J/AJ/162/14 Astrometry & radial velocity, Alpha Centauri system (Akeson+, 2021)
Precision millimeter astrometry of the α Centauri AB system.
Akeson R., Beichman C., Kervella P., Fomalont E., Benedict G.F.
<Astron. J., 162, 14-14 (2021)>
=2021AJ....162...14A 2021AJ....162...14A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple; Stars, G-type; Positional data;
Photometry, millimetric/submm; Optical; Radial velocities
Keywords: Fundamental parameters of stars; Main sequence stars; Radio astrometry
Astrometric binary stars
Abstract:
Alpha Centauri A is the closest solar-type star to the Sun and offers
the best opportunity to find and ultimately to characterize an
Earth-sized planet located in its habitable zone. Here, we describe
initial results from an Atacama Large Millimeter/submillimeter Array
(ALMA) program to search for planets in the α Cen AB system
using differential astrometry at millimeter wavelengths. Our initial
results include new absolute astrometric measurements of the proper
motion, orbital motion and parallax of the α Cen system. These
lead to an improved knowledge of the physical properties of both
α Cen A and B. Our estimates of ALMA's relative astrometric
precision suggest that we will ultimately be sensitive to planets of a
few tens of Earth mass in orbits from 1 to 3au, where stable orbits
are thought to exist.
Description:
We obtained a series of Atacama Large Millimeter/submillimeter Array
(ALMA) observations of α Cen in Cycle 6 between 2018 October and
2019 August at band 7, using the nominal continuum set-up of four
1.9GHz spectral windows at frequencies 336.5, 338.5, 348.5, and
350.5GHz.
We adopted radial velocity data from the large series of High Accuracy
Radial velocity Planet Searcher (HARPS) measurements of α Cen A
and B obtained since 2004, publicly available from the ESO archive.
Objects:
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RA (2000) DE Designation(s)
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14 39 36.49 -60 50 02.4 Alpha Centauri A = * alf Cen A
14 39 35.06 -60 50 15.1 Alpha Centauri B = * alf Cen B
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table6.dat 53 106 Relative astrometry of alpha Cen B with respect
to A
table7.dat 36 17567 Radial velocity measurements for alpha Cen A
and B from the HARPS instrument
table12.dat 123 801 Ephemeris of alpha Cen A and B between 2010 and
2050
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See also:
I/237 : The Washington Visual Double Star Catalog, 1996.0 (Worley+, 1996)
I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)
J/A+AS/107/235 : Photographic observations of visual binaries (Jasinta+, 1994)
J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)
J/ApJ/771/40 : Main-sequence A, F, G, and K stars photometry (Boyajian+, 2013)
J/A+A/615/A172 : alpha Cen A and B chemical composition (Morel, 2018)
J/AJ/155/24 : Radial velocity & planet detectability in alpha Cen (Zhao+, 2018)
Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 9 F9.4 yr Date [1940/2020] Epoch of observation
11- 18 F8.4 deg PA [6.5/350] Position angle
20- 25 F6.4 deg e_PA [0.003/4.3] Uncertainty in PA
27- 34 F8.5 arcsec Sep [2.03/22] Separation
36- 42 F7.5 arcsec e_Sep [0.0003/0.5] Uncertainty in sep
44- 53 A10 --- Ref Reference (1)
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Note (1): References as follow:
K16 = Kervella+, 2016A&A...594A.107K 2016A&A...594A.107K
K16/ALMA = Kervella+, (2016) measurements of data from
Liseau+, 2015A&A...573L...4L 2015A&A...573L...4L
An15 = Anton, 2015JDSO...11...81A 2015JDSO...11...81A
An14 = Anton, 2014JDSO...10..232A 2014JDSO...10..232A
An12 = Anton, 2012JDSO....8...15A 2012JDSO....8...15A
An11 = Anton, 2011JDSO....7...64A 2011JDSO....7...64A
An08 = Anton, 2008JDSO....4...40A 2008JDSO....4...40A
An06 = Anton, 2006JDSO....2..108A 2006JDSO....2..108A
WDS = Washington Double Star Catalog, Worley and Douglass, 1996, I/237
vL07 = Van Leeuwen+, 2007, I/311
J94 = Jasinta and Soegiartini, 1994, J/A+AS/107/235
P91 = Panjaitan and Herdiwijaya, 1991A&AS...88...63P 1991A&AS...88...63P
T85 = Torres, 1985A&AS...59..449T 1985A&AS...59..449T
F86 = Frengetto, Webb Society Handbook, 1986
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 11 F11.5 d MJD [53039/58242] Modified Julian Date; MJD-2400000.5
14 A1 --- ID Star identifier; A or B
16- 25 F10.5 km/s RVel [-24.89/-21.83] Radial Velocity (1)
30- 36 F7.5 km/s e_RVel [0.002/0.01] Uncertainty in RVel
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Note (1): Radial velocity measurements from the HARPS instrument taken from the
ESO archive. Filtered and correct as described in section 3.1.2.
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Byte-by-byte Description of file: table12.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 yr Date [2010/2050] Decimal year
9- 10 I2 h CRAh [14] Hour of center of mass Right Ascension
12- 13 I2 min CRAm [39] Minute of center of mass Right Ascension
15- 21 F7.4 s CRAs [11/31] Second of center of mass Right Ascension
23 A1 --- CDE- [-] Sign of center of mass Declination
24- 25 I2 deg CDEd [60] Degree of center of mass Declination
27- 28 I2 arcmin CDEm [49/50] Arcminute of center of mass Declination
30- 35 F6.3 arcsec CDEs Arcsecond of center of mass Declination
37- 38 I2 h ARAh [14] Star A hour of Right Ascension
40- 41 I2 min ARAm [39] Star A minute of Right Ascension
43- 49 F7.4 s ARAs [11/32] Star A second of Right Ascension
51 A1 --- ADE- [-] Star A sign of Declination
52- 53 I2 deg ADEd [60] Star A degree of Declination
55- 56 I2 arcmin ADEm [49] Star A arcminute of Declination
58- 63 F6.3 arcsec ADEs [24/60] Star A arcsecond of Declination
65- 66 I2 h BRAh [14] Star B hour of Right Ascension
68- 69 I2 min BRAm [39] Star B minute of Right Ascension
71- 77 F7.4 s BRAs [10/31] Star B second of Right Ascension
79 A1 --- BDE- [-] Star B sign of Declination
80- 81 I2 deg BDEd [60] Star B degree of Declination
83- 84 I2 arcmin BDEm [49/50] Star B arcminute of Declination
86- 91 F6.3 arcsec BDEs Star B arcsecond of Declination
94- 99 F6.3 arcsec dRa [-7.68/4.12] RA offset of B relative to A
101-107 F7.3 arcsec dEC [-16.8/9.78] Dec offset of B relative to A
109-114 F6.3 arcsec Sep [1.69/18.5] A-B separation
117-123 F7.3 deg PA [0.13/360] A-B position angle
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 08-Nov-2021