A high-school student teamed up with a professional
astronomer to make observations of the remains of a star
explosion with NASA’s Rossi X-ray Timing Explorer (RXTE)
spacecraft. Harish Khandrika, an 11th grade student at La
Jolla High School, La Jolla, Calif., joined Dr. Richard
Rothschild of the University of California, San Diego, to
make the observations, winning a series of awards at the
Greater San Diego Science and Engineering Fair and the Intel
International Science and Engineering Fair, Louisville, Ky.

Khandrika, whose room is plastered with posters of stars and
planets, channeled his curiosity about space into an award-
winning science fair project by reaching out to astronomers
at the local university. “I am very passionate about studying
the universe,” said Khandrika. “Last summer, I knocked on the
doors of scientists at the Center for Astrophysics and Space
Sciences (CASS) at the University of California, San Diego,
to ask if anyone would be kind enough to let me work in his
or her laboratory. I expressed my interest in supernovae and
black holes to Dr. Gene Harding Smith, who directed me to Dr.
Rothschild. It was Dr. Rothschild who suggested I look at
data from RXTE.”

Star explosions, called supernovae, can outshine a billion
Suns, and are intimately connected to our origin since they
create and/or distribute life-sustaining elements into space.
A supernova hurls trillions of tons of elements into space in
an enormous cloud, called a supernova remnant. These elements
are incorporated into later generations of stars and planets,
and, ultimately, life.

Khandrika used RXTE to look for gamma rays emitted by
radioactive Titanium (Ti-44) in supernova remnant Cassiopeia
A. Ti-44 changes into other elements relatively quickly by
radioactive decay, so its presence in a supernova remnant
indicates that the star must have exploded recently. (Half a
given amount of Ti-44 will change into Scandium in about 59
years.) Khandrika established that the Ti-44 in Cassiopeia A
could not be above a certain amount, or its gamma-ray
emission would have been seen by RXTE.

The upper limit is consistent with an actual detection made
by other researchers during the same period using Beppo SAX,
an Italian spacecraft. The results indicate that the
supernova produced an amount of Ti-44 about equal to 40 times
the mass of the Earth, and that during the supernova, the
star’s core should have collapsed to form a neutron star, an
incredibly dense sphere with the mass of about half a million
Earths compressed to the diameter of a large city.

Khandrika enjoyed his research experience tremendously, and
hopes to become an astronomer. “I just loved it. I enjoyed my
work at CASS. It was a pleasure working with Dr. Rothschild.
He provided a lot of motivation and inspiration for me. I am
very happy that the work was recognized too. I hope to pursue
graduate studies in space sciences and be a space scientist,
trying to understand my place in this awesome vast expanse.
Maybe one day I will work for NASA!”

“I enjoyed working with Harish, who is a very motivated and
inquisitive student,” said Rothschild. “He worked very
independently, gathering information on stellar formation,
supernova events and remnants from the Web and from books
loaned to him. I was very impressed with his level of
understanding and his curiosity. We have begun a second
project for this summer — this time emission from a massive
black hole at the center of the active galaxy NGC 529A.”

Khandrika’s project received lots of attention at the San
Diego science fair, where it earned him the Sweepstakes
Award, First Place in Earth and Space Sciences, the San Diego
Astronomy Association Award, the Mt. Laguna Observatory
Association award, the General Atomics Fusion award and the
Hughes Network Systems award.

At the San Diego science fair, two senior division projects
are selected as best-of-fair projects (selected from the best
in each category) to receive the Sweepstakes Awards and to
represent the county at the Intel International Science and
Engineering Fair. The award includes a $2000 scholarship from
the Reuben H. Fleet Science Center, San Diego.

Khandrika’s success at the San Diego science fair led him to
the Intel science fair, where he won another award, the
American Astronomical Society (AAS) and the Astronomical
Society of the Pacific (ASP) Priscilla and Bart Bok Second

The Priscilla and Bart Bok Award is presented annually by AAS
and ASP for two outstanding astronomical projects at the
International Science and Engineering fair. The second award
consists of a $3,000 scholarship, and the student’s school
science department receives $1,000. Support for this award
has been provided by a grant from the National Science

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