Comments:
1. The variability of USNO-A2.0 0900-00633070 was discovered by Sesar et al.
(2010; Id. 2488976).
They classified the variable as an RRC star with the light elements:
Max = HJD 2453675.338 + 0.405047 x E.
According to data from Catalina Surveys and from Sesar et al. (2010), it is
actually a double-mode
RR Lyrae star,
type RR(B), with the light elements:
| Mode |
Frequency, c/d |
Semi-amplitude, mag |
Period, days |
Epoch, JD |
| f1 |
2.468800 |
0.173 (CV), 0.183 (r) |
0.405055 |
2454700.620 |
| f0 |
1.842656 |
0.043 (CV), 0.044 (r) |
0.542695 |
2454700.985 |
The period ratio of the first-overtone and fundamental modes is P1/P0
= 0.7464.
J–H = 0.276 (2MASS).
2. The variability of USNO-A2.0 0900-0618505 was reported by Keller et al.
(2008; Id. 104395.54).
The AAVSO Variable Star Index (VSX; www.aavso.org/vsx/) suggests, on the base of
observations from the Catalina Surveys Data Release 1 (Drake et al. 2009),
type RRC, with the light elements: Max = HJD 2453466.780 + 0.285678 x E.
This period is wrong.
I reinvestigated the star using the same Catalina Surveys data. It is actually a
double-mode
RR Lyrae star, type RR(B),
with the light elements:
| Mode |
Frequency, c/d |
Semi-amplitude, SV mag |
Period, days |
Epoch, JD |
| f1 |
2.497758 |
0.154 |
0.400359 |
2454700.778 |
| f0 |
1.863846 |
0.063 |
0.536525 |
2454701.537 |
| f1 + f0 |
4.36161 |
0.024 |
0.229273 |
2454700.610 |
The period ratio of the first-overtone and fundamental modes is P1/P0
= 0.7462.
J–H = 0.320 (2MASS).
3. The variability of USNO-A2.0 0975-06247049 was reported by Keller et al. (2008;
Id. 117937.655).
The AAVSO Variable Star Index (VSX; www.aavso.org/vsx/) suggests, on the base of
observations from the Catalina Surveys Data Release 1 (Drake et al. 2009), type
RRAB with the elements:
Max = HJD 2454448.960 + 0.416358 x E.
I reinvestigated the star using the same Catalina Surveys data.
It is actually a double-mode RR Lyrae star, type RR(B), with the light elements:
| Mode |
Frequency, c/d |
Semi-amplitude, SV mag |
Period, days |
Epoch, JD |
| f1 |
2.401773 |
0.147 |
0.416359 |
2454700.862 |
| f0 |
1.793893 |
0.063 |
0.557447 |
2454701.577 |
| fN |
1.787729 |
0.057 |
0.559369 |
2454700.657 |
The period ratio of the first-overtone and fundamental modes is P1/P0
= 0.7469.
J–H = 0.267 (2MASS).
Probably a non-radial pulsation with the frequency fN close to the
fundamental mode f0 is excited.
4. The variability of AZ Com was discovered by Hoffmeister (1964).
Following Meinunger and Wenzel (1968),
the GCVS lists it as an RRC star with the elements:
Max = JD 2437696.590 + 0.39983 x E.
According to Catalina Surveys data, it is actually a double-mode RR Lyrae star,
type RR(B),
with the light elements:
| Mode |
Frequency, c/d |
Semi-amplitude, SV mag |
Period, days |
Epoch, JD |
| f1 |
2.501000 |
0.188 |
0.399840 |
2454700.822 |
| f0 |
1.865233 |
0.075 |
0.536126 |
2454700.975 |
| f1 – f0 |
0.635809 |
0.027 |
1.57280 |
2454701.85 |
| f1 + f0 |
4.36626 |
0.022 |
0.229029 |
2454700.632 |
The period ratio of the first-overtone and fundamental modes is P1/P0
= 0.7458.
J–H = 0.287 (2MASS).
5. The variability of GG Com was reported by Kinman et al. (1966).
The variable is listed in the GCVS as an RRAB star without light elements
(its GCVS epoch of maximum, JD 2437435.712, is from Plaut 1970).
The AAVSO Variable Star Index (VSX; www.aavso.org/vsx/) suggests, on the base of
observations from the Catalina Surveys Data Release 1 (Drake et al. 2009),
type RRAB with the light elements:
Max = HJD 2454141.91000 + 0.403333 x E.
I reinvestigated the star using the same Catalina Surveys data as well as
observations from Kinman et al. (1966).
It is actually a double-mode RR Lyrae star, type RR(B),
with the light elements:
GG Com = CSS_J131954.0+294222
Catalina Surveys data
| Mode |
Frequency, c/d |
Semi-amplitude, SV mag |
Period, days |
Epoch, JD |
| f1 |
2.479359 |
0.156 |
0.403330 |
2454700.518 |
| f0 |
1.849232 |
0.086 |
0.540765 |
2454700.774 |
| f1 + f0 |
4.32861 |
0.047 |
0.231021 |
2454700.617 |
Kinman et al. data
| Mode |
Frequency, c/d |
Semi-amplitude, mag |
Period, days |
Epoch, JD |
| f1 |
2.479365 |
0.204 |
0.403329 |
2437700.310 |
| f0 |
1.85014 |
0.148 |
0.54050 |
2437700.080 |
| f1 – f0 |
0.62933 |
0.101 |
1.5890 |
2437700.65 |
The period ratio of the first-overtone and fundamental modes is
P1/P0 = 0.7459 (Catalina) or 0.7462 (Kinman et al.).
J–H = 0.102 (2MASS).
6. The variability of USNO-A2.0 0900-08370751 was discovered by Kraus et al.
(2007; No.
MG1 807002).
The variable was classified as an RRAB star without light elements.
According to Catalina Surveys data, it is actually a double-mode RR Lyrae star,
type RR(B),
with the light elements:
| Mode |
Frequency, c/d |
Semi-amplitude, SV mag |
Period, days |
Epoch, JD |
| f1 |
2.806017 |
0.191 |
0.356377 |
2454700.503 |
| f0 |
2.089362 |
0.066 |
0.478615 |
2454700.867 |
The period ratio of the first-overtone and fundamental modes is P1/P0
= 0.7446.
J–H = 0.295 (2MASS).
7. The variability of USNO-A2.0 0825-09556585 was reported by Vivas et al. (2004;
No.
496).
The variable was classified as an RRC star with the light elements:
Max = HJD 2451236.9173 + 0.391583 x E.
According to Catalina Surveys data, it is actually a double-mode RR Lyrae star,
type RR(B),
with the light elements:
| Mode |
Frequency, c/d |
Semi-amplitude, CV |
Period, days |
Epoch, JD |
| f1 |
2.553639 |
0.168 |
0.391598 |
2454700.955 |
| f0 |
1.905753 |
0.063 |
0.524727 |
2454701.015 |
The period ratio of the first-overtone and fundamental modes is P1/P0
= 0.7463.
J–H = 0.238 (2MASS).
8. The variability of USNO-A2.0 0825-19238320 was discovered by Sesar et al.
(2010; Id. 2464128).
The variable was classified as an RRC star with the light elements:
Max = HJD 2453697.153 + 0.397669 x E.
According to data from Catalina Surveys and from Sesar et al. (2010), it is actually
a double-mode
RR Lyrae star,
type RR(B),
with the light elements:
| Mode |
Frequency, c/d |
Semi-amplitude, mag |
Period, days |
Epoch, JD |
| f1 |
2.514686 |
0.172 (CV), 0.157 (r) |
0.397664 |
2454700.550 |
| f0 |
1.878167 |
0.043 (CV), 0.046 (r) |
0.532434 |
2454700.685 |
| f1 + f0 |
4.39292 |
0.025 (CV) |
0.227639 |
2454700.590 |
| f1 – f0 |
0.636497 |
0.020 (r) |
1.5711 |
2454701.58 |
The period ratio of the first-overtone and fundamental modes is P1/P0
= 0.7469.
J–H = 0.211 (2MASS).
Remarks:
I present a new investigation of eight known RR Lyrae variable stars.
I analysed the
Catalina
Surveys data
(Drake et al. 2009) using the period-search software developed by Dr. V.P. Goranskij
for Windows environment.
According to Catalina Surveys data (sometimes appended with data from other sources),
the variables are double-mode RR Lyrae variables,
pulsating in the first-overtone and fundamental modes.
Their period ratios, P1/P0,
are typical of radially pulsating double-mode RR Lyrae stars.
Along with the light curves, I present power spectra of the RR Lyrae variables,
for the raw data and after subtraction of the first-overtone oscillations.
The structure of the power spectra shows that the secondary periods are real.
The tabulated coordinates of the variables were drawn either
from the 2MASS catalog or from the GCVS.
The column "Data" in the Table reproduces Catalina observations, with Julian Dates
(instead of modified Julian Dates) reported.
References:
Drake, A.J., Djorgovski, S.G., Mahabal, A., et al., 2009, Astrophys. J., 696, 870
Hoffmeister, C., 1964, Astron. Nachr., 288, 49
Keller, S.C., Murphy, S., Prior, S., et al., 2008, Astrophys. J., 678, 851
Kinman, T.D., Wirtanen, C.A., Janes, K.A., 1966, Astrophys. J. Suppl., 13, 379
Kraus, A.L., Craine, E.R., Giampapa, M.S., et al.,2007, Astron. J., 134, 1488
Meinunger, L., Wenzel, W., 1968, Veroff. Sternw. Sonneberg, 7, 389
Plaut, L., 1970, Astron. Astrophys., 6, 486
Sesar, B., Ivezic, Z., Grammer, S.H., et al., 2010, Astrophys. J., 708, 717
Vivas, A. K., Zinn, R., Abad, C., et al., 2004, Astron. J., 127, 1158
