NOAO >   Observing Info >   Approved Programs >   2016B-0076

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Program Information for 2016B-0076


PI: Nathan Smith, U. of Arizona, nathans@as.arizona.edu
Address: Department of Astronomy and Steward Observatory, 933 AVENUE, TUCSON, AZ 85721-0065 USA

Title: [Fe II] Kinematics of Magellanic Cloud Luminous Blue Variables

Abstract: We propose to use the Phoenix spectrograph on Gemini South to obtain high-resolution spectra of the circumstellar nebulae of luminous blue variables (LBVs) in the Magellanic Clouds. The goal of the observations is to provide a high precision (few km/s) measurement of the systemic velocities of these stars using the centroid velocities of slow-moving circumstellar nebulae. Visual-wavelength spectra of the central stars are not suitable to derive a precise systemic velocity because they are dominated by wind emission with broad P Cygni profiles. We have shown from previous low-resolution CTIO4m/OSIRIS spectra that LBV nebulae have bright emission from [Fe II] 16435 in the near-IR. The reason we are interested in the systemic velocities is because LBVs have anomolous environments: A recent study found that LBVs, which are the most luminous stars in any star-forming galaxy, actually show a surprising degree of isolation from other massive stars. This contradicts standard scenarios of massive star evolution that place LBVs in a brief transitional phase immediately following O stars and before He-burning Wolf-Rayet stars. The alternative hypothesis is that LBVs are preferentially the product of massive binary evolution, and that they may be isolated because they have received a kick from a companion's supernova. The expected kick speeds are small (10-20 km/s or less) and require high resolution. Our proposed observations will be a simple and direct test of this hypothesis.

Program Type: Standard/Galactic

Scheduled Nights:
Run 1 (2016B):  GEM-S-SVC/PHNX -- 30hrs band 2 (GS-2016B-Q-60)


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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