J/A+A/641/L4 Radio source J1402+5347 1.4GHz light curves (Oosterloo+, 2020)
Extreme intra-hour variability of the radio source J1402+5347 discovered with
Apertif.
Oosterloo T.A., Vedantham H.K., Kutkin A.M., Adams E.A.K., Adebahr B.,
Coolen A.H.W.M., Damstra S., de Blok W.J.G., Denes H., Hess K.M., Hut B.,
Loose G.M., Lucero D.M., Maan Y., Morganti R., Moss V.A., Mulder H.,
Norden M.J., Offringa A.R., Oostrum L.C., Orru E., Ruiter M., Schulz R.,
van den Brink R.H., van der Hulst J.M., van Leeuwen J., Vermaas N.J.,
Vohl D., Wijnholds S.J., Ziemke J.
<Astron. Astrophys. 641, L4 (2020)>
=2020A&A...641L...4O 2020A&A...641L...4O (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Radio sources ; Interstellar medium
Keywords: scattering - ISM: clouds - quasars: individual: J1402+5347
Abstract:
Propagation of the radio waves from distant compact radio sources
through turbulent interstellar plasma in our Galaxy leads to twinkling
of these sources, a phenomenon called interstellar scintillation. Such
scintillations are a unique probe of the micro-arcsecond structure of
radio sources as well as of the sub-AU-scale structure of the Galactic
interstellar medium. Weak scintillations (i.e. intensity modulation of
a few per cent) on timescales of a few days or longer are commonly
seen at centimetre wavelengths and are thought to result from the
line-of-sight integrated turbulence in the Milky Way's interstellar
plasma. So far, only three sources were known that show more extreme
variations, with modulations at the level of tens of per cent on
timescales less than an hour. This requires propagation through nearby
(d≲10pc) anomalously dense (ne>102cm3) plasma clouds. Here we
report the discovery with Apertif of a source (J1402+5347) showing
extreme (∼50%) and rapid variations on a timescale of just 6.5 minutes
in the decimetre band (1.4GHz). The spatial scintillation pattern is
highly anisotropic with a semi-minor axis of about 20,000 km.
Canonical theory of refractive scintillation constrains the scattering
plasma to be within the Oort cloud. The sight-line to J1402+5347
however passes unusually close to the B3 star Alkaid (eta UMa) at a
distance of 32pc. If the scintillations are associated with Alkaid,
then the angular size of J1402+5347 along the minor-axis of the
scintels must be smaller than 10 microarcseconds yielding an apparent
brightness temperature for an isotropic source of >1014K.
Description:
Lightcurves of J1402+5347 taken with Westerbork Synthesis Radio
Telescope at 1.4GHz.
Objects:
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RA (2000) DE Designation(s)
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14 02 43.6 +53 47 11 J1402+5347
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
09-04-19.dat 23 654 Light curve of Apr 9, 2019
11-05-19.dat 23 704 Light curve of May 11, 2019
08-06-19.dat 23 674 Light curve of June 8, 2019
07-08-19.dat 23 674 Light curve of July 7, 2019
12-07-19.dat 23 667 Light curve of August 7, 2019
13-09-19.dat 23 674 Light curve of September 13, 2019
10-10-19.dat 23 670 Light curve of October 10, 2019
04-11-19.dat 23 674 Light curve of November 4, 201
07-12-19.dat 23 672 Light curve of December 7, 2019
06-01-20.dat 23 666 Light curve of January 6, 2020
28-01-20.dat 23 667 Light curve of January 28, 2020
02-03-20.dat 23 674 Light curve of March 2, 2020
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Byte-by-byte Description of file: *.dat
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Bytes Format Units Label Explanations
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1- 14 F14.6 d JD Julian Date of data point
16- 23 F8.6 Jy Flux Flux density at 1.4GHz
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Acknowledgements:
Tom Oosterloo, oosterloo(at)astron.nl
(End) T. Oosterloo [Astron, the Netherlands], P. Vannier [CDS] 18-Aug-2020