Brugia Malayi - Clark Science Center - Smith College

Discovering Accretion Properties in Young Stars
Jenny Podel
T Tauri stars are only one million years old and are still surrounded by accretion disks that are in the early stage of planet
formation. Although we know that the power of the wind is proportional to the rate at which mass flows through the accretion
disk, we do not know where in the system the winds originate- from the star, from the disk, or the region at the interface between
the star and the disk.
I used a collection of high-resolution spectra of young stars taken with the Keck Telescopes using the optical HIRES and
the infrared NIRSPEC spectrographs. I analyzed this data with a fitting program DAVE 1 that ran through the IDL programming
environment. This allowed me to measure and study emission lines from hydrogen, helium, sodium, calcium, and iron, of which
my main focus was on the Helium I and calcium II transitions.
I created residual spectral emission line profiles, this means I removed the contributions from the stellar photosphere from
the emission lines by using a star of a similar spectral type as a template. Then I made multi-component Gaussian fits to the
residual profiles. It turned out something new arose in the HIRES data. Previously, it was published 2 that two Gaussian functions
could accurate represent the line profile, but with 1.5 X better resolution I discovered a third component was needed.
This will then be compared to different theories and models on star formation to find the density and temperature in the
line formation region. This will give me some clues for the to where these strong winds originate. The third component that I
discovered needs to be further investigated and added into theories to adjust their parameters to properly match the stellar data.
(Supported by the Schultz Foundation)
Advisor: Suzan Edwards
References:
1
DAVE Interface, Azuah, 2009, http://www.ncnr.nist.gov/dave/documentation.html.
2
Helium Emission from Classical T Tauri Stars: Dual Origin in Magnetospheric Infall and Hot Wind Georgina Beristain, Suzan Edwards, and John Kwan, Five
College Astronomy Department, Clark Science Center, Smith College, Northampton, MA 01063; sedwards@smith.edu, kwan@.umass.edu Received 2000
September 10; accepted 2000 December 8.
2012
3