J/AJ/149/26 Massive binary stars from an HST/FGS survey (Aldoretta+, 2015)
The multiplicity of massive stars: a high angular resolution survey with the
guidance sensor.
Aldoretta E.J., Caballero-Nieves S.M., Gies D.R., Nelan E.P., Wallace D.J.,
Hartkopf W.I., Henry T.J., Jao W.-C., Apellaniz J.M., Mason B.D.,
Moffat A.F.J., Norris R.P., Richardson N.D., Williams S.J.
<Astron. J., 149, 26 (2015)>
=2015AJ....149...26A 2015AJ....149...26A
ADC_Keywords: Surveys ; Stars, double and multiple ; Binaries, spectroscopic ;
Stars, O ; Stars, B-type ; Magnitudes ; Associations, stellar
Keywords: binaries: general - stars: early-type - stars: massive -
techniques: high angular resolution
Abstract:
We present the results of an all-sky survey made with the Fine
Guidance Sensor on the Hubble Space Telescope to search for angularly
resolved binary systems among massive stars. The sample of 224 stars
is comprised mainly of Galactic O- and B-type stars and luminous blue
variables, plus a few luminous stars in the Large Magellanic Cloud.
The FGS TRANS mode observations are sensitive to the detection of
companions with an angular separation between 0.01'' and 1.0'' and
brighter than δm=5. The FGS observations resolved 52 binary and
6 triple star systems and detected partially resolved binaries in 7
additional targets (43 of these are new detections). These numbers
yield a companion detection frequency of 29% for the FGS survey. We
also gathered literature results on the numbers of close spectroscopic
binaries and wider astrometric binaries among the sample, and we
present estimates of the frequency of multiple systems and the
companion frequency for subsets of stars residing in clusters and
associations, field stars, and runaway stars. These results confirm
the high multiplicity fraction, especially among massive stars in
clusters and associations. We show that the period distribution is
approximately flat in increments of logP. We identify a number of
systems of potential interest for long-term orbital determinations,
and we note the importance of some of these companions for the
interpretation of the radial velocities and light curves of close
binaries that have third companions.
Description:
We selected our targets primarily from the Galactic O-Star Catalog
(Maiz-Apellaniz et al. 2004, cat. V/116;
http://ssg.iaa.es/en/content/galactic-o-star-catalog/), which are
supplemented with other fainter targets from the catalog of
Cruz-Gonzalez et al. 1974 (cat. III/84) and with a selection of
luminous blue variable (LBV) stars (van Genderen 2001, cat.
J/A+A/366/508). Two interlopers were accidentally included in the
sample, the hot subdwarf CD-45°5058 = KS 292 (Rauch et al.,
1991A&A...241..457R 1991A&A...241..457R) and the K-giant BD-3°2178 (Pickles & Depagne
2010, cat. J/PASP/122/1437), which has been confused in the literature
with the nearby hot subdwarf BD-3°2179. The targets are listed in
order of increasing right ascension in Table 1.
We used the Fine Guidance Sensor (FGS) on the Hubble Space Telescope
(HST). The FGS on board the HST acts as a single aperture shearing
interferometer that forms interference fringes through a Koesters
prism due to tilt differences in the incoming wavefront. There are
three FGS instruments on HST that are used for precise pointing of the
telescope, and one of these, FGS1r, is designated for science
applications. In the TRANS mode of operation, the FGS1r scans across
the target in two orthogonal directions, and it produces an x and y
coordinate fringe visibility curve (or "S-curve"). FGS observations of
binary stars produce an S-curve that is the sum of fringe patterns for
each component at a position that corresponds to the projection of the
binary separation along the x and y vectors.
The observations began as a SNAP program in Cycle 16 (GO-11212), and
we selected targets all around the sky. The observations were made
over the period 2007-2009. All the observations were made with the ND5
filter (brighter targets) or F583W filter (fainter targets) that
record a broad range of the optical spectrum
(http://www.stsci.edu/hst/fgs/design/filters ; ∼4600-7000Å).
Multiple scans were recorded for each target with an angular step size
of 1mas, and the scans usually extended ±1.0'' from the main target
(or longer in some cases where a wider companion was known).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 133 307 Stellar parameters
table2.dat 112 76 Resolved companions
table3.dat 94 10 Partially resolved companions
table4.dat 52 172 Unresolved targets
refs.dat 86 113 References
notes.dat 1322 28 Notes
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See also:
B/wds : The Washington Visual Double Star Catalog (Mason+ 2001-2014)
III/274 : Galactic O-Star Spectroscopic Survey (Sota+, 2014)
V/116 : Galactic O star catalog (Maiz-apellaniz+, 2004)
III/84 : Galactic O Stars (Cruz-Gonzalez+ 1974)
II/82 : Galactic O-type Stars (Garmany+ 1982)
III/84 : Galactic O Stars (Cruz-Gonzalez+ 1974)
J/MNRAS/424/1925 : Spectrocopic Binarity of O and B type stars (Chini+, 2012)
J/A+A/518/A1 : Galactic massive stars with AstraLux (Maiz Apellaniz, 2010)
J/AJ/137/3358 : Speckle interferometry of massive stars (Mason+, 2009)
J/MNRAS/400/518 : Velocity & proper motion of OB associations (Melnik+, 2009)
J/A+A/366/508 : S Dor variables (van Genderen+, 2001)
http://ssg.iaa.es/en/content/galactic-o-star-catalog/ : Galactic O-Star Catalog
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- FGS Indicates a target with a prior Fine Guidance
Sensor (FGS) observation (1)
7- 24 A18 --- Star Stellar identifier (HHMMSS.ss+DDMMSS.s, J2000)
26- 36 A11 --- Name Common stellar name
38- 42 F5.2 mag Vmag [3.39/13.61] Johnson V band magnitude
44- 48 F5.2 mag B-V ? The (B-V) color index (2)
50- 66 A17 --- SpT Spectral type of the brightest component (3)
68- 78 A11 --- Cluster Cluster or association of membership (entry
"Field" if no membership is known) (4)
80- 82 A3 --- Run Runaway star (yes or no)
84- 87 F4.1 kpc Dist [0.3/50] Distance (5)
89 A1 --- u_SB [?] Indicates a suspected system (6)
90- 92 A3 --- SB Spectroscopic binary status (7)
94- 96 A3 --- n_SB [O,E ] Suffix on SB knowledge (8)
98-102 A5 --- r_SB Recent spectroscopic reference; in refs.dat file
104 I1 --- NSB [0/3]? Number of probable companions from
spectroscopic binary observations (9)
106 I1 --- NFGS [0/2]? Number of companions detected in the Fine
Guidance Sensor observations (table 2) (10)
108-109 I2 --- NWDS [0/13]? Number of companions from Washington
Double Star catalog (cat. B/wds)
111 I1 --- LBV [1]? Indicates a Luminous Blue Variable (LBV) or
LBV candidate
113-117 A5 --- r_FGS Reference of the FGS data; in refs.dat file
119-133 A15 --- OName Other commonly used name
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Note (1): 23 stars in the Carina association (Nelan et al. 2004AJ....128..323N 2004AJ....128..323N,
2010AJ....139.2714N 2010AJ....139.2714N; omitting HDE 303308 which is already part of our main
survey) and 58 stars from the Cyg OB2 association (Caballero-Nieves et al.
2014AJ....147...40C 2014AJ....147...40C).
Note (2): From Mermilliod & Mermilliod (1994cmud.book.....M 1994cmud.book.....M).
Note (3): From (in most cases) Sota et al. 2011, 2014 (cat. III/274). Luminous
Blue Variable (LBV) classifications are from contemporaneous spectra
described by Richardson et al. (2012ASPC..465..160R 2012ASPC..465..160R).
Note (4): Most of these assignments come from earlier work by Humphreys
(1978ApJS...38..309H 1978ApJS...38..309H), Moffat et al. (1979A&AS...38..197M 1979A&AS...38..197M),
Garmany et al. 1982 (cat. II/82), and the cluster database WEBDA
(http://www.univie.ac.at/webda/webda.html).
Note (5): Taken from WEBDA for cluster members and from Mel'Nik & Dambis (2009,
cat. J/MNRAS/400/518) for association stars. Distances for the field stars
were generally collected from spectroscopic parallaxes given by Garmany et
al. (1980ApJ...242.1063G 1980ApJ...242.1063G) or Gudennavar et al. (2012, cat. J/ApJS/199/8).
If no distance estimate was found, then we calculated the spectroscopic
parallax ourselves using the magnitude, colors, and spectral
classifications in Table 1 with intrinsic colors from Wegner
(1994MNRAS.270..229W 1994MNRAS.270..229W), a ratio of total-to-selective extinction of R=3.1,
and absolute magnitudes from Balona & Crampton (1974MNRAS.166..203B 1974MNRAS.166..203B) and
Martins et al. (2005A&A...436.1049M 2005A&A...436.1049M).
Note (6): For example, for systems with a large radial velocity range but no
orbit or those where double lines are reported.
Note (7): Spectroscopic binary status is:
SB1 = Single-lined spectroscopic binary;
SB2 = Double-lined spectroscopic binary;
SB3 = Spectroscopic binary with three spectral components observed;
SB4 = Spectroscopic binary with four spectral components observed;
C = Star with apparent constant radial velocity;
U = Unknown status in cases where there are only a few or no radial
velocity measurements.
Note (8): Flags on binary status:
O = System with orbital determinations;
E = Eclipsing or ellipsoidal system.
Note (9): Not including those detected in the Fine Guidance Sensor (FGS) survey.
Note (10): See Section 3 for details about the detection of companion star.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- Star Stellar identifier (HHMMSS.ss+DDMMSS.s, J2000)
20- 30 A11 --- Name Common stellar name
32 A1 --- f_Disc [F] Indicates that the Fine Guidance Sensor
(FGS) observation is the first detection (G1)
34- 40 A7 --- Disc Discovery designation from the Washington
Double Star catalog (cat. B/wds)
42- 46 A5 --- m_Disc Component (cat. B/wds)
48- 56 F9.4 yr Date [2007.6/2009.6] Besselian year of observation
58- 62 A5 --- Flt Fine Guidance Sensor (FGS) filter used
(F583W or F5ND) (G2)
64- 69 F6.2 deg PA [0/360]? Position angle θ (1)
71- 75 F5.2 deg e_PA ? Uncertainty in PA
77 A1 --- l_Sep [>] Lower limit flag on Sep
78- 84 F7.4 arcsec Sep [0.01/2]? Separation ρ (1)
86- 91 F6.4 arcsec e_Sep ? Uncertainty in Sep
93- 98 F6.3 mag Dmag [-0.9/5.2]? Companion magnitude difference (1)
100-104 F5.3 mag e_Dmag ? Uncertainty in Dmag
106-108 I3 --- Fig [3/245] Number of the Figure 1 plot that
corresponds to the observation (G3)
110 A1 --- N [N] Indicate a note about the object
112 I1 --- Res [2/6]? Additional note about the system (2)
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Note (1): Determined by our non-linear, least squares fits of the scans.
In most cases the component is resolved in both axes. Then the position
angle is determined from the projected axial separations and the
telescope orientation on the sky, the separation is the square root
of the sum of the squares of the projected axial separations, and the
magnitude difference is the error weighted average of the x and y
values. In other cases, the component is resolved on only one axis,
but has a significant second derivative coefficient a for the other
axis. Then the absolute value of the close separation |Δx| is
derived using the flux ratio r from the resolved axis result and the
relation between a, r, and |Δx| from Equation (2). This yields
a reliable value for ρ, but there are two possible θ angles
that correspond to the choice of ±|Δx|. We list in Table 2 the
θ estimate for +|Δx| and the note in column "N" give the
other possible θ value.
Note (2): The note codes are defined as follows:
2 = Resolved on the x-axis, unresolved on the y-axis, so the position angle
and separation are estimated assuming δy=0;
3 = Resolved on the y-axis, unresolved on the x-axis, so the position angle
and separation are estimated assuming δx=0;
4 = Resolved on the x-axis, off scan on the y-axis, so no position angle is
listed and only a lower limit on the separation is given;
5 = Resolved on the y-axis, off scan on the x-axis, so no position angle is
listed and only a lower limit on the separation is given;
6 = Reassignment of bright star designation for consistency with WDS.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- Star Stellar identifier
(HHMMSS.ss+DDMMSS.s, J2000) (1)
20- 29 A10 --- Name Common stellar name
31 A1 --- f_Disc [F] Indicates that the Fine Guidance Sensor
(FGS) observation is the first detection (G1)
33- 38 A6 --- Disc Discovery designation from the Washington
Double Star catalog (cat. B/wds)
40- 44 A5 --- m_Disc Component
46- 54 F9.4 --- Date [2007.9/2009.3] Besselian year of observation
56- 60 A5 --- Flt Fine Guidance Sensor (FGS) filter used
(F583W or F5ND) (G2)
62- 64 I3 deg PA1 Ambiguous position angle for
(+|Δx|, +|Δy|) (2)
66- 67 I2 deg e_PA1 Uncertainty in PA1
69- 71 I3 deg PA2 Ambiguous position angle for
(+|Δx, -|Δy|) (2)
73- 74 I2 deg e_PA2 Uncertainty in PA2
76- 81 F6.4 arcsec Sep Minimum separation ρmin for a flux ratio
r=1 (3)
83- 88 F6.4 arcsec e_Sep Error in Sep
90- 92 I3 --- Fig [34/239] Number of the Figure 1 plot that
corresponds to the observation (G3)
94 A1 --- N [N] Indicate a note about the object
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Note (1): This table lists the cases where the second derivative test indicated
the presence of a blended component along at least one axis (and the target
is not included in Table 2).
Note (2): There is a four-fold ambiguity in the derived position angle θ
depending on the signs of Δx and Δy. Add 180° to each of
PA1 and PA2 to arrive at the remaining two possibilities.
Note (3): ρmin=80.5(ax+ay)0.5 (Equation (3)), where ax and ay
are the positively valued, second derivative coefficients measured for the
x and y scans, respectively. If the flux ratio r eventually becomes known,
then the actual separation will be given by
ρ=ρmin(1+r)/2(r)0.5(Equation (4)).
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- Star Steller identifier (HHMMSS.ss+DDMMSS.s, J2000) (1)
20- 30 A11 --- Name Common stellar name
32- 40 F9.4 yr Date [2007.4/2009.55] Besselian year of observation
42- 46 A5 --- Flt Fine Guidance Sensor (FGS) filter used
(F583W or F5ND) (G2)
48- 50 I3 --- Fig [1/251] Number of the Figure 1 plot that
corresponds to the observation (G3)
52 A1 --- N [N] Indicate a note about the object
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Note (1): This table list the remaining systems for which we find no evidence of
a companion.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Ref Reference identifier
7- 25 A19 --- BibCode Bibliographic code
27- 64 A38 --- Aut Author's name
66- 86 A21 --- Cat VizieR catalog
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Byte-by-byte Description of file: notes.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- Star Stellar identifier (HHMMSS.ss+DDMMSS.s, J2000)
20-1322 A1303 --- Note Notes about the star
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Global Notes:
Note (G1): Then "FGS" is listed along with a component designation made
following the nomenclature used in the WDS (cat. B/wds).
Note (G2): ND5 filter for brighter targets, F583W filter for fainter targets.
Note (G3): Full collection of 251 merged scans of our targets associated with
Figure 1 in the paper. The central two panels of these figures show the
final scans along the orthogonal x and y axes.
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History:
* 2015-Feb-03: from electronic version of the journal
* 2015-Mar-30: full list of spectroscopic references in Table 1 provided by
the author
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 03-Feb-2015