Publications 2007

• (E) Martin, D. C.; Small, T.;  Schiminovich, D.; Wyder, T. K.; Pérez-González,
  P. G.;       Johnson, B.; Wolf, C.; Barlow, T. A.; Forster, K.; Friedman, P. G.;
  and 14 coauthors
  “The Star Formation and Extinction 0.05
  
  

Ongoing Research

G. Rieke continued to focus his research on data from Spitzer obtained under the
MIPS Guaranteed Time program. In the extragalactic area, we have completed an
initial study of the influence of the dense galaxy cluster environment on the
galaxy luminosity function. Surprisingly, we find luminosity functions that have
virtually the same shape and cosmic evolution as for the field, implying that
for most of the cluster volume the evolutionary effects are minor (work
primarily with L. Bai and D. Marcillac). We have also continued to refine
methods to identify active galactic nuclei using Spitzer data to supplement the
traditional samples derived from deep X-ray surveys. We found that many previous
studies may be significantly contaminated by luminous star forming galaxies. We
are developing this result further to place firm constraints on the proportion
of “missing” AGN that can be found by infrared methods (work with J. Donley). We
have developed a method to use Spitzer IRS spectra to determine the rate of star
formation in quasar host galaxies and used it to demonstrate that the hosts are
generally forming stars at a much higher rate than is the case for typical field
galaxies (work with Y. Shi).

G. Rieke and others continued with a broad study of circumstellar planetary
debris disks. We found that debris disk activity peaks at an age of 10-15Myr
before beginning its long decline (with T. Currie, S. Kenyon, Z. Balog). We
found that the overall pattern of this decline can be fitted to first order with
a model based on identical evolution of disks from starting points determined by
the mass distribution of protoplanetary disks (with M. Wyatt and K. Su). We
continue to find evidence, however, for individual eccentric disks that are
probably a result of departures from this overall trend. One example is that
binary stars have a tendency for a high incidence of disks (with D. Trilling et
al.). Another class is exceptionally massive disks that are occasionally found
in young stellar clusters, such as an object in the 30Myr-old cluster NGC 2547
(with N. Gorlova). The study of this cluster, however, has gathered attention
because of the relative rarity of such objects (1 or maybe 2 out of about 400
stars), implying that the kind of huge collision responsible for the formation
of our moon at a similar age for the Solar System is probably uncommon.

Publications 2007

• (E) Martin, D. C.; Small, T.;  Schiminovich, D.; Wyder, T. K.; Pérez-González,
  P. G.;       Johnson, B.; Wolf, C.; Barlow, T. A.; Forster, K.; Friedman, P. G.;
  and 14 coauthors “The Star Formation and Extinction 0.05
  
  

Ongoing Research

G. Rieke continued to focus his research on data from Spitzer obtained under the
MIPS Guaranteed Time program. In the extragalactic area, we have completed an
initial study of the influence of the dense galaxy cluster environment on the
galaxy luminosity function. Surprisingly, we find luminosity functions that have
virtually the same shape and cosmic evolution as for the field, implying that
for most of the cluster volume the evolutionary effects are minor (work
primarily with L. Bai and D. Marcillac). We have also continued to refine
methods to identify active galactic nuclei using Spitzer data to supplement the
traditional samples derived from deep X-ray surveys. We found that many previous
studies may be significantly contaminated by luminous star forming galaxies. We
are developing this result further to place firm constraints on the proportion
of “missing” AGN that can be found by infrared methods (work with J. Donley). We
have developed a method to use Spitzer IRS spectra to determine the rate of star
formation in quasar host galaxies and used it to demonstrate that the hosts are
generally forming stars at a much higher rate than is the case for typical field
galaxies (work with Y. Shi).

G. Rieke and others continued with a broad study of circumstellar planetary
debris disks. We found that debris disk activity peaks at an age of 10-15Myr
before beginning its long decline (with T. Currie, S. Kenyon, Z. Balog). We
found that the overall pattern of this decline can be fitted to first order with
a model based on identical evolution of disks from starting points determined by
the mass distribution of protoplanetary disks (with M. Wyatt and K. Su). We
continue to find evidence, however, for individual eccentric disks that are
probably a result of departures from this overall trend. One example is that
binary stars have a tendency for a high incidence of disks (with D. Trilling et
al.). Another class is exceptionally massive disks that are occasionally found
in young stellar clusters, such as an object in the 30Myr-old cluster NGC 2547
(with N. Gorlova). The study of this cluster, however, has gathered attention
because of the relative rarity of such objects (1 or maybe 2 out of about 400
stars), implying that the kind of huge collision responsible for the formation
of our moon at a similar age for the Solar System is probably uncommon.

Publications 2007

• (E) Martin, D. C.; Small, T.;  Schiminovich, D.; Wyder, T. K.; Pérez-González,
  P. G.;       Johnson, B.; Wolf, C.; Barlow, T. A.; Forster, K.; Friedman, P. G.;
  and 14 coauthors “The Star Formation and Extinction 0.05
  
  

Ongoing Research

G. Rieke continued to focus his research on data from Spitzer obtained under the
MIPS Guaranteed Time program. In the extragalactic area, we have completed an
initial study of the influence of the dense galaxy cluster environment on the
galaxy luminosity function. Surprisingly, we find luminosity functions that have
virtually the same shape and cosmic evolution as for the field, implying that
for most of the cluster volume the evolutionary effects are minor (work
primarily with L. Bai and D. Marcillac). We have also continued to refine
methods to identify active galactic nuclei using Spitzer data to supplement the
traditional samples derived from deep X-ray surveys. We found that many previous
studies may be significantly contaminated by luminous star forming galaxies. We
are developing this result further to place firm constraints on the proportion
of “missing” AGN that can be found by infrared methods (work with J. Donley). We
have developed a method to use Spitzer IRS spectra to determine the rate of star
formation in quasar host galaxies and used it to demonstrate that the hosts are
generally forming stars at a much higher rate than is the case for typical field
galaxies (work with Y. Shi).

G. Rieke and others continued with a broad study of circumstellar planetary
debris disks. We found that debris disk activity peaks at an age of 10-15Myr
before beginning its long decline (with T. Currie, S. Kenyon, Z. Balog). We
found that the overall pattern of this decline can be fitted to first order with
a model based on identical evolution of disks from starting points determined by
the mass distribution of protoplanetary disks (with M. Wyatt and K. Su). We
continue to find evidence, however, for individual eccentric disks that are
probably a result of departures from this overall trend. One example is that
binary stars have a tendency for a high incidence of disks (with D. Trilling et
al.). Another class is exceptionally massive disks that are occasionally found
in young stellar clusters, such as an object in the 30Myr-old cluster NGC 2547
(with N. Gorlova). The study of this cluster, however, has gathered attention
because of the relative rarity of such objects (1 or maybe 2 out of about 400
stars), implying that the kind of huge collision responsible for the formation
of our moon at a similar age for the Solar System is probably uncommon.