Novae are thermonuclear explosions that occur on the surface of a white dwarf following the accretion of matter from a nearby companion star. The authors seek to understand the geometry and velocity of the ejected material.
Previous authors have claimed that the black hole at the center of NGC 1365 is spinning extremely rapidly. But these claims are based on certain assumptions about the dominance of relativistic effects on the spectrum of NGC 1365. Risaliti et al., dig deeper into the spectral data of this X-ray source and use simulations to determine whether the signatures we see are caused by a rapidly-spinning black hole, or just cloudy (galactic) weather.
Unlike its candy bar namesake, the center of our Milky Way Galaxy is not actually a very pleasant place to be. There’s a supermassive central black hole to deal with, intense radiation from a population of massive stars, and hot clouds of molecular gas. In this paper, the authors use observations of three molecular spectral lines to measure the temperatures of these gas clouds in the center of the Galaxy, and find that the processes heating the clouds may not be what you expect!
Everything in our galaxy is moving– you, the earth underneath you, the sun, other stars– everything. However, it turns out that figuring out how fast some of these things are moving is surprisingly difficult, and can have Galactic-sized implications!
How would the spectrum of the Earth change if our planet orbited a hotter or cooler star? Would alien astronomers still be able to detect signs of life?
Using new data from the MOSFIRE spectrograph, the authors of this paper test the ability of classic emission line diagnostics to separate star formation activity from supermassive black hole accretion at high redshift. What they find may be important for understanding how the growth galaxies and black holes affect one another over cosmic time.