J/ApJ/950/92 Radial velocities and V-band phot. of DI Tau (Tang+, 2023)
Star-crossed lovers DI Tau A and B: orbit characterization and physical
properties determination.
Tang S.-Y., Stahl A.G., Prato L., Schaefer G.H., Johns-Krull C.M.,
Skiff B.A., Beichman C.A., Uyama T.
<Astrophys. J., 950, 92 (2023)>
=2023ApJ...950...92T 2023ApJ...950...92T
ADC_Keywords: Stars, double and multiple; Spectra, optical; Spectra, infrared;
Radial velocities; Photometry
Keywords: Binary stars ; Visual binary stars ; Pre-main sequence stars ;
Radial velocity ; High angular resolution ;
Fundamental parameters of stars
Abstract:
The stellar companion to the weak-line T Tauri star DI Tau A was first
discovered by the lunar occultation technique in 1989 and was
subsequently confirmed by a speckle imaging observation in 1991. It
has not been detected since, despite being targeted by five different
studies that used a variety of methods and spanned more than 20yr.
Here, we report the serendipitous rediscovery of DI Tau B during our
Young Exoplanets Spectroscopic Survey (YESS). Using radial velocity
data from YESS spanning 17yr, new adaptive optics observations from
Keck II, and a variety of other data from the literature, we derive a
preliminary orbital solution for the system that effectively explains
the detection and (almost all of the) non-detection history of
DI Tau B. We estimate the dynamical masses of both components, finding
that the large mass difference (q∼0.17) and long orbital period
(≳35yr) make the DI Tau system a noteworthy and valuable addition to
studies of stellar evolution and pre-main-sequence models. With a long
orbital period and a small flux ratio (f2/f1) between DI Tau A and B,
additional measurements are needed for a better comparison between
these observational results and pre-main-sequence models. Finally, we
report an average surface magnetic field strength ({bar}B) for
DI Tau A, of ∼0.55kG, which is unusually low in the context of young
active stars.
Description:
Three different types of data are used in this study: spectroscopy, AO
imaging, and photometry.
Optical spectra were obtained with the Robert G. Tull Coude
Spectrograph mounted on the 2.7m Harlan J. Smith telescope at the
McDonald Observatory. In total, we obtained 22 spectra of DI Tau
between 2005 January and 2022 January, spanning about 17yr (Table 3).
Typical exposure times were ∼2500s, but ranged from 1600 to 3600s
depending on the sky conditions. Each observation used a 1.2" slit
width, achieving a resolving power R∼60000 and covering 3986-9952Å.
See Section 2.1.1.
NIR spectra were taken using the high-resolution immersion grating
infrared spectrometer (IGRINS). IGRINS is a cross-dispersed echelle
spectrograph that simultaneously covers the full H (1.49-1.80um split
into 25 orders) and K bands (1.96-2.46um split into 22 orders). With
no moving parts, the spectrograph's fixed 0.8" width slit delivers an
R∼45000. IGRINS has been deployed at the McDonald Observatory's 2.7m
Harlan J. Smith Telescope, the 4.3m Lowell Discovery Telescope (LDT,
formerly the Discovery Channel Telescope, DCT), and the Gemini South
telescope.
DI Tau was observed once with IGRINS at McDonald Observatory on 2015
October 10 and four more times at the LDT in 2016 and 2017 (Table 3).
See Section 2.1.2.
We obtained AO images for DI Tau on UT 2022 February 13, October 19,
and December 29 using the near-infrared camera (NIRC2) on the 10m
Keck II Telescope at the W. M. Keck Observatory in J, H, K, L' filters.
See Section 2.2.
CCD photometry for DI Tau was obtained between 2012 and 2020 using the
Lowell Observatory's 0.7m telescope in robotic mode. The exposure
times were typically 3 minutes through a V band filter. Two or more
visits were obtained on every night of observation.
See Section 2.3 (and Table 4).
Objects:
------------------------------------------------------------
RA (ICRS) DE Designation(s) (Prot)
------------------------------------------------------------
04 29 42.47 +26 32 49.1 DI Tau = V* DI Tau (P=7.709d)
------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 39 31 DI Tau radial velocities
table4.dat 26 871 DI Tau Lowell Observatory V photometry
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/332 : c2d Spitzer final data release (DR4) (Evans+, 2003)
II/328 : AllWISE Data Release (Cutri+ 2013)
I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)
VII/233 : 2MASS All-Sky Extended Source Catalog (XSC) (IPAC/UMass, 2003-2006)
J/ApJS/101/117 : UBVRIJHKLMNQ photometry in Taurus-Auriga (Kenyon+ 1995)
J/A+A/461/183 : Variability of classical T Tauri (Grankin+, 2007)
J/A+A/479/827 : UBVR LCs of weak-line T Tauri stars (Grankin+, 2008)
J/PASJ/60/209 : Faint companions around YSOs in TMC (Itoh+, 2008)
J/ApJ/731/8 : Multiple star formation in Taurus-Auriga (Kraus+, 2011)
J/ApJ/745/119 : Companions to young stars. I. ChaI & Tau (Nguyen+, 2012)
J/ApJ/786/97 : Photospheric properties of T Tauri stars (Herczeg+, 2014)
J/MNRAS/441/2361 : Stellar magnetism, age and rotation (Vidotto+, 2014)
J/ApJ/799/155 : Sub-stellar companions in Taurus (Daemgen+, 2015)
J/A+A/587/A65 : Visible and near-infrared solar spectra (Reiners+, 2016)
J/A+A/638/A85 : 3Dview of Taurus with Gaia & Herschel (Roccatagliata+, 2020)
J/AJ/160/35 : NIR phot. in the T Tauri system with Keck (Schaefer+, 2020)
J/ApJ/921/53 : IGRINS YSO survey. I. Tau-Aur (Lopez-Valdivia+, 2021)
J/A+A/649/A3 : Gaia EDR3 photometric passbands (Riello+, 2021)
J/AJ/161/283 : Radial velocities of 4 stars with IGRINS (Stahl+, 2021)
J/ApJ/925/21 : IRTF/iSHELL K-band sp. obs. of PMS stars (Flores+, 2022)
J/AJ/163/156 : THYME. VI. TOI-1227 radial velocity (Mann+, 2022)
J/ApJ/928/134 : NIR phot. & opt. veiling in T Tauri stars (Sullivan+, 2022)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 yr Obs.Y [2005/2022] Year of the observation
6- 7 I2 "month" Obs.M Month of the observation
9- 10 I2 d Obs.D Day of the observation
12- 22 F11.6 d JD [3374.6/9901.8] Julian Date; JD-2450000
24- 29 F6.3 km/s RVel [13.2/16.9] Radial velocity
31- 35 F5.3 km/s e_RVel [0.05/0.6] Uncertainty in RVel
37- 39 A3 --- Type Observation type (1)
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Note (1): Type as follows:
opt = McDonald optical radial velocity (26 occurrences)
nir = IGRINS near-Infrared radial velocity (5 occurrences)
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 F13.5 d HJD [2456256.6/2459610.7] Heliocentric Julian Date
15- 20 F6.3 mag Vmag [12.83/12.96] Apparent V band magnitude
22- 26 F5.3 mag e_Vmag [0.001/0.05] Uncertainty in Vmag
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 30-Jul-2025