NOAO >   Observing Info >   Approved Programs >   2015A-0067

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Program Information for 2015A-0067


PI: Kimberly A Herrmann, Penn State Mont Alto, kah259@psu.edu
Address: 1 Campus Drive, Mont Alto, Pennsylvania 17237 United States

CoI: Robin B Ciardullo, Pennsylvania State U.

Title: Planetary Nebula Kinematics of NGC 6946

Abstract: \centerline{Look at a spiral; what do you see? Stars zooming `round in the galaxy!} \centerline{Their motions indicate total mass, but how much is DM, stars, and gas?} \centerline{Study motions in and out; first find monochromatic stars- that's my kind.} \centerline{Find us, get our velocities, then: determine disk mass! I'm a PN!} Rotation curves indicate the total mass of spirals, but halo mass profiles cannot be decoupled from the visible disk mass using rotation curves alone. To break this disk-halo degeneracy, we have been imaging the disks of face-on spiral galaxies, identifying planetary nebulae (PNe) out to large numbers of scale lengths ($h_R$), performing follow- up PN spectroscopy to measure the z-component of the stellar velocity dispersion ($\sigma_z$), and converting these dispersion measurements into disk-mass estimates. Our results indicate that in the inner regions of spiral galaxies ($R < 3.5 h_R$), the values of $\sigma_z$ are generally consistent with those expected from a constant mass-to-light ratio ($M/L$), constant scale height disk. However, in the outer parts the properties diverge: in some objects, the constant $M/L$ behavior continues, while in others, $\sigma_z$ flattens out, either due to a increasing disk $M/L$ and$/$or a flaring disk scale height, and possibly due to the effects of satellite accretion. To date, we have imaged seven galaxies, and have performed follow-up PN spectroscopy on six of them. Here, we propose to use WIYN$+$Hydra to extend our PN spectroscopy to the final galaxy of our spiral sample, NGC~6946, where we have a sample of 235 PNe extending out past $7 h_R$.

Program Type: Standard/Extragalactic

Scheduled Nights:
Run 1 (2015A):  WIYN/HYDR -- 4n on Jun 12 - Jun 15 2015


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NOAO >   Observing Info >   Approved Programs >   2015A-0067

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