J/MNRAS/461/1032 M5 RR Lyrae times of maxima (Arellano Ferro+, 2016)
A new overview of secular period changes of RR Lyrae stars in M5.
Arellano Ferro A., Ahumada J.A., Kains N., Luna A.
<Mon. Not. R. Astron. Soc., 461, 1032-1044 (2016)>
=2016MNRAS.461.1032A 2016MNRAS.461.1032A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable
Keywords: stars: variables: RR Lyrae - globular clusters: individual: NGC 5904
Abstract:
Secular period variations, β=dP/dt, in 76 RR Lyrae stars in the
globular cluster M5 are analysed using our most recent CCD V
photometry and the historical photometric data base available in the
literature since 1889. This provides a time baseline of up to 118 yr
for these variables. The analysis was performed using two independent
approaches: first, the classical O-C behaviour of the time of maximum
light, and second, via a grid (P, β), where the solution
producing the minimum scatter in the phased light curve is chosen. The
results of the two methods agree satisfactorily. This allowed a new
interpretation of the nature of the period changes in many RR Lyrae
stars in M5. It is found that in 96 per cent of the stars studied no
irregular or stochastic variations need to be claimed, but that 66 per
cent of the population shows steady period increases or decreases, and
that 34 per cent of the periods seem to have been stable over the last
century. The lack of systematic positive or negative period variations
in RR Lyrae stars in other globular clusters is addressed, and the
paradigm of period changes being a consequence of stellar evolution is
discussed in terms of chemical variations near the stellar core and of
multiple stellar populations. In M5 we found a small positive average
value of β and a small surplus of RRab stars with a period
increase. Nevertheless, in M5 we have been able to isolate a group of
likely evolved stars that systematically show positive, and in some
cases large, period change rates.
Description:
Secular period changes in RR Lyrae M5 stars are analysed by means of
two approac hes, taking advantage of the data long time-base of about
118 years. Few authentically evolved stars are identified.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 86 76 New periods and period change rates for RR Lyrae
stars in M5
table2a.dat 29 83 Fundamental periods of studied stars
table2b.dat 51 1061 Observed times of maximum light O for RR Lyrae stars
in M5 and the corresponding O-C residuals calculated
with the given ephemerides for each variable
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See also:
J/MNRAS/411/1744 : Observations of RR Lyr stars in M5 (Szeidl+, 2011)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- VName Variable name
6- 14 A9 --- VType Varialbe type
15- 22 F8.6 d P0 Period at E0 from Arellano Ferro et
al. (2016, Cat. J/other/ApSS/351.175)
24- 32 F9.4 d E0 Epoch (HJD-2450000)
34- 42 F9.4 d E0+A0 ?=- Corrected epoch (HJD-2450000)
44- 53 F10.8 d P0+A1 ?=- Corrected period
55- 60 F6.3 d/Myr beta0(O-C) ?=- Period change rate, dP/dt, from (O-C)
62- 63 I2 10-3d/Myr e_beta0(O-C) ? rms uncertainty on beta0(O-C)
64 A1 --- u_beta0(O-C) Uncertainty flag on beta0(O-C) (1)
65 A1 --- f_beta0(O-C) [*] * for recommended beta0 value
67- 71 F5.2 10-3d/Myr beta0(Pb) ?=- Period change rate, dP/dt,
from (P,beta)
72 A1 --- u_beta0(Pb) ? rms uncertainty on beta0(Pbeta)
73 A1 --- f_beta0(Pb) [*] * for recommended beta0 value
75- 82 F8.6 d P0(Pb) ?=- Period at E0 from (P,beta)
84- 86 A3 --- Notes Notes (2)
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Note (1): corresponds to the uncertainty in coefficient A2 in equation (9) of
the paper.
Note (2): Notes as follows:
a = There is a comment for this star in Section 4.4.
b = All these stars display a linear O-C diagram and in fact β is not
significantly different from zero. Therfore, we recommend a value of
β=0.0.
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Byte-by-byte Description of file: table2a.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- VName Variable name
6- 13 F8.6 d P0 Period at E0
15- 26 F12.4 d E0 Epoch (HJD)
28- 29 I2 --- Nobs Number of observations in table2b
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Byte-by-byte Description of file: table2b.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- VName Variable name (VNNN)
6- 15 F10.4 d O Observed time of maximum light (JD-2400000)
21- 27 F7.4 d O-C O-C residual
32- 40 F9.1 --- Ncycles Number of cycles elapsed between E0 and C
48- 51 A4 --- Ref Reference (1)
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Note (1): References as follows:
AF16 = calculated from data by Arrellano Ferro et al.
(2016, Cat. J/other/ApSS/361.175)
BRO = calculated in this work from data by Brocato, Castellani &
Ripepi (1996AJ....111..809B 1996AJ....111..809B)
COH = calculated in this work from data by Cohen & Sarajedini (2012,
Cat. J/MNRAS/419/342)
COU = listed by Coutts (1971PDDO....3...81C 1971PDDO....3...81C) from Mount Wilson 1917 data
CSH = listed by Coutts & Sawyer-Hogg (1969PDDO....3.....C 1969PDDO....3.....C) from
Oosterhoff's 1941 data
KAL = calculated from data by Kaluzny et al. 1999A&A...350..469K 1999A&A...350..469K
B24 = calculated from the data in Table 1 of Szeidl et al., 2011,
Cat. J/MNRAS/411/1744
A48 = calculated from the data in Table 1 of Szeidl et al., 2011,
Cat. J/MNRAS/411/1744
L24 = calculated from the data in Table 1 of Szeidl et al., 2011,
Cat. J/MNRAS/411/1744
P40 = calculated from the data in Table 1 of Szeidl et al., 2011,
Cat. J/MNRAS/411/1744
KK = listed by Kukarkin & Kukarkina (1971PZP.....1....1K 1971PZP.....1....1K)
STO = calculated in this work from data by Storm et al.
(1991PASP..103.1264S 1991PASP..103.1264S)
hDDO = calculated in this work from DDO data published by
Coutts & Sawyer-Hogg (1969PDDO....3.....C 1969PDDO....3.....C)
hOOS = calculated in this work from Oosterhoff's (1941AnLei..17d...1O 1941AnLei..17d...1O) data
hWil = calculated in this work from Mount Wilson 1917 data published by
Coutts & Sawyer-Hogg (1969PDDO....3.....C 1969PDDO....3.....C)
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Acknowledgements:
Armando Arellano Ferro, armando(at)astro.unam.mx
History:
* 12-Dec-2016: on-line version with non heliocentric JD in table2b.dat
* 20-Dec-2016: corrected table2b.dat with HJD (from author)
(End) Armando Arelano Ferro [IA-UNAM, Mexico] Patricia Vannier [CDS] 12-Dec-2016