2020A&A...641L...4O


C.D.S. - SIMBAD4 rel 1.7 - 2020.11.28CET21:29:00

2020A&A...641L...4O - Astronomy and Astrophysics, volume 641, L4-4 (2020/9-1)

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. and ZIEMKE J.

Abstract (from CDS):

The propagation of radio waves from distant compact radio sources through turbulent interstellar plasma in our Galaxy causes these sources to twinkle, 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. an intensity modulation of a few percent) 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 interstellar plasma of the Milky Way. So far, only three sources were known that show more extreme variations, with modulations at the level of some dozen percent on timescales shorter than an hour. This requires propagation through nearby (d≤10pc) anomalously dense (ne∼102cm–3) 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 min in the decimetre band (1.4GHz). The spatial scintillation pattern is highly anisotropic, with a semi-minor axis of about 20000km. The canonical theory of refractive scintillation constrains the scattering plasma to be within the Oort cloud. The sightline to J1402+5347, however, passes unusually close to the B3 star Alkaid (η 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 ≃10µas, yielding an apparent brightness temperature for an isotropic source of ≥1014K.

Abstract Copyright: © ESO 2020

Journal keyword(s): scattering - ISM: clouds

VizieR on-line data: <Available at CDS (J/A+A/641/L4): 09-04-19.dat 11-05-19.dat 08-06-19.dat 07-08-19.dat 12-07-19.dat 13-09-19.dat 10-10-19.dat 04-11-19.dat 07-12-19.dat 06-01-20.dat 28-01-20.dat 02-03-20.dat>

Status at CDS : Examining the need for a new acronym.

Simbad objects: 7

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Number of rows : 7

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 ICRF J054236.1+495107 Sy1 05 42 36.13789843 +49 51 07.2337251   18.45 17.80 17.210   ~ 1287 1
2 * alf Vir bC* 13 25 11.57937 -11 09 40.7501 -0.20 0.74 0.97 1.06 1.30 B1V 826 2
3 * eta UMa PM* 13 47 32.43776 +49 18 47.7602 0.99 1.67 1.86 1.98 2.16 B3V 581 0
4 M 101 GiP 14 03 12.583 +54 20 55.50   8.46 7.86 7.76   ~ 2579 2
5 3C 295 Sy2 14 11 20.467 +52 12 09.52   22.34 20.80 18.54   ~ 905 5
6 * alf Lyr dS* 18 36 56.33635 +38 47 01.2802 0.03 0.03 0.03 0.07 0.10 A0Va 2526 0
7 NGC 7293 PN 22 29 38.5453078023 -20 50 13.746093105 11.894 13.158 13.524 13.689 13.898 DAO.5 905 0

    Equat.    Gal    SGal    Ecl

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2020.11.28-21:29:00

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