NGC 6809 / C1936-310 / Messier 55 (Updated August 2014) RA: 19:39:59.71 DEC: -30:57:53.1 (J2000) ============================================================ Bytes Format Explanation 1-8 A8 Star ID 10-32 A11,1x,A11 Position 34-35 A2 Units for position R0 denotes RA, DEC in the J2000 coordinates R5 denotes RA, DEC in the 1950 coordinates XA denotes X, Y in arcseconds XP denotes X, Y in pixels 37-44 F8.4 Period (days) 46-51 F6.3 Mean magnitude (or maximum magnitude if "max" is indicated in the remarks column) 53-57 F5.3 Light amplitude (range of variability) 59 A1 Colour for mean magnitude and amplitude e.g. B, V, R, I, J, K or P (for photographic). 61-65 A5 Type of variable (draft 2006 GCVS classifications) CST denotes non variable stars previously designated as variables 67-80 A19 Notes and Remarks (f denotes field star) "--" or "----" indicates no data available ========================================================================= ID Position Period ampl C Type Notes/ RA/X Dec/Y Units Remarks ========================================================================= 1 19:40:22.45 -30:58:24.3 R0 0.5800 14.38 1.28 V RR0 2 19:39:42.24 -30:57:57.5 R0 0.4061 14.41 0.44 V RR1 3 19:40:05.27 -31:02:34.5 R0 0.6620 14.28 0.85 V RR0 4 19:40:07.43 -30:56:32.1 R0 0.3842 14.33 0.40 V RR1 5 19:39:55.89 -30:58:44.4 R0 0.3761 14.32 0.43 V RR1 6 19:40:07.69 -30:57:50.0 R0 0.3888 14.38 0.47 V RR1 7 19:39:59.89 -30:57:33.1 R0 0.6826 14.26 1.03 V RR0 8 19:40:02.08 -30:58:58.4 R0 0.7220 14.37 0.62 V RR0 9 19:40:27.38 -30:57:59.1 R0 0.3163 14.43 0.41 V RR1 Note 10 19:40:08.51 -30:54:49.0 R0 0.3318 14.41 0.31 V RR1 Note 11 19:40:12.02 -30:56:14.1 R0 0.3100 14.42 0.21 V RR1 12 19:39:59.80 -30:58:02.7 R0 0.3259 14.34 0.26 V RR1 Note 13 19:39:53.08 -30:50:30.6 R0 0.3978 14.44 0.39 V RR1 14 19:39:54.76 -30:50:10.2 R0 0.5216 17.97 1.03 V RR0 f;Sgr 15 19:39:43.95 -31:00:36.3 R0 0.6373 18.33 0.40 V RR0 f;Sgr 16 19:40:09.20 -30:56:42.0 R0 0.0534 16.94 0.016 V SXPHE 17 19:40:11.33 -30:59:25.1 R0 0.0413 17.18 0.049 V SXPHE 18 19:40:06.87 -30:56:32.1 R0 0.0466 16.98 0.029 V SXPHE 19 19:39:57.67 -30:57:01.3 R0 0.0382 17.27 0.033 V SXPHE 20 19:39:54.95 -30:58:21.3 R0 0.0332 17.04 0.102 V SXPHE 21 19:39:58.27 -30:59:06.1 R0 0.1356 15.76 0.036 V SXPHE 22 19:40:07.80 -31:00:12.6 R0 0.0456 16.81 0.337 V SXPHE 23 19:39:51.82 -30:55:52.8 R0 0.0414 17.22 0.050 V SXPHE 24 19:39:45.49 -30:56:02.7 R0 0.0418 17.06 0.026 V SXPHE 25 19:39:51.55 -30:56:21.3 R0 0.0985 15.88 0.899 V SXPHE 26 19:39:47.06 -30:57:34.0 R0 0.0820 16.11 0.173 V SXPHE Note 27 19:39:54.05 -30:58:07.5 R0 0.0410 17.09 0.029 V SXPHE 28 19:40:15.04 -31:05:15.0 R0 0.0538 20.61 0.260 V SXPHE f;Sgr 29 19:39:42.58 -30:55:58.3 R0 0.0343 20.71 0.295 V SXPHE f;Sgr 30 19:39:41.02 -30:50:25.2 R0 0.0563 20.35 0.258 V SXPHE f;Sgr 31 19:40:00.99 -30:57:56.5 R0 0.0388 17.23 0.041 V SXPHE 32 19:39:58.14 -30:58:32.7 R0 0.0415 16.92 0.097 V SXPHE 33 19:39:54.56 -30:59:57.9 R0 0.0593 16.40 0.054 V SXPHE 34 19:40:01.02 -31:00:37.9 R0 0.0370 17.23 0.029 V SXPHE 35 19:39:50.37 -30:55:12.4 R0 0.0487 16.57 0.070 V SXPHE 36 19:39:48.56 -30:56:45.0 R0 0.0394 16.74 0.067 V SXPHE 37 19:39:49.87 -30:57:42.5 R0 0.0438 16.96 0.051 V SXPHE 38 19:39:58.86 -30:58:14.8 R0 0.0392 16.69 0.044 V SXPHE Note 39 19:40:11.99 -31:02:04.5 R0 0.0358 17.21 0.034 V SXPHE 40 19:40:01.90 -30:55:38.2 R0 0.0370 17.20 0.028 V SXPHE 41 19:40:02.95 -30:58:28.3 R0 0.0452 16.53 0.106 V SXPHE Note 42 19:39:58.61 -30:57:23.9 R0 0.0367 17.16 0.053 V SXPHE 43 19:40:08.59 -30:58:51.1 R0 ---- 18.98 2.90 V UG max 44 19:40:10.46 -30:58:07.0 R0 2.1661 17.843 0.25 V EA max;Note 45 19:40:08.82 -30:57:16.5 R0 0.0308 16.330 0.004 V SXPHE 46 19:40:06.12 -30:58:22.1 R0 0.3194 16.462 0.35 V EW max 47 19:40:04.66 -30:57:57.9 R0 0.0249 16.786 0.003 V SXPHE 48 19:40:02.94 -30:57:29.4 R0 0.0331 16.113 0.024 V SXPHE 49 19:40:12.12 -30:58:15.6 R0 1.9590 19.15 0.47 V EA max;f 50 19:40:13.45 -30:59:45.4 R0 ---- 17.08 0.30 V ? max;f 51 19:40:11.28 -30:54:55.2 R0 0.4522 18.445 0.07 V EW max;f 52 19:40:06.46 -30:59:28.0 R0 0.0277 16.153 0.003 V SXPHE 53 19:40:05.23 -30:59:22.3 R0 0.3252 16.545 0.05 V EW max 54 19:39:37.43 -30:57:04.0 R0 9.2692 18.300 0.36 V EA max;Note 55 19:40:07.93 -30:56:50.5 R0 0.0324 17.228 0.002 V SXPHE 56 19:40:01.09 -30:57:21.0 R0 0.2919 17.74 0.36 V EW max 57 19:39:59.58 -30:56:54.0 R0 0.0219 16.644 0.003 V SXPHE 58 19:39:58.96 -30:57:04.8 R0 8.6205 18.01 0.20 V EA max 59 19:40:04.02 -30:58:13.7 R0 0.0262 16.650 0.007 V SXPHE 60 19:39:57.71 -30:57:46.4 R0 1.1830 16.83 1.78 V EA max;Note 61 19:40:00.67 -30:59:28.5 R0 0.0349 17.305 0.008 V SXPHE 62 19:39:49.80 -30:54:03.9 R0 1.2358 20.26 0.49 V EA max 63 19:39:49.29 -30:56:31.8 R0 0.0531 16.399 0.002 V SXPHE 64 19:39:47.20 -30:57:12.3 R0 12.945 17.02 0.18 V ? max;Note 65 19:39:51.18 -30:59:01.1 R0 5.5875 17.22 0.19 V ? max;Note 66 19:39:46.12 -30:59:35.6 R0 0.5497 20.22 0.41 V EA max 67 19:39:45.36 -30:00:32.9 R0 0.1211 18.31 0.12 V ? max;Note 68 19:40:01.02 -31:00:42.2 R0 0.5386 20.65 0.52 V EA max 69 19:39:53.77 -31:00:47.4 R0 0.0451 17.027 0.007 V SXPHE 70 19:39:33.48 -30:54:07.0 R0 0.2229 19.40 0.72 V EW max 71 19:40:03.30 -30:59:05.5 R0 8.0399 16.87 0.69 V ? max;Note =================================================================== Supplementary Notes All the data listed for V1-V15 are from Olech et al. (1999). The data for V16-V42 are from the discovery paper by Pych et al. (2001). They classified V16-V30 as single-mode SXPhe variables and V31-V42 as double-mode SXPhe variables. For all of the double-mode stars (except V41), one of the modes is considered to be non-radial in origin. The periods listed for V31-V42 in the above table are the longer of the stars' two periods and the amplitudes are the amplitudes associated with these longer periods (except in the case of V38). The data for V43 are from the discovery paper by Kaluzny et al. (2005) The data for V44-V71 are from the discovery paper by Kaluzny et al. (2010). However, it should be noted that the amplitudes listed for the SX Phe variables seem to be unusually low. It appears that they represent half of the total light range. More than 20 of the SXPhe variables in M55 were studied by Pych et al. (2001) and when the amplitudes they derived are compared with the values of Kaluzny et al. (2010), Pych's amplitudes are more than a factor of 2 larger. The Sagittarius (Sgr) dwarf galaxy is visible in the background field of M55. As a result, some of the variables in the M55 field are associated with the Sgr galaxy and not the cluster. This is noted in the remarks column. A proper motion study by Zloczewski et al. (2011) showed that variables V2, V4, V5, V6, V7, V8, V10, V11, V12, V16-V27, V31-V38, V41, V42, V44, V45, V47, V48, V53-V55, V57, V60-V65, V67 and V69 are all probably cluster members and that V15 and V49-V51 are field stars. Some of the variables (V5, V24, V35, V38, V40) were included in the proper motion study by Sariya et al. (2012) and all were found to be cluster members. ========================================================================= Notes on individual stars V9, V10, V12: Olech et al. (1999) found evidence for non-radial pulsations in these three variables. V26: Kaluzny et al. (2010) showed that the V-band amplitude of this star decreased significantly between 2004 and 2008. V38: The period listed is the longer period, but the amplitude corresponds to the shorter period. V41: Pych et al. (2001) tentatively concluded that this star is pulsating in the first and second radial overtone modes. V44, V54: These stars were the subject of an intensive investigation by Kaluzny et al (2014). They found that both are cluster members based on their radial velocities, confirming the result of the proper motion study by Zloczewski et al. (2011). V60: This binary system was the subject of an intensive investigation by Rozyczka et al. (2013) because it is undergoing mass change. They derived a mean radial velocity which indicated cluster membership, confirming the result of the proper motion study by Zloczewski et al. (2011). V64, V65, V67, V71: Kaluzny et al. (2010) concluded that V64 and V65 are probably binaries and that V67 is either a binary at low inclination or an ellipsoidal variable. They also noted that V65 and V71 might be the optical counterparts of Bassa et al.'s Chandra X-ray sources CX7 and CX8 respectively. ===================================================================== Discovery of the variable stars in M55: V1-2 Bailey (1902) with x,y coordinates (page 243) and an ID chart (plate XII: Fig 1, page 252.23, description on page 251) V3-6 King (1951) with x,y coordinates. No finding chart was provided, but in a later paper (King & Bruzual 1976), he pointed out that Figures 2 and 3 in a paper by Alcaino (1975) serve as convenient finding charts. V1-V6 are equivalent to Alcaino #59, 366, 96, 433, 592, and 456, respectively. V7-15 Olech et al. (1999) with RA, dec and findng charts. V16-42 Pych et al. (2001) with RA, dec and finding charts V43 = CV1 (a dwarf nova) Kaluzny et al. (2005) with RA, dec and finding chart. The number V43 was assigned in this electronic catalogue. These authors also detected a blue variable (M55-B1) that they concluded might be a candidate quasar. The extragalactic nature of this source was confirmed by Webb et al. (2006). It was their X-ray source #39. V44-71 Kaluzny et al. (2010) with RA, dec and finding charts =============================================================== Additional candidate variables Webb et al. (2006) identified 47 X-ray sources in the vicinity of M55 with XMM-Newton, four within the core radius (2.83 arcmin) and one at the half mass radius (2.89 arcmin). In their Table 7, they classified the sources that might be related to M55. They concluded that their source #30 was the Kaluzny et al. (2005) dwarf nova. In their Table 6, they listed sources that had varied since Rosat observations obtained in 1993. Bassa et al. (2008) identified 16 X-ray sources within the half mass radius, based on Chandra data. They expected about half of these to be background sources. Their CX1 was the dwarf nova announced by Kaluzny et al. They concluded that their source CX2 could be a faint cataclysmic variable and CX7, CX10 and CX16 might be associated with active binaries. ========================================================================= References Alcaino, G. 1975, A&AS, 22, 193 Bailey, S. I. 1902, Harv. Ann., 38, 1 Bassa, C. G., Pooley, D., Verbunt, F., Homer, L., Anderson, S. F., Lewin, W. H. G. 2008, A&A 488, 921 Kaluzny, J., Pietrukowicz, P., Thompson, I. B., Krzeminski, W., Schwarzenberg-Czerny, A., Pych, W., Stachowski, G. 2005, MNRAS, 359, 677 Kaluzny, J., Thompson, I. B., Dotter, A., Rozyczka, M., Pych, W., Rucinski, S. M., Burley, G. S. 2014, Ac. A., 64, 11 Kaluzny, J., Thompson, I. B., Krzeminski, W., Zloczewski, K. 2010, Ac. A., 60, 245 King, I. 1951, Harv. Bull., 920, 16 King, I. R. & Bruzual, A. G. 1976, A&A, 50, 459 Olech, A., Kaluzny, J., Thompson, I. B., Pych, W., Krzeminski, W., Schwarzenberg-Czerny, A. 1999, AJ, 118, 442 Pych, W., Kaluzny, J., Krzeminski, W., Schwarzenberg-Czerny, A., Thompson, I. B. 2001, A&A, 367, 148 Rozyczka, M., Kaluzny, J., Thompson, I. B., Rucinski, S. M., Pych, W., Krzeminski, W. 2013, Ac. A., 63, 67 Sariya, D. P., Yadav, R. K. S., Bellini, A. 2012, A&A, 543, A87 Webb, N. A., Wheatley, P. J., Barret, D. 2006, A&A, 445, 155 Zloczewski, K., Kaluzny, J., Thompson, I. B. 2011, MNRAS, 414, 3711 ==========================================================================