# Hubble in the News

Read captivating science stories from the observatory in 2018.

NASA’s Hubble Space Telescope has been delivering breathtaking views of the universe since it launched in 1990. Although the telescope has made more than 1.5 million observations of over 40,000 space objects, it is still uncovering stunning celestial phenomena with unprecedented scientific detail. Read the top stories our news team publicized in 2018.

### Interstellar Object Gets a Speed Boost

Is it a comet, an asteroid, or a new type of object? Using observations from Hubble and ground-based observatories, an international team of scientists confirmed Oumuamua (oh-MOO-ah-MOO-ah)—the first known interstellar object to travel through our solar system—got an unexpected boost in speed and shift in trajectory as it passed through the inner Solar System last year, behaving more like an icy comet than a rocky asteroid. The team concluded that the most likely explanation is that the object was jetting out gaseous material. This extra push could explain the small but measurable perturbation of the object’s path. This hypothesized outgassing (not directly visible in any observations) was likely produced by heating from the Sun, which caused ices to sublimate and vent away from the object. Keep reading about Oumuamua.

### Uncovering the Farthest Star Ever Seen

Astronomers using Hubble pinpointed the farthest individual star that has ever been detected. The star, nicknamed Icarus after the Greek mythological character that flew too close to the Sun, is so far away that its light has taken 9 billion years to reach Earth. It appears as it did when the universe was about 30 percent of its current age. That places the “superstar” 100 times farther away than the next farthest individual star ever observed.

The cosmic quirk that makes this star visible is a phenomenon called gravitational lensing. Gravity from a foreground, massive cluster of galaxies acts as a natural lens in space, bending and amplifying light. In the case of Icarus, a natural “magnifying glass” is created by the galaxy cluster MACS J1149+2223, which is located about 5 billion light-years away, between Earth and the remote star. The discovery of Icarus offers a unique opportunity for astronomers to study individual stars in distant galaxies. These observations provide a rare, detailed look at how stars evolve. Learn more about this faraway star.

### Improving Our Understanding of Star Formation

Much of the light in the universe comes from stars, and yet star formation is still a confounding challenge to our understanding of astronomy. To piece together a more complete picture, astronomers used Hubble to look at 50 galaxies in the nearby universe. Called the Legacy ExtraGalactic UV Survey (LEGUS), the survey is the sharpest, most comprehensive ultraviolet-light look at nearby star-forming galaxies.

The LEGUS survey combines new Hubble observations with archival Hubble images of star-forming spiral and dwarf galaxies, offering a valuable resource for understanding the complexities of star formation and galaxy evolution. Astronomers are releasing the star catalogs for each of the LEGUS galaxies, cluster catalogs for 30 of the galaxies, and images of the galaxies themselves. The catalogs provide detailed information about young stars, massive stars, and star clusters—and how their environment affects their development.

The local universe, stretching between us and the great Virgo cluster of galaxies, is ideal for study because astronomers can amass a big enough sample of galaxies, and the galaxies are close enough to Earth that Hubble can resolve individual stars. The survey will also help astronomers better understand galaxies in the distant universe, where rapid star formation took place. Keep reading about LEGUS.

### Debating the Universe’s Expansion Rate

Using the Hubble and Gaia space telescopes, astronomers took a big step toward refining the Hubble constant, one of cosmology’s fundamental values needed for measuring the universe’s age. This number is the rate at which the universe is expanding since the big bang, 13.8 billion years ago.

Intriguingly, the new results further intensify the discrepancy between measurements for the expansion rate of the nearby universe, and those of the distant, primeval universe—before stars and galaxies existed. In mapping the cosmic afterglow of the big bang, the European Space Agency’s Planck telescope yields a slightly different expansion rate for the primordial universe. However, because the universe is expanding uniformly, these measurements should be the same.

The so-called “tension” between the two sets of observations implies that there could be new physics underlying the foundations of the universe. The researchers’ goal is to work with Gaia to refine the Hubble constant to a value of only 1 percent by the early 2020s. Meanwhile, astrophysicists will likely continue to grapple with revisiting their ideas about the physics of the early universe. Dive into the details.

### Water Found in an Exoplanet’s Atmosphere

Scientists used the Hubble and Spitzer space telescopes to identify the “fingerprints” of water in the atmosphere of a hot, bloated, Saturn-mass exoplanet some 700 light-years away. And they found a lot of water. In fact, the planet, known as WASP-39 b, has three times as much water as Saturn.

Although the researchers predicted they’d see water, they were surprised by how much water they found. The amount of water suggests that the planet actually developed far away from the star, where it was bombarded by a lot of icy material. WASP-39 b likely had an interesting evolutionary history as it migrated in toward its host star, taking an epic journey across its planetary system and perhaps disrupting other planets along its trajectory.

Though no planet like this resides in our solar system, WASP-39 b can provide new insights into how and where planets form around a star. This exoplanet underscores the fact that the more astronomers learn about the complexity of other worlds, the more there is to learn about their origins. This latest observation is a significant step toward characterizing these worlds. Learn more about WASP-39 b.

### A Comprehensive Image of the Evolving Universe

Astronomers have assembled one of the most comprehensive portraits yet of the universe’s evolutionary history, based on a broad array of observations by Hubble and other space- and ground-based telescopes. In particular, Hubble’s ultraviolet vision opens a new window on the evolving universe, tracking the birth of stars over the last 11 billion years back to the cosmos’ busiest star-forming period, about 3 billion years after the big bang. This photo from the Hubble Deep Ultraviolet Legacy Survey encompasses a sea of approximately 15,000 galaxies widely distributed in time and space. By comparing images of star formation in the distant and nearby universe, astronomers glean a better understanding of how nearby galaxies grew from small clumps of hot young stars long ago. Download the Hubble Deep Ultraviolet Legacy Survey.

### Possible Moon Outside the Solar System

Using the Hubble and Kepler space telescopes, astronomers uncovered tantalizing evidence for what could be the first discovery of a moon orbiting a planet outside our solar system. This moon candidate, which is 8,000 light-years from Earth, orbits a gas-giant planet that, in turn, orbits a star called Kepler-1625. Researchers caution that the moon hypothesis is tentative and must be confirmed by follow-up Hubble observations. (It is too far away to be directly photographed. Instead, its presence is inferred when it passes in front of the star, momentarily dimming its light.) Our solar system has eight major planets and nearly 200 moons. If our solar system is a typical example, this finding promises a new frontier for characterizing the nature of moons around extrasolar planets. Keep reading about this discovery.

### Young Red Dwarf Superflares Imperil Planets

Approximately three-quarters of the stars in our galaxy are red dwarfs. Therefore, they host most of the planets in our galaxy that are potential abodes of life. However, young red dwarfs are very active stars, producing ultraviolet flares that blast out million-degree plasma with an intensity that could possibly strip off the atmospheres of planets, making them unsuitable for hosting life as we know it (at least on their surfaces). Hubble is observing such stars through a large program called HAZMAT (HAbitable Zones and M dwarf Activity across Time), an ultraviolet survey of red dwarfs at three different ages: young, intermediate, and old. The HAZMAT team found that flares from the youngest red dwarfs they surveyed (around 40 million years old) are 100 to 1,000 times more energetic than when the stars are older. Next, the HAZMAT program will study intermediate-aged red dwarfs that are 650 million years old, ultimately comparing each population of red dwarfs to understand their evolution. Learn more about the program.

### Infrared Light Around a Neutron Star

A neutron star is the remnant of an exploded star that has been squeezed into a solid ball of neutrons with the extreme density of an atomic nucleus. Spinning neutron stars that radiate sweeping “lighthouse beams” of energy are called pulsars. These beams are normally seen in X-rays, gamma-rays, and radio waves. When astronomers used Hubble’s near-infrared vision to look at a nearby neutron star, they were surprised to see a gush of infrared light as well. That infrared light might come from a circumstellar disk 18 billion miles across. If confirmed as a disk, this result could change the understanding of neutron star evolution. Another idea is that a wind of subatomic particles from the pulsar’s magnetic field is slamming into interstellar gas. Astronomers will be able to further explore this discovery in the infrared by using NASA’s upcoming James Webb Space Telescope to better understand neutron star evolution. Keep reading about the neutron star.

### Faint Glow Within Galaxy Clusters Illuminates Dark Matter

Using Hubble’s prior observations of six massive galaxy clusters in the Frontier Fields program, astronomers demonstrated that intracluster light—the diffuse glow between galaxies in a cluster—traces the path of dark matter, illuminating its distribution more accurately than existing methods that observe X-ray light. Intracluster light is an excellent tracer of dark matter in a galaxy cluster, because both the dark matter and the stars are freefloating—following exactly the same gravity. This method allows researchers to illuminate, with a very faint glow, the position of dark matter. Not only is the method accurate, but it is also more efficient since it relies only on deep imaging. This means more clusters and objects can be studied in less time, which may lead to more evidence of what dark matter consists of and how it behaves. Learn about dark matter.