Time domain astronomy

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Time domain astronomy is the study of how astronomical objects change with time. Though the study may be said to begin with Galileo's Letters on Sunspots , the term now refers especially to variable objects beyond the Solar System. This may be due to movement or changes in the object itself. Common targets included are supernovae, novas, flare stars, blazars and active galactic nuclei. Visible light time domain studies include HAT-South, the Large Synoptic Survey Telescope, PanSTARRS, SkyMapper, the Wide Angle Search for Planets and the Catalina Real-time Transient Survey.

In radio astronomy the LOFAR is looking for radio transients. Radio time domain studies have long included pulsars and scintillation. Cherenkov Telescope Array, eROSITA, AGILE, Fermi, HAWC, INTEGRAL, MAXI, Swift Gamma-Ray Burst Mission and Space Variable Objects Monitor will look for transients in X-ray and gamma rays. Gamma ray bursts are a well known high energy electromagnetic transient. [1]

Time domain astronomy uses robotic telescopes, automatic classification of transient events, and rapid notification of interested people. Blink comparators have long been used to detect differences between two photographic plates, and image subtraction became more used when digital photography eased the normalization of pairs of images. [2] Time domain work involves storing and transferring a huge amount of data. This includes data mining techniques, classification, and the handling of heterogeneous data. [3]

Historically time domain astronomy has come to include appearance of comets, and cepheid variable. [2] Old astronomical plates exposed from the 1880s through the early 1990s held by the Harvard College Observatory are being digitized by the DASCH project. [4]

Other causes of time variability are asteroids, eclipses, microlensing, planetary transits, and variable stars. [2]

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A transient astronomical event, often shortened by astronomers to a transient, is an astronomical object or phenomenon whose duration may be from seconds to days, weeks, or even several years. This is in contrast to the timescale of the millions or billions of years during which the galaxies and their component stars in our universe have evolved. Singularly, the term is used for violent deep-sky events, such as supernovae, novae, dwarf nova outbursts, gamma-ray bursts, and tidal disruption events, as well as gravitational microlensing, transits, eclipses, and comets. These events are part of the broader topic of time domain astronomy.

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Joshua Simon Bloom is an American astrophysicist, full professor of astronomy at the University of California, Berkeley, and was the CTO and co-founder of the machine-learning company wise.io. He received a Bachelor of Arts in astronomy and astrophysics and physics from the Harvard College in 1996, an M.Phil from Cambridge University in 1997, and a PhD in astronomy from the California Institute of Technology in 2002. He was a Junior Fellow of the Harvard Society of Fellows from 2002 to 2005. His astronomy research focuses on gamma-ray bursts and other astrophysical transients such as supernovae and tidal disruption events. He is author of the book What Are Gamma-Ray Bursts? published by Princeton University Press in 2011.

Anna N. Żytkow is a Polish astrophysicist working at the Institute of Astronomy of the University of Cambridge. Żytkow and Kip Thorne proposed a model for what is called the Thorne–Żytkow object, which is a star within another star. Żytkow in 2014 was part of the team led by Emily M. Levesque which discovered the first candidate for such an object.

ULTRASAT

ULTRASAT is an astronomical mini-satellite whose unprecedentedly large field of view, 210 square degrees, will detect and monitor transient astronomical events in the near-ultraviolet spectral region. ULTRASAT will observe a large patch of sky, alternating every six months between the southern and northern hemisphere. The satellite will be launched into geosynchronous orbit in 2023. All ULTRASAT data will be transmitted to the ground in real time. Upon detection of a transient event, ULTRASAT will provide alerts within 20 minutes to other ground-based and space telescopes to be directed to the source for further observation of the event in other wavelength bands.

The Space Variable Objects Monitor (SVOM) is a planned small X-ray telescope satellite under development by China National Space Administration (CNSA) and the French Space Agency (CNES), to be launched in June 2022.

References

  1. "Multi-Messenger Time Domain Astronomy Conference" . Retrieved 5 May 2013.
  2. 1 2 3 Schmidt, Brian (28 September 2011). "Transient Studies have played a key role in the history of Astronomy" (PDF). Retrieved 5 May 2013.[ permanent dead link ]
  3. Graham, Matthew J.S.; G. Djorgovski; Ashish Mahabal; Ciro Donalek; Andrew Drake; Giuseppe Longo (August 2012). "Data challenges of time domain astronomy". Distributed and Parallel Databases. 30 (5–6): 371–384. arXiv: 1208.2480 . doi:10.1007/s10619-012-7101-7.
  4. Drout, Maria (12 November 2012). "A Big Step Backward for Time Domain Astronomy". astrobites. Retrieved 5 May 2013.