Poster Title

Analysis of stellar accretion of pre-main sequence stars

Research Mentor(s)

Kevin Covey

Affiliated Department

Astrophysics and Astronomy

Sort Order

03

Start Date

17-5-2017 12:00 PM

End Date

17-5-2017 3:00 PM

Document Type

Event

Abstract

Context: Young stars grow by accreting gas from a circumstellar disk. These stars also possess strong magnetic fields that channel the ionized gas from the disc down to the surface of the star. This infalling material creates a shock when it impacts the stellar surface, and then cools down by emitting photons corresponding to Hydrogen spectral lines as these atoms recombine. Measuring these emission lines can allow us to determine the mass accretion rate, temperature, and density of the material accreting onto these stars. Methods: We have created a catalogue of potential accreting young stars with spectra in the APOGEE Data Release 13. From each spectrum we calculate the “equivalent width” of the Brackett 11 Hydrogen emission line. The equivalent width is a measurement of the relative strength of a particular spectral feature relative to the local continuum. Using a equivalent width threshold of 1.2, we have found 2585 potential stars that exhibit a feature strong enough to distinguish from the surrounding continuum. When the locations of these stars are plotted, we find that they are located overwhelmingly in the galactic plane thereby supporting their status as young stars. Future Work: We are working now to measure Brn>11/Br11 line ratios which we plan to compare to current models of young stellar accretion. We will use these models to determine the temperature and density of the accretion streams, informing our understanding of pre-main sequence star evolution.

Comments

Outstanding Poster Award Recipient

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this documentation for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.

Language

English

Format

application/pdf

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May 17th, 12:00 PM May 17th, 3:00 PM

Analysis of stellar accretion of pre-main sequence stars

Astrophysics and Astronomy

Context: Young stars grow by accreting gas from a circumstellar disk. These stars also possess strong magnetic fields that channel the ionized gas from the disc down to the surface of the star. This infalling material creates a shock when it impacts the stellar surface, and then cools down by emitting photons corresponding to Hydrogen spectral lines as these atoms recombine. Measuring these emission lines can allow us to determine the mass accretion rate, temperature, and density of the material accreting onto these stars. Methods: We have created a catalogue of potential accreting young stars with spectra in the APOGEE Data Release 13. From each spectrum we calculate the “equivalent width” of the Brackett 11 Hydrogen emission line. The equivalent width is a measurement of the relative strength of a particular spectral feature relative to the local continuum. Using a equivalent width threshold of 1.2, we have found 2585 potential stars that exhibit a feature strong enough to distinguish from the surrounding continuum. When the locations of these stars are plotted, we find that they are located overwhelmingly in the galactic plane thereby supporting their status as young stars. Future Work: We are working now to measure Brn>11/Br11 line ratios which we plan to compare to current models of young stellar accretion. We will use these models to determine the temperature and density of the accretion streams, informing our understanding of pre-main sequence star evolution.