Friday, 17 November 2017  


 

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Alycia J. Weinberger

Alycia Weinberger


In 2000 Alycia Weinberger was honored with the Annie Jump Cannon Award from the American Astronomical Society. The award, established in 1934, is given to outstanding postdoctoral astronomers for "significant research in astronomy." She was also cowinner of the 2000 Vainu Bappu Gold Medal of the Astronomical Society of India in recognition of her exceptional contributions as a young astronomer.

 

Mid-infrared imaging of the young star B Pictoris

Mid-infrared imaging of the young star ß Pictoris by Alycia Weinberger and colleagues reveals spatial asymmetries in its dusty circumstellar disk. Visible for the first time is an inner (within about 1 arcsecond, or 20 AU, of the star) warp in the disk (tilting at about 15° from upper left to lower right) that is aligned differently from a larger-scale warp seen in scattered light by the Hubble Space Telescope. At the top is a false-color image, at a wavelength of about 18 µm, of dust heated by the star to temperatures of 150-500 K; the bottom version of the image incorporates a deconvolution procedure to sharpen resolution.

Unfortunately, we can't go back in time to watch our infant solar system as it formed the planets we know so well today. The next best thing, as the work of astronomer Alycia Weinberger illustrates, is to study the disks surrounding nearby young stars as analogues to help us determine what the conditions for planet formation really are.

Young disks contain the raw materials for building planets, including lots of dust. This dust absorbs light from the star, heats up, and radiates in the infrared (IR), leaving a telltale signature for Weinberger to seek in looking for new disks. To determine how protoplanets form, Weinberger tries to measure how much dust there is over time around stars of different masses. The dust also reflects shorter wavelength light from the star. Weinberger uses this mirroring property of disks to determine their structures, finding such features as rings, gaps, and warps. Some of these distortions may be due to the influence of orbiting planets. For her many kinds of disk observations, she uses space-based and ground-based instruments, including two different imagers on the Hubble Space Telescope (HST), a midinfrared camera and spectrograph at the W. M. Keck Observatory in Hawaii, and now Carnegie's 6.5-meter Magellan telescopes at Las Campanas, Chile.

Weinberger also looks at the chemistry of disk dust at varying distances from the central star to discover how materials are formed and distributed during early planet formation. Using large ground-based telescopes for infrared spectra, she studies the distribution of silicate dust, an important constituent of our own solar system, in other disks. In addition, she was the Principal Investigator of an HST program to take visual spectra of dust disks, which had been nearly impossible in the past because of contamination of the disk region by scattered light from the central stars.

Weinberger is working with high-angular-resolution imaging techniques on large ground-based telescopes to remove the distorting effects of atmospheric turbulence. To study the orbital motions of binary stars, she uses the techniques of speckle imaging—where many short exposures of an object are subjected to algorithms, eliminating the atmospheric effects—and adaptive optics, where real-time corrections are made for the same purpose. Weinberger also collaborates on searches for massive planets and brown dwarfs around nearby stars and studies active galactic nuclei-massive black holes at the centers of galaxies.

SELECTED PUBLICATIONS

  • Weinberger, A. J., E. E. Becklin, and B. Zuckerman. 2003. The first spatially resolved mid-infrared spectra of ß Pictoris, Astrophys. J. Lett. 584, L33- L37.

  • Weinberger, A. J. 2002. Planetary disks: A dusty business, Science 295, 2027-2028.

  • Weinberger, A. J., E. E. Becklin, G. Schneider, E. I. Chiang, P. J. Lowrance, M. Silverstone, B. Zuckerman, D. C. Hines, and B. A. Smith. 2002. Infrared views of the TW Hydra disk, Astrophys. J. 566, 409-418.

  • Schneider, G., E. E. Becklin, B. A. Smith, A. J. Weinberger, M. Silverstone, and D. C. Hines. 2001. NICMOS coronagraphic observations of 55 Cancri, Astron. J. 121, 525-537.

  • Soifer, B. T., G. Neugebauer, K. Matthews, E. Egami, A. J. Weinberger, M. Ressler, N. Z. Scoville, S. R. Stolovy, J. J. Condon, and E. E. Becklin. 2001. High-resolution mid-infrared imaging of infrared-luminous starburst galaxies, Astron. J. 122, 1213-1237.

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