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An Updated Ephemeris for the Single-lined Orbit of the Supergiant μ Sagittarii

Johnson, Rachel A. and Richardson, Noel D. and Moffat, Anthony F. J. and Thomas, Joshua D. and Bohlsen, Terry and Cacella, Paulo and Heathcote, Bernard and Luckas, Paul and West, Julian and Couperus, Andrew and Dulaney, Nicholas A. and Fabian, Emily and Fowler, Carlie and Greco, Jennifer J. and Gullingsrud, Allison D. and Habel, Nolan and Hardegree-Ullman, Kevin K. and Kuchta, Heidi and Legeza, Scott and Maki, Courtney and McBride, Brendan and Mishra, Ashish and Oswald, Wayne and Peploski, Maurice and Trucks, Jesica and Windsor, James and Wood, Mackenna (2018) An Updated Ephemeris for the Single-lined Orbit of the Supergiant μ Sagittarii. Research Notes of the AAS, 2 (3). Art. No. 138. ISSN 2515-5172. doi:10.3847/2515-5172/aad6ed.

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μ Sagittarii (HD 166937, HR 6812) is a blue supergiant (B8Ia) in an eclipsing binary system. The stellar masses of evolved supergiants are ill-defined due, in part, to their rarity and long orbital periods when in binary systems. Most supergiants begin their lives as massive stars, which can typically be found in binary systems (Sana et al. 2012, 2014). Understanding the orbit and derived masses of these systems increases our understanding of their evolution, particularly with respect to both mass loss and transfer. In this research note, we present an updated orbit derived from 61 radial velocities collected between 1899 and 2017, including previous results from Campbell (1901), Frost & Adams (1904), Ichinohe (1907), Frost et al. (1926), and Buscombe (1963). We collected spectra with the University of Toledo's Ritter Observatory equipped with an échelle spectrograph, Clarkson University's Reynolds Observatory, and with personal telescopes equipped with amateur spectrographs such as the LHIRES III during 2016 and 2017. Data were reduced with standard techniques to subtract biases, darks, and remove pixel-to-pixel variations. The spectra were normalized individually and then stacked with respect to their instrument. This allowed them to be more easily compared to one another. Si IIλλ6347, 6371, Hα, and C  IIλλ6578, 6582 lines were recorded for the measurement of radial velocities and stellar wind activity. Both Hα and C ii were contaminated with telluric lines, so we measured the Si ii doublet in this research note, resulting in 35 new measurements of the radial velocity. We present our new radial velocity measurements in conjunction with the values from the aforementioned papers in Figure 1.

Item Type:Article
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URLURL TypeDescription
Richardson, Noel D.0000-0002-2806-9339
Greco, Jennifer J.0000-0002-4649-1568
Hardegree-Ullman, Kevin K.0000-0003-3702-0382
Wood, Mackenna0000-0003-2758-6155
Additional Information:© 2018 The American Astronomical Society. Received 2018 July 26; Accepted 2018 July 28; Published 2018 August 3. NDR acknowledges support from the Helen Brooks endowed professorship at the University of Toledo. We thank our amateur colleagues for their enthusiasm and dedication to this project, as well as Nancy Morrison for some data.
Group:Infrared Processing and Analysis Center (IPAC)
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University of ToledoUNSPECIFIED
Issue or Number:3
Record Number:CaltechAUTHORS:20180808-154347845
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Official Citation:Rachel A. Johnson et al 2018 Res. Notes AAS 2 138
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:88675
Deposited By: Tony Diaz
Deposited On:09 Aug 2018 15:01
Last Modified:16 Nov 2021 00:28

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