NOAO >   Observing Info >   Approved Programs >   2017B-0290

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Program Information for 2017B-0290


PI: Nicole Karnath, U. of Toledo, Nicole.Karnath@rockets.utoledo.edu
Address: Department of Physics and Astronomy, 2801 W BANCROFT AVE, TOLEDO, OH 43606 USA

CoI: Tom Megeath, U. of Toledo
CoI: John Tobin, U. of Oklahoma
CoI: Will Fischer, STScI
CoI: Manoj Puravankara, Tata Institute of Fundamental Research
CoI: Rohan Rahatgaonkar, U. of Toledo

Title: GNIRS Spectroscopy of Orion Protostars: Placing Constraints on the Initial Conditions of Pre-Main Sequence Contraction and the Ages of Young Stellar Populations

Abstract: We propose GNIRS K-band spectroscopy of 20 Orion protostars to detect photospheric features, accretion lines, and thereby determine their effective temperatures, intrinsic luminosities and radii. These data will characterize the properties of late stage protostars near the onset of pre-main sequence contraction, and calibrate the ages of derived from pre-main sequence tracks. These observations build on a multi-wavelength study of Orion protostars using Spitzer, HST, and Herschel. The HOPS collaboration has obtained well sampled 1.2-870 micron SEDs and high resolution HST data at 1.6 micron. While the envelopes of the protostars can be characterized by the SEDs and scattered light nebula in the images, near-IR spectroscopy is needed to study the central protostar themselves. Our observations of protostars with high dispersion (> 30,000) resolution spectrometers on 4 meter telescopes show that we can detect atomic and molecular lines needed to determine the temperatures of the photosphere and the accretion luminosity. These previous instruments allowed for higher spectral resolution but are limited to the brightest protostars in our sample. The sensitivity of GNIRS allows us to observe fainter protostars to extend the sample luminosities to below 1 solar luminosity, and thereby obtain a more representative sample. Using ALMA, we plan to determine masses for a sub-sample via keplerian rotation of protostellar disks. Using the masses from ALMA and the radii from this proposals, we will directly compare these to models of stellar birthlines and assess the initial conditions for pre-main sequence contraction.

Program Type: Standard/Galactic

Scheduled Nights:
Run 1 (2017B):  GEM-NQ/GNIRS -- 8.4hrs band 3 (GN-2017B-Q-67)


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NOAO >   Observing Info >   Approved Programs >   2017B-0290

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