J/MNRAS/459/4360 Field RR Lyrae stars (Liska+, 2016)
Cyclic variations in O-C diagrams of field RR Lyrae stars as a result of LiTE.
Liska J., Skarka M., Zejda M., Mikulasek Z., de Villiers S.N.
<Mon. Not. R. Astron. Soc. 459, 4360 (2016)>
=2016MNRAS.459.4360L 2016MNRAS.459.4360L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Stars, horizontal branch ; Binaries, orbits ;
Photometry ; Photometry, CCD
Keywords: methods: data analysis - techniques: photometric -
binaries: general - stars: horizontal branch -
stars: variables: RR Lyrae
Abstract:
This paper presents an extensive overview of known and proposed RR
Lyrae stars in binaries. The aim is to revise and extend the list with
new Galactic field systems. We utilized maxima timings for 11 RRab
type stars with suspicious behaviour from the GEOS database, and
determined maxima timings from data of sky surveys and our own
observations. This significantly extended the number of suitable
maxima timings. We modelled the proposed Light Time Effect (LiTE) in
O-C diagrams to determine orbital parameters for these systems. In
contrast to recent studies, our analysis focused on decades-long
periods instead of periods in the order of years. Secondary components
were found to be predominantly low-mass objects. However, for two of
the stars, RZ Cet and AT Ser, the mass of the suspected companion of
more than one solar mass suggests that it is a massive white dwarf, a
neutron star or even a black hole. We found that the semi-major axes
of the proposed orbits are between 1 and 20au. Because the studied
stars belong to the closest RR Lyraes, maximal angular distances
between components during orbit should at least be between 1 and 13mas
and this improves the chance to detect both stars using current
telescopes and interferometers. However, our interpretation of the O-C
diagrams as a consequence of the LiTE should be considered as
preliminary without reliable spectroscopic measurements. On the other
hand, our models give a prediction of the period and radial velocity
evolution which should be sufficient for plausible proof of binarity.
Description:
Differential photometry for VX Her in 'table1.dat' file. New
photometric measurements for VX Her were performed at Masaryk
University Observatory, Brno, Czech Republic during 13 nights
(April-August 2014) with 0.6-m (24-inch) Newtonian telescope, CCD
G2-0402, in BVRI bands. CCD images were calibrated in a standard way
(dark frame and flat field corrections). The C-Munipack software
(Motl 2009) was used for this processing as well as for differential
photometry. TYC 1510-269-1 and TYC 1510-149-1 were used as comparison
and check stars, respectively.
Differential photometry for AT Ser and SS Leo is in 'table2.dat' file.
New photometric measurements for these two stars were obtained using
1-inch refractor (a photographic lens Sonnar 4/135mm, lens focal
ratio/focal length) and ATIK 16IC CCD camera with green photometric
filter with similar throughput as the Johnson V filter. Exposures were
30s and each five frames were combined to a single image to achieve a
better signal-to-noise ratio. The time resolution of a such combined
frame is about 170s. The comparison stars were HD 142799 for AT Ser
and HD 100763 for SS Leo.
List with candidates for binaries with RR Lyrae component -
RRLyrBinCan database (version 2016 May 5) is in 'table3.dat' file.
'table4.dat' file contains false-positives binary candidates among RR
Lyrae stars.
'table5.dat' and 'table6.dat' files contain used maxima timings given
in GEOS RR Lyr database, or newly determined in this study.
Objects:
------------------------------------------------------------------
RA (2000) DE Designation(s)
------------------------------------------------------------------
02 28 32.44 -08 21 30.1 RZ Cet = AN 36.1929 = HIP 11517
11 33 54.49 -00 02 00.0 SS Leo = AN 69.1919 = HIP 56409
11 37 56.61 +67 19 47.0 SU Dra = AN 43.1907 = HIP 56734
12 32 45.63 +27 01 45.4 S Com = AN 83.1910 = HIP 61225
13 33 18.09 +53 59 14.6 RV UMa = AN 139.1907 = HIP 66122
13 51 40.78 +06 25 51.4 BB Vir = AN 23.1935 = HIP 67653
13 59 33.28 +31 39 04.3 RU CVn = AN 6.1914
14 33 33.21 +31 45 16.6 RS Boo = AN 14.1907 = HIP 71186
15 55 40.44 +07 59 18.7 AT Ser = AN 46.1935 = HIP 77997
16 30 40.73 +18 22 00.2 VX Her = AN 30.1917 = HIP 80853
21 52 02.79 +22 34 29.4 AV Peg = AN 90.1931 = HIP 107935
------------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 28 700 BVRI-photometry of VX Her
table2.dat 39 321 Green-photometry of AT Ser and SS Leo
table3.dat 262 93 RRLyrBinCan database - candidates (64 stars)
table4.dat 231 14 RRLyrBinCan database - false positives
table5.dat 96 2229 *Maxima timings from GEOS RR Lyr database
for the 11 stars
table6.dat 61 539 *Maxima timings determined in this study,
for the 11 stars
refs.dat 114 289 References
--------------------------------------------------------------------------------
Note on table5.dat,table6.dat: data for AT Ser, AV Peg, BB Vir, RS Boo, RU CVn,
RV UMa, RZ Cet,S Com , SS Leo, SU Dra, and X Her).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 F13.5 d HJD Heliocentric Julian Date
15- 20 F6.3 mag mag Magnitude in Band
22- 26 F5.3 mag e_mag Uncertainty of magnitude
28 A1 --- Band [BVRI] Photometric band, Johnson-Cousins band
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- Name Name of the RR Lyrae star
8- 20 F13.5 d HJD Heliocentric Julian Date
22- 27 F6.3 mag mag Magnitude in Band
29- 33 F5.3 mag e_mag Uncertainty of magnitude
35- 39 A5 --- Band [green] Photometric band, green band
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 20 A20 --- Name Name of the RR Lyrae star
22- 23 I2 h RAh Right ascension (J2000)
25- 26 I2 min RAm Right ascension (J2000)
28- 32 F5.2 s RAs Right ascension (J2000)
34 A1 --- DE- Declination sign (J2000)
35- 36 I2 deg DEd Declination (J2000)
38- 39 I2 arcmin DEm Declination (J2000)
41- 44 F4.1 arcsec DEs Declination (J2000)
46- 51 F6.3 mag mag Upper value of brightness range,
mean brightness in given band
53 A1 --- --- [-]
55- 60 F6.3 mag magL ? Lower value of brightness range,
mean brightness in given band
62- 63 A2 --- Band [V pg Kp] Band for brightness range
65- 66 A2 --- Blaz [B B? -] Blazhko (1)
68- 71 A4 --- Type [RRab RRc] RR Lyrae type
73 A1 --- l_Porb Limit flag on Porb
75- 86 F12.6 d Porb ?=- Expected orbital period
87 A1 --- n_Porbu [-,]
88- 97 F10.5 --- Porbu ? upper value of Porb interval or second value
98- 99 A2 --- x_Porb [d yr] Expected orbital period unit
101-109 A9 --- Meth Method of detection (2)
111-146 A36 --- Ref Reference, in refs.dat file
148-262 A115 --- Rem Remarks
--------------------------------------------------------------------------------
Note (1): Blazhko code as follows:
B = known Blazhko effect
B? = possible Blazhko effect
- = Blazhko effect is not reported
Note (2): Method of detection code as follows:
COL = systematic colour discrepancy in comparison with other RR Lyrae stars
ED = Eclipse(s) Detected - detached eclipsing system
EDM = Eclipse(s) Detected + Model calculated
LiTE = Light Time Effect is apparent in O-C diagram
LiTEM = Light Time Effect + Model calculated
RV = systematic shifts in Radial Velocities detected
RVM = systematic shifts in Radial Velocities + Model calculated
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 20 A20 --- Name Name of the RR Lyrae star
22- 23 I2 h RAh Right ascension (J2000)
25- 26 I2 min RAm Right ascension (J2000)
28- 32 F5.2 s RAs Right ascension (J2000)
34 A1 --- DE- Declination sign (J2000)
35- 36 I2 deg DEd Declination (J2000)
38- 39 I2 arcmin DEm Declination (J2000)
41- 44 F4.1 arcsec DEs Declination (J2000)
46- 51 F6.3 mag mag Upper value of brightness range,
mean brightness in given band
52 A1 --- --- [-]
53- 57 F5.2 mag magL ? Lower value of brightness range,
mean brightness in given band
58- 61 F4.2 mag e_mag ? rms uncertainty on mag
62 A1 --- Band [V] Band for brightness range
64- 65 A2 --- Blaz [B B? -] Blazhko (1)
67- 77 F11.9 d Ppuls ?=- Pulsation period
79- 90 F12.6 --- Porb ?=- Expected orbital/secondary pulsation period
91 A1 --- u_Porb [?] Uncertainty flag on Porb
92- 93 A2 --- x_Porb [d yr] Expected orbital/secondary pulsation
period unit
95-103 A9 --- Type Binary type (2)
105-157 A53 --- Ref Reference, in refs.dat file
158-231 A74 --- Rem Remarks
--------------------------------------------------------------------------------
Note (1): Blazhko code as follows:
B = known Blazhko effect
B? = possible Blazhko effect
- = Blazhko effect is not reported
Note (2): Binary type as follows:
RRab+ED = RRab star in Detached Eclipsing system (blend)
RRab+RR? = RRab star creates blend with other RR Lyrae star
DSCT+LiTE = Delta Scuti variable showing Light Time Effect
RRab+LiTE = RRab showing Light Time Effect
HADS+LiTE = High Amplitude Delta Scuti variable showing Light Time Effect
ED = Detached Eclipsing system
RV = RR Lyrae star showing systemic shifts in Radial Velocities
EW = Eclipsing system of W Ursae Majoris
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- Star GCVS name
8- 19 F12.4 d HJD Heliocentric Julian Date, time of maximum
21- 26 F6.4 d e_HJD ?=9.9999 Uncertainty of time of maximum (1)
28- 69 A42 --- Ref Reference, in refs.dat file
71- 91 A21 --- Obs Observer
93- 96 A4 --- ObsMet Observation method
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Note (1): value 9.9999 = unknown uncertainty
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- Star GCVS name
8- 19 F12.4 d HJD Heliocentric Julian Date, time of maximum
21- 26 F6.4 d e_HJD Uncertainty of time of maximum
28- 30 A3 --- ObsMet Observation method
32- 61 A30 --- Obs Observing project/observer and instrument
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Byte-by-byte Description of file: refs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 37 A37 --- Ref Reference code
39- 57 A19 --- BibCode BibCode
59-114 A56 --- Com Comments
--------------------------------------------------------------------------------
Acknowledgements:
Jiri Liska, jiriliska(at)post.cz
DTPA, Masaryk University, Czech Republic
(End) Jiri Liska [DTPA, Czech Republic], Patricia Vannier [CDS] 06-May-2016