2010A&A...521A..32S


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.03CET10:34:27

2010A&A...521A..32S - Astronomy and Astrophysics, volume 521, A32-32 (2010/10-1)

Recurring millimeter flares as evidence for star-star magnetic reconnection events in the DQ Tauri PMS binary system.

SALTER D.M., KOSPAL A., GETMAN K.V., HOGERHEIJDE M.R., VAN KEMPEN T.A., CARPENTER J.M., BLAKE G.A. and WILNER D.

Abstract (from CDS):

Observations of the T Tauri spectroscopic binary DQ Tau in April 2008 captured an unusual flare at 3mm, which peaked at an observed maximum flux of ∼0.5Jy (about 27 times the quiescent value). Here we present follow-up millimeter observations that demonstrate a periodicity to the phenomenon. While monitoring 3 new periastron encounters, we have detected flares within 17.5h (or 4.6%) of the orbital phase of the first reported flare and constrained the main emitting region to a stellar height of 3.7-6.8R*. The recorded activity is consistent with the proposed picture for synchrotron emission initiated by a magnetic reconnection event when the two stellar magnetospheres of the highly eccentric (e=0.556) binary are believed to collide near periastron as the stars approach a minimum separation of 8R*(∼13R). The similar light curve decay profiles allow us to estimate an average flare duration of 30 h. Assuming one millimeter flare per orbit, DQ Tau could spend approximately 8% of its 15.8-day orbital period in an elevated flux state. These findings continue to serve as a small caution for millimeter flux points in spectral energy distributions that could contain unrecognized flare contributions. Our analysis of the millimeter emission provides an upper limit of 5% on the linear polarization. We discuss the extent to which a severely entangled magnetic field structure and Faraday rotation effects are likely to reduce the observed polarization fraction. We also predict that, for the current picture, the stellar magnetospheres must be misaligned at a significant angle or, alternatively, that the topologies of the outer magnetospheres are poorly described by a well-ordered dipole inside a radius of 7R*. Finally, to investigate whether reorganization of the magnetic field during the interaction affects mass accretion, we also present simultaneous optical (VRI) monitoring of the binary, as an established tracer of accretion activity in this system. We find that an accretion event can occur coincident in both time and duration with the synchrotron fallout of a magnetic reconnection event. While the pulsed accretion mechanism has been attributed previously to the dynamical motions of the stars alone, the similarities between the millimeter and optical light curves evoke the possibility of a causal or co-dependent relationship between the magnetospheric and dynamical processes.

Abstract Copyright:

Journal keyword(s): stars: individual: DQ Tau - stars: pre-main sequence - binaries: spectroscopic - stars: flare - stars: magnetic field - radio continuum: stars

CDS comments: Table A.2, Fig. A.1 : comparison stars not in Simbad.

Simbad objects: 14

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Number of rows : 14

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 3C 84 Sy2 03 19 48.1597607660 +41 30 42.114155434   13.10 12.48 11.09   ~ 3620 3
2 GD 50 WD* 03 48 50.1861716368 -00 58 32.290158840 12.596 13.787 14.063 14.210 14.388 DA1.2 239 0
3 HD 283447 Or* 04 14 12.9232870093 +28 12 12.378540314 13.17 12.07 10.68 9.45 8.67 K3Ve 386 0
4 QSO B0420-0127 QSO 04 23 15.80072776 -01 20 33.0654034   17.50 17.00 16.28   ~ 1084 3
5 ICRF J044021.1+143756 QSO 04 40 21.1393890 +14 37 56.951149           ~ 32 1
6 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 3646 0
7 V* DQ Tau Or* 04 46 53.0577037389 +17 00 00.135310040 14.56 13.67 12.00 13.21   M1Ve 299 0
8 QSO B0446+113 BLL 04 49 07.67110088 +11 21 28.5964577     20 18.58   ~ 230 1
9 QSO B0507+179 QSO 05 10 02.36912982 +18 00 41.5816534   20.0 19.0 19.09   ~ 339 1
10 QSO J0530+13 Bla 05 30 56.41672 +13 31 55.1495     20.0 19.35   ~ 893 1
11 COUP 450 TT* 05 35 11.8040700 -05 21 49.266135           K5V 53 0
12 HD 65079 Be* 07 57 03.9943098835 +02 57 03.043441437 6.93 7.62 7.77     B2V(n)(e?) 57 0
13 3C 273 BLL 12 29 06.6996828061 +02 03 08.598846466   13.05 14.830 14.11   ~ 5405 1
14 EM* SR 9 Or* 16 27 40.2858402419 -24 22 04.132012501   12.91 11.533 11.11 10.00 K5e 259 0

    Equat.    Gal    SGal    Ecl

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