Calán/Tololo Survey

The Calán/Tololo Supernova Survey was a supernova survey that ran from 1989-1995 at the University of Chile and the Cerro Tololo Inter-American Observatory[1] to measure a Hubble diagram out to redshifts of 0.1. It was founded by Mario Hamuy, Jose Maza, Mark M. Phillips, and Nicholas B. Suntzeff in 1989 out of discussions at the UC Santa Cruz meeting on supernovae on how to improve the Hubble diagram using Type Ia supernovae.[2] It was also motivated by the suggestion of Allan Sandage to restart a supernova survey after the Sandage and Tammann survey failed due to poor quality photographic plates in 1986. The Survey built on the original supernova survey of Maza done at the f/3 Maksutov Camera at the Cerro Roble Observatory of the University of Chile between 1979 and 1984.[3] The Survey used the CTIO Curtis Schmidt telescope with IIa-O photographic plates, each plate covering a field of 25 sq-deg on the sky. The plates were developed and sent to Santiago Chile the next morning, and searched for supernovae at the Department of Astronomy[4] at the University of Chile. Any supernova candidates were then observed the next night using the 0.9m telescope at CTIO with a CCD camera. This was one of the first studies done in astronomy where the telescope time was scheduled to observe objects not yet discovered.

The survey discovered 50 supernovae between 1990 and 1993, of which 32 were Type Ia supernovae. The survey provided a uniform photometric and spectroscopic dataset of all classes of supernovae, which led to the discovery of a method of using Type Ia supernovae as standard candles, the Phillips relationship,[5][6] as well as providing data for a Hubble diagram of Type II supernovae using the Expanding Photosphere method.[7]

The calibration of Type Ia supernovae as standard candles led to the precise measurements of the Hubble Constant H0[8][9] and the deceleration parameter q0,[10] the latter indicating the presence of a dark energy or cosmological constant dominating the mass/energy of the Universe.

Calan Tololo Team Members
The original team members of the Calan/Tololo Survey. Left to right: Mark M. Phillips, Nicholas Suntzeff, José Maza Sancho, Mario Hamuy, 2012.
Calán/Tololo Survey

References

  1. ^ Hamuy, M. et al. 1993, Astronomical Journal, 106, 2392
  2. ^ Leibundgut, B. 1991, Supernovae Type-Ia as Standard Candles, Supernovae. The Tenth Santa Cruz Workshop in Astronomy and Astrophysics, held July 9–21, 1989, Lick Observatory. Editor, S.E. Woosley; Springer-Verlag, New York, p.1751
  3. ^ Maza, J. et al. 1981, Publications of the Astronomical Society of the Pacific, 93, 239
  4. ^ Department of Astronomy, UChile
  5. ^ Phillips, M. M. 1993, Astrophysical Journal Letters",413, 105
  6. ^ Hamuy, M. et al. 1993, Astronomical Journal, 106, 2392
  7. ^ Schmidt, B. P., et al. 1994, Astrophysical Journal, 432, 32
  8. ^ Suntzeff, N.B. et al. 1999, Astronomical Journal, 119, 1175
  9. ^ Freedman, W. et al. 2001, Astrophysical Journal, 553, 47
  10. ^ Riess, A. et al. 1998, Astronomical Journal, 119, 1009; Schmidt, B. P., et al. 1998, Astrophysical Journal, 507, 46; see also Perlmutter, S. et al. 1999, Astrophysical Journal, 517, 565
Adam Riess

Adam Guy Riess (born December 16, 1969) is an American astrophysicist and Bloomberg Distinguished Professor at Johns Hopkins University and the Space Telescope Science Institute and is known for his research in using supernovae as cosmological probes. Riess shared both the 2006 Shaw Prize in Astronomy and the 2011 Nobel Prize in Physics with Saul Perlmutter and Brian P. Schmidt for providing evidence that the expansion of the universe is accelerating.

Cerro Tololo Inter-American Observatory

The Cerro Tololo Inter-American Observatory (CTIO) is an astronomical observatory located on Cerro Tololo in the Coquimbo Region of northern Chile, with additional facilities located on Cerro Pachón about 10 kilometres (6.2 mi) to the southeast. It is within the Coquimbo Region and approximately 80 kilometres (50 mi) east of La Serena, where support facilities are located. The site was identified by a team of scientists from Chile and the United States in 1959, and it was selected in 1962. Construction began in 1963 and regular astronomical observations commenced in 1965. Construction of large buildings on Cerro Tololo ended with the completion of the Víctor Blanco Telescope in 1974, but smaller facilities have been built since then. Cerro Pachón is still under development, with two large telescopes inaugurated since 2000, and one in the early stages of construction.

The principal telescopes at CTIO are the 4 m Víctor M. Blanco Telescope, named after Puerto Rican astronomer Victor Manuel Blanco, and the 4.1 m Southern Astrophysical Research (SOAR) telescope, which is situated on Cerro Pachón. Other telescopes on Cerro Tololo include the 1.5 m, 1.3 m, 1.0 m, and 0.9 m telescopes operated by the SMARTS consortium. CTIO also hosts other research projects, such as PROMPT, WHAM, and LCOGTN, providing a platform for access to the southern hemisphere for U.S. and worldwide scientific research.

Nicholas B. Suntzeff

Nicholas B. Suntzeff (born November 22, 1952, San Francisco) is an American University Distinguished Professor and holds the Mitchell/Heep/Munnerlyn Chair of Observational Astronomy in the Department of Physics & Astronomy at Texas A&M University where he is Director of the Astronomy Program. He is an observational astronomer specializing in cosmology, supernovae, stellar populations, and astronomical instrumentation. With Brian Schmidt he founded the High-z Supernova Search Team, which was honored with the Nobel Prize in Physics in 2011 to Schmidt and Adam Riess.

Supernova

A supernova ( plural: supernovae or supernovas, abbreviations: SN and SNe) is a transient astronomical event that occurs during the last stellar evolutionary stages of the life of a massive star, whose dramatic and catastrophic destruction is marked by one final, titanic explosion. This causes the sudden appearance of a "new" bright star, before slowly fading from sight over several weeks or months or years.

Supernovae are more energetic than novae. In Latin, nova means "new", referring astronomically to what appears to be a temporary new bright star. Adding the prefix "super-" distinguishes supernovae from ordinary novae, which are far less luminous. The word supernova was coined by Walter Baade and Fritz Zwicky in 1931.

Only three Milky Way, naked-eye supernova events have been observed during the last thousand years, though many have been observed in other galaxies. The most recent directly observed supernova in the Milky Way was Kepler's Supernova in 1604, but the remnants of recent supernovae have also been found. Observations of supernovae in other galaxies suggest they occur on average about three times every century in the Milky Way, and that any galactic supernova would almost certainly be observable with modern astronomical telescopes.

Theoretical studies indicate that most supernovae are triggered by one of two basic mechanisms: the sudden re-ignition of nuclear fusion in a degenerate star or the sudden gravitational collapse of a massive star's core. In the first instance, a degenerate white dwarf may accumulate sufficient material from a binary companion, either through accretion or via a merger, to raise its core temperature enough to trigger runaway nuclear fusion, completely disrupting the star. In the second case, the core of a massive star may undergo sudden gravitational collapse, releasing gravitational potential energy as a supernova. While some observed supernovae are more complex than these two simplified theories, the astrophysical mechanics have been established and accepted by most astronomers for some time.

Supernovae can expel several solar masses of material at speeds up to several percent of the speed of light. This drives an expanding and fast-moving shock wave into the surrounding interstellar medium, sweeping up an expanding shell of gas and dust observed as a supernova remnant. Supernovae are a major source of elements in the interstellar medium from oxygen through to rubidium. The expanding shock waves of supernova can trigger the formation of new stars. Supernova remnants might be a major source of cosmic rays. Supernovae might produce strong gravitational waves, though, thus far, the gravitational waves detected have been from the merger of black holes and neutron stars.

Timothy Schrabback

Tim Richard Walter Schrabback–Krahe is KIPAC Fellow at the Kavli Institute of Particle Astrophysics and Cosmology, which is based at Stanford University. He is working within the X-ray Astronomy and Observational Cosmology Group. His research focuses on weak gravitational lensing and its applications for cosmology and astrophysics.

•CFHTLens

•Euclid

•The MAD Cluster SurveyWorking within the Leiden Observatory,he led a team of scientists conducting an intensive study of over 446 000 galaxies within the COSMOS survey field, the result of the largest survey ever conducted with Hubble,showing independent confirmation that the expansion of the Universe is accelerated by an additional, mysterious component named dark energy. A handful of other such independent confirmations exist.

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