Peremennye Zvezdy

"Peremennye Zvezdy",
Prilozhenie
,
vol. 12, N 9 (2012)

Eight Double-Mode RR Lyrae Variables

A. V. Khruslov
Institute of Astronomy, Russian Academy of Sciences, Moscow, Russia

Received:   27.04.2012;   accepted:   6.09.2012
(E-mail for contact: khruslov@bk.ru)


#NameOtherCoord (J2000)TypeMaxMinSystemPeriodEpoch (JD)typeSpCommentL.CurveFind.ChartData
1 USNO-A2.0 0900-0063307002 42 27.13, +01 13 32.0RR(B)14.6715.22CV(see Comments)(see Comments)max Comm. 11.PNGchart1.PNG1.txt
2 USNO-A2.0 0900-0618505508 51 47.16, +07 23 53.7RR(B)16.0616.64CV(see Comments)(see Comments)max Comm. 22.PNGchart2.PNG2.txt
3 USNO-A2.0 0975-0624704909 27 30.68, +11 07 38.3RR(B)15.7016.40CV(see Comments)(see Comments)max Comm. 33.PNGchart3.PNG3.txt
4AZ ComGSC 1455-0026512 53 50.10, +22 18 39.2RR(B)15.2615.89CV(see Comments)(see Comments)max Comm. 44.PNGchart4.PNG4.txt
5GG ComUSNO-A2.0 1125-0669941513 19 54.04, +29 42 22.2RR(B)15.7116.35CV(see Comments)(see Comments)max Comm. 55.PNGchart5.PNG5.txt
6 USNO-A2.0 0900-0837075116 01 39.89, +03 25 58.9RR(B)15.1115.71CV(see Comments)(see Comments)max Comm. 66.PNGchart6.PNG6.txt
7 USNO-A2.0 0825-0955658516 40 28.29, -00 42 39.1RR(B)15.8016.46CV(see Comments)(see Comments)max Comm. 77.PNGchart7.PNG7.txt
8 USNO-A2.0 0825-1923832021 29 33.65, -00 43 30.0RR(B)14.3814.88CV(see Comments)(see Comments)max Comm. 88.PNGchart8.PNG8.txt

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:

ModeFrequency, 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:

ModeFrequency, c/d Semi-amplitude, V 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:

ModeFrequency, c/d Semi-amplitude, V 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:

ModeFrequency, c/d Semi-amplitude, V 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
ModeFrequency, c/d Semi-amplitude, V 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
ModeFrequency, 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:

ModeFrequency, c/d Semi-amplitude, V 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:

ModeFrequency, 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:

ModeFrequency, 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



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