GeminiFocus October 2017 - Page 15

The very small number of BLAPs known so far points to a rare, unexplored episode in stellar evolution. This work is published in the journal Nature Astronomy, and is avail- able online (subscription required). The ar- ticle is also on astro-ph. The Little Star That Could … Survive a Supernova Explosion Astronomers have identified a white dwarf star in our solar neighborhood moving fast- er than the escape velocity of the Milky Way. The internation al team, led by Stephane Vennes (Astronomical Institute in the Czech Republic), used telescopes in Arizona and the Canary Islands, as well as the GRACES (Gemini Remote Access to CFHT ESPaDOnS) spectrograph atop Maunakea to study this celestial speedster, which is thought to have been expelled like shrapnel from a peculiar Type Ia supernova explosion some 50 mil- lion years ago. The speedy white dwarf, known as LP40-365, was first identified with the National Science Foundation’s (NSF) Mayall 4-meter telescope at Kitt Peak National Observatory in Arizona. Over the next two years, the discovery team received critical follow-up observations from the Canary Islands and Maunakea, which they analyzed using state-of-the-art com- puter codes. The analysis proved the star’s compact nature and exotic chemical com- position, as well as its extraordinary Galactic trajectory, which puts it on a path out of the Milky Way with no return. Astronomers once thought that nothing sur- vives a Type Ia supernova, which occurs in a binary system that includes a white dwarf. However, a new class of models called “Sub- luminous type Ia Supernova” (also known as type Iax) can leave a partially burned rem- nant that is instantly ejected at high velocity. LP40-365 is the first observational evidence that such high-velocity remnants of failed October 2017 Type Ia supernovae actually exist in our Gal- axy, and therefore it is an invaluable object to improve our understanding of these cos- mological standard candles. Many more of these objects may be lurking in the Milky Way and awaiting discovery. The recent European Space Agency’s Gaia mis- sion may well help us discover many more of these objects and help us understand how a little white dwarf star can survive a super- nova explosion. This research is published in the August 18, 2017, issue of Science. Gemini North Unmasks the Infrared Quintuplet The “Infrared Quintuplet” has long been a mystery to astronomers. These five infrared- luminous stars lie at the center of hundreds of hot and massive stars (collectively known as the Quintuplet Cluster) only 30 parsecs from the central supermassive black hole at the core of our Galaxy. Most objects in the center of the Milky Way are highly obscured from our view by intervening dust at visible wavelengths. The stars in the Infrared Quin- tuplet, however, are further obscured by their own dust shells. These warm, cocoon- like shells emit bright infrared continuum ra- diation, diluting any infrared light from the stars themselves. The combination of these effects has made it very challenging, if not impossible, at any infrared wavelength to detect light from the interiors of the shells … or so it was thought. As reported in the August 18, 2017, edition of The Astrophysical Journal, Gemini astron- omer Tom Geballe and his team used the Gemini Near-InfraRed Spectrometer (GNIRS) and Near-infrared Integral Field Spectrom- eter (NIFS) on the Gemini North telescope to penetrate the dusty cocoons of the Infrared Quintuplet and gather data on its members (Figure 2). GeminiFocus 13