Lunch talk on Jun. 15th, 2018

Planetary Nebulae in the Circumnuclear Region of M31: Identification and Spectroscopic Observation

Speaker:李安琪（南京大学）/ Anqi Li (Nanjing University)

Venue:Gewu 4410

Time:12:30 PM, Friday, 15th June, 2018

Abstract:Understanding the circumnuclear region of galaxies is crucial for the study of galaxy formation and evolution. Thanks to its proximity and low line-of-sight extinction that ensure observations with high resolution and sensitivity, M31 provides a unique laboratory of studing the circumnuclear region. With its wide distribution and strong emission lines, planetary nebulae (PNe) become an important tool for studing the dynamics and chemical evolution of galaxies in the local Universe. By constrasting narrow band images from HST/WFC3 filter F502N and F547M, we found 249 PNe candidates, which are located within the central ~ 500 pc region of M31, and obtained their m5007. Using the WIYN/Hydra multi-fiber spectrograph, we obtained optical (4119 - 6882 Angstroms) spectra of 77 PN candidates. The spectra of 300 previously known PNe and HII regions, which primarily reside in the disk, are also taken for comparison. All 77 circumnuclear PN candidates exhibit prominent emission lines, especially [OIII]λ5007, strongly suggesting that they are genuine PNe. We derive and present line intensities, radial velocities and line widths for all objects. We find that the radial velocities of the circumnuclear PNe trace rotation of the inner bulge. We also estimate a dynamical mass of (6.4±0.5)×10⁹M_⊙enclosed within an effective deprojected galactocentric radius of 340 pc, which is compatible with previously estimated stellar mass in this region.

Personal Information:

李安琪，女，2015年在南京大学天文与空间科学学院获学士学位，2018年获硕士学位。主要从事光学光谱观测、行星状星云、超新星遗迹等方面的研究。