPL and Caltech – the pair conducted a more detailed analysis of the Spitzer data to determine the likelihood and composition of an atmosphere around 55 Cancri e.
Previous studies of the planet noted that this super-Earth (which is twice as large as our planet), orbits very close to its star. As a result, it has a very short orbital period of about 17 hours and 40 minutes and is tidally locked (with one side constantly facing towards the star). Between June and July of 2013, Spitzer observed 55 Cancri e and obtained temperature data using its special infrared camera.
Initially, the temperature data was seen as being an indication that large deposits of lava existed on the surface. However, after re-analyzing this data and combining it with a new model previously develop by Hu, the team began to doubt this explanation. According to their findings, the planet must have a thick atmosphere, since lava lakes exposed to space would create hots spots of high temperatures.
What’s more, they also noted that the temperature differences between the day and night side were not as significant as previously thought – another indication of an atmosphere. By comparing changes in the planet’s brightness to energy flow models, the team concluded that an atmosphere with volatile materials was the best explanation for the high temperatures. As Renyu Hu explained in a recent NASA press statement:
“If there is lava on this planet, it would need to cover the entire surface. But the lava would be hidden from our view by the thick atmosphere. Scientists have been debating whether this planet has an atmosphere like Earth and Venus, or just a rocky core and no atmosphere, like Mercury. The case for an atmosphere is now stronger than ever.”
Using Hu’s improved model of how heat would flow throughout the planet and radiate back into space, they found that temperatures on the day side would average about 2573 K (2,300 °C; 4,200 °F). Meanwhile, temperatures on the “cold” side would average about 1573 – 1673 K (1,300 – 1,400 °C; 2,400 – to 2,600 °F). If the planet had no atmosphere, the differences in temperature would be far more extreme.
As for the composition of this atmosphere, Angelo and Hu revealed that it is likely similar to Earth’s – containing nitrogen, water and even oxygen. While much hotter, the atmospheric density also appeared to be similar to that of Earth, which suggests the planet is most likely rocky (aka. terrestrial) in composition. On the downside, the temperatures are far too hot for the surface to maintain liquid water, which makes habitability a non-starter.
Ultimately, this study was made possible thanks to Hu’s development of a method that makes the study exoplanet atmospheres and surfaces easier. Angelo, who led the study, worked on it as part of her internship with JPL and adapted Hu’s model to 55 Cancri e. Previously, this model had only been applied to mass gas giants that orbit close to their respective suns (aka. “Hot Jupiters”).
Naturally, there are unresolved questions that this study helps to raise, such as how 55 Cancri e has avoided losing its atmosphere to space. Given how close the planet orbits to its star, and the fact that it’s tidally locked, it would be subject to intense amounts of radiation. Further studies may help to reveal how this is the case, and will help advance our understanding of large, rocky planets.
The application of this model to a Super-Earth is the perfect example of how exoplanet research has been evolving in recent years. Initially, scientists were restricted to studying gas giants that orbit close to their stars (as well as their respective atmospheres) since these are the easiest to spot and characterize. But thanks to improvements in instrumentation and methods, the range of planets we are capable of studying is growing.
The mystery of KIC 8462852 (aka. Boyajian’s Star or Tabby’s Star) continues to excite and intrigue! Ever since it was first seen to be undergoing strange and sudden dips in brightness (back in October of 2015) astronomers have been speculating as to what could be causing this. Since that time, various explanations have been offered, including large asteroids, a large planet, a debris disc or even an alien megastructure.
Many studies have been produced that have sought to assign some other natural explanation to the star’s behavior. The latest comes from an international team of scientists – which included Tabetha Boyajian, the lead author on the original 2016 paper. According to this latest study, which was recently published in The Astrophysical Journal, the star’s long-term dimming patterns are likely the result of an uneven dust cloud moving around the star.
For the sake of their study, the team consulted data that was obtained by NASA’s Spitzer Space Telescope and the Swift Gamma-Ray Burst mission between January and December of 2016. Whereas Spitzer conducted observations in the infrared band, Swift gathered data in the ultraviolet band. This was then compared to visible light gathered during the same period by AstroLAB IRIS’s 68-cm (27-inch) reflecting telescope.
What they found was that KIC 8462852 experienced less dimming in the infrared band than in the ultraviolet. This, they concluded, was a strong indication that material transiting in front of the star was likely no larger than a few micrometers (about one ten-thousands of an inch) in diameter, since anything larger would cause the light to dim equally across all wavelengths.
This finding contradicts many theories that have been ventured since the mysterious dimming of Tabby’s Star was first noticed. As Dr. Meng indicated in a recent NASA press statement:
“This pretty much rules out the alien megastructure theory, as that could not explain the wavelength-dependent dimming. We suspect, instead, there is a cloud of dust orbiting the star with a roughly 700-day orbital period.”
Based on the strong dip in the ultraviolet band, the research team also concluded that the particles must be larger than interstellar dust. Otherwise, the pressure caused by KIC 8462852’s solar wind would drive these particles out into space over time. A circumstellar disk of dust particles would not only be able to remain in orbit, it would also explain the uneven changes in the star’s brightness.
So far, this is the best explanation for the mysterious long-term behavior of Tabby’s Star. As with previous observations, much of the credit for this latest study goes to amateur astronomers who assisted in the observations. It was participants in the Planet Hunters project, which provides open to access Kepler mission data, that first noticed that light coming from KIC 8462852 was experiencing strange dips.
In addition, it was the work of amateur astronomers – who provided the necessary technical and software support to AstroLAB – allowed for this study to take place. After the Astrolab group posted the data they had obtained on Tabby’s star in a public astronomy archive, George Rieke (one of the co-authors on this latest study) contacted them and proposed combining their results.
The AstroLAB group consists of Franky Dubois, who operated the telescope during the Tabby’s Star observations, Ludwig Logie, who helps with technical issues on the telescope, and Steve Rau, who processes observations of star brightness, is a trainer at a Belgian railway company. Together, they began monitoring Tabby’s Star after they read Dr. Boyajian 2016 study.
Naturally, more observations and research is needed to confirm this latest study. While it does fit the long-term observations, there is still the matter of shorter-term dimming events. These include the three-day spurts that were noticed in 2017, as well as the major 20-percent dips that were observed during Kepler’s primary mission. The theory that these could have been the result of a swarm of comets is also still a possible explanation.
This theory, which was based on data collected by the Wide-field Infrared Survey Explorer (WISE) mission, could explain both the short period dips and the longer-term dips. Whereas the comets passing in front of the star could explain the former, dust produced by the sublimation of material from the comets as they draw nearer the star (or through collisions) could explain the latter. As Vanaverbeke said:
“Tabby’s Star could have something like a solar activity cycle. This is something that needs further investigation and will continue to interest scientists for many years to come.”
So for those hoping that Tabby’s Star was the first indication of an alien megastructure, there’s still hope (albeit a faint one)! As Professor Loeb of the Harvard Smithsonian Center for Astrophysics (CfA) told Universe Today recently (with regards to a new study he co-authored), there’s always the possibility that dimming patterns are due to massive structures – like a magnetic shield – passing in front of a host star:
“The imprint of a shield built by another civilization could involve the changes it induces in the brightness of the host star due to occultation (similar behavior to Tabby’s star) if the structure is big enough,” he said. “The situation could be similar to Dyson’s spheres, but instead of harvesting the energy of the star the purpose of the infrastructure is to protect a technological civilization on a planet from the flares of its host star.”
Collapsing stars are a rare thing to witness. And when astronomers are able to catch a star in the final phase of its evolution, it is a veritable feast for the senses. Ordinarily, this process consists of a star undergoing gravitational collapse after it has exhausted all of its fuel, and shedding its outer layers in a massive explosion (aka. a supernova). However, sometimes, stars can form black holes without the preceding massive explosion.
This process, what might be described as “going out not with a bang, but with a whimper”, is what a team of astronomers witnessed when observing N6946-BH1 – a star located in the Fireworks Galaxy (NGC 6946). Originally, astronomers thought that this star would exploded because of its significant mass. But instead, the star simply fizzled out, leaving behind a black hole.
The Fireworks Galaxy, a spiral galaxy located 22 million light-years from Earth, is so-named because supernova are known to be a frequent occurrence there. In fact, earlier this month, an amateur astronomer spotted what is now designated as SN 2017eaw. As such, three astronomers from Ohio Sate University (who are co-authors on the study) were expecting N6946-BH1 would go supernova when in 2009, it began to brighten.
However, by 2015, it appeared to have winked out. As such, the team went looking for the remnants of it with the help of colleagues from Ohio State University and the University of Oklahoma. Using the combined power of the Large Binocular Telescope (LBT) and NASA’s Hubble and Spitzer space telescopes, they realized that the star had completely disappeared from sight.
After it experienced a weak optical outburst in 2009, they had anticipated that this red supergiant would go supernova – which seemed logical given that it was 25 times as massive as our Sun. After winking out in 2015, they had expected to find that the star had merely dimmed, or that it had cast off a dusty shell of material that was obscuring its light from view.
Their efforts included an LBT survey for failed supernovae, which they combined with infrared spectra obtained by the Spitzer Space Telescope and optical data from Hubble. However, all the surveys turned up negative, which led them to only one possible conclusion: that N6946-BH1 must have failed to go supernova and instead went straight to forming a blackhole.
“N6946-BH1 is the only likely failed supernova that we found in the first seven years of our survey. During this period, six normal supernovae have occurred within the galaxies we’ve been monitoring, suggesting that 10 to 30 percent of massive stars die as failed supernovae. This is just the fraction that would explain the very problem that motivated us to start the survey, that is, that there are fewer observed supernovae than should be occurring if all massive stars die that way.”
A major implication of this study is the way it could shed new light on the formation of very massive black holes. For some time now, astronomers have believed that in order to form a black hole at the end of its life cycle, a star would have to be massive enough to cause a supernova. But as the team observed, it doesn’t make sense that a star would blow off its outer layers and still have enough mass left over to form a massive black hole.
As Christopher Kochanek – a professor of astronomy at The Ohio State University, the Ohio Eminent Scholar in Observational Cosmology and a co-author of the team’s study – explained:
“The typical view is that a star can form a black hole only after it goes supernova. If a star can fall short of a supernova and still make a black hole, that would help to explain why we don’t see supernovae from the most massive stars.”
This information is also important as far as the study of gravitational waves goes. In February of 2016, scientists at the Laser Interferometer Gravitational-wave Observatory (LIGO) announced the first detection of this strange phenomena, which were apparently generated by a massive black hole. If in fact massive black holes form from failed supernova, it would help astronomers to track down the sources more easily.
Be sure to check out this video of the observations made of this failed SN and black hole:
The announcement of a seven-planet system around the star TRAPPIST-1 earlier this year set off a flurry of scientific interest. Not only was this one of the largest batches of planets to be discovered around a single star, the fact that all seven were shown to be terrestrial (rocky) in nature was highly encouraging. Even more encouraging was the fact that three of these planets were found to be orbiting with the star’s habitable zone.
Since that time, astronomers have been seeking to learn all they can about this system of planets. Aside from whether or not they have atmospheres, astronomers are also looking to learn more about their orbits and surface conditions. Thanks to the efforts of a University of Washington-led international team of astronomers, we now have an accurate idea of what conditions might be like on its outermost planet – TRAPPIST-1h.
According to the team’s study – “A seven-planet resonant chain in TRAPPIST-1“, which was recently published in the journal Nature Astronomy – they relied on data from the Kepler mission to determine the planet’s orbital period. Specifically, they consulted data obtained during Campaign 12 of the K2 mission, a 79-day observation period that ran from December 15th, 2016 to March 4th, 2017.
Led by Rodrigo Luger, a graduate student at the University of Washington, the team was already aware of pattern in the orbits of the system’s six inner planets. This was based on prior data provided by the Spitzer Space Telescope, which indicated that these planets are in an orbital resonance – i.e. their respective orbital periods are mathematically related and influence one other.
From this data, the team had already calculated that TRAPPIST-1h would have an orbital period of just less than 19 days. Once they consulted the K2 data, they noticed that during the 79-day observation period, TRAPPIST-1h made four transit of the star – which worked out to an orbital period of 18.77 days. In other words, the team found that their observations were consistent with their calculations.
This finding was a welcome relief to Luger and his colleagues. As he stated in a UW press release:
“TRAPPIST-1h was exactly where our team predicted it to be. It had me worried for a while that we were seeing what we wanted to see. Things are almost never exactly as you expect in this field – there are usually surprises around every corner, but theory and observation matched perfectly in this case.”
The discovery of this resonance means that TRAPPIST-1 has set another record. For starters, it is already renowned from being one of only two star systems to host seven extra-solar planets – the other being the HR 8832 star system, a main-sequence K3V-type variable star located 21 light years away. Second, it has the most confirmed terrestrial planets to be discovered in a single star system to date.
But with this latest data, TRAPPIST-1 now holds the record for having the most planets in an orbital resonance as well. The previous place holders were Kepler-80 and Kepler-223, both of which have four planets in an orbital resonance. According to Luger, this resonance was likely established when the TRAPPIST-1 system was still young and the planets were still in the process of formation. As Luger explained:
“The resonant structure is no coincidence, and points to an interesting dynamical history in which the planets likely migrated inward in lock-step. This makes the system a great testbed for planet formation and migration theories. We could therefore be looking at a planet that was once habitable and has since frozen over, which is amazing to contemplate and great for follow-up studies.”
The possibility that the planets achieved their current orbital dance early in the system’s history could also mean that TRAPPIST-1h was once habitable. While three planets orbit with the star’s habitable zone (TRAPPIST-1 d, e, and f), TRAPPIST-1h orbits the star at a distance of about 10 million km (6 million mi), which places it well beyond the reach of the star’s habitable zone.
In fact, at this distance, TRAPPIST-1h gets about as much energy from the Sun as the dwarf planet Ceres (located in our Solar System in Main Asteroid Belt, between Mars and Jupiter), which results in an average surface temperature of 173 K (-100 °C; -148 °F). But in the past, when its star was brighter and hotter, the planet may have received enough energy that its surface would have been warm enough to support liquid water.
“We could therefore be looking at a planet that was once habitable and has since frozen over, which is amazing to contemplate and great for follow-up studies,” said Luger. TRAPPIST-1 is also a prime candidate for follow-up study given its proximity. Located just 39.5 light years from Earth, this star and its system of planets present some exceptional opportunities for the study of exoplanets and M-type star habitability.
Beyond that, this study also demonstrated that despite the failure of two reaction wheels, the Kepler mission is still extremely useful when it comes to the study of exoplanets. Despite the fact that maintaining a steady eye on the TRAPPIST-1 system presented instrumental challenges, Kepler still managed to produce reliable information that was consistent with the team’s calculations.
Besides determining TRAPPIST-1h’s orbital period, the team used the K2 data to further characterize the orbits of the other six planets, rule out the possibility of there being more planets in the system, and learn more about the star itself (such as its rotation period and level of activity). This information will also be crucial in determining whether or not any of the planets located within the star’s habitable zone could in fact be habitable.
The discovery of the TRAPPIST-1’s system was an event that was many years in the making. But the rate at which new discoveries have turned up has been very impressive. In the coming years, with the deployment of next-generation planet-hunters – like the James Webb Telescope and the Transitting Exoplanet Survey Satellite (TESS) – we will be able to dig deeper and learn even more.
And be sure to enjoy this video of TRAPPIST-1’s orbital resonance, courtesy of Assistant Professor Daniel Fabrycky of the University of Chicago:
Images of the Crab Nebula are always a treat because it has such intriguing and varied structure. Also, just knowing that this stellar explosion was witnessed and recorded by people on Earth more than 900 years ago (with the supernova visible to the naked eye for about two years) gives this nebula added fascination.
A new image just might be the biggest Crab Nebula treat ever, as five different observatories combined forces to create an incredibly detailed view, with stunning details of the nebula’s interior region.
Data from the five telescopes span nearly the entire breadth of the electromagnetic spectrum, from radio waves seen by the Karl G. Jansky Very Large Array (VLA) to the powerful X-ray glow as seen by the orbiting Chandra X-ray Observatory. And, in between that range of wavelengths, the Hubble Space Telescope’s crisp visible-light view, and the infrared perspective of the Spitzer Space Telescope.
The Crab is 6,500 light-years from Earth and spans about 10 light-years in diameter. The supernova that created it was first witnessed in 1054 A. D. At its center is a super-dense neutron star that is as massive as the Sun but with only the size of a small town. This pulsar rotates every 33 milliseconds, shooting out spinning lighthouse-like beams of radio waves and light. The pulsar can be seen as the bright dot at the center of the image.
Scientists say the nebula’s intricate shape is caused by a complex interplay of the pulsar, a fast-moving wind of particles coming from the pulsar, and material originally ejected by the supernova explosion and by the star itself before the explosion.
For this new image, the VLA, Hubble, and Chandra observations all were made at nearly the same time in November of 2012. A team of scientists led by Gloria Dubner of the Institute of Astronomy and Physics (IAFE), the National Council of Scientific Research (CONICET), and the University of Buenos Aires in Argentina then made a thorough analysis of the newly revealed details in a quest to gain new insights into the complex physics of the object. They are reporting their findings in the Astrophysical Journal (see the pre-print here).
About the central region, the team writes, “The new HST NIR [near infrared] image of the central region shows the well-known elliptical torus around the pulsar, composed of a series of concentric narrow features of variable intensity and width… The comparison of the radio and the X-ray emission distributions in the central region suggests the existence of a double-jet system from the pulsar, one detected in X-rays and the other in radio. None of them starts at the pulsar itself but in its environs.”
“Comparing these new images, made at different wavelengths, is providing us with a wealth of new detail about the Crab Nebula. Though the Crab has been studied extensively for years, we still have much to learn about it,” Dubner said.