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J/ApJ/835/8   UBVR photometry of the T Tauri binary DQ Tau   (Tofflemire+, 2017)

Accretion and magnetic reconnection in the classical T Tauri binary DQ Tau. Tofflemire B.M., Mathieu R.D., Ardila D.R., Akeson R.L., Ciardi D.R., Johns-Krull C., Herczeg G.J., Quijano-Vodniza A. <Astrophys. J., 835, 8-8 (2017)> =2017ApJ...835....8T (SIMBAD/NED BibCode)
ADC_Keywords: Photometry, UBVRI ; YSOs ; Stars, double and multiple Keywords: accretion, accretion disks; binaries: close; stars: individual: DQ Tau; stars: formation Abstract: The theory of binary star formation predicts that close binaries (a<100au) will experience periodic pulsed accretion events as streams of material form at the inner edge of a circumbinary disk (CBD), cross a dynamically cleared gap, and feed circumstellar disks or accrete directly onto the stars. The archetype for the pulsed accretion theory is the eccentric, short-period, classical T Tauri binary DQ Tau. Low-cadence (∼daily) broadband photometry has shown brightening events near most periastron passages, just as numerical simulations would predict for an eccentric binary. Magnetic reconnection events (flares) during the collision of stellar magnetospheres near periastron could, however, produce the same periodic, broadband behavior when observed at a one-day cadence. To reveal the dominant physical mechanism seen in DQ Tau's low-cadence observations, we have obtained continuous, moderate-cadence, multiband photometry over 10 orbital periods, supplemented with 27 nights of minute-cadence photometry centered on four separate periastron passages. While both accretion and stellar flares are present, the dominant timescale and morphology of brightening events are characteristic of accretion. On average, the mass accretion rate increases by a factor of five near periastron, in good agreement with recent models. Large variability is observed in the morphology and amplitude of accretion events from orbit to orbit. We argue that this is due to the absence of stable circumstellar disks around each star, compounded by inhomogeneities at the inner edge of the CBD and within the accretion streams themselves. Quasiperiodic apastron accretion events are also observed, which are not predicted by binary accretion theory. Description: The Las Cumbres Observatories Global Telescope (LCOGT) 1m network consists of nine 1m telescopes spread across four international sites: McDonald Observatory (USA), CTIO (Chile), SAAO (South Africa), and Siding Springs Observatory (Australia). Over the 2014-2015 winter observing season, our program requested queued "visits" of DQ Tau 20 times per orbital cycle for 10 continuous orbital periods. Given the orbital period of DQ Tau, the visit cadence corresponded to ∼20hr. Each visit consisted of three observations in each of the broadband UBVRIY and narrowband Hα and Hβ filters, requiring ∼20 minutes. In this work we present only the UBVR observations, which overlap with our high-cadence observations. Indeed, two eight-night observing runs centered on separate periastron passages of DQ Tau (orbital cycles 3 and 5 in Figure 1) were obtained from the WIYN 0.9m telescope located at the Kitt Peak National Observatory. In addition to our two eight-night observing runs, a synoptic observation program was also in place at the WIYN 0.9m that provided approximately weekly observations of DQ Tau in UBVR during the 2014-B semester. Also, using Apache Point Observatory's ARCSAT 0.5m telescope, we performed observing runs of seven and ten nights centered on two separate periastron passaged of DQ Tau (orbital cycles 2 and 7 in Figure 1). Objects: -------------------------------------------------------------- RA (ICRS) DE Designation(s) (Period) -------------------------------------------------------------- 04 46 53.06 +17 00 00.2 DQ Tau = V* DQ Tau (P=15.8016) -------------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file fig1.dat 30 8948 DQ Tau UBVR lightcurves
See also: VI/135 : All-sky spectrally matched Tycho2 stars (Pickles+, 2010) J/A+A/299/89 : COYOTES II (Bouvier+, 1995) J/ApJS/101/117 : UBVRIJHKLMNQ photometry in Taurus-Auriga (Kenyon+ 1995) J/AJ/130/873 : Properties of BQS objects in the SDSS DR3 area (Jester+, 2005) J/AJ/131/1184 : A recalibration of optical photometry (Maiz-Apellaniz+, 2006) J/A+A/479/827 : UBVR light curves of weak-line T Tauri stars (Grankin+, 2008) J/AJ/140/483 : Flares of UV Cet type stars (Dal+, 2010) J/ApJS/190/1 : A survey of stellar families (Raghavan+, 2010) J/ApJ/731/8 : Multiple star formation in Taurus-Auriga (Kraus+, 2011) J/ApJ/751/115 : Millimeter emission from Taurus binary systems (Harris+, 2012) J/ApJS/207/15 : M dwarf flare spectra (Kowalski+, 2013) J/A+A/561/A2 : 36 accreting YSOs emission lines (Alcala+, 2014) J/AJ/147/82 : Monitoring of disk-bearing stars in NGC 2264 (Cody+, 2014) J/ApJ/786/97 : Photospheric properties of T Tauri stars (Herczeg+, 2014) J/A+A/570/A82 : Mapping accretion variability in NGC 2264 (Venuti+, 2014) J/ApJ/788/59 : Parametric model for disks gas masses (Williams+, 2014) Byte-by-byte Description of file: fig1.dat
Bytes Format Units Label Explanations
1 A1 --- Filt [UBVR] Filter used in the observation (1) 3- 15 F13.5 d HJD Heliocentric Julian Date 17- 22 F6.3 mag mag [11.8/16.4] Apparent magnitude in Filt 24- 28 F5.3 mag e_mag [0.003/0.2] Error in mag (2) 30 A1 --- Tel Telescope used in the observation (3)
Note (1): Johnson system for the U and B filters and Cousins for the V and R filters. Note (2): The systematic errors in the UBVR magnitudes are 0.24, 0.10, 0.05, and 0.07 magnitudes, respectively. Note (3): Description of data reduction and calibration procedures can be found in Section 2 of the paper. ARCSAT data are transformed from SDSS to Johnson filters. Telescope as follows: 0 = Las Cumbres Observatories Global Telescope (LCOGT) 1m network; 1 = Apache Point Observatory's ARCSAT 0.5m telescope; 2 = WIYN0.9m/S2BK; 3 = WIYN0.9m/HDI.
History: From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 02-Aug-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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