Free Astronomy Magazine January-February 2020

28 JANUARY-FEBRUARY 2020 EXOPLANETS sion between rocky planets within 1 AU of the stars, or the overheating of an ancient belt of cold dust caused either by its sliding towards the stars or by an increase in the flow of radiation emitted by one or both the stars themselves. To find out the cause of that abnormal ex- cess of infrared radiation, in 2011-2012, as- tronomers conducted further studies of BD +20 307 with the Herschel space telescope, and then again in 2015 with the airborne telescope SOFIA (acronym of Stratospheric Observatory for Infrared Astronomy). SOFIA is a 2.7-meter-diameter telescope housed in- side a modified Boeing 747 and equipped with various scientific instruments working at infrared wavelengths. In particular, the observations carried out with the Faint Ob- ject Infrared Camera for the SOFIA Tele- scope (FORCAST) provided the key to un- derstanding the origin of the material sur- rounding BD +20 307. The data collected by this instrument, in fact, showed an increase of approximately 10% in the infrared emissions between 8.8 and 12.5 microns in the last ten years, as compared to the first Spitzer measurements. Such signifi- cant growth in such a short timeframe is well T he SOFIA fly- ing observa- tory, with the open tailgate that reveals the 2.7-meter-diame- ter telescope for infrared astron- omy. With this instrument, the remnants of a collision between planets have been observed. [DLR/NASA] O n the left, a video presen- tation of SOFIA. At right, the mir- ror of the tele- scope housed in the fuselage of the Boeing 747. [DLR/NASA]