NGC 6254 / C1654-040 / Messier 10 (Updated April 2022) RA: 16:57:09.05 DEC: -04:06:01.1 (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 16:57:10.12 -04:05:36.1 R0 48.94 11.94 1.5 V SR Note 2 16:57:11.74 -04:03:59.7 R0 18.70 12.08 1.2 V CW Note 3 16:56:55.95 -04:04:16.3 R0 7.833 12.78 0.3 V CW Note 4 16:57:11.63 -04:10:37.9 R0 ---- -- -- CST? Note 5 16:57:08.59 –04:06:16.3 R0 0.0585 17.079 0.53 V SXP 6 16:57:10.70 –04:05:33.4 R0 0.0599 16.717 0.09 V SXP 7 16:57:10.37 –04:07:03.3 R0 0.0481 17.592 0.10 V SXP 8 16:57:08.38 –04:05:08.7 R0 0.0510 17.012 0.10 V SXP f?;Note 9 16:57:10.57 –04:05:51.8 R0 0.0513 17.303 0.60 V SXP f?;Note 10 16:57:08.43 –04:06:54.8 R0 0.0223 17.555 0.10 V SXP 11 16:57:10.82 –04:05:55.9 R0 0.0480 17.515 0.265 V SXP f 12 16:57:04.05 –04:06:07.3 R0 0.0228 17.305 0.04 V SXP 13 16:57:08.80 –04:06:24.5 R0 0.0369 16.896 0.04 V SXP Note 14 16:57:09.19 –04:06:05.4 R0 0.0382 17.641 0.10 V SXP f?:Note 15 16:57:13.28 –04:05:49.0 R0 0.0348 17.496 0.07 V SXP 16 16:57:06.23 –04:06:42.5 R0 -- 16.904 – V CST? Note 17 16:57:05.52 –04:07:47.3 R0 0.0369 17.284 0.10 V SXP 18 16:57:20.23 –04:04:52.2 R0 0.0424 17.534 0.07 V SXP 19 16:57:38.66 –04:08:57.4 R0 0.0438 –– – V SXP 20 16:57:02.97 –04:04:00.6 R0 0.0506 16.987 0.59 V SXP 21 16:57:13.69 –04:07:28.1 R0 0.2450 19.682 0.32 V EW 22 16:57:08.32 –04:02:19.8 R0 0.4046 14.637 0.39 V RR1 23 16:57:01.15 –04:07:49.7 R0 1.4466 17.657 0.09 V sin 24 16:57:07.55 –04:05:42.4 R0 2.3075 14.023 0.353 V CW 25 16:57:05.83 –04:03:46.0 R0 4.4570 17.322 0.07 V ? Note 26 16:57:13.20 –04:04:11.8 R0 21.7847 16.573 0.18 V sin Note 27 16:57:15.07 –04:05:52.4 R0 21.040 11.915 0.68 V SR 28 16:57:10.76 –04:04:43.8 R0 60.4838 11.87 0.09 V SR 29 16:57:27.38 –04:01:24.7 R0 68.3883 11.872 0.20 V SR 30 16:57:07.78 –04:06:06.0 R0 71.6680 12.447 0.18 V SR 31 16:57:00.63 –04:04:12.5 R0 0.2051 15.882 V Var? Note 32 16:57:26.85 –04:04:31.3 R0 0.8480 17.973 – V Var? Note 33 16:57:21.58 –04:02:18.6 R0 0.9335 17.581 0.10 V sin Note 34 16:57:08.49 –04:05:55.7 R0 3.3391 16.996 – V E Note 35 16:57:08.95 -04:05:44.5 R0 0.0553 17.147 0.18 V SXP 36 16:57:10.72 -04:05:58.7 R0 1.0825 14.470 0.025 V sin 37 16:57:21.00 -04:06:38.1 R0 0.1908 14.692 0.02 V sin PSR:A,B -- -- ---- -- -- PSR ========================================================================= Supplementary Notes NGC 6254 (M10) is a relatively metal poor globular cluster, with [Fe/H] = -1.56, according to Harris (2010), and a predominantly blue horizontal branch in its CM diagram (Arellano Ferro et al. 2020). As a result, only three variables, two of which were type II Cepheids, were confirmed from photographic studies. However, numerous additional variables were identified after M10 was observed with CCD detectors. V5 to V16 were announced by Salinas et al. (2016), V17 to V34 by Rozyczka et al. (2018), hereafter R18, and V35-V37 by Arellano Ferro et al. (2020), hereafter AF20, In the above table, the data are from the following sources: V1-4: The RA and dec are from Samus et al. (2009). The sources for the remaining data are indicated in the Notes on individual stars. V5-37: The data for V5-37 are from Table 3 in the paper by AF20. In their table, AF20 listed periods that were derived by R18, in addition to their own, because the R18 observations were more extensive. As a result, in the above table, the R18 periods have been listed for V5-34, the stars that R18 observed. R18 also listed the membership status for the stars in their study. These were obtained from a proper motion study by Narloch et al. (2017). The field (f) designations in the above table are from R18 unless indicated otherwise in the notes on individual stars. ============================================================================= Notes on individual stars V1: The variability classification is from Clement et al. (1985). The remaining data are from Karmakar et al. (2022). The period is the one they derived from the ASAS-SN g-data that they analysed and the V magnitude and amplitude are from their own CCD observations. V2: The variability classification is from Arp (1955a). The remaining data are from Karmakar et al. (2022). The period is the one they derived from the ASAS-SN g-data that they analysed and the V magnitude and amplitude are from their own CCD observations. In their paper, Karmakar et al. also gave a good discussion of the period doubling effect in the light curve of V2, particularly the ASAS-SN data. V3: The variability classification is from Arp (1955a). The remaining data are from Karmakar et al. (2022). The period is the one they derived from the ASAS-SN g-data that they analysed and the V magnitude and amplitude are from their own CCD observations. V4: Voroshilov (1971) classified V4 as a possible RR Lyrae based on the fact that it was located in the instabiity strip of the CMD. However, its variability has not been detected in any subsequent investigation. R18 found that it was constant to an accuracy of 0.01 mag in the V band. However, they concluded that, since it is a proper motion member of M10, and it is located near the HB in the CM diagram, it would be an interesting target for a follow-up study. V8: The membership status for V8 is uncertain because R18 found a discrepancy in proper motion between their data and the values they obtained from Gaia. AF20 did not derive membership status. Thus it is classified as a possible field star, but membership is not ruled out. V9: Salinas et al. (2016) noted that, in HST photometry, V9 was brighter than the blue stragglers of similar colour. This led them to conclude that it might be a foreground Delta Scuti variable, although its proximity to the cluster centre would indicate cluster membership. R18 inspected archival HST frames and found that V9 was a blend of two nearly equally bright stars which would account for its non-standard brightness and colour. Neither R18 or AF20 were able to derive membership status based on proper motions. Thus it is classified as a possible field star, but membership is not ruled out. V14: R18 concluded that V14 was a cluster member, but AF20 were unable to determine membership status from proper motion data. Both investigations showed that the star's location in the CM diagram was consistent with memebership. V16: The observations of Salinas et al. (2016) showed a steady increase in brightness (~ 0.02 mag) for this star located on the subgiant branch of the CM diagram, throughout the 6.65 hour time span of their observations. They suggested that its properties might be similar to a group of variable K giants that Kaluzny et al. (1998) identified on the subgiant branch in 47 Tucanae. However, AF20 did not detect any variabiity in V16 and R18 detected variability on only a small fraction of the nights they observed. They also noted that V16 splits into three objects in HST archival frames. It therefore appears that V16 is constant. V25: The classification for V25 is uncertain. Both R18 and AF20 found that the star was located at the extreme blue end of the horizontal branch in the CM diagram. In spite of this, R18 classified it as SR and derived a period of 4.457, but he acknowledged that this classification was difficult to understand. He therefore suggested that the star might be tightly blended with a field binary. This would account for an irregularity in its light curve shape as well as its unusual location in the CM diagram. V26: R18 classified V26 as a red straggler with a period of 21.785 days. Both R18 and AF20 showed that its light curve is sinusoidal. Although both studies confirmed that V26 is a cluster member, AF20 thought ths could be an example of a false positive. V31, V32: R18 classified V31 and V32 as suspected variables. They exhibited low amplitude sinusoidal variations that should be independendtly confirmed. AF20 did not confirm their variabiity. V33: R18 classified V33 as a suspected variable. It exhibited low low amplitude sinusoidal variations that should be independendtly confirmed. In this case, AF20 confirmed the variability and noted that V33 had properties similar to V25. V34: According to Shishkovsky et al. (2018), this star is the optical counterpart of an active radio and X-ray source associated with a binary system that might have a back hole primary. R18 showed that the spectroscopic period (3.3391 days) gives a good fit to the optical light curve, but a different period (3.3389) gives a slightly better fit while preservng the overall agreement with the radial velocity data. Shishkovsky et al. concluded that the star is a cluster member because it has a radial velocity consistent with the cluster systemic velocity. Membership status based on proper motion is not available because no proper motion measures have been published. ================================================================== Discovery of the variable stars in M10: V1-2 Sawyer (1938) with ID chart and x,y coordinates V3 Arp (1955a) with ID chart for V2&3. Sawyer (1955) listed the x,y coords in her 2nd catalogue V4 = Arp IV-37 (see Arp 1955b) by Voroshilov (1971) who found that this was an HB star in the instability strip. The number V4 was assigned by Sawyer Hogg (1973) in her 3rd catalogue. V5-16 Salinas et al. (2016) with RA and dec (J2000) V17-33 R18 with RA and dec (J2000) and individual finder charts. They concluded that all of these variables were probably cluster members. In addition, they announced six variables, N1-6, that were located within their field of view, but not considered to be cluster members. V34 This is the optical counterpart of the radio source M10-VLA1 observed by Shishkovsky et al. (2018) who published its RA and dec (J2000). They also made optical spectroscopic observations and derived a binary period 0f 3.3391 days. This period was confirmed in photometric observations by R18 who who assigned the number V34. V35-37 AF20 with an ID chart. The RA and dec (J2000) listed in the above table were provided by Arellano Ferro (2022, private communication). AF20 also published RA and dec (J2000) and an ID chart for all of the other variables that were in their field of view. In their investigation, they found inconsistencies between the identifications of Salinas et al. (2016) and R18 for some of the stars. Therefore we have adopted the RA and dec published by AF20 for all of the variables numbered V4-34. PSR: According to Paulo Freire's website, there are 2 milli-second pulsars in NGC 6254. (www.naic.edu/~pfreire/GCpsr.html) ====================================================================== ----------------------------------------------------------------- Additional field variables not listed above M10:V1-3 by von Braun et al. (2002) vB#1 is a foreground WUMa, #2 is a background RR0 and #3 is a background SXPhe (or delta Scuti) ------------------------------------------------------------------- Pietrukowicz et al. (2008, MNRAS 388, 1111) searched for dwarf novae in M10 and found none. --------------------------------------------------------------------- Dalessandro et al. (2013) counted 120 blue straggler stars within the tidal radius of M10, but did not carry out a variability search. ----------------------------------------------------------------- Narloch et al. (2017) derived proper motions and membership probabilities for more than 24,000 stars in the field of M10. According to R18, their proper motions generally agree with those of Gaia. ===================================================================== References Arellano Ferro, A., Yepez, M. A., Muneer, S., Bustos Ferro, I. H., Schroder, K. P., Giridhar, S., Calderson, J. H. 2020, MNRAS, 499, 4026 Arp, H. C. 1955a, AJ, 60, 1 Arp, H. C. 1955b, AJ, 60, 317 Clement, C. M., Hogg, H. S., Wells, T. R. 1985, AJ 90, 1238 Dalessandro, E., Ferraro, F. R., Lanzoni, B., Schiavon, R. P., O'Connell, R. W., Beccari, G. 2013, ApJ, 770, 45 Harris, W. E. 2010, arXiv:1012.3224 Kaluzny, J., Kubiak, M., Szymanski, M., Udalski, A., Krzeminski, W., Mateo, M., Stanek, K. Z. 1998, A&AS, 128, 19 Karmakar, P., Smith, H. A., Osborn, W., Stetson, P.B. 2022, JAAVSO, 50, No. 1 Narloch, W., Kaluzny, J., Poleski, R., Rozyczka, M., Pych, W., Thompson, I. B. 2017, MNRAS, 471, 1446 Pietrukowicz, P., Kaluzny, J., Schwarzenberg-Czerny, A., Thompson, I. B., Pych, W., Krzeminski, W., Mazur, B. 2008, MNRAS, 388, 1111 Rozyczka, M., Narloch, W., Schwarzenberg-Czerny, A., Thompson, I. B., Poleski, I. B., Pych, W. 2018, Acta Ast., 68, 237 Samus, N. N., Kazarovets, E. V., Pastukhova, E. N., Tsvetkova, T. M., Durlevich, O. V. 2009, PASP, 121, 1378 Salinas, R., Contreras Ramos, R., Strader, J., Hakala, P., Catelan, M., Peacock, M. B., Simunovic, M. 2016, AJ, 152, 55 Sawyer, H. B. 1938, Publ. DAO, 7, no.5 Sawyer, H. B. 1955, Publ. DDO, 2, No. 2 Sawyer Hogg, H. 1973, Publ. DDO, 3, No. 6 Shishkovsky, L., Strader, J., Chomiuk, L., Bahramian, A., Tremou, E., Li, K.-L., Salinas, R. and 5 co-authors, 2018, ApJ, 855, 55 von Braun, K., Mateo, M., Chiboucas, K., Athey, A., Hurley-Keller, D. 2002, AJ, 124, 2067 Voroshilov, Yu. V. 1971, Astron. Tsirk., 623, 7 =============================================================