[astro] REU student description

[Heidi Newberg]

Here are some words for use in the SEI REU proposal.  Malik has agreed 
to contact our program monitor, I think Bolek has agreed to submit it 
(assuming our program monitor is positive), and Carlos has agreed to 
update the two CS sections to include this year's progress towards the 
outlined goals (he needs Bolek for forward last year's proposal to him).

Cheers,
Heidi


        In summer 2007 we hired Jacob Simones from University of 
Minnesota, Mankato.  He researched the distribution of luminosities of 
the F turnoff stars in old stellar populations using data he extracted 
from public SDSS databases.  We are currently using the F turnoff stars 
to trace the density of the stellar spheroid, and the distribution of 
intrinsic luminosities of these stars is important for estimating the 
distances to these stars given the observed brightness of each star.  He 
compared the SDSS data with the stellar spheroid populations used in the 
Bescancon^1 model of the galaxy and with the two-tailed Gaussian we had 
been using in our research.  He found that the Bescancon model was a 
very poor fit to the data and that our two-tailed Gaussian was better.  
Though not all all old stellar populations are identical, our single 
intrinsic luminosity distribution was better than expected.

       He participated in the activities of Rensselaer's NSF-funded 
physics REU site, including oral and poster presentations.  He traveled 
with Heidi Newberg to the American Astronomical Society Meeting in 
Austin, Texas to present a poster^2 on his results.  He has already been 
accepted to at least two graduate schools in physics/astronomy but has 
not yet selected where he will go.  We plan to submit a short paper on 
the interesting results that he has found.

       We propose to hire another astronomy student in summer 2008 who 
will study the three-dimensional structure of the Sagittarius dwarf 
tidal stream.  Our current maximum likelihood algorithm for finding 
streams analyzes a set of 2.5-degree wide stripes of the sky, which are 
oriented in the direction that the data was scanned.  We have already 
run our algorithm on sections of the sky that contain the Sagittarius 
dwarf tidal stream and have traced the path of the center of this 
stream.  The specific task would be to select 2.5-degree wide stripes of 
the sky that are perpendicular to the path of the stream so that we can 
study the distribution of stream stars in cross section.  Our maximum 
likelihood algorithm currently assumes that the cross sectional density 
profile is Gaussian.  We will test how well this approximates the 
density profile and at the same time provide new information about the 
structure of this tidal stream which will be important both for guiding 
our maximum likelihood algorithm and for matching to N-body models of 
tidal disruption.

        The student will be invited to participate in writing up the 
results for publication and to travel to an American Astronomical 
Society meeting to present the results.  He or she will also present the 
results in a poster session for undergraduate researchers held locally 
at Rensselaer Polytechnic Institute.

1 Robin, A. C., Reyle, C., Derriere, S., Picaud, S., 2003, Astronomy and 
Astrophysics, 409, 523
2 Simones, J., Newberg, H., Cole, N., 2008, Bulletin of the American 
Astronomical Society, #104.03

-- 
Heidi Newberg <heidi at rpi.edu> (518) 276-2652
J-ROWL 1C25
Department of Physics, Applied Physics, and Astronomy
Rensselaer Polytechnic Institute
Troy, NY  12180
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