Africa-Press – Rwanda. Christian Aganze, a physics PhD student at University of California, San Diego in the US, was awarded the Beth Brown Memorial Award for his work on discovering faint stars out of the solar system.
He got the award at the 2020 National Society of Black Physicists (NSBP) conference in November 2020.
The Beth Brown Memorial Award recognises exceptional research presented by undergraduate and graduate students at the NSBP meeting, and is co-organised by NSBP and the American Astronomical Association (AAS).
Christian was cited for giving the Best Graduate Student Poster Presentation at the NSBP conference for his work titled “Searching for Distant Ultracool Dwarfs in Deep HST/WFC3 Survey”.
The Beth Brown Memorial award honours Dr. Beth Brown, the first African American woman to earn a PhD in 1998 from the University of Michigan’s astronomy department.
Brown made a significant impact on the field of astronomy, as a National Academy of Science & National Research Council Postdoctoral Research Fellow, an Astrophysics Fellow at NASA Goddard Space Flight Center, and a visiting Assistant Professor at Howard University. She passed away unexpectedly in 2008 aged 39 years.
Award recipients get complimentary registration at a future AAS meeting (including costs of travel) to present their research, and free membership as a student member or affiliate for one year.
They are also invited to present their research at Howard University and the University of Michigan, two of Dr. Beth Brown’s alma maters.
The ultra-cool dwarf data
Ultra-cool dwarfs are the lowest-mass stars and brown dwarfs –failed stars about the size of Jupiter, with a much larger mass but not quite large enough to become stars. They also have lower luminosity than stars.
They trace the structure, star-formation history and chemical evolution of the Milky Way (galaxy), due in part to the cooling evolution of non-fusing brown dwarfs.
According to the abstract of Aganze’s survey, the wide-field surveys using colour and light that have uncovered the majority of ultra-cool dwarfs currently known are generally limited to the local volume (distances < 100 pc) due to these objects’ faint luminosities.
The parsec (pc) is the unit of length used to measure the large astronomical object distances outside the solar system, approximately equal to 3.26 light-years equivalent to about 30.9 trillion kilometres.
To expand this sample, the survey searched for distant ultracool dwarfs in 0.5 square degrees of low-resolution near-infrared spectral survey data in the WFC3 Infrared Spectroscopic Parallel Survey (WISPS) and the 3D-HST parallel survey – an observation method.
The survey reported the discovery of 182 dwarfs in these samples, with spectro-photometric distances up to 2 kpc for L dwarfs and 400 pc for T dwarfs, implying that it discovered those astronomical objects from up to 2,000 times more distant locations compared to the common surveys.
WFC3 refers to the Wide Field Camera Three, the most used instrument on board the Hubble Space Telescope (HST), providing a broad range of high-quality imaging capabilities.
Some ultra-cool dwarfs could be habitable
In 2017, US’s National Aeronautics and Space Administration (NASA)’s Spitzer Space Telescope revealed the first known system of seven Earth-size planets around a single star – named TRAPPIST-1 star, which is classified as an ultra-cool dwarf.
The discovery sets a new record for the greatest number of habitable-zone planets found around a single star outside our solar system. All of these seven planets could have liquid water, which is key to life – under the right atmospheric conditions.
In contrast to our sun, the TRAPPIST-1 star – classified as an ultra-cool dwarf – is so cool that liquid water could survive on planets orbiting very close to it, closer than is possible on planets in our solar system.
Aganze is a graduate of Morehouse College (class of 2016) where he majored in physics.
His aspires to become a physics professor helping young people from economically disadvantaged backgrounds to pursue careers in physics and astronomy.
He is a member of the Cool Star Lab at the University of California, San Diego.
His research interests are in observational astronomy revolving around low-mass stars and exoplanets – planets that orbit around other stars apart from the Sun– and he is interested in characterising population statistics to investigate the Milky Way’s galactic structure and chemical history.
He is also interested in studying brown dwarfs atmospheres. Before pursuing research in astronomy he worked at Morehouse College where he examined fundamental properties of dye-sensitised solar cells.