J/ApJ/811/131 UBV light curves of DQ Tau and UZ Tau E (Ardila+, 2015)
Magnetospheric accretion in close pre-main-sequence binaries.
Ardila D.R., Jonhs-Krull C., Herczeg G.J., Mathieu R.D., Quijano-Vodniza A.
<Astrophys. J., 811, 131 (2015)>
=2015ApJ...811..131A 2015ApJ...811..131A (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, spectroscopic ; Photometry, UBV
Keywords: binaries: spectroscopic; stars: pre-main sequence;
stars: variables: T Tauri, Herbig Ae/Be; techniques: spectroscopic;
ultraviolet: stars
Abstract:
The transfer of matter between a circumbinary disk and a young binary
system remains poorly understood, obscuring the interpretation of
accretion indicators. To explore the behavior of these indicators in
multiple systems, we have performed the first systematic time-domain
study of young binaries in the ultraviolet. We obtained far- and
near-ultraviolet HST/COS spectra of the young spectroscopic binaries
DQ Tau and UZ Tau E. Here we focus on the continuum from 2800 to
3200Å and on the CIV doublet (λλ1548.19,1550.77Å)
as accretion diagnostics. Each system was observed over three or four
consecutive binary orbits, at phases ∼0, 0.2, 0.5, and 0.7. Those
observations are complemented by ground-based U-band measurements.
Contrary to model predictions, we do not detect any clear correlation
between accretion luminosity and phase. Further, we do not detect any
correlation between CIV flux and phase. For both stars the appearance
of the CIV line is similar to that of single Classical T Tauri Stars
(CTTSs), despite the lack of stable long-lived circumstellar disks.
However, unlike the case in single CTTSs, the narrow and broad
components of the CIV lines are uncorrelated, and we argue that the
narrow component is powered by processes other than accretion, such as
flares in the stellar magnetospheres and/or enhanced activity in the
upper atmosphere. We find that both stars contribute equally to the
narrow component CIV flux in DQ Tau, but the primary dominates the
narrow component CIV emission in UZ Tau E. The CIV broad component
flux is correlated with other accretion indicators, suggesting an
accretion origin. However, the line is blueshifted, which is
inconsistent with its origin in an infall flow close to the star. It
is possible that the complicated geometry of the region, as well as
turbulence in the shock region, are responsible for the blueshifted
line profiles.
Description:
DQ Tau was observed with HST/COS four times per binary orbit, during
three consecutive binary orbits, at phases ∼0, ∼0.2, ∼0.5, and ∼0.7
(in 2011 Feb, Mar). The original experimental design called for
observations of UZ Tau E with the same cadence. However, the NUV
observations at phase ∼0.7 in the second orbit and both the FUV and
NUV observations at phase ∼0 in the third orbit failed. They were
replaced by observations at phases ∼0 and ∼0.5 in a fourth binary
orbit (in 2011 Feb, Mar, Apr).
We obtained contemporaneous ground-based UBV photometry with the 14"
telescope from the University of Narino Observatory, optical
spectroscopy with the Sandiford Echelle Spectrometer on the 2.1m Otto
Struve Telescope at McDonald Observatory, near-infrared spectroscopy
with the CSHELL spectrograph on the NASA Infrared Telescope Facility,
and near-infrared spectroscopy with GNIRS instrument on Gemini North.
In this paper we focus on the U-band photometry only. UBV observations
were obtained before and during the HST campaign. See table 3.
Objects:
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RA (ICRS) DE Designation(s) (Period)
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04 46 53.06 +17 00 00.1 DQ Tau = 2MASS J04465305+1700001 (P=15.804)
04 32 42.83 +25 52 31.4 UZ Tau E = 2MASS J04324282+2552314 (P=19.131)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 46 98 University of Narino Observatory - observation log
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See also:
I/274 : CCDM (Catalog of Components of Double Multiple stars) (Dommanget+ 2002)
J/ApJ/799/155 : Sub-stellar companions in Taurus (Daemgen+, 2015)
J/ApJ/771/129 : Submillimetric Class II sources of Taurus (Andrews+, 2013)
J/ApJ/751/115 : Millimeter emission from Taurus binary systems (Harris+, 2012)
J/ApJ/745/119 : Close companions to young stars. I. ChaI + Tau (Nguyen+, 2012)
J/ApJ/745/19 : Binary systems in Taurus-Auriga (Kraus+, 2012)
J/ApJ/744/121 : Far-UV spectroscopy of T Tau stars (Yang+, 2012)
J/ApJ/703/1964 : Spectra of three nearby star-forming regions (Furlan+, 2009)
J/A+A/468/379 : XMM Optical Monitor Survey of TMC (Audard+, 2007)
J/A+A/409/1037 : AK Sco ubvy & Geneva differential photometry (Alencar+, 2003)
J/ApJS/101/117 : UBVRIJHKLMNQ photometry in Taurus-Auriga (Kenyon+ 1995)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Target Target identifier
10- 19 A10 "M/D/Y" Obs.date UT date of the observation
21- 28 A8 "h:m:s" Obs.time UT time of the observation
30 A1 --- Band [BUV] Band (U, B or V)
32- 35 I4 s Exp [45/3600] Exposure time
37- 40 F4.1 mag mag [11.7/16.2] Observed magnitude in Band
42- 46 F5.2 --- Phase [-4.3/3.3] Phase
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 18-Jan-2016