J/AJ/156/144 The very high-eccentricity binary HR 7345 (Farrington+, 2018)
Separated Fringe Packet observations with the CHARA Array.
III. The very high-eccentricity binary HR 7345.
Farrington C.D., Fekel F.C., Schaefer G.H., ten Brummelaar T.A.
<Astron. J., 156, 144 (2018)>
=2018AJ....156..144F 2018AJ....156..144F (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, orbits ; Interferometry ; Spectroscopy
Keywords: binaries: close - infrared: stars - stars: individual (HD 181655) -
techniques: high angular resolution - techniques: interferometric -
techniques: spectroscopic
Abstract:
After an 11-year observing campaign, we present the combined
visual-spectroscopic orbit of the formerly unremarkable bright star
HR 7345 (HD 181655, HIP 94981, GJ 754.2). Using the Separated Fringe
Packet method with the CHARA Array, we were able to determine a
difficult-to-complete orbital period of 331.609±0.004 days. The 11-month
period causes the system to be hidden from interferometric view behind
the Sun for three years at a time. Due to the high-eccentricity orbit
of about 90% of a year, after 2018 January the periastron phase will not
be observable again until late 2021. Hindered by its extremely high
eccentricity of 0.9322±0.0001, the double-lined spectroscopic phase
of HR 7345 is observable for 15 days. Such a high eccentricity for HR 7345
places it among the most eccentric systems in catalogs of both visual and
spectroscopic orbits. For this system, we determine nearly identical
component masses of 0.941±0.076 M☉ and 0.926±0.075 M☉
as well as an orbital parallax of 41.08±0.77 mas.
Description:
We obtained observations of HR 7345 from 2005 October through 2018
January with multiple combinations of baselines using the Classic and
CLIMB (ten Brummelaar et al. 2013JAI.....240004T) beam combiners of
the CHARA Array at Mount Wilson Observatory in southern California
(ten Brummelaar et al. 2005ApJ...628..453T 2005ApJ...628..453T). All one-dimensional (1D)
observations from the CHARA Array and subsequent two-dimensional (2D)
calculations from 2005 to 2018 are listed in Table 1.
We obtained observations of HR 7345 from 2014 June through 2018 January
with the Tennessee State University (TSU) 2 m automatic spectroscopic
telescope (AST) and a fiber-fed echelle spectrograph (Eaton & Williamson
2007PASP..119..886E 2007PASP..119..886E). That telescope is situated at Fairborn Observatory
near Washington Camp in southeastern Arizona. The detector is a Fairchild
486 CCD having a 4096x4096 array of 15 µm pixels. For our observations,
we used a 200 µm fiber that results in a spectral resolution of
0.24 Å. The signal-to-noise ratio of the spectra was typically about
90 per resolution element at 6000 Å. All of the spectroscopic
observations for this system are listed in Table 2.
Objects:
-------------------------------------------------
RA (ICRS) DE Designation(s)
-------------------------------------------------
19 19 39.00 +37 19 49.9 HR 7345 = HD 181655
-------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 85 215 Visual binary measurements for Separated Fringe
Packet (SFP) system HR 7345
table2.dat 31 132 Spectroscopic observations for system HR 7345
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See also:
B/sb9 : SB9: 9th Catalogue of Spectroscopic Binary Orbits
(Pourbaix+ 2004-2014)
J/ApJ/683/424 : CHARA observations of 3 late-type stars (Boyajian+, 2008)
J/ApJ/745/24 : A search for new companions with CHARA (Raghavan+, 2012)
J/AJ/148/48 : CHARA obs. of omega And, HD 178911, xi Cep (Farrington+, 2014)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 F11.5 d HJD1 ? Heliocentric Julian Date from 1D measurement
(HJD-2400000)
13- 18 F6.2 m B [138.5/330.66]? Baseline length of 1D measurement
20- 21 A2 --- f_rho1 [≤] Limit flag on rho1
22- 26 F5.2 mas rho1 [2.92/91.14]? Fringe separation of 1D measurement
ρ
28- 33 F6.2 deg theta1 [0.17/359.39]? Position angle of baseline of
1D measurement θ
35- 47 F13.5 d HJD2 ? Heliocentric Julian Date of 2D calculations
49 A1 --- n_theta1 [1] Flag on theta1 (1)
51- 60 F10.5 yr JY ? Calculated Julian Year of 2D calculations
62- 66 F5.2 mas rho2 [3.4/92.88]? Companion separation of 2D
calculations (2)
68- 72 F5.2 mas e_rho2 [0.04/11.06]? Uncertainty in rho2 (2)
74- 79 F6.2 deg theta2 [2.73/359.5]? Companion position angle of 2D
calculations (2)
81- 85 F5.2 deg e_theta2 [0.04/22.89]? Uncertainty in theta2 (2)
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Note (1): Flag as follows:
1 = The residuals from these measurements compared with the orbit fit were
more than three times the measurement error, so we increased their
uncertainties by a factor of 10 to minimize their impact on the orbit fit.
Note (2): The last data line contains the periastron observation taken during
2018 January by three-baseline CLIMB and does not include 1-D information.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 F10.4 d HJD Heliocentric Julian Date (HJD-2400000)
12- 17 F6.2 km/s K1 [-46.3/2.21] Primary amplitude
19- 21 F3.1 --- w_K1 [0/1] Weight on K1
23- 27 F5.2 km/s K2 [4.48/50.5]? Secondary amplitude
29- 31 F3.1 --- w_K2 [0/1]? Weight on K2
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History:
From electronic version of the journal
References:
Farrington et al. Paper I. 2010AJ....139.2308F 2010AJ....139.2308F
Farrington et al. Paper II. 2014AJ....148...48F 2014AJ....148...48F, Cat. J/AJ/148/48
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 12-Mar-2019