Universe Today

September 11, 2017September 11, 2017 by Tammy Plotner

Messier 56 – the NGC 6779

Messier 56 and Messier 57 (the Ring Nebula). Credit: Wikisky

Welcome back to Messier Monday! We continue our tribute to our dear friend, Tammy Plotner, by looking at the the globular star cluster known as Messier 56. Enjoy!

In the 18th century, while searching the night sky for comets, French astronomer Charles Messier kept noting the presence of fixed, diffuse objects in the night sky. In time, he would come to compile a list of approximately 100 of these objects, with the purpose of making sure that astronomers did not mistake them for comets. However, this list – known as the Messier Catalog – would go on to serve a more important function.

One of these objects is Messier 56, a globular star cluster located in the small northern constellation of Lyra, roughly 32,900 light years from Earth. Measuring roughly 84 light-years in diameter, this cluster has an estimated age of 13.70 billion years. It is also relatively easy to spot because of its proximity to well-known asterisms like the celestial Swan, the Northern Cross, and the bright star Vega.

Description:

Spanning about 85 light years in diameter, this incredible ball of stars is moving towards planet Earth at a speed of 145 kilometers per second… yet still remains about 32,900 light-years away. As one of the less dense of the Milky Way’s halo globulars, it is also less dense in variable stars – containing only perhaps a dozen. But out of that twelve, there a very special one… a Cepheid bright enough to be followed with amateur instruments. However, astronomers never stopped looking for the curious – and they found what they were looking for!

*NASA/ESA Hubble image of the globular star cluster known as Messier 56. Credit: NASA/ESA/HST/Gilles Chapdelaine*

The CURiuos Variables Experiment (CURVE) was performed on M56 in 2008. As P. Pietrukowicz (et al) wrote of the cluster in the accompanying study:

“We surveyed a 6.5’×6.5′ field centered on the globular cluster M56 (NGC 6779) in a search for variable stars detecting seven variables, among which two objects are new identifications. One of the new variables is an RRLyrae star, the third star of that type in M56. Comparison of the new observations and old photometric data for an RV Tauri variable V6 indicates a likely period change in the star. Its slow and negative rate of -0.005±0.003 d/yr would disagree with post-AGB evolution, however this could be a result of blue-loop evolution and/or random fluctuations of the period.”

But could other things exist inside M56? Events, perhaps, like nova? As astronomer Tim O’Brien wrote:

“Classical nova outbursts are the result of thermonuclear explosions on the surface of a white dwarf star in a close binary system. Material from the other star in the system (one not unlike our own sun) falls onto the surface of the white dwarf over thousands of years. The pressure at the base of this layer of accreted material builds up until thermonuclear reactions begin explosively. An Earth’s mass or more of material is ejected from the surface of the white dwarf at speeds of a few hundred to a few thousand kilometres per second. Old novae are therefore surrounded by shells of ejected matter illuminated by the light from the central binary system.”

And as M.E.L. Hopwood (et al.) wrote in a 2000 study:

“We report the possible detection of diffuse X-ray emission in the environment of NGC 6779, and find the emission to be well aligned with the proper motion of the cluster. The position of the emission suggests we are observing heated ISM in the wake of the cluster that could be the result of an interaction between the intracluster medium and the halo gas surrounding it.”

Globular cluster Messier 56 in Lyra. Credit: Wikipedia Commons/Hewholooks

History of Observation:

Charles Messier first discovered M56 on January 23rd, 1779. As he wrote of his discovery at the time:

“Nebula without stars, having little light; M. Messier discovered it on the same day as he found the comet of 1779, January 19. On the 23rd, he determined its position by comparing it with the star 2 Cygni, according to Flamsteed: it is near the Milky Way; and close to it is a star of 10th magnitude. M. Messier reported it on the chart of the comet of 1779.”

However, it would be Sir William Herschel who revealed its true nature in 1807. In his private notes he writes: “The 56th of the Connoiss. is a globular cluster of very compressed and very small stars. They are gradually more compressed towards the centre.” His son John would go on to observe it many times, even after cataloging it! His best description reads: “Large; round; very gradually brighter toward the middle. I see the stars which are very small and of different sizes. It fades gradually away to the borders.”

As always, it would be Admiral Smyth who would be perhaps a bit more descriptive when he included in his observing notes:

“A globular cluster, in a splendid field, between the eastern joke of Lyra’s frame and the Swan’s head: it is 5 1/4 deg distant from Beta Lyrae, on the south-east line leading to Beta Cygni, which is about 3 1/2 deg further. This object was first registered by M. Messier in 1778, and, from his imperfect means, described as a nebula of feeble light, without a star. In 1784, it was resolved by Sir William Herschel, who, on gauging, considered its profundity to be of the 344th order.”

*Messier 56 location. Credit: IAU/Sky & Telescope magazine (Roger Sinnott & Rick Fienberg)*

Locating Messier 56:

Finding M56 isn’t too hard since it’s located about half-way between Beta Cygni (Albireo) and Gamma Lyrae. In both binoculars and finder scope, you will see a triangle of stars when progressing from Gamma towards the southeast that will almost point directly at it! Because M56 isn’t particularly large or bright, it does require dark skies – but makes a great object for both binoculars and small telescopes.

Enjoy this pincushion of stars! And here are the quick facts on this Messier Object to help you get started”

Object Name: Messier 56
Alternative Designations: M56, NGC 6779
Object Type: Class X Globular Cluster
Constellation: Lyra
Right Ascension: 19 : 16.6 (h:m)
Declination: +30 : 11 (deg:m)
Distance: 32.9 (kly)
Visual Brightness: 8.3 (mag)
Apparent Dimension: 8.8 (arc min)

We have written many interesting articles about Messier Objects here at Universe Today. Here’s Tammy Plotner’s Introduction to the Messier Objects, M1 – The Crab Nebula, and David Dickison’s articles on the 2013 and 2014 Messier Marathons.

Be to sure to check out our complete Messier Catalog. And for more information, check out the SEDS Messier Database.

Sources:

September 10, 2017September 15, 2017 by Matt Williams

Juno Mission Makes Mysterious Finds about Auroras on Jupiter

Reconstructed view of Jupiter's northern lights through the filters of the Juno Ultraviolet Imaging Spectrograph instrument on Dec. 11, 2016, as the Juno spacecraft approached Jupiter, passed over its poles, and plunged towards the equator. Credit: NASA/JPL-Caltech/Bertrand Bonfond

Even after decades of study, Jupiter’s atmosphere continues to be something of a mystery to scientists. Consistent with the planet’s size, its atmosphere is the largest in the Solar System, spanning over 5,000 km (3,000 mi) in altitude and boasting extremes in temperature and pressure. On top of that, the planet’s atmosphere experiences the most powerful auroras in the Solar System.

Studying this phenomena has been one of the main goals of the Juno probe, which reached Jupiter on July 5th, 2016. However, after analyzing data collected by the probe’s instruments, scientists at Johns Hopkins University Applied Physics Laboratory (JHUAPL) were surprised to find that Jupiter’s powerful magnetic storms do not have the same source as they do on Earth.

The study which details these findings, “Discrete and Broadband Electron Acceleration in Jupiter’s Powerful Aurora“, recently appeared in the scientific journal Nature. Led by Barry Mauk, a scientist with the JHUAPL, the team analyzed data collected by Juno’s Ultraviolet Spectrograph (UVS) and Jovian Energetic Particle Detector Instrument (JEDI) to study Jupiter’s polar regions.

*Ultraviolet auroral images of Jupiter from the Juno Ultraviolet Spectrograph instrument. Credit: NASA/SwRI/Randy Gladstone*

As with Earth, on Jupiter, auroras are the result of intense radiation and Jupiter’s magnetic field. When this magnetosphere aligns with charged particles, it has the effect of accelerating electrons towards the atmosphere at high energy levels. In the course of examining Juno’s data, the JHUAPL team observed signatures of electrons being accelerated toward the Jovian atmosphere at energy levels of up to 400,000 electron volts.

This is roughly 10 to 30 times higher than what is experienced here on Earth, where only several thousand volts are typically needed to generate the most intense aurora. Given that Jupiter has the most powerful auroras in the Solar System, the team was not surprised to see such powerful forces at work within the planet’s atmosphere. What was surprising, however, was that this was not the source of the most intense auroras.

As Dr. Mauk, who leads the investigation team for the APL-built JEDI instrument and was the lead author on the study , explained in a JHUAPL press release:

“At Jupiter, the brightest auroras are caused by some kind of turbulent acceleration process that we do not understand very well. There are hints in our latest data indicating that as the power density of the auroral generation becomes stronger and stronger, the process becomes unstable and a new acceleration process takes over. But we’ll have to keep looking at the data.”

*Image compiled using data from Juno’s Ultraviolet Spectrograph, which marks the path of Juno’s readings of Jupiter’s auroras. Credit: NASA/SwRI/Randy Gladstone*

These findings could have significant implications for the study of Jupiter, who’s composition and atmospheric dynamics continue to be a source of mystery. It also has implications or the study of extra-solar gas giants and planetary systems. In recent decades, the study of these systems has revealed hundreds of gas giants that have ranged in size from being Neptune-like to many times the size of Jupiter (aka. “Super-Jupiters”).

These gas giants have also shown significant variations in orbit, ranging from being very close to their respective suns to very far (i.e. “Hot Jupiters” to “Cold Gas Giants”). By studying Jupiter’s ability to accelerate charged particles, astronomers will be able to make more educated guesses about space weather, radiation environments, and the risks they pose to space missions.

This will come in handy when it comes time to mount future missions to Jupiter, as well as deep-space and maybe even interstellar space. As Mauk explained:

“The highest energies that we are observing within Jupiter’s auroral regions are formidable. These energetic particles that create the auroras are part of the story in understanding Jupiter’s radiation belts, which pose such a challenge to Juno and to upcoming spacecraft missions to Jupiter under development. Engineering around the debilitating effects of radiation has always been a challenge to spacecraft engineers for missions at Earth and elsewhere in the solar system. What we learn here, and from spacecraft like NASA’s Van Allen Probes and MMS that are exploring Earth’s magnetosphere, will teach us a lot about space weather and protecting spacecraft and astronauts in harsh space environments. Comparing the processes at Jupiter and Earth is incredibly valuable in testing our ideas of how planetary physics works.”

Before the Juno mission is scheduled to wrap up (in February of 2018), the probe is likely to reveal a great many things about the planet’s composition, gravity field, magnetic field and polar magnetosphere. In so doing, it will address long-standing mysteries about how the planet formed and evolved, which will also shed light on the history of the Solar System and extra-solar systems.

Further Reading: JHUAPL, Nature

September 9, 2017September 10, 2017 by Ken Kremer

NASA’s Kennedy Space Center Closes as Deadly Hurricane Irma Targets Direct Hit on Florida Forcing Millions to Evacuate

Storm clouds from looming Cat 4 Hurricane Irma obscure the view of the iconic Vehicle Assembly Building and Launch Complex 39A as seen from Titusville, forcing NASA to close the Kennedy Space Center until the storm passes. Credit: Ken Kremer/kenkremer.com

TITUSVILLE/CAPE CANAVERAL, FL– NASA and Air Force officials have ordered the closure of the Kennedy Space Center and Cape Canaveral Air Force Station as deadly Cat 4 Hurricane Irma relentlessly targets a direct hit on Florida and forces millions of residents and tourists to evacuate catastrophic consequences coming tonight, Saturday, Sept. 9 and throughout the weekend.

The Kennedy Space Center Visitor Complex also announced its closure.

The Florida Space Coast base and Visitor Complex closings were ordered just hours after SpaceX successfully launched the secretive X-37B military spaceplane to orbit for the U.S. Air Force on a Falcon 9 rocket from historic pad 39A on the Kennedy Space Center on Thursday, Sept. 7.

“NASA’s Kennedy Space Center in Florida is closing Friday, Sept. 8 through at least Monday, Sept. 11, due to the approach of Hurricane Irma, KSC officials said.

“Irma could potentially bring heavy rain and strong winds to the spaceport. Essential personnel will make final preparations to secure center facilities and infrastructure.”

“I have declared Hurricane Condition II (HURCON II) as of 9:00 p.m. today [9/9],” declared Brig Gen. Wayne R. Monteith, Commander, 45th Space Wing.

“As we enter HURCON II, we continue to monitor Hurricane Irma’s progress. HURCON II indicates surface winds in excess of 58 mph could arrive in the area of the base within 24 hours.”

“This is a deadly major storm,” said Florida Gov. Rick Scott at an update briefing today. “Our state has never seen anything like it.”

“We are under a state of emergency!”

18 million people are currently under Hurricane warnings throughout Florida and the dire warnings from the Governor have been nothing short of catastrophic.

Here’s the latest Hurricane Irma storm track from the National Hurricane Center (NHC) updated to Saturday evening, Sept 9.

Hurricane Irma Cone forecast on Sept. 9, 2017 from the National Hurricane Center. Credit: NHC

It is being closely tracked in incredibly high resolution by the new NASA/NOAA GOES-16 (GOES-R) satellite launched late last year on a ULA Atlas V in Nov 2016.

Only a ride out team of roughly 130 or so KSC personnel based at the Emergency Operations Center (EOC) inside the Launch Control Center will remain on site to monitor spaceport facilities over the weekend and beyond.

“We’re closed until further notice except for Ride-Out Team. Stay safe!” said KSC officials.

“Ride-Out Team to remain in place until #Irma passes.”

At the Emergency Operations Center (EOC) located inside the Launch Control Center at the Kennedy Space Center; Brady Helms, Wayne Kee, and John Cosat discuss #Irma on Sept. 9, 2017. Credit: NASA KSC

Both KSC and the Cape’s Air Force Base will remain closed until Irma passes and until further notice and the facilities are deemed safe.

“After the storm has left the area, Kennedy’s Damage Assessment and Recovery Team will evaluate all center facilities and infrastructure for damage. The spaceport will reopen after officials determine it is safe for employees to return.”

USAF X-37B military mini-shuttle lifts off at 10 a.m. EDT Sept. 7, 2017 on a SpaceX Falcon 9 rocket from Launch Complex 39A at the Kennedy Space Center. Credit: Ken Kremer/kenkremer.com

State officials also ordered the mandatory evacuation of the Cape’s surrounding barrier islands including Merritt Island which is home to the space center and Cocoa Beach, as of Friday at 3 p.m. EDT.

This is the second year in a row that a deadly looming hurricane has forced the closure of KSC and Cape Canaveral Air Force Station.

When Hurricane Matthew struck last October 2016 it left over $100 million in damages to NASA and AF installations and ironically caused the postponed of the advanced GOES-16 (GOES-R) weather satellite now tracking Irma with unprecedented clarity and timing.

NASA’s iconic VAB and the Launch Control Center (right, front) are home to the ‘ride out’ crew remaining on site at the Kennedy Space Center during Hurricane Irma to monitor facilities as the storm passes by on Sept. 10 – in this view taken Sept. 8, 2017. Credit: Ken Kremer/kenkremer.com

Strong wind gusts and heavy downpours have already drenched Titusville and other local Space Coast cities periodically today, Sat., Sept 9.

NASA’s iconic VAB was barely visible from my perch along Titusville river front, ghostlike in appearance when it peeked only rarely through the clouds.

As I write this late Saturday, Sept. 9, Irma is just hours and less than 100 miles away from striking the Florida Keys with a predicted impact of an unsurvivable storm surge.

The eye is currently off the north coast of Cuba and moving in a west northwesterly WNW direction at 7 MPH.

Hurricane Irma as seen from the International Space Station. Credit: Randy Bresnik/NASA

Monster storm Irma is the size of Texas. The outer bands are already lashing the Florida Keys.

Landfall is currently projected to be on the west coast of Florida, perhaps around the Tampa area and causing catastrophic storm surges, flooding and destruction of property and homes.

“Millions of Floridians will see major impacts with DEADLY DEADLY DEADLY storm surge and life threatening winds,” elaborated Gov. Scott.

“There is a serious threat of significant storm surge flooding along the entire west coast of Florida.

This has increased to 15 feet of impact above ground level.”

“Think about that. 15 feet is devastating and will cover your house. A typical first story is 7 to 10 feet. The storm surge will rush in and could kill you.”

“This is a life threatening situation,” warned Scott. “Central Florida is under a hurricane warning and will see dangerous and life threatening wind and torrential rainfall of more than a foot. Rainfall has already started and wind will begin tonight.”

“We could also see tornadoes.”

Hurricane Irma’s clouds Extend over the Florida Peninsula in this GOES East satellite image at 9:30 p.m. EDT Sept. 9, 2017. At 8 PM EDT the eye of Hurricane Irma was near latitude 23.3 North, longitude 80.8 West. That’s about 110 miles (175 km) southeast of Key West, FL. Credit: NASA/GOES

90+ MPH wind gusts are expected virtually statewide.

Widespread power outages are expected. Over 190,000 power outages have already been reported as of Saturday evening.

Millions more are expected to lose power – including half of all residents says Florida Power and Light (FPL) !

Hundreds of power crews are already prepositioned in place to get the juice flowing as soon as possible after Irma marches northward.

As a precaution earlier this week Scott already ordered all schools and government offices closed statewide until further notice.

Florida hurricane shelters are filling up in some areas and overflowing in others. 385 designated shelters are open already and more are coming. Over 375,000 people have already taken shelter.

Finding open gas stations is increasingly problematical because many are now closing as the storms impact is imminent. Tanker trucks had been replenishing empty storage tanks as best as possible throughout the state over the past few days.

“We are working to keep gas stations open,” said Scott.

8 to 18 inches of rain are expected across the state.

Storm surge warnings are in effect especially for the west coast notably in the Tampa and Sarasota areas where it could reach 5 – 10 feet in Tampa Bay and even higher to 10 to 15 feet along the southwest Florida coast is possible.

“Millions of Floridians will see life threatening winds starting tonight,” Scott warned.

“This is a life-threatening situation.”

“Over 6.5 million have been ordered to evacuate. Get out now if you have been ordered to do so.”

That’s 6.5 million people ordered to evacuate out of the total state population of 20 million – unfathomable.

Watch for Ken’s continuing onsite X-37B OTV-5 and NASA mission reports direct from the Kennedy Space Center and Cape Canaveral Air Force Station, Florida.

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer

September 9, 2017 by Matt Williams

Exoplanet-Hunting Aliens Could Be Looking at Earth Right Now!

Artist's impression of an extra-solar planet transiting its star. Credit: QUB Astrophysics Research Center

In the past few decades, the search for extra-solar planets has turned up a wealth of discoveries. Between the many direct and indirect methods used by exoplanet-hunters, thousands of gas giants, rocky planets and other bodies have been found orbiting distant stars. Aside from learning more about the Universe we inhabit, one of the main driving forces behind these efforts has been the desire to find evidence of Extra-Terrestrial Intelligence (ETI).

But suppose there are ETIs out there that are are also looking for signs of intelligence other than their own? How likely would they be to spot Earth? According to a new study by a team of astrophysicists from Queen’s University Belfast and the Max Planck Institute for Solar System Research in Germany, Earth would be detectable (using existing technology) from several star systems in our galaxy.

This study, titled “Transit Visibility Zones of the Solar System Planet“, was recently published in the Monthly Notices of the Royal Astronomical Society. Led by Robert Wells, a PhD student at the Astrophysics Research Center at Queen’s University Belfast, the team considered whether or not Earth would be detectable from other star systems using the Transit Method.

Diagram of a planet (e.g. the Earth, blue) transiting in front of its host star (e.g. the Sun, yellow). The lower black curve shows the brightness of the star noticeably dimming over the transit event, when the planet is blocking some of the light from the star. Credit: R. Wells.

This method consists of astronomers observing stars for periodic dips in brightness, which are attributed to planets passing (i.e. transiting) between them and the observer. For the sake of their study, Wells and his colleagues reversed the concept in order to determine if Earth would be visible to any species conducting observations from vantage points beyond our Solar System.

To answer this question, the team looked for parts of the sky from which one planet would be visible crossing the face of the Sun – aka. “transit zones”. Interestingly enough, they determined that the terrestrial planets that are closer to the Sun (Mercury, Venus, Earth and Mars) would easier to detect than the gas and ice giants – i.e. Jupiter, Saturn, Uranus and Neptune.

While considerably larger, the gas/ice giants would be more difficult to detect using the transit method because of their long-period orbits. From Jupiter to Neptune, these planets take about 12 to 165 years to complete a single orbit! But more important than that is the fact that they orbit the Sun at much greater distances than the terrestrial planets. As Robert Wells indicated in a Royal Astronomical Society press statement:

”Larger planets would naturally block out more light as they pass in front of their star. However the more important factor is actually how close the planet is to its parent star – since the terrestrial planets are much closer to the Sun than the gas giants, they’ll be more likely to be seen in transit.”

How the transit zone of a Solar System planet is projected out from the Sun. The observer on the green exoplanet is situated in the transit zone and can therefore see transits of the Earth. Credit: R. Wells

Ultimately, what the team found was that at most, three planets could be observed from anywhere outside of the Solar System, and that not all combinations of these three planets was possible. For the most part, an observer would see only planet making a transit, and it would most likely be a rocky one. As Katja Poppenhaeger, a lecturer at the School of Mathematics and Physics at Queen’s University Belfast and a co-author of the study, explained:

“We estimate that a randomly positioned observer would have roughly a 1 in 40 chance of observing at least one planet. The probability of detecting at least two planets would be about ten times lower, and to detect three would be a further ten times smaller than this.”

What’s more, the team identified sixty-eight worlds where observers would be able to see one or more of the Solar planets making transits in front of the Sun. Nine of these planets are ideally situated to observe transits of the Earth, though none of them have been deemed to be habitable. These planets include HATS-11 b, 1RXS 1609 b, LKCA 15 b, WASP-68 b, WD 1145+017 b, and four planets in the WASP-47 system (b, c, d, e).

On top of that, they estimated (based on statistical analysis) that there could be as many as ten undiscovered and potentially habitable worlds in our galaxy which would be favorably located to detect Earth using our current level of technology. This last part is encouraging since, to date, not a single potentially habitable planet has been discovered where Earth could be seen making transits in front of the Sun.

Image showing where transits of our Solar System planets can be observed. Each line represents where one of the planets could be seen to transit, with the blue line representing Earth; an observer located here could detect us. Credit: 2MASS/A. Mellinger/R. Wells.

The team also indicated that further discoveries made by the Kepler and K2 missions will reveal additional exoplanets that have “a favorable geometric perspective to allow transit detections in the Solar System”. In the future, Wells and his team plan to study these transit zones to search for exoplanets, which will hopefully reveal some that could also be habitable.

One of the defining characteristics in the Search for Extra-Terrestrial Intelligence (SETI) has been the act of guessing about what we don’t know based on what we do. In this respect, scientists are forced to consider what extra-terrestrial civilizations would be capable of based on what humans are currently capable of. This is similar to how our search for potentially habitable planets is limited since we know of only one where life exists (i.e. Earth).

While it might seem a bit anthropocentric, it’s actually in keeping with our current frame of reference. Assuming that intelligent species could be looking at Earth using the same methods we do is like looking for planets that orbit within their star’s habitable zones, have atmospheres and liquid water on the surfaces.

In other words, it’s the “low-hanging fruit” approach. But thanks to ongoing studies and new discoveries, our reach is slowly extending further!

Further Reading: RAS, MNRAS

September 8, 2017September 8, 2017 by Matt Williams

X-ray Study Shows Older Stars May be More Supportive to Life

A study using data from NASA's Chandra X-ray Observatory and ESA's XMM-Newton suggests X-rays emitted by a planet's host star may provide critical clues to how hospitable a star system could be. Credit: NASA/CXC/M.Weiss

Astronomers have long understood that there is a link between a star’s magnetic activity and the amount of X-rays it emits. When stars are young, they are magnetically active, due to the fact that they undergo rapid rotation. But over time, the stars lose rotational energy and their magnetic fields weaken. Concurrently, their associated X-ray emissions also begin to drop.

Interestingly, this relationship between a star’s magnetic activity and X-ray emissions could be a means for finding potentially-habitable star systems. Hence why an international team led by researchers from Queen’s University Belfast conducted a study where they cataloged the X-ray activity of 24 Sun-like stars. In so doing, they were able to determine just how hospitable these star systems could be to life.

This study, titled “An Improved Age-Activity Relationship for Cool Stars Older than a Gigayear“, recently appeared in the Monthly Notices of the Royal Astronomical Society. Led by Rachel Booth, a PhD student from the Astrophysics Research Center at Queen’s University Belfast, the team used data from NASA’s Chandra X-ray Observatory and the ESA’s XMM-Newton to examine how the X-ray brightness of 24 Sun-like stars changed over time.

*This artist’s impression shows the magnetar in the very rich and young star cluster Westerlund 1. Credit: ESO/L. Calçada*

To understand how stellar magnetic activity (and hence, X-ray activity) changes over time, astronomers require accurate age assessments for many different stars. This has been difficult in the past, but thanks to mission like NASA’s Kepler Space Observatory and the ESA’s Convection, Rotation and planetary Transits (CoRoT) mission, new and precise age estimates have become available in recent years.

Using these age estimates, Booth and her colleagues relied on data from the Chandra X-ray observatory and the XMM-Newton obervatory to examine 24 nearby stars. These stars were all similar in mass to our Sun (a main sequence G-type yellow dwarf star) and at least 1 billion years of age. From this, they determined that there was a clear link between the star’s age and their X-ray emissions. As they state in their study:

“We find 14 stars with detectable X-ray luminosities and use these to calibrate the age-activity relationship. We find a relationship between stellar X-ray luminosity, normalized by stellar surface area, and age that is steeper than the relationships found for younger stars…”

In short, of the 24 stars in their sample, the team found that 14 had X-ray emissions that were discernible. From these, they were able to calculate the star’s ages and determine that there was a relationship between their longevity and luminosity. Ultimately, this demonstrated that stars like our Sun are likely to emit less high-energy radiation as they exceed 1 billion years in age.

And while the reason for this is not entirely clear, astronomers are currently exploring various possible causes. One possibility is that for older stars, the reduction in spin rate happens more quickly than it does for younger stars. Another possibility is that the X-ray brightness declines more quickly for older, more slowly-rotating stars than it does for younger, faster ones.

Regardless of the cause, the relationship between a star’s age and its X-ray emissions could provide astronomers and exoplanet hunters with another tool for gauging the possible habitability of a system. Wherever a G-type or K-type star is to be found, knowing the age of the star could help place constraints on the potential habitability of any planets that orbit it.

Further Reading: Chandra, MNRAS

September 8, 2017June 20, 2020 by Matt Williams

New Study Claims that TRAPPIST-1 Could Also Have Gas Giants

Most exoplanets orbit red dwarf stars because they're the most plentiful stars. This is an artist's illustration of what the TRAPPIST-1 system might look like from a vantage point near planet TRAPPIST-1f (at right). Credits: NASA/JPL-Caltech

In February of 2017, NASA scientists announced the existence of seven terrestrial (i.e. rocky) planets within the TRAPPIST-1 star system. Since that time, the system has been the focal point of intense research to determine whether or not any of these planets could be habitable. At the same time, astronomers have been wondering if all of the system’s planets are actually accounted for.

For instance, could this system have gas giants lurking in its outer reaches, as many other systems with rocky planets (for instance, ours) do? That was the question that a team of scientists, led by researchers from the Carnegie Institute of Science, sought to address in a recent study. According to their findings, TRAPPIST-1 may be orbited by gas giants at a much-greater distance than its seven rocky planets.

Continue reading “New Study Claims that TRAPPIST-1 Could Also Have Gas Giants”

September 8, 2017September 8, 2017 by Matt Williams

Detection of Mineral on Mars Bolsters Argument that Mars was Once Habitable

Mosaic image of the Curiosity rover on Mars, which recently turned up more evidence that supports the idea that the planet was once habitability. Credit: NASA/JPL-Caltech/MSSS.

It has become a well-known scientific fact that billions of years ago, Mars once had a thicker atmosphere and liquid water on its surface. Scientists have also discovered that it was the gradual loss of this atmosphere, between 4.2 and 3.7 billion years ago, that caused Mars to go from being a warmer, wetter environment to the dry, freezing environment it is today.

Despite the existence of both a thicker atmosphere and water, questions remain as to whether or not Mars was truly habitable in the past. According to a new study from a team of researchers from the Los Alamos National Laboratory (LANL), the discovery of a specific mineral (boron) has added weight to the argument that Mars was once a potentially life-bearing world.

The study, titled “In situ detection of boron by ChemCam on Mars“, was recently published in the scientific journal Geophysical Research Letters. For the sake of this study, the LANL research team consulted data collected by the Chemistry and Camera (ChemCam) instrument aboard the Curiosity rover, which showed evidence of boron on the surface of Mars.

*Mars, as it may have looked 4.2 billion years ago (left) and today (right). Credit: Kevin Gill*

Boron, an element which is created by cosmic rays and is relatively rare in the Solar System, is necessary for the creation of ribonucleic acid – which is present in all forms of modern life. Essentially, RNA requires a key ingredient to form, which is a sugar called ribose. Like all sugars, ribose is highly unstable and decomposes quickly in water. As such, it needs another element to stabilize it, which is where boron comes into play.

As Patrick Gasda, a postdoctoral researcher at the Los Alamos National Laboratory and lead author on the paper, explained in a LANL press statement:

“Because borates may play an important role in making RNA – one of the building blocks of life – finding boron on Mars further opens the possibility that life could have once arisen on the planet. Borates are one possible bridge from simple organic molecules to RNA. Without RNA, you have no life. The presence of boron tells us that, if organics were present on Mars, these chemical reactions could have occurred.”

When boron is dissolved in water (which, as noted, Mars once had in abundance) it becomes borate. This compound (when combined with ribose) would act as a stabilizing agent, keeping the sugar together long enough so that RNA can form. As Gasda explained, “We detected borates in a crater on Mars that’s 3.8 billion years old, younger than the likely formation of life on Earth.”

*Artist rendition of how the “lake” at Gale Crater on Mars may have looked millions of years ago. Credit and copyright: Kevin Gill.*

The boron was detected by Curiosity’s laser-shooting ChemCam instrument, which was developed by the LANL in conjunction with France’s space agency, the National Center of Space Studies (CNES). It detected the element in veins of calcium sulfate minerals located in the Gale Crater, which means that boron was present in Mars’ groundwater and was preserved with other minerals when the water dissolved, leaving behind rich mineral veins.

This provides further evidence that the lake that is now known to have once filled the Gale Crater could have had life in it. During the time period in question, this lake would have experienced temperatures ranging from from 0 to 60 ° C (32 to 140 °F) and had a pH level that would have been neutral-to-alkaline. It also means that on ancient Mars, the conditions necessary for life would have existed, and independent of Earth to boot.

This is just one of many findings Curiosity has made related to the composition of Martian rocks. Since it touched down in the Gale Crater in 2012, the rover has been gathering chemical evidence of the ancient lake that once existed there, as well as geological evidence that has been preserved by sedimentary deposits. As the rover began to scale the slope of Mount Sharp, the composition of the surface began to change.

Whereas samples taken from the crater floor tended to contain more in the way of clays, samples collected higher up Mount Sharp contained more boron. These and other chemical traces are indications of how conditions under which sediments were deposited changed over time. Analysis conducted of the mountain’s layers has also showed how the movement of groundwater through these layers of sediment altered and transported elements (like boron).

*MRO image of Gale Crater illustrating the landing location and trek of the Rover Curiosity. Credits: NASA/JPL, illustration, T.Reyes*

All of this is providing a picture of how Mars’ environment changed over the course of billions of years and affected the planet’s potential favorability for microbial life. And while scientists have a general picture of how Mars underwent a very significant transition billions of years ago, whether or not Martian life ever existed remains unknown.

The main goal of the Curiosity mission was to determine whether the area ever offered a habitable environment. Thanks to evidence of past water and the discovery of minerals like boron, this has been confirmed. In the coming years, the deployment of the Mars 2020 rover is expected to follow-up on these findings and shed more light on Mars’ case for past habitability.

Once it reaches the surface, the Mars 2020 rover – which relies on much of the same technology as Curiosity – will use an instrument called the Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals (SHERLOC). Also developed by the LANL, this “SuperCam” instrument will use spectrometers, a laser and a camera to search for organics and minerals that could indicate the existence of past microbial life.

If there is still preserved evidence of life to be found on Mars or – fingers crossed! – microbial life still exists there today, we can expect to find it before long. If that should be the case, human beings will finally know with certainty that life evolved on a planet other than Earth, and perhaps independent of it!

Further Reading: LANL, Geophysical Research Letters

September 8, 2017November 6, 2017 by Susie Murph

Astronomy Cast Ep. 456: Pluto Revisited

This week, we return to our starting point, where Astronomy Cast began: Pluto. 11 years on, we have a whole new appreciate for the dwarf planet Pluto. We’ve visited it, probed it and taken pictures. It’s time for an update.

We usually record Astronomy Cast every Friday at 1:30 pm PDT / 4:30 pm EDT/ 20:30 PM UTC (8:30 GMT). You can watch us live on AstronomyCast.com, or the AstronomyCast YouTube page.

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September 8, 2017September 8, 2017 by Matt Williams

Chinese Astronomers Spot Two New Hypervelocity Stars

An artist's conception of a hypervelocity star that has escaped the Milky Way. Credit: NASA

Most stars in our galaxy behave predictably, orbiting around the center of the Milky Way at speeds of about 100 km/s (62 mi/s). But some stars achieve velocities that are significantly greater, to the point that they are even able to escape the gravitational pull of the galaxy. These are known as hypervelocity stars (HVS), a rare type of star that is believed to be the result of interactions with a supermassive black hole (SMBH).

The existence of HVS is something that astronomers first theorized in the late 1980s, and only 20 have been identified so far. But thanks to a new study by a team of Chinese astronomers, two new hypervelocity stars have been added to that list. These stars, which have been designated LAMOST-HVS2 and LAMOST-HVS3, travel at speeds of up to 1,000 km/s (620 mi/s) and are thought to have originated in the center of our galaxy.

The study which describes the team’s findings, titled “Discovery of Two New Hypervelocity Stars From the LAMOST Spectroscopic Surveys“, recently appeared online. Led by Yang Huang of the South-Western Institute for Astronomy Research at Yunnan University in Kunming, China, the team relied on data from Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) to detect these two new hypervelocity stars.

*Footprint of the LAMOST pilot survey and the first three years’ general survey. Credit: LAMOST*

Astronomers estimates that only 1000 HVS exist within the Milky Way. Given that there are as many as 200 billion stars in our galaxy, that’s just 0.0000005 % of the galactic population. While these stars are thought to originate in the center of our galaxy – supposedly as a result of interaction with our SMBH, Sagittarius A* – they manage to travel pretty far, sometimes even escaping our galaxy altogether.

It is for this very reason that astronomers are so interested in HVS. Given their speed, and the vast distances they can cover, tracking them and creating a database of their movements could provide constraints on the shape of the dark matter halo of our galaxy. Hence why Dr. Huang and his colleagues began sifting through LAMOST data to find evidence of new HVS.

Located in Hebei Province, northwestern China, the LAMOST observatory is operated by the Chinese Academy of Sciences. Over the course of five years, this observatory conducted a spectroscopic survey of 10 million stars in the Milky Way, as well as millions of galaxies. In June of 2017, LAMOST released its third Data Release (DR3), which included spectra obtained during the pilot survey and its first three years’ of regular surveys.

Containing high-quality spectra of 4.66 million stars and the stellar parameters of an additional 3.17 million, DR3 is currently the largest public spectral set and stellar parameter catalogue in the world. Already, LAMOST data had been used to identify one hypervelocity star, a B1IV/V-type (main sequence blue subgiant/subdwarf) star that was 11 Solar Masses, 13490 times as bright as our Sun, and had an effective temperature of 26,000 K (25,727 °C; 46,340 °F).

*Artist’s impression of hypervelocity stars (HVSs) speeding through the Galaxy. Credit: ESA*

This HVS was designated LAMOST-HSV1, in honor of the observatory. After detecting two new HVSs in the LAMOST data, these stars were designated as LAMOST-HSV2 and LAMOST-HSV3. Interestingly enough, these newly-discovered HVSs are also main sequence blue subdwarfs – or a B2V-type and B7V-type star, respectively.

Whereas HSV2 is 7.3 Solar Masses, is 2399 times as luminous as our Sun, and has an effective temperature of 20,600 K (20,327 °C; 36,620 °F), HSV3 is 3.9 Solar Masses, is 309 times as luminous as the Sun, and has an effective temperature of 14,000 K (24,740 °C; 44,564 °F). The researchers also considered the possible origins of all three HVSs based on their spatial positions and flight times.

In addition to considering that they originated in the center of the Milky Way, they also consider alternate possibilities. As they state in their study:

“The three HVSs are all spatially associated with known young stellar structures near the GC, which supports a GC origin for them. However, two of them, i.e. LAMOST-HVS1 and 2, have life times smaller than their flight times, indicating that they do not have enough time to travel from the GC to the current positions unless they are blue stragglers (as in the case of HVS HE 0437-5439). The third one (LAMOST-HVS3) has a life time larger than its flight time and thus does not have this problem.

In other words, the origins of these stars is still something of a mystery. Beyond the idea that they were sped up by interacting with the SMBH at the center of our galaxy, the team also considered other possibilities that have suggested over the years.

*Artist’s impression of the ESA’s Gaia spacecraft, looking into the heart of the Milky Way Galaxy. Credit: ESA/ATG medialab/ESO/S. Brunier*

As they state in these study, these “include the tidal debris of an accreted and disrupted dwarf galaxy (Abadi et al. 2009), the surviving companion stars of Type Ia supernova (SNe Ia) explosions (Wang & Han 2009), the result of dynamical interaction between multiple stars (e.g, Gvaramadze et al. 2009), and the runaways ejected from the Large Magellanic Cloud (LMC), assuming that the latter hosts a MBH (Boubert et al. 2016).”

In the future, Huang and his colleagues indicate that their study will benefit from additional information that will be provided by the ESA’s Gaia mission, which they claim will shed additional light on how HVS behave and where they come from. As they state in their conclusions:

“The upcoming accurate proper motion measurements by Gaia should provide a direct constraint on their origins. Finally, we expect more HVSs to be discovered by the ongoing LAMOST spectroscopic surveys and thus to provide further constraint on the nature and ejection mechanisms of HVSs.”

Further Reading: arXiv

September 7, 2017September 9, 2017 by Ken Kremer

X-37B Secret Air Force Spaceplane Blasts Off on SpaceX Falcon 9 as Monster Hurricane Irma Threatens Florida Peninsula

USAF X-37B military spaceplane blasts off with picturesque water reflections at 10 a.m. EDT (1400 UTC) Sept. 7, 2017 on a SpaceX Falcon 9 rocket from Launch Complex 39A at the Kennedy Space Center. Credit: Ken Kremer/kenkremer.com

KENNEDY SPACE CENTER, FL – Amidst the frenzy of ‘Sunshine State’ preparations for Cat 5 monster Hurricane Irma and quite dismal weather favorability odds, the skies surrounding the Florida Space Coast suddenly parted just in the nick of time enabling the Air Force’s secret military X-37B spaceplane to blast off this morning (Sept. 7) on a SpaceX Falcon 9 as the booster nailed another thrilling ground landing back at the Cape.

The SpaceX Falcon 9 roared to life at 10 a.m. EDT (1400 UTC) Thursday morning and soared aloft from seaside Launch Complex 39A on NASA’s Kennedy Space Center into nearly clear blue skies after the classified launch time was kept guarded until just 10 minutes before liftoff.

Due to the potential for catastrophic destruction from approaching Hurricane Irma this was the last chance for the X-37B to escape Florida to orbit before the Kennedy Space Center and Cape Canaveral Air Force Station almost certainly close on Friday, the backup launch opportunity.

The X-37B OTV spaceplane reached orbit as planned on SpaceX’s 13th launch of the year.

“The 45th Space Wing successfully launched a SpaceX Falcon 9 launch vehicle Sept. 7, 2017, from Kennedy Space Center’s Launch Complex 39A,” the USAF and 45th Space Wing confirmed in a post launch statement.

The Falcon 9 launch was absolutely gorgeous taking place under near perfect weather conditions at launch time and putting on a long sky show as the rocket accelerated to orbit with its precious cargo.

The nine Merlin 1D first stage engines ignited to generate a combined 1.7 million pounds of thrust fueled by liquid oxygen and RP-1 propellants, sending a huge exhaust plume billowing from behind as the rocket ascended off pad 39A and thundered aloft.

After first stage burnout and main engine cutoff the stages separated at T plus 2 min 26 seconds.

After successfully delivering the secret USAF mini-shuttle to orbit, SpaceX engineers completed the 2nd half of the double headed space spectacular when the Falcon 9 first stage booster successfully made a guided soft landing back at Cape Canaveral Air Force Station (CCAFS).

The boosters high speed descent generated multiple shockingly loud sonic booms as the 156-foot-tall first stage approached SpaceX’s dedicated Landing Zone-1 (LZ-1) on CCAFS that reverberated for dozens and dozens of miles across and beyond the Space coast region.

The mid-morning daylight first stage precision guided landing offered spectators a magnificent up close view of the rocket reusability technology envisioned by SpaceX’s billionaire CEO Elon Musk to drastically slash the high costs of launching people and payloads to space.

SpaceX Falcon 9 first stage fires Merlin 1D engine in final moments of descent to accomplish successful propulsive touchdown at Landing Zone-1 (LZ-1) after SpaceX launched the USAF X-37B military spaceplane on its 5th flight to space on the OTV-5 mission at 10 a.m. EDT (1400 UTC) Sept. 7, 2017 from pad 39A at KSC. Credit: Ken Kremer/Kenkremer.com

Meanwhile, Hurricane Irma continues barreling towards Florida packing winds of 185 mph as one of the strongest Atlantic storms ever. It is being closely tracked in incredibly high resolution by the new NASA/NOAA GOES-16 (GOES-R) satellite launched late last year on a ULA Atlas V in Nov 2016.

Here’s the latest storm track updated to Friday morning Sep 8:

Hurricane Irma Cone forecast on Sept 8, 2017 from the National Hurricane Center. Credit: NHC

The X-37B reusable mini-shuttle is a secretive technology testing spaceplane flying on its fifth mission overall for the U.S. Air Force Rapid Capabilities Office.

“The OTV is designed to demonstrate reusable spacecraft technologies for America’s future in space and operate experiments, which can be returned to and examined on Earth,” said the USAF.

Launch of the SpaceX Falcon 9 on Sept. 7 , 2017 carrying the X-37B mini-shuttle to orbit for the USAF. Credit: Julian Leek

Also known as the Orbital Test Vehicle, the X-37B launched on the OTV-5 mission marks the programs maiden liftoff on the 230-foot-tall SpaceX Falcon 9.

All four prior OTV missions launched on the United Launch Alliance Atlas V and ended with runway landings in either California of Florida.

The X-37B launches vertically like a satellite but lands horizontally like an airplane and functions as a reliable and reusable space test platform for the U.S. Air Force.

The Boeing-built X-37B is processed for flight at the Kennedy Space Center, FL, using refurbished former NASA space shuttle processing facilities (OPFs) now dedicated to the reusable mini-shuttle, also named the Orbital Test Vehicle (OTV).

The USAF X-37B Orbital Test Vehicle is set for blastoff on Sept. 7, 2017, onboard a SpaceX Falcon 9 launch vehicle from Launch Complex 39A (LC-39A) at Kennedy Space Center in Florida. Photo: Boeing/USAF

The last blastoff of the X-37B took place more than 2 years ago on May 20, 2015 when the OTV-4 mission launched on a ULA Atlas V on May 20, 2015 from Space Launch Complex-41 on Cape Canaveral Air Force Station.

After spending a record setting 718 days in orbit, the X-37B vehicle completed its fourth mission with a runway landing back at KSC’s Shuttle Landing Facility earlier this year on May 7, 2017.

Overall the OTV unmanned spacecraft have spent a total of 2,085 days in orbit.

The 11,000 pound (4990 kg) state-of-the art reusable OTV space plane is about a quarter the size of a NASA space shuttle. The vehicle measures 29 ft 3 in (8.9 m) in length with a wingspan of 14 ft 11 in (4.5 m).

The X-37B was originally developed by NASA but was transferred to the Defense Advanced Research Projects Agency (DARPA) in 2004.

Since then most but not all of the spaceplane’s goals have been shrouded in secrecy.

Sept. 7 , 2017 liftoff of the SpaceX Falcon 9 on Sept. 7, 2017 carrying the X-37B mini-shuttle to orbit for the USAF. Credit: Jeff Seibert

SpaceX Falcon 9 rocket rolls horizontally up incline at Launch Complex 39A at the Kennedy Space Center on 6 Sept. 2017. The rocket is being processed for liftoff of the X-37B OTV-5 mini-shuttle mission scheduled for Sept. 7, 2017. Credit: Ken Kremer/kenkremer.com

Watch for Ken’s continuing onsite X-37B OTV-5 and NASA mission reports direct from the Kennedy Space Center and Cape Canaveral Air Force Station, Florida.

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer