J/ApJ/757/29 Astrometric measurements of HD 143275 (Che+, 2012)
Imaging disk distortion of Be binary system δ Scorpii near periastron.
Che X., Monnier J.D., Tycner C., Kraus S., Zavala R.T., Baron F.,
Pedretti E., ten Brummelaar T., McAlister H., Ridgway S.T., Sturmann J.,
Sturmann L., Turner N.
<Astrophys. J., 757, 29 (2012)>
=2012ApJ...757...29C 2012ApJ...757...29C
ADC_Keywords: Stars, double and multiple ; Interferometry ; Positional data
Keywords: binaries: general; stars: emission-line, Be;
stars: fundamental parameters; stars: imaging;
stars: individual: * del Sco; techniques: interferometric
Abstract:
The highly eccentric Be binary system δ Sco reached periastron
during early 2011 July, when the distance between the primary and
secondary was a few times the size of the primary disk in the H band.
This opened a window of opportunity to study how the gaseous disks
around Be stars respond to gravitational disturbance. We first refine
the binary parameters with the best orbital phase coverage data from
the Navy Precision Optical Interferometer. Then we present the first
imaging results of the disk after the periastron, based on seven
nights of five telescope observations with the MIRC combiner at the
CHARA array. We found that the disk was inclined 27°.6±6°.0
from the plane of the sky, had a half-light radius of 0.49mas (2.2
stellar radii), and consistently contributed 71.4%±2.7% of the total
flux in the H band from night to night, suggesting no ongoing transfer
of material into the disk during the periastron. The new estimation of
the periastron passage is UT 2011 July 3 07:00±4:30. Re-analysis of
archival VLTI-AMBER interferometry data allowed us to determine the
rotation direction of the primary disk, constraining it to be inclined
either ∼119° or ∼171° relative to the orbital plane of the
binary system. We also detect inner disk asymmetries that could be
explained by spot-like emission with a few percent of the disk total
flux moving in Keplerian orbits, although we lack sufficient angular
resolution to be sure of this interpretation and cannot yet rule out
spiral density waves or other more complicated geometries.
Description:
The near-infrared observations of δ Sco were carried out using
the Georgia State University Center for High Angular Resolution
Astronomy (CHARA) interferometer array. It contains six 1m telescopes
with baselines ranging from 34m to 331m, offering high angular
resolution up to (λ/(2xBaseline))∼0.5mas at the H band (1.4um
to 1.8um). We observed δ Sco on seven nights in 2011 July just
after periastron with the upgraded MIRC (Michigan Infra-Red Combiner).
The visible interferometric observations were obtained as an extension
of the results presented in Tycner et al. (2011, Cat. J/ApJ/729/L5),
which focused on refining the orbital parameters of the δ Sco
system before the periastron passage of 2011. In this study we
utilized all 96 nights (covering the 2000-2010 time frame) that were
presented in Tycner et al. with the Navy Prototype Optical
Interferometer (NPOI), and we complemented this set with newly
acquired additional observations on 32 nights in 2011, including three
nights close to the periastron passage in 2011 July.
Objects:
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RA (ICRS) DE Designation(s) (Period)
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16 00 20.01 -22 37 18.1 δ Sco = * del Sco (P=3945.4)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 53 128 The δ Sco astrometric measurements from NPOI
(Navy Prototype Optical Interferometer)
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See also:
J/A+A/546/A69 : Orbits of visual binaries and dynamical masses (Malkov+, 2012)
J/MNRAS/424/1925 : Spectrocopic Binarity of O and B type stars (Chini+, 2012)
J/ApJ/729/L5 : The revised orbit of the δ Sco system (Tycner+, 2011)
J/ApJS/187/228 : Hα profiles of Be stars (Silaj+, 2010)
J/AJ/139/743 : Speckle interferometry in 2008-09 (Tokovinin+, 2010)
J/AJ/137/3358 : Speckle interferometry of massive stars (Mason+, 2009)
J/ApJ/629/507 : Observed orbital eccentricities for 391 binaries (Abt+, 2005)
J/ApJS/151/299 : Spectra classification from ISO PHT-S database (Hodge+, 2004)
J/A+A/408/305 : Spectroscopic obs. of delta Sco (Miroshnichenko+, 2003)
http://varsao.com.ar/delta_Sco.htm : delta Scorpii updates light curve page
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 A11 "YYYY/MMM/DD" Date UT date of the observation
13- 21 F9.3 d MJD Modified Julian Date of the observation
(JD-2400000.5)
23- 28 F6.2 mas Sep [6.1/192.2] Separation between components
30- 35 F6.2 deg PA2 [1.2/358.2] Position angle of secondary,
East of North
37- 41 F5.3 mas eeMaj [0.2/3.3] Semi-major axis of error ellipse
43- 47 F5.3 mas eeMin [0.03/0.3] Semi-minor axis of error ellipse
49- 53 F5.1 deg eePA [0/180] Position angle of error ellipse;
East of North
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 20-May-2014