June 09 | 2017
There happens to also be a class of stars that co-exist in a similar way. Data from our Chandra X-ray Observatory and other telescopes, is helping us understand how volatile this close stellar relationship can be. Located at a distance of about 710 light years from Earth, R Aquarii (R Aqr, for short) is one of the best known of the symbiotic stars. Changes in its brightness were first noticed with the naked eye almost a thousand years ago. Since then, astronomers have studied this object and determined that R Aqr is not one star, but two: a small, dense white dwarf and a cool red, giant star. Since shortly after Chandra launched in 1999, astronomers began using the X-ray telescope to monitor the behavior of R Aqr, giving them a better understanding in more recent years. Chandra data reveal a jet of X-ray emission that extends to the upper left. The X-rays have likely been generated by shock waves, similar to sonic booms around supersonic planes, caused by the jet striking surrounding material. Image credit: X-ray: NASA/CXC/SAO/R. Montez et al. ; Optical: Adam Block/Mt. Lemmon SkyCenter/U. Arizona
February 07 | 2018
Darker, cooler areas on the Sun – known as sunspots – have been absent for almost two weeks, as of Feb. 1.
February 06 | 2018
A single, tiny one appeared on Jan. 31, but even that is hard to see in this rotating view from our Solar Dynamics Observatory. The video shows a rotating sun in filtered light for the past week, but it is even hard to tell the sun is rotating since there are just about no features. This spotless period is a prelude to the approaching period of solar minimum next year, when the Sun’s activity will be at the low end of its 11-year cycle. Credit: NASA/SDO