Ultra-cool Diminutive Star Weighs In

ACS has increased Hubble's potential for new discoveries by a factor of ten. COS Cosmic Origins Spectrograph - COS focuses exclusively on ultraviolet UV light and is the most sensitive ultraviolet spectrograph ever, increasing the sensitivity at least 10 times in the UV spectrum and up to 70 times when looking at extremely faint objects. It is best at observing points of light, like stars and quasars. STIS is used to obtain high resolution spectra of resolved objects.

STIS has the special ability to simultaneously obtain spectra from many different points along a target. The STIS instrument has a mass of kg and a wavelength range of nm. STIS spreads out the light gathered by a telescope so that it can be analyzed to determine such properties of celestial objects as chemical composition and abundances, temperature, radial velocity, rotational velocity, and magnetic fields. Its spectrograph can be switched between two different modes of usage:.

Ultra-cool dwarf

STIS also has a so-called coronagraph which can block light from bright objects, and in this way enables investigations of nearby fainter objects. It has a camera that records visible and ultraviolet UVIS, nm wavelengths of light and is 35 times more sensitive in the UV wavelengths than its predecessor. A second camera that is built to view infrared NIR, nm light increases Hubble's IR resolution from 65, to 1 million pixels.

Its combination of field-of-view, sensitivity, and low detector noise results in a time improvement over Hubble's previous IR camera. The FGS can also function as a scientific instrument by precisely measuring the relative positions of stars, detecting rapid changes in a star's brightness, and resolving double-star systems that appear as point sources even to Hubble's cameras.

Hubble has three FGSs onboard the observatory. The speed and distance at which planets orbit their respective blazing stars can determine each planet's fate - whether the planet remains a longstanding part of its solar system or evaporates into the universe's dark graveyard more quickly. Planets such as "super" Earths and "hot" Jupiters orbit more closely to their stars and are therefore hotter, causing the outermost layer of their atmospheres to be blown away by evaporation.

Researchers hypothesize that these Neptunes get stripped of their atmospheres and ultimately become smaller planets. GJ b is 96 light-years away and circles a red dwarf star in the general direction of the constellation Cancer. This graphic plots exoplanets based on their size and distance from their star.

Each dot represents an exoplanet. Planets the size of Jupiter located at the top of the graphic and planets the size of Earth and so-called super-Earths at the bottom are found both close and far from their star. But planets the size of Neptune in the middle of the plot are scarce close to their star. This so-called desert of hot Neptunes shows that such alien worlds are rare, or, they were plentiful at one time, but have since disappeared. The detection that GJ b, a warm Neptune at the border of the desert, is fast losing its atmosphere suggests that hotter Neptunes may have eroded down to smaller, rocky super-Earths image credit: By comparing different planets, we can start piecing together the larger picture in how they evolve.

Using Hubble, the upcoming NASA James Webb Space Telescope which will have a greater sensitivity to helium , and a new instrument called Carmenes that Sing recently found can precisely track the trajectory of helium atoms, astronomers will be able to broaden their pursuit of distant planets. Twenty-five years ago this week, NASA held its collective breath as seven astronauts on space shuttle Endeavour caught up with the Hubble Space Telescope miles kilometers above Earth. The largest optical telescope launched into space, where it could observe the universe free from the distorting effects of Earth's atmosphere, Hubble had a lot riding on it.

But after the first images were obtained and carefully analyzed following the telescope's deployment on April 25, , it was clear that something was wrong: The images were blurry. They all came to the same conclusion: Hubble's primary mirror, which looks like a very shallow bowl, had been polished into the wrong shape. The error was smaller than the width of a human hair, but the effect was significant.

If the error went uncorrected, Hubble would never reach its full potential. WFPC2, which actually contains four cameras, would go on to produce many of Hubble's breathtaking images , helping transform our view of the cosmos. It generated breathtaking snapshots of galaxies, exploded stars and nebulae where new stars are born. During the instrument's tenure, Hubble managers pointed the telescope at a single, black patch of sky for more than a week and found thousands of previously unseen galaxies. The instrument was built on an incredibly tight timeline, and designing it to correct the flaw was something JPL's John Trauger, principal investigator for WFPC2, would later describe as being akin to "trying to play baseball on the side of a hill.

Replacing the Wide Field and Planetary Camera. WFPC2 team members say they remember that the reaction from the public and the media was often pessimistic or even incredulous. Trauger watched network news anchor Tom Brokaw begin his program that evening by saying, "The Hubble Telescope you've heard so much about - it's broken. The telescope's primary and secondary mirrors collected light and fed it to the five onboard science instruments. The primary mirror could not be replaced and could not be returned to Earth for repairs. A solution would have to be found for each of Hubble's instruments.

The COSTAR device provided corrective optics for three of them, eliminating the need to fully replace those instruments. The primary mirror error caused light striking different parts of the mirror to come into focus at different locations, so the team had to figure out how to redirect it to the appropriate focal point. Their solution was to reverse-engineer the problem: They would place four identical nickel-sized mirrors inside the instrument - one for each of the four cameras inside WFPC2 - with the same error as the flawed primary mirror, but where the primary mirror was too flat, the new mirrors would be curved too deeply.

Together, these two errors would cancel each other, producing the equivalent of a single mirror with the correct shape. The agency had planned to carry out Hubble repair missions every three years and decided to maintain this schedule. The first repair mission was set for the fall of JPL would need to deliver the replacement by the winter of - just over 2 years away.

The race to repair Hubble was on. They would be inserting WFPC2 into a cavity in the telescope's body, as if sliding it in a drawer. And although they would need to make sure that the electrical connections at the back of the instrument were secure, they had no way of reaching those connections; they could control only how they inserted the instrument. At more than pounds kilograms , it was unwieldy even in the microgravity of low-Earth orbit.

One of the instrument's mirrors, called the pickoff mirror, was mounted on a short arm located outside the protective casing. Merely bumping the mirror would misalign the system and essentially ruin the entire instrument. During WFPC2's construction, Trauger and colleagues showed a model of the instrument to an astronaut, who bumped the pickoff mirror. Trauger couldn't help but wonder, "Is this an omen? After departing Kennedy and seeking out an early breakfast, Gallagher remembers looking up at the predawn sky to see the space shuttle passing overhead and nearing Hubble; the objects appeared as two faint points of light in the sky as they orbited Earth.

Everything seemed to go as planned, but the real test was yet to come.

Celebrity Weight Loss: Did These Stars Get Too Thin?

The team put the data through the image-processing software and watched anxiously as the pictures began to ratchet across the screen. There was instant relief. There were things in the images that we'd never seen before. More than 3, science papers were written based on that data before the instrument was retired in , and over 2, more have been published since. Gazing across million light-years into a monstrous city of galaxies, astronomers have used NASA's Hubble Space Telescope to do a comprehensive census of some of its most diminutive members: In fact, the Coma cluster is one of the first places where observed gravitational anomalies were considered to be indicative of a lot of unseen mass in the universe — later to be called "dark matter.

They are integral to the birth and growth of a galaxy.

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About globular clusters zip around our Milky Way galaxy, and, because they contain the oldest known stars in the universe, were present in the early formative years of our galaxy. The survey found the globular clusters scattered in the space between the galaxies. They have been orphaned from their home galaxy due to galaxy near-collisions inside the traffic-jammed cluster. Hubble revealed that some globular clusters line up along bridge-like patterns.

This is telltale evidence for interactions between galaxies where they gravitationally tug on each other like pulling taffy. The ACS was later repaired by astronauts during a Hubble servicing mission. This is a Hubble Space Telescope mosaic of a portion of the immense Coma cluster of over 1, galaxies, located million light-years from Earth. Hubble's incredible sharpness was used to do a comprehensive census of the cluster's most diminutive members: Among the earliest homesteaders of the universe, globular star clusters are snow-globe-shaped islands of several hundred thousand ancient stars.

They have been orphaned from their home galaxies through galaxy tidal interactions within the bustling cluster. Astronomers will use the globular cluster field for mapping the distribution of matter and dark matter in the Coma galaxy cluster [image credit: Madrid Australian Telescope National Facility ]. He assembled a mosaic of the central region of the cluster, working with students from the National Science Foundation's Research Experience for Undergraduates program.

The program used globular clusters' color dominated by the glow of aging red stars and spherical shape to eliminate extraneous objects — mostly background galaxies unassociated with the Coma cluster. This dark, tangled web is an object named SNR It formed in a very violent fashion — it is a supernova remnant, created after a massive star ended its life in a cataclysmic explosion and threw its constituent material out into surrounding space.

The remnant is likely the result of a Type Ia supernova explosion; this category of supernovae is formed from the death of a white dwarf star , which grows and grows by siphoning material from a stellar companion until it reaches a critical mass and then explodes. Tangled — cosmic edition image credit: Astronomers may have finally uncovered the long-sought progenitor to a specific type of exploding star by sifting through NASA Hubble Space Telescope archival data.

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The supernova, called a Type Ic, is thought to detonate after its massive star has shed or been stripped of its outer layers of hydrogen and helium. Even after shedding some of their material late in life, they are expected to be big and bright. So it was a mystery why astronomers had not been able to nab one of these stars in pre-explosion images.

A nearby star ended its life as a Type Ic supernova. Two teams of astronomers pored through the archive of Hubble images to uncover the putative precursor star in pre-explosion photos taken in The supernova, catalogued as SN ein, appeared near the center of the nearby spiral galaxy NGC , located roughly 65 million light-years away. You need one of these massive, bright stars in a nearby galaxy to go off. It looks like most Type Ic supernovas are less massive and therefore less bright, and that's the reason we haven't been able to find them.

This is an artist's concept of a blue supergiant star that once existed inside a cluster of young stars in the spiral galaxy NGC , located 65 million light-years away. It exploded as a supernova in , and Hubble Space Telescope archival photos were used to locate the doomed progenitor star, as it looked in The star may have been as massive as 50 suns and burned at a furious rate, making it hotter and bluer than our Sun. It was so hot, it had lost its outer layers of hydrogen and helium.

When it exploded in , astronomers categorized it as a Type Ic supernova because of the lack of hydrogen and helium in the supernova's spectrum. In an alternative scenario not shown here a binary companion to the massive star may have stripped off its hydrogen and helium layers [image credits: Based on that assessment, both teams suggest two possibilities for the source's identity. The progenitor could be a single hefty star between 45 and 55 times more massive than our Sun.

Another idea is that it could have been a massive binary-star system in which one of the stars weighs between 60 and 80 solar masses and the other roughly 48 suns. In this latter scenario, the stars are orbiting closely and interact with each other. The more massive star is stripped of its hydrogen and helium layers by the close companion, and eventually explodes as a supernova.

The exploded star is a Type Ic supernova, thought to detonate after its massive star has shed or been stripped of its outer layers of hydrogen and helium. Progenitor stars to Type Ic supernovas have been hard to find. But astronomers sifting through Hubble archival images may have uncovered the star that detonated as supernova ein. The location of the candidate progenitor star is shown in the left pullout box at the bottom, taken in The bright object in the box at bottom right is a close-up image of the supernova, taken by Hubble in , shortly after the stellar blast.

NGC resides 65 million light-years away in the constellation Ursa Major. The Hubble image of NGC was taken in [image credits: Van Dyk Caltech , and W. Li University of California ]. Astronomers have known that the supernovas were deficient in hydrogen and helium, and initially proposed that some hefty stars shed this material in a strong wind a stream of charged particles before they exploded. When they didn't find the progenitors stars, which should have been extremely massive and bright, they suggested a second method to produce the exploding stars that involves a pair of close-orbiting, lower-mass binary stars.

In this scenario, the heftier star is stripped of its hydrogen and helium by its companion. But the "stripped" star is still massive enough to eventually explode as a Type Ic supernova. They account for about 20 percent of massive stars that explode from the collapse of their cores. The astronomers hope to use either Hubble or the upcoming NASA James Webb Space Telescope to see whether the candidate progenitor star has disappeared or has significantly dimmed. They also will be able to separate the supernova's light from that of stars in its environment to calculate a more accurate measurement of the object's brightness and mass.

But it took the sharp resolution of Hubble to pinpoint the exact location of the possible source. The astronomers used that image to pinpoint the candidate progenitor star nestled in one of the host galaxy's spiral arms in archival Hubble photos taken in December by the Wide Field Planetary Camera 2. Keck Observatory in Hawaii. The team then analyzed the same archival Hubble photos as Van Dyk's team to uncover the possible source. After a comprehensive review of their scientific merits and technical status, the SPC has decided to extend the operation of the five missions led by ESA's Science Program: Every two years, all missions whose approved operations end within the following four years are subject to review by the advisory structure of the Science Directorate.

Extensions are granted to missions that satisfy the established criteria for operational status and science return, subject to the level of financial resources available in the science program. These extensions are valid for the following four years, subject to a mid-term review and confirmation after two years. Cluster, for example, is the only mission that, by varying the separation between its four spacecraft, allows multipoint measurements of the magnetosphere in different regions and at different scales, while Gaia is performing the most precise astrometric survey ever realized, enabling unprecedented studies of the distribution and motions of stars in the Milky Way and beyond.

Extended life for ESA's science missions Blue compact dwarf galaxies take their name from the intensely blue star-forming regions that are often found within their cores. One such region can be seen embedded in ESO , which is populated with bright young stars voraciously consuming hydrogen. These massive stars are doomed to a short existence, as despite their vast supplies of hydrogen fuel.

The nuclear reactions in the cores of these stars will burn through these supplies in only millions of years — a mere blink of an eye in astronomical terms. This galactic interaction disrupted the clouds of gas and dust surrounding ESO and led to the rapid formation of a new population of stars.

This image depicts the blue compact dwarf galaxy ESO , which can be found in the constellation of Corona Australis the Southern Crown , image credit: These emit photons at specific visible wavelengths or colors — green and red for oxygen, blue and purple for nitrogen — and fill the sky with an eerie auroral glow. The observations also helped to locate Uranus' magnetic poles, and allowed scientists to track two so-called interplanetary shocks that propagated through the Solar System. These shocks were triggered by two powerful bursts of material flung out by the Sun via the solar wind, an ongoing flow of charged particles constantly emanating from our star, and caused the most intense auroras ever seen on Uranus.

This image, originally published in , shows the auroras as wispy patches of white against the planet's azure blue disc, and combines optical and ultraviolet observations from Hubble with archive data from NASA's Voyager 2 probe. Voyager 2 was the first and only craft to visit the outermost planets in the Solar System; it flew past Uranus in January , and past Neptune in August These icy planets have not been visited since. NASA and ESA have been studying a possible joint mission that would target the two ice giant planets in order to explore their intriguing role in our planetary system image credit: This young star casts a striking shadow — nicknamed the Bat Shadow — on the nebula behind it, revealing telltale signs of its otherwise invisible protoplanetary disc.

By clinging tightly to the star the disc creates an imposing shadow, much larger than the disc — approximately times the diameter of our own Solar System. The disc's shadow is similar to that produced by a cylindrical lamp shade.

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Light escapes from the top and bottom of the shade, but along its circumference, dark cones of shadow form. However, the shadow feature — nicknamed the Bat Shadow — reveals details of the disc's shape and nature. The presence of a shadow implies that the disc is being viewed nearly edge-on. Using the shape and color of the shadow, they can determine the size and composition of dust grains in the disc.

The nebula envelops hundreds of young stars, many of which could also be in the process of forming planets in a protoplanetary disc. However, in an unlikely coincidence, a similar looking shadow phenomenon can be seen emanating from another young star, in the upper left of the image. The planetary system we live in once emerged from a similar protoplanetary disc when the Sun was only a few million years old. By studying these distant discs we get to uncover the formation and evolution of our own cosmic home.

Within the nebula, in the upper right of the image, a shadow is created by the protoplanetary disc surrounding the star HBC While the disc of debris is too tiny to be seen even by Hubble, its shadow is projected upon the cloud in which it was born. In this view, the feature — nicknamed the Bat Shadow — spans approximately times the diameter of our own Solar System.

The return to conducting science comes after successfully recovering a backup gyroscope, that had replaced a failed gyro three weeks earlier. However, the backup incorrectly returned rotation rates that were far in excess of the actual rates. Next, the team monitored and tested the gyro with additional maneuvers to make sure that the gyro was stable. The team then installed additional safeguards on the spacecraft in case the excessive rate values return, although this is not anticipated.

Hubble successfully completed maneuvers to get on target for the first science observations, and the telescope collected its first science data since 5 October. Originally required to last 15 years, Hubble has now been at the forefront of scientific discovery for more than 28 years. The team expects the telescope will continue to yield amazing discoveries well into the next decade, enabling it to work alongside the James Webb Space Telescope.

The constellation of Cassiopeia, named after a vain queen in Greek mythology, forms the easily recognizable "W" shape in the night sky. The central point of the W is marked by a dramatic star named Gamma Cassiopeiae. This star is 19 times more massive and 65, times brighter than our Sun. It also rotates at the incredible speed of 1. This frenzied rotation gives it a squashed appearance.

The fast rotation causes eruptions of mass from the star into a surrounding disk. This mass loss is related to the observed brightness variations. The hydrogen within IC 63 is being bombarded with ultraviolet radiation from Gamma Cassiopeiae, causing its electrons to gain energy which they later release as hydrogen-alpha radiation — visible in red in this image.

This is light from Gamma Cassiopeiae that has been reflected by dust particles in the nebula, meaning that IC 63 is also a reflection nebula. However, IC 63 is not the only object under the influence of the mighty star. It is part of a much larger nebulous region surrounding Gamma Cassiopeiae that measures approximately two degrees on the sky — roughly four times as wide as the full Moon. Though it is high in the sky and visible all year round from Europe, it is very dim, so observing it requires a fairly large telescope and dark skies.

IC 63, the Ghost Nebula. From above Earth's atmosphere, Hubble gives us a view that we cannot hope to see with our eyes. This photo is possibly the most detailed image that has ever been taken of IC 63, and it beautifully showcases Hubble's capabilities image credit: An international team of astronomers have discovered two stars in a binary pair that complete an orbit around each other in a little over three hours, residing in the planetary nebula M Remarkably, the stars could drive a nova explosion, an entirely unexpected event based on our current understanding of binary star evolution.

In many cases, interaction with a nearby companion star plays an important role in the ejection of this material and the formation of the elaborate structures seen in the resulting planetary nebulae. M was a firm candidate to host a binary central star, as its structure with prominent jets and filaments is typical of these binary star interactions. In the process they discovered and studied the binary stars in the center of the nebula. An image obtained with the Hubble Space Telescope of the planetary nebula M, the central star of which is actually a binary system with one of the shortest orbital periods known image credit: David Jones - IAC.

The ESO observations also show that the two stars — most likely a white dwarf with a low-mass main sequence companion — are almost touching. When this reaches a critical mass, a violent thermonuclear explosion takes place and the system temporarily increases in brightness by up to a million times. A nova explosion could take place in just a few thousand years from now.

It should then take a long time before they begin to interact again and events such as novae become possible. By the time the two stars are close enough for a nova, the material in the planetary nebula should have expanded and dissipated so much that it's no longer visible. NASA took great strides last week to press into service a Hubble Space Telescope backup gyroscope gyro that was incorrectly returning extremely high rotation rates.

The backup gyro was turned on after the spacecraft entered safe mode due to a failed gyro on Friday, 5 October. The rotation rates produced by the backup gyro have since reduced and are now within an expected range. Additional tests will be performed to ensure Hubble can return to science operations with this gyro.

This wheel is mounted in a sealed cylinder, called a float, which is suspended in a thick fluid. Electricity is carried to the motor by thin wires, approximately the size of a human hair, that are immersed in the fluid. Electronics within the gyro detect very small movements of the axis of the wheel and communicate this information to Hubble's central computer.

These gyros have two modes — high and low. High mode is a coarse mode used to measure large rotation rates when the spacecraft turns across the sky from one target to the next. Low mode is a precision mode used to measure finer rotations when the spacecraft locks onto a target and needs to stay very still. This procedure turned the gyro off for one second, and then restarted it before the wheel spun down.

The intention was to clear any faults that may have occurred during startup on 6 October, after the gyro had been off for more than 7. However, the resulting data showed no improvement in the gyro's performance. During each maneuver, the gyro was switched from high mode to low mode to dislodge any blockage that may have accumulated around the float.

On 19 October, the operations team commanded Hubble to perform additional maneuvers and gyro mode switches, which appear to have cleared the issue. Gyro rates now look normal in both high and low mode. The team saw no problems and continued to observe the gyro through the weekend to ensure that it remained stable. After these engineering tests have been completed, Hubble is expected to soon return to normal science operations. Today we know that globular clusters are some of the oldest known objects in the universe and that they are relics of the first epochs of galaxy formation.

While we already have a pretty good picture on the globular clusters of the Milky Way — still with many unanswered questions — our studies on globular clusters in nearby dwarf galaxies just started. The observations of NGC will help to determine whether their properties are similar to the ones found in the Milky Way, or if they have different features, due to being in a different cosmic environment.

This glittering ball of stars is the globular cluster NGC , which lies toward the center of the Large Magellanic Cloud — one of our closest cosmic neighbors. The Large Magellanic Cloud is a dwarf galaxy that hosts an extremely rich population of star clusters, making it an ideal laboratory for investigating star formation image credit: New observations by two Arizona State University astronomers using the Hubble Space Telescope have caught a red dwarf star in a violent outburst, or superflare.

The blast of radiation was more powerful than any such outburst ever detected from the Sun, and would likely affect the habitability of any planets orbiting it. The program surveys red dwarfs also known as M dwarfs at three different ages—young, intermediate, and old—and observes them in ultraviolet light, where they show the most activity.

The flares are believed to be powered by intense magnetic fields that get tangled by the roiling motions of the stellar atmosphere. When the tangling gets too intense, the fields break and reconnect, unleashing tremendous amounts of energy. That's a sobering thought. Violent outbursts of seething gas from young red dwarfs may make conditions uninhabitable on fledgling planets. In this artist's rendering, an active, young red dwarf right is stripping the atmosphere from an orbiting planet left. ASU astronomers have found that flares from the youngest red dwarfs they surveyed — approximately 40 million years old — are to times more energetic than when the stars are older.

They also detected one of the most intense stellar flares ever observed in ultraviolet light — more energetic than the most powerful flare ever recorded from our Sun [image credit: Most of the galaxy's "habitable-zone" planets—planets orbiting their stars at a distance where temperatures are moderate enough for liquid water to exist on their surface—orbit red dwarfs.

In fact, the nearest star to our Sun, a red dwarf named Proxima Centauri, has an Earth-size planet in its habitable zone. Observations with the Hubble Space Telescope discovered a superflare red line that caused a red dwarf star's brightness in the far ultraviolet to abruptly increase by a factor of nearly image credit: These stars show that young low-mass stars flare much more frequently and more energetically than old stars and middle-age stars like our Sun—as evidenced by the superflare.

This means that we're looking at superflares happening every day or even a few times a day. But that doesn't necessarily mean doom and gloom for life on the planet. It just might be different life than we imagine. Or there might be other processes that could replenish the atmosphere of the planet. It's certainly a harsh environment, but I would hesitate to call it a sterile environment. Then the oldest red dwarfs will be analyzed and compared with the young and intermediate stars to understand the evolution of the high-energy-radiation environment for planets around these low-mass stars.

Messier was primarily a comet hunter, and was often left frustrated by objects in the sky that resembled comets but turned out not to be. To help other astronomers avoid confusing these objects in the future, he created his famous catalog of Messier objects. The galaxy has a bar cutting through its center, surrounded by an inner ring currently forming new stars. Also our own Milky Way is a barred spiral.

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In March a spectacular supernova named SN aw was observed in the outer regions of one of Messier 95's spiral arms. Once the light from the supernova had faded, astronomers were able to compare observations of the region before and after the explosion to find out which star had "disappeared" — the progenitor star. In this case, the star was an especially huge red supergiant up to 26 times more massive than the Sun. This Hubble image reveals a detailed view of part of the spiral galaxy Messier 95 image credit: NASA is working to resume science operations of the Hubble Space Telescope after the spacecraft entered safe mode on Friday, 5 October , shortly after 6: Hubble's instruments still are fully operational and are expected to produce excellent science for years to come.

Safe mode puts the telescope into a stable configuration until ground control can correct the issue and return the mission to normal operation. Hubble usually uses three gyros at a time for maximum efficiency, but can continue to make scientific observations with just one. The remaining three gyros available for use are technically enhanced and therefore expected to have significantly longer operational lives. Upon powering on the third enhanced gyro that had been held in reserve, analysis of spacecraft telemetry indicated that it was not performing at the level required for operations.

As a result, Hubble remains in safe mode. An Anomaly Review Board, including experts from the Hubble team and industry familiar with the design and performance of this type of gyro, is being formed to investigate this issue and develop the recovery plan. If the outcome of this investigation results in recovery of the malfunctioning gyro, Hubble will resume science operations in its standard three-gyro configuration. While reduced-gyro mode offers less sky coverage at any particular time, there is relatively limited impact on the overall scientific capabilities. A pair of Columbia University astronomers using NASA's Hubble Space Telescope and the Kepler Space Telescope have assembled compelling evidence for the existence of a moon orbiting a gas-giant planet 8, light-years away.

Such gargantuan moons do not exist in our own solar system, where nearly natural satellites have been cataloged. Artist's impression of the exoplanet Keplerb, transiting the star, with the candidate exomoon in tow image credit: The observations measured the momentary dimming of starlight as a planet passed in front of its star, called a transit. The researchers found one instance, in Kepler b, that had intriguing anomalies. Artist's impression of the exoplanet Keplerb transiting the star with the candidate exomoon in tow image credit: The researchers monitored the planet before and during its hour-long transit across the face of the star.

After it ended, Hubble detected a second and much smaller decrease in the star's brightness 3. This is consistent with the planet and moon orbiting a common center of gravity barycenter that would cause the planet to wobble from its predicted location. But we knew our job was to keep a level head testing every conceivable way in which the data could be tricking us until we were left with no other explanation. This value is close to the mass-ratio between the Earth and its moon. But in the case of the Earth-Moon system and the Pluto-Charon system—the largest of the five known natural satellites of the dwarf planet Pluto—an early collision with a larger body is hypothesized to have blasted off material that later coalesced into a moon.

Kepler b and its satellite, however, are gaseous, not rocky, and, therefore, such a collision may not lead to the condensation of a satellite. The astronomers calculated the mass ratio of the system from these brightness measurements. Finally, the mass of each component could be determined. Only the world's very largest telescopes have a resolution comparable to Hubble's to resolve the binary pair. This is possible after using adaptive optics to cancel out atmospheric blur.

Both components of the binary system belong to the L spectral class that includes the lowest mass stars and the highest mass brown dwarfs in our solar neighborhood. The L class is characterized by the formation of dust grains in the object's atmosphere, which dramatically changes the visible-light spectrum. Theoretically predicted for a long time, these sub-stellar objects called "brown dwarfs" were only discovered in Indirect techniques were conceived to identify brown dwarf candidates. However, the mass measurement is the only direct way to identify a star as a brown dwarf. There is no technique to directly measure the mass of any star in the universe, unless the star belongs to a binary system.

Binary brown dwarfs are especially challenging because they are often faint and lie very close to each other. The Astrophysical Journal Letters. Exoplanet Methods of detecting exoplanets Planetary system. Accretion Merging stars Nebular hypothesis Planetary migration. Astrometry Direct imaging list Microlensing list Polarimetry Pulsar timing list Radial velocity list Transit method list Transit-timing variation.

Astrobiology Circumstellar habitable zone Earth analog Extraterrestrial liquid water Habitability of natural satellites Superhabitable planet. Exoplanetary systems Host stars Multiplanetary systems Stars with proplyds Exoplanets List of exoplanets Discoveries Extremes Firsts Nearest Largest Most massive Terrestrial candidates Kepler Potentially habitable Discovered exoplanets by year before — Discoveries of exoplanets Search projects. Retrieved from " https: