Category Archives: Deep Space Objects
In what’s being called a “record-breaking exoplanet discovery” NASA announced today the detection of not one, not two, not three or four but seven exoplanets orbiting the ultra-cool dwarf star TRAPPIST-1, located just under 40 light-years away in the constellation Aquarius. (That’s astronomically very close, although still 235 trillion miles distant.) What’s more, these exoplanets aren’t bloated hot Jupiters or frigid Neptune-like worlds but rather dense, rocky planets similar in size to Earth…and at least three of them are well-positioned around their dim red star to permit liquid water to exist on their surfaces.
TRAPPIST-1 and its planets are like a miniature version of our inner Solar System; the star itself is only slightly larger than Jupiter with a mass about 8% of our Sun, and the planets B through H all have orbits smaller than the diameter of Mercury’s. Still, even an ultra-cool dwarf star has a habitable zone, and three of these planets lie within it. The others may very well also possess habitable regions on or inside them too.
“This discovery could be a significant piece in the puzzle of finding habitable environments, places that are conducive to life,” said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate in Washington, D.C. “Answering the question ‘are we alone’ is a top science priority and finding so many planets like these for the first time in the habitable zone is a remarkable step forward toward that goal.”
The seven-planet system was confirmed through (and named for) the ground-based TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) telescope, observations from NASA’s Spitzer Space Telescope.
“This is the most exciting result I have seen in the 14 years of Spitzer operations,” said Sean Carey, manager of NASA’s Spitzer Science Center at Caltech/IPAC in Pasadena. “Spitzer will follow up in the fall to further refine our understanding of these planets so that the James Webb Space Telescope can follow up. More observations of the system are sure to reveal more secrets.”
A star’s violent death by black hole has been spotted by researchers from the University of New Hampshire, using observations made by three orbiting x-ray space telescopes. Located in a small galaxy 1.8 billion light-years away, the event demonstrates what happens when a star gets too close to a supermassive black hole and gets torn apart, some of its material falling into the black hole but also some getting thrown outwards at high speeds—all heated to temperatures intensely high enough to shine in x-ray wavelengths.
“We have witnessed a star’s spectacular and prolonged demise,” said Dacheng Lin, a research scientist at UNH’s Space Science Center and the study’s lead author. “Dozens of these so-called tidal disruption events [TDEs] have been detected since the 1990s, but none that remained bright for nearly as long as this one.”
The extraordinary long bright phase of this TDE means that either this was the most massive star ever to be torn apart during one of these events, or the first where a smaller star was completely torn apart.
Read the rest of this story from the University of New Hampshire here: UNH Researcher Discovers a Black Hole Feeding Frenzy that Breaks Records
This image from the Hubble Space Telescope shows the Calabash Nebula, the cosmic death throes of a low-mass star like our Sun. Caught during the astronomically brief phase between a red giant and a planetary nebula, the star is ejecting much of its mass out into space at velocities of over 620,000 mph.
So why does it “stink?” The bright yellow jets are known to contain a lot of sulphur compounds, so if the image were a scratch ‘n’ sniff sticker it would smell like rotten eggs (hence its nickname, Rotten Egg Nebula.)
This spectacular display won’t last long; with its eruption begun in earnest about 800 years ago, in another 1,000 years this will resemble a more typical planetary nebula. In fact, given that this object is 5,000 light-years away, it’s technically already done with its sulfurous outburst! We’re just now seeing the light from the event as it arrives at Earth.
Read more in the NASA release: Hubble Captures Brilliant Star Death in “Rotten Egg” Nebula
Observations from some of the world’s most powerful telescopes—NASA’s Chandra X-ray Observatory, the Giant Metrewave Radio Telescope (GMRT) in India, the National Science Foundation’s Karl G. Jansky Very Large Array in New Mexico, and Japan’s Subaru Telescope in Hawai’i have been combined to create an image of two incredibly powerful cosmic forces colliding, two billion light-years away. Hot gas fired out from supermassive black holes inside one cluster of galaxies is accelerated to high speeds when it meets the shockwaves caused by a collision with a neighboring cluster, huge interactions spanning hundreds of thousands of light-years but only visible in X-ray and radio wavelengths.
Like anything else, stars have life spans. They are born (from collapsing clouds of interstellar dust), they go through a long main phase where they fuse various elements in their cores, and eventually they die when they run out of fuel. The finer details of these steps are based on what the star is made of, how massive it is, and what sort of company it keeps. Stars like our Sun have lifespans in the 9-10 billion year range—of which ours is near the middle—but other stars can have much shorter or longer lifespans, and as astronomers look out into the galaxy they can find stars at all different phases of their lives…of course, the longer a phase lasts, the more likely it is to find stars existing within it. We’ve found stars that are only a few thousand years old and we know of regions where stars are, right now, in the process of being born, but what is the oldest star we know of?
Actually, it’s not all that far away, in cosmic terms. Just 190 light-years distant in our own galaxy, HD 140283 (aka the Methuselah star) is, as of 2013, the oldest star ever discovered. Based on its stage as a subgiant and its remarkably low amount of heavy elements, astronomers have estimated the age of this star as 14.3 billion years old. Now this number is actually more than the estimated age of the Universe itself, but don’t worry—there’s a reason for that.
Read the rest of this story by astronomer Phil Plait on Slate here: The Oldest Known Star in the Universe.
For the past couple of years the astronomy world has been abuzz with news of the strange and randomly-occurring dimming of the star KIC 8462852—aka Tabby’s Star—located 1,276 light-years away in the constellation Cygnus and recently observed by NASA’s Kepler spacecraft. Hypotheses about the cause range from conservative (a transiting cloud of comets) to quite speculative (an “alien megastructure” constructed around the star) but to date nothing seems to perfectly fit the observations. Now, researchers from Columbia University and UC Berkeley are proposing a new idea: the dimming of Tabby’s Star is being caused by debris left over from a planet that was consumed by the star thousands of years ago, the orbiting scraps from a case of stellar infanticide.
Read more in a Universe Today article by Matt Williams: Finally, An Explanation for the Alien Megastructure?