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Time-domain astronomy

January 01, 1970

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. Changes over time may be due to movements or changes in the object itself. Common targets included are supernovae, pulsating stars, novas, flare stars, blazars and active galactic nuclei. Visible light time domain studies include OGLE, HAT-South, PanSTARRS, SkyMapper, ASAS, WASP, CRTS, GOTO and in a near future the LSST at the Vera C. Rubin Observatory.

Light curve of NGC 2525 after a supernova

Time-domain astronomy studies transient astronomical events, often shortened by astronomers to a transients as well as various types of variable stars, including periodic, quasi-periodic, and that of changing behavior or type. Other causes of time variability are asteroids, high proper motion stars, planetary transits and comets.

Transients characterize astronomical objects or phenomena whose duration of presentation may be from milliseconds 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.[1]

Time-domain astronomy also involves long-term studies of variable stars and their changes on the timescale of minutes to decades. Variability studied can be intrinsic, including periodic or semi-regular pulsating stars, young stellar objects, stars with outbursts, asteroseismology studies; or extrinsic, which results from eclipses (in binary stars, planetary transits), stellar rotation (in pulsars, spotted stars), or gravitational microlensing events.

Modern time-domain astronomy surveys often 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] Due to large fields of view required, the 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]

The importance of the time-domain astronomy was recognized in 2018 by German Astronomical Society by awarding a Karl Schwarzschild Medal to Andrzej Udalski for "pioneering contribution to the growth of a new field of astrophysics research, time-domain astronomy, which studies the variability of brightness and other parameters of objects in the universe in different time scales."[4] Also the 2017 Dan David Prize was awarded to the three leading researchers in the field of time-domain astronomy: Neil Gehrels (Swift Gamma-Ray Burst Mission),[5] Shrinivas Kulkarni (Palomar Transient Factory),[6] Andrzej Udalski (Optical Gravitational Lensing Experiment).[7]

History edit

Before the invention of telescopes, transient events that were visible to the naked eye, from within or near the Milky Way Galaxy, were very rare, and sometimes hundreds of years apart. However, such events were recorded in antiquity, such as the supernova in 1054 observed by Chinese, Japanese and Arab astronomers, and the event in 1572 known as "Tycho's Supernova" after Tycho Brahe, who studied it until it faded after two years.[8] Even though telescopes made it possible to see more distant events, their small fields of view – typically less than 1 square degree – meant that the chances of looking in the right place at the right time were low. Schmidt cameras and other astrographs with wide field were invented in the 20th century, but mostly used to survey the unchanging heavens.

Historically time domain astronomy has come to include appearance of comets and variable brightness of Cepheid-type variable stars.[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.[9]

The interest in transients has intensified when large CCD detectors started to be available to the astronomical community. As telescopes with larger fields of view and larger detectors come into use in the 1990s, first massive and regular survey observations were initiated - pioneered by the gravitational microlensing surveys such as Optical Gravitational Lensing Experiment and the MACHO Project. These efforts, beside the discovery of the microlensing events itself, resulted in the orders of magnitude more variable stars known to mankind.[10] [11] Subsequent, dedicated sky surveys such as the Palomar Transient Factory, the spacecraft Gaia and the LSST, focused on expanding the coverage of the sky monitoring to fainter objects, more optical filters and better positional and proper motions measurement capabilities. In 2022, the Gravitational-wave Optical Transient Observer (GOTO) began looking for collisions between neutron stars.[12]

The ability of modern instruments to observe in wavelengths invisible to the human eye (radio waves, infrared, ultraviolet, X-ray) increases the amount of information that may be obtained when a transient is studied.

In radio astronomy the LOFAR is looking for radio transients. Radio time domain studies have long included pulsars and scintillation. Projects to look for transients in X-ray and gamma rays include Cherenkov Telescope Array, eROSITA, AGILE, Fermi, HAWC, INTEGRAL, MAXI, Swift Gamma-Ray Burst Mission and Space Variable Objects Monitor. Gamma ray bursts are a well known high energy electromagnetic transient.[13] The proposed ULTRASAT satellite will observe a field of more than 200 square degrees continuously in an ultraviolet wavelength that is particularly important for detecting supernovae within minutes of their occurrence.

See also edit

References edit

  1. ^ Schmidt, Brian (20 April 2012). "Optical Transient Surveys". Proceedings of the International Astronomical Union. 7 (S285): 9–10. Bibcode:2012IAUS..285....9S. doi:10.1017/S1743921312000129.
  2. ^ a b 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. S2CID 11166899.
  4. ^ Press release from the Foundation for Polish Science
  5. ^ "Neil Gehrels". 17 August 2021.
  6. ^ "Shrinivas Kulkarni". 17 August 2021.
  7. ^ "Andrzej Udalski". 17 August 2021.
  8. ^ Lecture by Prof. Carolin Crawford, 2014, “The Transient Universe”
  9. ^ Drout, Maria (12 November 2012). "A Big Step Backward for Time Domain Astronomy". Astrobites. Retrieved 5 May 2013.
  10. ^ 68 000 variables in the Magellanic Clouds: K. Żebruń et al. (2001) Acta Astronomica, Vol. 51 (2001), No. 4
  11. ^ 200 000 variables toward the Galactic bulge, P. Woźniak et al. (2002) Acta Astronomica, Vol. 52 (2002), No. 2
  12. ^ Steeghs, D. T. H. "The Gravitational-wave Optical Transient Observer (GOTO): prototype performance and prospects for transient science". arXiv:2110.05539.
  13. ^ "Multi-Messenger Time Domain Astronomy Conference". Retrieved 5 May 2013.

Further reading edit

  • Vedrenne, G. & Atteia, J.-L. (2009). Gamma-Ray Bursts: The brightest explosions in the Universe. Springer. ISBN 978-3-540-39085-5.
  • Gezari, S.; Martin, D. C.; Forster, K.; Neill, J. D.; Huber, M.; Heckman, T.; Bianchi, L.; Morrissey, P.; Neff, S. G.; Seibert, M.; Schiminovich, D.; Wyder, T. K.; Burgett, W. S.; Chambers, K. C.; Kaiser, N.; Magnier, E. A.; Price, P. A.; Tonry, J. L. (2013). "Thegalextime Domain Survey. I. Selection and Classification of over a Thousand Ultraviolet Variable Sources". The Astrophysical Journal. 766 (1): 60. arXiv:1302.1581. Bibcode:2013ApJ...766...60G. doi:10.1088/0004-637X/766/1/60. S2CID 13841776.

External links edit

  • "Centre for Time-Domain Informatics". Retrieved 5 May 2013. "possible present URL of Centre for Time-Domain Informatics". Retrieved 4 September 2022.
  • Bernardini, E. (2011). "Astronomy in the Time Domain". Science. 331 (6018): 686–687. Bibcode:2011Sci...331..686B. doi:10.1126/science.1201365. ISSN 0036-8075. PMID 21212319. S2CID 206531635.
  • SIMBAD Astronomical Database
  • Sidoli, L. (2008). "Transient outburst mechanisms in Supergiant Fast X-ray Transients". arXiv:0809.3157 [astro-ph].

January 01, 1970
time, domain, astronomy, study, astronomical, objects, change, with, time, though, study, said, begin, with, galileo, letters, sunspots, term, refers, especially, variable, objects, beyond, solar, system, changes, over, time, movements, changes, object, itself. 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 Changes over time may be due to movements or changes in the object itself Common targets included are supernovae pulsating stars novas flare stars blazars and active galactic nuclei Visible light time domain studies include OGLE HAT South PanSTARRS SkyMapper ASAS WASP CRTS GOTO and in a near future the LSST at the Vera C Rubin Observatory Light curve of NGC 2525 after a supernova Time domain astronomy studies transient astronomical events often shortened by astronomers to a transients as well as various types of variable stars including periodic quasi periodic and that of changing behavior or type Other causes of time variability are asteroids high proper motion stars planetary transits and comets Transients characterize astronomical objects or phenomena whose duration of presentation may be from milliseconds 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 1 Time domain astronomy also involves long term studies of variable stars and their changes on the timescale of minutes to decades Variability studied can be intrinsic including periodic or semi regular pulsating stars young stellar objects stars with outbursts asteroseismology studies or extrinsic which results from eclipses in binary stars planetary transits stellar rotation in pulsars spotted stars or gravitational microlensing events Modern time domain astronomy surveys often 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 Due to large fields of view required the 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 The importance of the time domain astronomy was recognized in 2018 by German Astronomical Society by awarding a Karl Schwarzschild Medal to Andrzej Udalski for pioneering contribution to the growth of a new field of astrophysics research time domain astronomy which studies the variability of brightness and other parameters of objects in the universe in different time scales 4 Also the 2017 Dan David Prize was awarded to the three leading researchers in the field of time domain astronomy Neil Gehrels Swift Gamma Ray Burst Mission 5 Shrinivas Kulkarni Palomar Transient Factory 6 Andrzej Udalski Optical Gravitational Lensing Experiment 7 Contents 1 History 2 See also 3 References 4 Further reading 5 External linksHistory editBefore the invention of telescopes transient events that were visible to the naked eye from within or near the Milky Way Galaxy were very rare and sometimes hundreds of years apart However such events were recorded in antiquity such as the supernova in 1054 observed by Chinese Japanese and Arab astronomers and the event in 1572 known as Tycho s Supernova after Tycho Brahe who studied it until it faded after two years 8 Even though telescopes made it possible to see more distant events their small fields of view typically less than 1 square degree meant that the chances of looking in the right place at the right time were low Schmidt cameras and other astrographs with wide field were invented in the 20th century but mostly used to survey the unchanging heavens Historically time domain astronomy has come to include appearance of comets and variable brightness of Cepheid type variable stars 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 9 The interest in transients has intensified when large CCD detectors started to be available to the astronomical community As telescopes with larger fields of view and larger detectors come into use in the 1990s first massive and regular survey observations were initiated pioneered by the gravitational microlensing surveys such as Optical Gravitational Lensing Experiment and the MACHO Project These efforts beside the discovery of the microlensing events itself resulted in the orders of magnitude more variable stars known to mankind 10 11 Subsequent dedicated sky surveys such as the Palomar Transient Factory the spacecraft Gaia and the LSST focused on expanding the coverage of the sky monitoring to fainter objects more optical filters and better positional and proper motions measurement capabilities In 2022 the Gravitational wave Optical Transient Observer GOTO began looking for collisions between neutron stars 12 The ability of modern instruments to observe in wavelengths invisible to the human eye radio waves infrared ultraviolet X ray increases the amount of information that may be obtained when a transient is studied In radio astronomy the LOFAR is looking for radio transients Radio time domain studies have long included pulsars and scintillation Projects to look for transients in X ray and gamma rays include Cherenkov Telescope Array eROSITA AGILE Fermi HAWC INTEGRAL MAXI Swift Gamma Ray Burst Mission and Space Variable Objects Monitor Gamma ray bursts are a well known high energy electromagnetic transient 13 The proposed ULTRASAT satellite will observe a field of more than 200 square degrees continuously in an ultraviolet wavelength that is particularly important for detecting supernovae within minutes of their occurrence See also editList of gamma ray bursts Gravitational microlensing List of gravitational wave observations List of exoplanets detected by microlensing X ray transient Cataclysmic variable star Stellar pulsationReferences edit Schmidt Brian 20 April 2012 Optical Transient Surveys Proceedings of the International Astronomical Union 7 S285 9 10 Bibcode 2012IAUS 285 9S doi 10 1017 S1743921312000129 a b 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 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 S2CID 11166899 Press release from the Foundation for Polish Science Neil Gehrels 17 August 2021 Shrinivas Kulkarni 17 August 2021 Andrzej Udalski 17 August 2021 Lecture by Prof Carolin Crawford 2014 The Transient Universe Drout Maria 12 November 2012 A Big Step Backward for Time Domain Astronomy Astrobites Retrieved 5 May 2013 68 000 variables in the Magellanic Clouds K Zebrun et al 2001 Acta Astronomica Vol 51 2001 No 4 200 000 variables toward the Galactic bulge P Wozniak et al 2002 Acta Astronomica Vol 52 2002 No 2 Steeghs D T H The Gravitational wave Optical Transient Observer GOTO prototype performance and prospects for transient science arXiv 2110 05539 Multi Messenger Time Domain Astronomy Conference Retrieved 5 May 2013 Further reading editVedrenne G amp Atteia J L 2009 Gamma Ray Bursts The brightest explosions in the Universe Springer ISBN 978 3 540 39085 5 Gezari S Martin D C Forster K Neill J D Huber M Heckman T Bianchi L Morrissey P Neff S G Seibert M Schiminovich D Wyder T K Burgett W S Chambers K C Kaiser N Magnier E A Price P A Tonry J L 2013 Thegalextime Domain Survey I Selection and Classification of over a Thousand Ultraviolet Variable Sources The Astrophysical Journal 766 1 60 arXiv 1302 1581 Bibcode 2013ApJ 766 60G doi 10 1088 0004 637X 766 1 60 S2CID 13841776 External links edit Centre for Time Domain Informatics Retrieved 5 May 2013 possible present URL of Centre for Time Domain Informatics Retrieved 4 September 2022 Bernardini E 2011 Astronomy in the Time Domain Science 331 6018 686 687 Bibcode 2011Sci 331 686B doi 10 1126 science 1201365 ISSN 0036 8075 PMID 21212319 S2CID 206531635 SIMBAD Astronomical Database Sidoli L 2008 Transient outburst mechanisms in Supergiant Fast X ray Transients arXiv 0809 3157 astro ph Portals nbsp Astronomy nbsp Stars nbsp Spaceflight nbsp Outer space nbsp Solar System Retrieved from https en wikipedia org w index php title Time domain astronomy amp oldid 1225803185, wikipedia, wiki, book, books, library,

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