It’s (active?) galaxy season! We can peer farther than our Milky Way into the universe. Below are our challenge targets — and a mini astrophysics challenge along with those.
The first row; skill targets. Second row, a new active campaign and our famous T CrB.
3C273:
The red shift king (thanks Tom!)- at R≈100, take a spectrum of 3C 273 and identify broad emission features shifted from their normal wavelengths to measure its redshift. Even at low resolution, detecting these shifted bumps shows that this star-like object is actually a distant quasar moving away at high speed. Use stacking and long exposures.
NGC 4151:
At R≈600, take a spectrum of NGC 4151 and resolve the broad Halpha emission line alongside nearby narrow lines like [N II]. By comparing the width of the broad line to the narrow components, you can directly see the signature of the fast-moving gas in the active nucleus. This experiment reveals the presence of a supermassive black hole through its emission-line structure.
M81 :
A BPT experiment; at R≈2000, take two spectra of Messier 81: one tightly on the nucleus and one slightly off in the disk. Measure the Hα and [N II] lines in both spectra and compare their ratios—at this resolution you can cleanly separate them. If the nucleus shows a much higher [N II]/Hα ratio than the disk, you’ve directly detected LINER/AGN-like activity in M81 using your own data.
clear skies!
Matt
