Michael Osadciw/University of Rochester
Artist’s conception of Scholz’s star and its brown dwarf companion (foreground) during its flyby of the solar system 70,000 years ago. The sun would have appeared as a brilliant star. The pair is now about 20 light years away.
NASA/JPL-Caltech/K. Su (Univ. of Arizona)
NASA's Spitzer Space Telescope was launched 10 years ago and has since peeled back an infrared veil on the Cosmos. The mission has worked in parallel with NASA's other "Great Observatories" (Hubble and Chandra) to provide coverage of the emissions from galaxies, interstellar dust, comet tails and the solar system's planets. But some of the most striking imagery to come from the orbiting telescope has been that of nebulae. Supernova remnants, star-forming regions and planetary nebulae are some of the most iconic objects to be spotted by Spitzer. So, to celebrate a decade in space, here are Discovery News' favorite Spitzer nebulae.
First up, the Helix Nebula -- a so-called planetary nebula -- located around 700 light-years from Earth. A planetary nebula is the remnants of the death throes of a red giant star -- all that remains is a white dwarf star in the core, clouded by cometary dust.
NASA/JPL-Caltech/B. Williams (NCSU)
Spitzer will often work in tandem with other space telescopes to image a broad spectrum of light from celestial objects. Here, the supernova remnant RCW 86 is imaged by NASA's Spitzer, WISE and Chandra, and ESA's XMM-Newton.
Staring deep into the Messier 78 star-forming nebula, Spitzer sees the infrared glow of baby stars blasting cavities into the cool nebulous gas and dust.
The green-glowing infrared ring of the nebula RCW 120 is caused by tiny dust grains called polycyclic aromatic hydrocarbons -- the bubble is being shaped by the powerful stellar winds emanating from the central massive O-type star.
NASA/JPL-Caltech/J. Stauffer (SSC/Caltech)
Spitzer stares deep into the Orion nebula, imaging the infrared light generated by a star factory.
X-Ray: NASA/CXC/J.Hester (ASU); Optical: NASA/ESA/J.Hester & A.Loll (ASU); Infrared: NASA/JPL-Caltech/R.Gehrz (Univ. Minn.)
In the year 1054 A.D. a star exploded as a supernova. Today, Spitzer was helped by NASA's other "Great Observatories" (Hubble and Chandra) to image the nebula that remains. The Crab Nebula is the result; a vast cloud of gas and dust with a spinning pulsar in the center.
The Tycho supernova remnant as imaged by Spitzer (in infrared wavelengths) and Chandra (X-rays). The supernova's powerful shockwave is visible as the outer blue shell, emitting X-rays.
NASA/JPL-Caltech/E. Churchwell (University of Wisconsin - Madison)
Over 2,200 baby stars can be seen inside the bustling star-forming region RCW 49.
X-ray: NASA/CXC/Univ.Potsdam/L.Oskinova et al; Optical: NASA/STScI; Infrared: NASA/JPL-Caltech
The "Wing" of the Small Magellanic Cloud (SMC) glitters with stars and warm clouds of dust and gas. By combining observations by Spitzer, Chandra and Hubble, the complex nature of this nebulous region can be realized.
Star Blasted Through Solar System 70,000 Years Ago
Astronomers have discovered a star that carried out a stellar hit-and-run 70,000 years ago… and our solar system was the victim.
Highlighted by astronomers at the University of Rochester and the European Southern Observatory, the star — nicknamed “Scholz’s star” — has a very low tangential velocity in the sky, but it has been clocked traveling at a breakneck speed away from us.
In other words, from our perspective, Scholz’s star is fleeing the scene of a collision with us.
“Most stars this nearby show much larger tangential motion,” said Eric Mamajek, of the University of Rochester. “The small tangential motion and proximity initially indicated that the star was most likely either moving towards a future close encounter with the solar system, or it had ‘recently’ come close to the solar system and was moving away. Sure enough, the radial velocity measurements were consistent with it running away from the Sun’s vicinity — and we realized it must have had a close flyby in the past.”
Scholz’s star was named after its 2013 discoverer Ralf-Dieter Scholz of the Leibniz-Institut für Astrophysik Potsdam (AIP) in Germany, but its official designation is “WISE J072003.20-084651.2″ after being positioned in data collected by NASA’s Wide-field Infrared Survey Explorer (WISE) telescope between 2010 and 2011.
Using data from the Southern African Large Telescope (SALT) and the Magellan telescope at Las Campanas Observatory in Chile, Mamajek and his collaborators were able to measure the star’s spectra and radial velocity. Through these observations they were able to deduce that Scholz’s star is a dim red dwarf approximately 20 light-years away. It is actually part of a binary system, with its partner being a small brown dwarf (or a ‘failed star’).
Taking these data, the researchers were able to model several different orbital possibilities and deduce that the star almost definitely (to a 98 percent certainty) came within 0.8 light years from the sun. Although this is still quite a margin, the star would have careened though the Oort Cloud — a hypothetical region filled with frozen cometary nuclei surrounding the solar system.
Like a car speeding through a cloud of mosquitoes, Scholz’s star would have likely splatted some comets and scattered many more during its close encounter, although the overall effect on the Oort Cloud would have likely been minimal, the researchers point out.
The researchers also calculated that at its closest approach, Scholz’s star would have only been a 10th magnitude star, approximately 50 times dimmer than what we could normally see on a clear night without the aid of a telescope. However, as the star is known to be magnetically active, our ancestors may have looked up in wonder at flaring events on the star that would have lasted for minutes to hours at a time. To any observers paying attention at the time, these flaring events would have appeared out of nowhere in the night sky, boosting the brightness of the red dwarf by a thousand times.
Although rare over evolutionary timescales, as this most recent discovery shows, close encounters with stars do happen regularly over galactic timescales and astronomers are working to spot any more stars that may have buzzed our solar system in the recent past or may do in the future.