First Publicly Available Science Observations for Webb Announced
The Space Telescope Science Institute is announcing some of the first science programs NASA's James Webb Space Telescope will conduct following its launch and commissioning. These specific observations are part of a program of Director’s Discretionary Early Release Science (DD-ERS), which will provide the scientific community with immediate access to Webb data. These data will help inform proposals for observations in the second year of Webb operations. The 13 ERS programs will address a broad variety of science areas, from black hole growth and the assembly of galaxies to star formation and the study of exoplanets.
Light from Supernova Bouncing Off Giant Dust Cloud
Voices reverberating off mountains and the sound of footsteps bouncing off walls are examples of an echo. Echoes happen when sound waves ricochet off surfaces and return to the listener.
Space has its own version of an echo. It’s not made with sound but with light, and occurs when light bounces off dust clouds.
The Hubble telescope has just captured one of these cosmic echoes, called a “light echo,” in the nearby starburst galaxy M82, located 11.4 million light-years away. A movie assembled from more than two years’ worth of Hubble images reveals an expanding shell of light from a supernova explosion sweeping through interstellar space three years after the stellar blast was discovered. The “echoing” light looks like a ripple expanding on a pond. The supernova, called SN 2014J, was discovered on Jan. 21, 2014.
A light echo occurs because light from the stellar blast travels different distances to arrive at Earth. Some light comes to Earth directly from the supernova blast. Other light is delayed because it travels indirectly. In this case, the light is bouncing off a huge dust cloud that extends 300 to 1,600 light-years around the supernova and is being reflected toward Earth.
So far, astronomers have spotted only 15 light echoes around supernovae outside our Milky Way galaxy. Light echo detections from supernovae are rarely seen because they must be nearby for a telescope to resolve them.
Asteroid Trails Streak Across This Deep-Space View of Thousands of Galaxies
Photobombing asteroids from our solar system have snuck their way into this deep image of the universe taken by NASA’s Hubble Space Telescope. These asteroids are right around the corner in astronomical terms, residing roughly 160 million miles from Earth. Yet they’ve horned their way into this picture of thousands of galaxies scattered across space and time at inconceivably farther distances.
Nighttime Titanium Dioxide Snow Leaves Dayside Cloud-Free and Cooler
Travelers to the nightside of exoplanet Kepler-13Ab should pack an umbrella because they will be pelted with precipitation. But it's not the kind of watery precipitation that falls on Earth. On this alien world, the precipitation is in the form of sunscreen.
Ironically, the sunscreen (titanium dioxide) is not needed on this side of the planet because it never receives any sunlight. But bottling up some sunlight protection is a good idea if travelers plan on visiting the sizzling hot, permanent dayside, which always faces its star. Visitors won't find any desperately needed sunscreen on this part of the planet.
Astronomers didn't detect the titanium dioxide directly. They used Hubble to find that the atmospheric temperature grows increasingly colder with altitude on the dayside of Kepler-13Ab, which was contrary to what they had expected. On this super-hot dayside, titanium dioxide should exist as a gas, called titanium oxide. If titanium oxide were present in the daytime atmosphere, it would absorb light and heat the upper atmosphere. Instead, high winds carry the titanium oxide around to the permanently dark side of the planet where it condenses to form clouds and precipitation, and rains down as titanium dioxide. The planet's crushing gravity pulls all the titanium dioxide so far down it can't be recycled back into the upper atmosphere on the daytime side.
The Hubble observations represent the first time astronomers have detected this precipitation process, called a "cold trap," on an exoplanet.
Kepler-13Ab is one of the hottest known planets, with a dayside temperature of nearly 5,000 degrees Fahrenheit. The Kepler-13 system resides 1,730 light-years from Earth.
Neutron Star Collision Cooks Up Exotic Elements, Gravitational Waves
When some people get in the kitchen, they create a delicious meal but leave behind a chaotic mess of splattered food and dirty dishes. Cosmic cookery can be just as messy. While a star can create chemical elements as heavy as iron within its core, anything heavier needs a more powerful source like a stellar explosion or the collision of two neutron stars.
Colliding neutron stars can yield gold, plutonium, and a variety of other elements. Theoretically, they also generate gravitational waves as they spiral together at breakneck speed before merging. The first gravitational wave signal from a neutron star merger was detected on August 17. It was accompanied by gamma rays and other light, allowing astronomers to locate a gravitational wave source for the first time.
Hubble photographed the glow from this titanic collision, shining within the galaxy NGC 4993 at a distance of 130 million light-years. Hubble also obtained an infrared spectrum that may yield signs of exotic, radioactive elements. The analysis will continue while astronomers wait for the gravitational wave source to emerge from behind the Sun from Earth’s point of view, where it slipped just days after discovery.