J/MNRAS/454/2344 Radial velocities of δ Sagittae (Pugh+, 2015)
The orbit and variations of δ Sagittae.
Pugh T., Gray D.F., Griffin R.F.
<Mon. Not. R. Astron. Soc., 454, 2344-2352 (2015)>
=2015MNRAS.454.2344P 2015MNRAS.454.2344P (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, spectroscopic ; Radial velocities
Keywords: techniques: radial velocities - binaries: spectroscopic -
stars: individual: * del Sge - stars: late-type -
stars: variables: general
Abstract:
Radial-velocity observations spanning more than a century are used to
produce a reliable orbit of the δ Sagittae system. We find an
orbital period of 3703.7±1.5 d and a semi-amplitude of 7.73±0.05 km/s.
In addition, we find quasi-periodic variations with time-scales in the
range of 550-750 d and a typical amplitude of 1 km/s. The phase and
amplitude are both irregular, sometimes changing very abruptly. We
consider pulsation, rotational modulation and convection as possible
causes of the variations, finally favouring convection.
Description:
28 spectra were obtained by Gray and Pugh between 2008 July and 2010
October (MJD 2454674-2455479) with the high-resolution (R∼100000) coude
spectrograph of the Elginfield Observatory of Western University
(Gray 2009ApJ...697.1032G 2009ApJ...697.1032G). The signal-to-noise ratios in the continuum,
estimated from the photon counts, ranged from 152 to 314 with a mean
of 220. The spectrograph has a dispersion of ∼0.013 Å/mm and can reach
a radial-velocity precision of 25 m/s by reference to water vapour lines
inside the spectrograph (Gray & Brown 2006PASP..118.1112G 2006PASP..118.1112G). In the current
case our measurement errors (based on exposures taken within a few nights
of one another) range from 27 to 160 m/s, with a mean value of 90 m/s.
The radial velocities were determined by measuring the positions of the
spectral lines at 85 per cent of the line depth for 15 neutral metal lines
in the λ6250-Å region.
Objects:
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RA (ICRS) DE Designation(s)
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19 47 23.26 +18 32 03.4 δ Sagittae = * del Sge
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 29 481 Radial Velocities
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See also:
J/AJ/145/41 : Radial velocities of 33 spectroscopic binaries (Katoh+, 2013)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 F8.2 d MJD Modified Julian Date
10- 14 F5.3 --- Phase Phase
16- 20 F5.1 km/s RV Radial velocity
22- 26 F5.1 km/s O-C Residual radial velocity
28- 29 I2 --- Source [1/16] Source (1)
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Note (1): Source as follows:
1 = Campbell (1928PLicO..16....1C 1928PLicO..16....1C);
2 = Kustner (1914AN....198..409K 1914AN....198..409K), Spencer Jones (1928AnCap..10....8S 1928AnCap..10....8S), and
Tremblot (1938, Bull. Astron., 11, 377);
3 = Abt (1973ApJS...26..365A 1973ApJS...26..365A);
4 = Harper (1934PDAO....6..149H 1934PDAO....6..149H);
5 = private communication;
6 = Tremblot (1938, Bull. Astron., 11, 377);
7 = Hynek (1942ApJ....95..324H 1942ApJ....95..324H);
8 = Reimers & Schroder (1983A&A...124..241R 1983A&A...124..241R);
9 = Griffin - Cambridge Spectrometer;
10 = Griffin - Palomar;
11 = Batten - DAO;
12 = Griffin - OHP;
13 = Griffin - ESO;
14 = Griffin - DAO;
15 = Griffin - Cambridge Coravel;
16 = Pugh & Gray - Elginfield.
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History:
From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 18-Jan-2018