Planetary nebulae ( PNe ) are an important tool for studying the dynamics and chemical evolution of galaxies in the Local Universe , given their characteristic , bright emission line spectra .
The Andromeda Galaxy ( M31 ) provides a unique laboratory for studying PNe in the circumnuclear region , thanks to its proximity and almost uniformly low line-of-sight extinction that ensures observations with high resolution and sensitivity .
Using the WIYN/Hydra multi-fiber spectrograph , we have obtained optical ( 4119–6882 Å ) spectra of 77 PN candidates selected from Hubble Space Telescope narrow-band imaging , which are located within the central \sim 500 pc region of M31 .
Among these candidates , 49 ( 64 % ) are spectroscopically observed for the first time .
The spectra of 300 previously known PNe and H ii regions , which primarily reside in the disk , are also taken for comparison .
All 77 circumnuclear PN candidates exhibit prominent emission lines , including [ O iii ] \lambda 5007 , [ N ii ] \lambda 6583 , H \alpha and H \beta , strongly suggesting that they are genuine PNe .
We measured the line fluxes , radial velocities and line widths for all objects , and found that the radial velocities of the circumnuclear PNe generally trace rotation of the inner bulge .
We also estimated a dynamical mass of \sim 6.4 \pm 0.5 \times 10 ^ { 9 } M _ { \odot } enclosed within an effective galactocentric radius of 340 pc , which is compatible with the previously estimated total stellar mass in this region .