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J/AJ/108/222 Pop. II variable stars (Nemec+, 1994)
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Period-luminosity-metallicity relations, pulsation modes, absolute magnitudes,
and distances for population II variable stars
Nemec J.M., Linnell Nemec A.F., Lutz T.E.
<Astron. J. 108, 222 (1994)>
=1994AJ....108..222N (SIMBAD/NED Reference)
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ADC_Keywords: Stars, variable ; Stars, population II ; Magnitudes
Abstract:
Period-luminosity-metallicity (P-L-[Fe/H]) relations are presented for
RR Lyrae stars, Pop. II Cepheids, anomalous Cepheids and SX Phe stars
pulsating in the fundamental (F) and first-overtone (H) modes. The
relations were derived by fitting regression lines to the observed
pulsation periods and mean B, V, and K magnitudes of over 1200 stars in
~40 stellar systems. Analysis of covariance methods, which allow the
simultaneous computation of more than one P-L-[Fe/H] relation, were
used to estimate the slopes and intercepts. Of the 24 possible
P-L-[Fe/H] relations for the four kind of stars, two pulsation modes,
and three passbands considered here, 18 relations have been derived --
the others could not be derived because of a lack of photometry in one
or more of the three passbands. The slopes for the F and H pulsators
were tested for departures from equality for all types of stars and
passbands; the results suggest that the observations are consistent
with the assumption that, for each kind of star (except possibly the
Pop. II Cepheids), the P-L-[Fe/H] relations for the F and H pulsation
modes are parallel but vertically offset, with a family of lines
corresponding to a range of metallicities. Pulsation modes and
absolute magnitudes are presented for the non-RR Lyrae variable stars
considered in the analysis, and distances are estimated for the program
clusters. It is well established from previous studies that the P-L
relations for RR Lyrae stars are approximately flat for the B passband,
and have a slope DeltaM(K)/DeltalogP~-2.4 for the K passband. We
recover these slopes, and find that the P-L-[Fe/H] relation in V has an
intermediate slope, Delta M(V)/DeltalogP=-0.52+/-0.11. A similar
dependence of slope on passband is seen for classical Cepheids [see
Madore & Freedman, PASP, 103, 933 (1991)]. The available B,V
photometry for ~40 of the known globular cluster Cepheids are found to
be consistent with Arp's [AJ, 60, 1 (1955)] assumption that Pop. II
Cepheids pulsate in the F and H modes (and not in the F mode only, as
has often been assumed). The estimated slopes of the corresponding
P-L-[Fe/H] relations are Delta M(B)/Delta log P=-1.69+/-0.05 and
DeltaM(V)/DeltalogP=-1.93+/-0.05, with a separation between the
F and H modes of 0.59 mag in B, and 0.45 mag in V. As in the case of
the RR Lyrae stars the redder passband has the steeper slope. We find
that 15 of the 21 short-period BL Her Cepheids (P<=8days) appear to
be H pulsators, while 15 of the 19 W Cir Cepheids (12<=P<=30days)
appear to be F pulsators. The period-amplitude (P-A(B)) diagram
suggests that at a given period the first-overtone pulsators have
larger amplitudes than the fundamental mode pulsators. For the
Anomalous Cepheids the estimated P-L-[Fe/H] relations have slopes
DeltaM(B)/DeltalogP=-3.20+/-0.18, and DeltaM(V)/DeltalogP=-3.13+/-0.28.
The offsets between the F and H mode relations are 0.68 and
0.66mag in B and V, respectively. The estimated P-L-[Fe/H] relations
in B and V for the SX Phe stars have slopes
DeltaM(B)/DeltalogP=-2.66+/-0.52 and DeltaM(V)/DeltalogP=-2.56+/-0.54,
and the F and H relations are separated by 0.34 and 0.29mag in B and V,
respectively. These relations are consistent with the observed period
ratio for the double-mode star SX Phe. In a period-amplitude diagram
the longest period SX Phe stars have the largest amplitudes, with no
dependence on metallicity. The (B-V)0 color range of the SX Phe stars
is from 0.12 to 0.29.
Addresses:
Nemec J.M. nemec@das.nrc.ca
Department of Astronomy, University of Washington, Seattle,
Washington 98195 and Program in Astronomy, Washington State University,
Pullman, Washington 99164
Linnell Nemec A.F. anemec@galaxy.gov.bc.ca
International Statistics & Research Corporation, Brentwood Bay,
British Columbia, Canada V8M 1R3
Lutz T.E. tlutz@beta.math.wsu.edu
Program in Astronomy, Washington State University, Pullman,
Washington 99164
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 137 50 Pop. II Cepheids in galactic globular clusters
table4.tex 106 315 TeX version of table4.dat
table5.dat 158 24 Anomalous Cepheids: puls. modes and abs. mags
table5.tex 89 235 TeX version of table5.dat
table6.dat 151 21 SX Phe Stars: pulsation modes and abs. mags
table6.tex 109 239 TeX version of table6.dat
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Star name
13- 17 F5.2 --- [Fe/H] []? Assumed metal abundance
19- 22 F4.2 --- E(B-V) []? Assumed reddening
24- 32 F9.6 d P []? Pulsation period
34- 40 F7.4 d logP []? Log base 10 of P
42- 45 A4 --- Type Type of Cepheid and pulsation mode (1)
47- 50 F4.2 mag AB []? Blue amplitude of the Cepheid
52- 56 F5.2 mag Bmag []? Assumed mean B magnitude
58- 62 F5.2 mag B0 Dereddened B magnitude
64- 68 F5.2 mag Vmag []? Assumed mean V magnitude
70- 74 F5.2 mag V0 []? Dereddened V magnitude
76- 79 F4.2 mag B-V []? B-V color
81- 84 F4.2 mag (B-V)0 []? Dereddened B-V color
86- 90 F5.2 mag B0obs Observed M15-normalized apparent B mag (2)
92- 96 F5.2 mag B0pred Predicted M15-normalized apparent B mag (2)
98-102 F5.2 mag V0obs []? Observed M15-normalized
apparent V mag (2)
104-108 F5.2 mag V0pred []? Predicted M15-normalized
apparent V mag (2)
110-114 F5.2 mag MBobs Observed absolute B magnitude
116-120 F5.2 mag MBpred Predicted absolute B magnitude
122-126 F5.2 mag MVobs []? Observed absolute V magnitude
128-132 F5.2 mag MVpred []? Predicted absolute V magnitude
134-137 A4 --- Ref Reference for source of data (3)
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Note (1): Cepheid Types: BL=BL Her WV=W Vir RV=RV Tau
Pulsation Modes: F = fundamental mode H = first-overtone mode
Note (2): Observed and predicted apparent B and V magnitudes after correcting
and normalizing the metallicity and distance to that of M15
(i.e., the magnitudes are the values that the stars would have if
they were all at the distance of M15 and had the metallicity
[Fe/H] = -2.15). See equation 5 in the printed paper.
Note (3): References:
C88 = Clement, Sawyer Hogg & Yee, 1988AJ.....96.1642C
CS78 = Clement & Sawyer Hogg, 1978AJ.....83..167C
D69 = Demers, 1969AJ.....74..925D
DH74 = Demers & Harris, 1974AJ.....79..627D
DC67 = Dickens & Carey, 1967RGOB..129..355D
E72 = Eggen, 1972ApJ...172..639E
G93 = Gonzalez 1993, Ph.D. thesis, U. of Washington, Seattle, WA
H85 = Harris 1985, in Cepheids: Theory and Observations. IAU
Colloquim No. 82, edited by B. F. Madore (Cambridge
University Press, Cambridge), p. 232
K68 = Kwee, 1968BAN....19..374K
L74 = Lee, 1974Obs....94...74L
PM77 = Pike & Meston, 1977MNRAS.180..613P
PR77 = Pinto & Rosino, 1977A&AS...28..427P
W86 = Wehlau et al., 1986AJ.....91.1340W
WS84 = Wehlau & Sawyer Hogg, 1984AJ.....89.1005W
WS85 = Wehlau & Sawyer Hogg, 1985AJ.....90.2514W
W92 = Wehlau 1992, private communication
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name Star name
16- 20 F5.2 --- [Fe/H] Assumed metal abundance
22- 25 F4.2 --- E(B-V) Assumed reddening
27- 34 F8.5 h Ph Pulsation period
36- 43 F8.6 d Pd Pulsation period
45- 51 F7.4 d logP Log base 10 of P
53 A1 --- Mode Pulsation mode (1)
55- 59 F5.2 mag Bmag Assumed mean B magnitude
61- 65 F5.2 mag B0 Dereddened B magnitude
67- 70 F4.2 mag AB []? B pulsation amplitude
72- 76 F5.2 mag Vmag []? Assumed mean V magnitude
78- 82 F5.2 mag V0 []? Dereddened V magnitude
84- 87 F4.2 mag AV []? V pulsation amplitude
89- 92 F4.2 mag B-V []? B-V color
94- 97 F4.2 mag (B-V)0 []? Dereddened B-V color
99-103 F5.2 mag B0obs Observed M15-normalized apparent B mag
105-109 F5.2 mag B0pred Predicted M15-normalized apparent B mag
111-115 F5.2 mag dB0 Difference between B0obs-B0pred
117-121 F5.2 mag V0obs []? Observed M15-normalized apparent V mag
123-127 F5.2 mag V0pred []? Predicted M15-normalized apparent V mag
129-133 F5.2 mag dV0 []? Difference between V0obs-V0pred
135-139 F5.2 mag MBobs Observed absolute B magnitude
141-145 F5.2 mag MBpred Predicted absolute B magnitude
147-151 F5.2 mag MVobs []? Observed absolute V magnitude
153-157 F5.2 mag MVpred []? Predicted absolute V magnitude
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Note (1): Pulsation Modes: F = fundamental mode H = first-overtone mode
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name Star name
16- 20 F5.2 --- [Fe/H] Assumed metal abundance
22- 24 A3 --- r_[Fe/H] Source of metal abundance (1)
26- 29 F4.2 --- E(B-V) Assumed reddening
31- 33 A3 --- r_E(B-V) Source of reddening (2)
35- 40 F6.2 min Pm Pulsation period
42- 47 F6.4 d Pd Pulsation period
49- 54 F6.3 --- logP Log base 10 of P
56 A1 --- Mode Pulsation mode (3)
58- 62 F5.2 mag B Assumed mean B magnitude
64- 68 F5.2 mag B0 Dereddened B magnitude
70- 74 F5.2 mag V Assumed mean V magnitude
76- 80 F5.2 mag V0 Dereddened V magnitude
82- 85 F4.2 mag AV V pulsation amplitude
87- 90 F4.2 mag B-V B-V color
92- 95 F4.2 mag (B-V)0 Dereddened B-V color
97-101 F5.2 mag B0obs Observed M15-normalized apparent B mag
103-107 F5.2 mag B0pred []? Predicted M15-normalized apparent B mag
109-113 F5.2 mag dB0 []? Difference between B0obs-B0pred
115-119 F5.2 mag V0obs Observed M15-normalized apparent V mag
121-125 F5.2 mag V0pred []? Predicted M15-normalized apparent V mag
127-131 F5.2 mag dV0 []? Difference between V0obs-V0pred
133-136 F4.2 mag MBobs Observed absolute B magnitude
138-141 F4.2 mag MBpred []? Predicted absolute B magnitude
143-146 F4.2 mag MVobs Observed absolute V magnitude
148-151 F4.2 mag MVpred []? Predicted absolute V magnitude
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Note (1): References for [Fe/H]
ADZ = Armandroff, Demarque & Zinn, 1993 (reference not specified)
BM = Burki & Meylan, 1986A&A...159..261B
EI = Eggen & Iben, 1989AJ.....97..431E
GMC = Geisler, Minniti & Claria, 1992AJ....104..627G
KK = Kaluzny & Krzeminski, 1993MNRAS.264..785K
MB = McNamara & Budge, 1985PASP...97..322M
MF = McNamara & Feltz, 1978PASP...90..275M
ZW = Zinn & West, 1984ApJS...55...45Z
Note (2): References for B-V
FRN = Fahlman, Richer & Nemec, 1991ApJ...380..124F
RF = Richer & Fahlman, 1988ApJ...325..218R
Z85 = Zinn, 1985ApJ...293..424Z
Note (3): Pulsation Modes: F = fundamental mode, H = first-overtone mode
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Origin: AAS CD-ROM series, Volume 3, 1995
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(End) Lee Brotzman [ADS] 10-Oct-1994, Patricia Bauer [CDS] 16-Feb-1995