NGC 362 / C0100-711 (Updated November 2016) RA: 01:03:14.26 DEC: -70:50:55.6 (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 01:02:24.02 -70:51:56.4 R0 0.5851 15.55 0.91 V RR0 Sz15 2 01:03:21.83 -70:54:20.1 R0 105.0 13.45 1.0 V SR Note 3 01:03:32.57 -70:53:19.7 R0 0.4745 15.60 1.10 V RR0 Sz68 4 01:03:04.29 -70:51:19.8 R0 0.5304 14.751 0.707 V RR0 Sz31a;Note 5 01:02:58.08 -70:51:23.6 R0 0.4901 15.50 1.44 V RR0 Sz27;Note 6 01:03:31.24 -70:50:41.7 R0 0.5146 15.52 1.17 V RR0 Sz67 7 01:03:40.35 -70:51:18.7 R0 0.5286 15.54 1.09 V RR0 Sz71;Note 8 01:03:19.37 -70:56:03.3 R0 3.9013 15.86 1.12 V CEP f;Sz60 9 01:01:54.55 -70:46:59.7 R0 0.5475 15.80 1.32 V RR0 Sz7;Note 10 01:04:10.11 -70:57:21.5 R0 4.205 -- 0.66 V CEP f;Sz75;Note 11 01:02:46.55 -70:51:16.7 R0 0.4202 15.37 0.41 V RR1 Sz23;Note 12 01:03:07.55 -70:52:49.2 R0 0.6526 15.46 0.87 V RR0 Sz35 13 01:03:17.57 -70:50:15.7 R0 0.5098 15.49 1.15 V RR0 Sz55 14 01:03:09.08 -70:52:00.2 R0 0.5177 15.535 0.983 V RR0 Sz40;R16 15 01:03:44.13 -70:54:01.1 R0 1.4305 17.34 1.19 V CEP f;Sz72 16 01:03:15.07 -70:50:32.5 R0 135.0 13.52 2.4 V M Sz51;Note 17 01:02:46.95 -70:45:46.4 R0 0.0346 18.168 0.015 V SX 18 01:03:18.08 -70:50:34.2 R0 0.0679 17.671 0.451 V SX 19 01:02:33.40 -70:47:03.2 R0 0.2314 19.673 0.449 V EW max 20 01:03:19.48 -70:50:41.8 R0 0.4022 17.251 0.737 V EB/EW max 21 01:03:16.63 -70:50:52.3 R0 0.5204 14.550 0.460 V RR0 blend 22 01:03:12.39 -70:50:47.0 R0 0.5663 15.888 0.236 V RR0 blend? 23 01:02:55.69 -70:51:09.7 R0 0.9208 18.385 0.210 V EA max 24 01:03:22.09 -70:50:44.7 R0 8.1405 16.272 0.266 V EA max;Note 25 01:03:34.45 -70:53:58.3 R0 12.5146 15.727 0.681 V spot? 26 01:02:38.19 -70:54:51.6 R0 14.7240 15.495 0.020 V spot? 27 01:03:30.05 -70:55:22.1 R0 15.0522 15.079 0.091 V spot? 28 01:02:40.56 -70:49:00.5 R0 24.3049 15.529 0.028 V spot? VN01 01:03:04.18 -70:50:28.2 R0 0.2613 18.811 0.840 V EW f? VN02 01:02:16.32 -70:51:42.5 R0 0.7646 16.692 0.111 V var? f? VN03 01:02:47.75 -70:40:07.1 R0 1.0812 16.037 0.131 V Var? f? VN04 01:01:56.56 -70 57:49.0 R0 13.4573 18.255 0.247 V spot? f? Sz3 01:01:06.09 -70:54:35.5 R0 ---- 16.18 0.1 V SX? f?;Note Sz17 01:02:38.05 -70:51:21.7 R0 67.738 13.391 0.156 V L R16 Sz18 01:02:37.93 -70:50:42.3 R0 ---- -- -- EA? Sz20 01:02:42.10 -70:47:00.3 R0 0.3566 17.567 0.124 V EW R16;Note Sz26 01:02:57.22 -70:50:40.8 R0 0.3333 15.07 0.47 V RR1 Sz29 01:03:01.93 -70:49:43.2 R0 0.6271 15.44 0.67 V RR0 Sz31b 01:03:04.37 -70:51:20.2 R0 0.5588 -- -- RR0 Note Sz32 01:03:05.19 -71:00:06.3 R0 0.5856 17.045 0.148 V Ell? f?;R16;Note Sz33 01:03:05.31 -70:51:03.7 R0 0.6447 15.540 0.613 V RR0 R16 Sz34 01:03:07.23 -70:50:53.4 R0 0.64336 15.414 0.549 V RR0 R16 Sz36 01:03:07.8 -70:49:46.5 R0 ---- 12.94 0.2 V Lb =LW1;Note Sz37 01:03:07.88 -70:50:38.7 R0 ---- -- -- CST? Note Sz38 01:03:07.92 -70:50:42.4 R0 ---- 15.45 -- V CST? Note Sz39 01:03:08.06 -70:50:06.8 R0 0.5828 -- 0.82 V RR0 Sz41 01:03:09.16 -70:49:45.1 R0 ---- 15.44 0.54 V CST? Note Sz42 01:03:09.17 -70:50:43.2 R0 ---- 15.43 0.69 V RR? Note Sz43 01:03:11.31 -70:50:25.4 R0 0.5471 15.40 1.00 V RR0 blend? Sz44 01:03:11.62 -70:50:46.8 R0 0.5492 15.206 0.751 V RR0 R16 Sz45 01:03:11.62 -70:50:51.1 R0 0.5147 15.005 0.785 V RR0 R16 Sz46 01:03:12.52 -70:50:49.8 R0 0.5542 -- 1.85 V RR0 blend Sz47 01:03:13.14 -70:51:00.8 R0 ---- -- -- CST? Note Sz48 01:03:13.89 -70:50:53.1 R0 ---- -- -- CST? Note Sz49 01:03:14.09 -70:50:41.5 R0 ---- -- 0.90 V RR? Note Sz50 01:03:14.50 -70:51:50.7 R0 0.4894 15.245 0.373 V RR01 R16 Sz52 01:03:17.11 -70:51:28.1 R0 0.08 -- -- SX Note Sz53 01:03:17.19 -70:50:43.4 R0 0.5320 -- -- RR0 Sz54 01:03:17.28 -70:50:37.9 R0 0.5280 -- -- RR0 Sz57 01:03:17.63 -70:49:27.4 R0 0.6790 15.54 0.25 V RR0 Sz58 01:03:18.56 -70:51:16.7 R0 0.5506 -- -- RR0 blend Sz61 01:03:20.35 -70:50:54.7 R0 ---- 12.65 -- V Lb? =LW13;Note Sz62 01:03:21.30 -70:50:35.2 R0 ---- 15.56 -- V CST? Note Sz63 01:03:22.87 -70:51:14.6 R0 ---- -- -- SX Note Sz64 01:03:22.87 -70:50:35.8 R0 0.6073 15.327 0.634 V RR0 R16 Sz65 01:03:24.17 -70:50:43.7 R0 0.6847 15.417 0.268 V RR0 R16 Sz69 01:03:34.09 -70:41:42.8 R0 ---- -- -- CST? crowded Sz74 01:03:56.72 -70:46:19.0 R0 0.3425 15.55 0.48 V RR1 Note LW1 -- -- ---- -- -- =Sz36 LW2 01:03:10.7 -70:50:54.0 R0 44.0 12.66 0.13 V Lb LW3 01:03:13.62 -70:50:37.0 R0 173.5635 12.897 0.749 V Lb R16 LW4 01:03:13.6 -70:50:13.8 R0 46.0 12.60 0.14 V Lb? Note LW5 01:03:15.2 -70:51:03.3 R0 37.0 12.89 0.21 V Lb? Note LW6 01:03:17.2 -70:50:49.7 R0 34.0 12.71 0.075 V Lb? Sz56;Note LW7 01:03:19.0 -70:50:51.4 R0 45.0 12.58 0.24 V Lb LW8 01:03:33.0 -70 49 37.4 R0 186.825 12.645 0.242 V Lb R16 LW9 01:03:35.7 -70:50:52.1 R0 41.0 12.58 0.23 V Lb LW10 01:03:14.5 -70:50:58.1 R0 41.0 12.44 0.25 V Lb ========================================================================== Supplementary Notes NGC 362 is located near the Small Magellanic Cloud in the sky and as a result, many SMC stars are included in the field surrounding NGC 362. It was one of the clusters investigated by Bailey (1902) in his classic paper on globular cluster variables. CCD studies of the variables in the field around NGC 362 have been made by Szekely et al. (2007 = S07), Lebzelter & Wood (2011) and Rozyczka et al. (2016 = R16). S07 tabulated data for 84 variables in and around the cluster. Among these were 15 of the 16 previously known variables. In the above table, we use the original numbering system of Bailey (1902) and Sawyer Hogg (1973) for these variables and indicate the Szekely (Sz) numbers in the remarks column. The new Sz variables that were considered to be cluster members are listed by their Sz numbers in the table and the published data for these variables are from S07 unless indicated otherwise in the Notes/Remarks column. A discussion of the status of the remaining variables announced by S07 is given below, at the end of the section on discovery of the variables. Lebzelter & Wood (2011) studied the long period variables, two previously known and 10 new discoveries. Their new varables are designated as LW1-10. R16 obtained light curves for 151 variables, including 100 new and 4 suspected new variables. Among the "new" variables, 12 (V17-V28) are proper motion members of the cluster and 4 (VN01-VN04) are likely members. These 16 stars are all listed in the above table. The rest were considered to be field variables and are not included. R16 also published significant new information for some of the previously known variables. Their new results are included in the above table. In the table, all the data for V17-V28 and VN01-VN04 are from the discovery paper by Rozyczka et al. (R16). The data for the LW variables are from the discovery paper by Lebzelter & Wood (2011) and for the remaining variables, the data are from Szekely et al. (S07) unless indicated otherwise in the Notes on individual stars or in the Notes/Remarks column, where R16 indicates that the data are from Rozyczka et al. (R16). ========================================================================== Notes on individual stars V2, V16(Sz51): The periods, magnitudes and amplitudes are from Lebzelter & Wood (2011) and the type classifications are from Lloyd Evans (1983) who also derived a radial velocity for V16 and confirmed its cluster membership. R16 observed both stars and confirmed their cluster membership from a proper motion study. The RA and dec listed for these stars is from R16. V4(Sz31a), Sz31b: S07 found that the image of V4 was blended and was composed of two stars separated by 0.16 arcseconds. They concluded that both components were RR Lyrae variables, but were unable to derive a period. R16 disentangled the light curves and found that the components had periods of 0.530366 and 0.558817 days respectively. In the above table, the first component is listed as V4 and the second component is listed as Sz31b. V5(Sz27), V7(Sz71), V9 (Sz7), V11 (Sz23), Sz74: These stars were observed spectroscopically by Szekely et al. (2007) and in every case, the radial velocities confirm their cluster membership. V10(Sz75), V11 (Sz23): S07 mistakenly designated Sz23 as Sawyer Hogg's V10 (see Table 3). However, Sz23 is V11. Sz75 is Sawyer Hogg's V10, but this designation was not acknowledged by S07 in their Table 6. V10(Sz75) is a Cepheid with a period of 4.2 days, a conclusion reached by both Sawyer (1931) and by S07. V24: R16 pointed out that V24 coincides with a Chandra X-ray source Sz3: With r=11.1 arcmin, Sz3 lies beyond the tidal radius, 10.6 arcmin, but its position in the CMD is appropriate for membership in NGC 362. It is a possible member and is therefore included in the table. Sz20: R16 observed this star and concluded that it was a W UMa-type binary and not an SX variable as suggested by S07. However, they noted that, since their coordinates differed by 1.5 arcsec from the S07 values, they could not exclude a misidentification. They did not find any SX Phe-type variability within 10 pixels of S07's published position for the star. Sz32: Sz32 is located at ~9 arcmin from the cluster centre and lies in the blue straggler region of the CMD. S07 classified it as an eclipsing binary, but R16 did not confirm this. They derived a sinusoidal light curve whose physical origin was difficult to establish. They were unable to determine its membership status from proper motion, but concluded that it might be a field star. All the data listed for Sz32 in the table are from R16. Sz36 (LW1): R16 confirmed the cluster membership of this star and found the light curve to be multiperiodic. It could be phased with a period of 238.1 days, but also with 26.43, 39.62, and 46.5 days respectively. Sz37, Sz38, Sz41, Sz48, Sz62: S07 classified these stars as RR Lyrae but did not derive periods or amplitudes. They noted that the image of Sz37 was blended. R16 did not detect variability in any of them. Therefore they are all classified as "CST?" in the above table. Sz42, Sz49: S07 published differential magnitude vs time plots that covered an interval of approximately 8 hours and showed steady changes in brightness. They concluded that both stars were RR Lyrae type and derived tentative periods. However, R16 did not detect variablity in either star. Therefore their classification is uncertain. Sz47: According to S07, the light curve of this star is characteristic of an Algol-type eclisping binary. It is in a crowded field within a few arcseconds of the cluster centre. As a result, reliable photometry could not be obtained. They noted that a radial velocity was listed for this star in the globular cluster catalogue of Monella (1985). However, this is incorrect. The data listed by Monella pertain to the cluster as a whole, not to an individual star. R16 did not detect any variability in this star. Sz52, Sz63: These two SX variables stars appeared too bright to be cluster members according to the study of Szekely et al. (2007). However, their excessive brightness is attributed to the effects of crowding. In a subsequent study, Dalessandro et al. (2013) detected both of them. They confirmed that they are SX Phe variables and cluster members, based on their proper motion. Sz58: This star is considered to be a cluster member even though its magnitude seems too bright and its colour too red for an RR Lyrae variable. Sz58 is located near the cluster centre and its observed magnitude and colour are probably the result of a blend with a red giant. Sz61(LW13): S07 classified Sz61 as a long period variable and based on its position in the CM diagram, it appears to be a cluster member. However, R16 did not detect any variability in Sz61. Therefore its classification is uncertain. Sz69: S07 classified Sz69 as an SX Phe variable with a V amplitude less than 0.05. In view of the fact that the star is located in a crowded field and R16 did not detected any variablility, it is classified as "CST?" in the above table. LW4, LW5: R16 observed these stars but did not detect variability. LW6(Sz56): This star is near the cluster centre and was classified as an eclipsing binary by S07. However, Lebzelter & Wood (2011) questioned this classification. They believe that Sz56 is the same star as their LW6 which is a long period variable. Therefore Sz56 is listed as LW6 in the above table. R16 did not detect any variability in Sz56. ======================================================================= Discovery of the variable stars in NGC 362: V1-14 Bailey (1902) with x,y coordinates on pages 237-238 and an ID chart (see Plate IX, Fig 1, page 252.15) V15 Fourcade et al. (1966) with x,y coordinates and an ID chart According to Samus et al. (2009), these x,y coordinates are not accurate. They do not agree with the position labelled on the ID chart that Fourcade et al. published. The RA and dec listed in the above table are from Szekely et al. (2007) who identified a variable star near V15's position on Fourcade's chart. V16 Lloyd Evans (1983) with an ID chart V17-28 Rozyczka et al. (2016) with RA, dec and individual finding charts and found them all to be cluster members based on proper motion. VN01-04 Rozyczka et al. (2016) identified these variables as possible cluster members and listed their RA and dec. In addition they discovered and derived periods for 42 field variables which they numbered VN05 to VN46. A few of these had been previously announced by Soszynski et al. (2016) in the OGLE survey. Sz variables Szekely et al. (2007) with RA and dec The Sz variables that are probably cluster members are listed in the above table. The others are discussed in the note at the end of this section. LW1-10 Lebzelter & Wood (2011) with RA and dec These authors also noticed three other red stars LW11-13 that showed light variability but did not follow any (semi-)periodicity. R16 observed LW12 and LW13(Sz61), but did not detect any variability. LW13 is the same star as Sz61 and is listed as a possible long period variable in the above table. ------------------------------------------------------------------------ Dalessandro et al. (2013) announced the discovery of 7 new variables in the cluster: 4 W UMa stars (C_WUMa 1 to 4) and 3 SX Phe stars (C_SX 1 to 3) See section 5.2 of their paper. They plotted light curves (Figs 10 and 11), but did not publish positions, magnitudes or periods. Therefore it is not known whether or not these variables were among the WUMa and SXPhe variables subsequently announced by R16 ----------------------------------------------------------------------- Pietrukowicz et al. (2008) searched for dwarf novae in the area outside the core of NGC 362. Their data consisted of 1424 V frames obtained on 90 nights over the years 1997 to 2005. No outbursts were detected. ------------------------------------------------------------------------ Margon et al. (2010) identified approximately 100 X-ray sources in NGC 362 on Chandra images. The majority are assumed to be cluster members. Multi-colour HST photometry of objects within 1 arcsec of these sources indicates that many are probably associated with CVs. In addition, one is probably a classical quiescent low-mass X-ray binary (qLMXB) based on its position in an X-ray "luminosity-colour" diagram. Their investigation is ongoing. ------------------------------------------------------------------------ Notes about the Sz variables Szekely et al. (2007) listed RA and dec for 84 variables in NGC 362 and the surrounding field. Of these, 69 were new discoveries and 15 were previously known. It should be noted that Szekely (2006) announced some of these variables earlier, but in the earlier paper, he used a different numbering system. The numbering system adopted in this catalogue is from Szekely et al. (2007). In the above table, the original numbering system is maintained for the previously known variables. Thus Sz7=V9, Sz15=V1, Sz23=V11, Sz27=V5, Sz31=V4, Sz35=V12, Sz40=V14, Sz51=V16, Sz55=V13, Sz60=V8, Sz67=V6, Sz68=V3, Sz71=V7, Sz72=V15, Sz75=V10. Szekely's numbers are noted in the remarks column. (The semiregular variable V2 was not recovered by Szekely et al.) A montage of CMDs plotted by Szekely et al. for different radial distances shows significant contamination by field stars in the outer regions. In fact, many of these field stars are located inside the tidal radius which Harris (1996) estimated to be 10.4 arcmin in the 2010 revision of his catalogue. The Sz variables which are considered to be possible cluster members are listed in the above table. An explanation for why the remaining variables are excluded is given in the discussion below. RR Lyrae The RR Lyrae variables Sz1, Sz6, Sz8, Sz12, Sz16, Sz73, Sz80, Sz81 are too faint to be cluster members. R16 determined that Sz12 is not a cluster member, based on proper motion and concluded the star is an SMC RR Lyrae variable. Sz10: The classification of this star is uncertain because R16 did not detect any regular variability. Furthermore S07 did not list a mean magnitude, colour or period for this star, even though it was located well outside the crowded central region. Sz78: S07 did not list a mean magnitude or colour even though the star is located well outside the crowded central region. Furthermore, the period-amplitude data they listed for it are not appropriate for an NGC 362 RR Lyrae variable. Sz78 was not discussed by R16. It is assumed that Sz78 is not an NGC 362 RR Lyrae variable. Cepheids The Cepheids Sz5, Sz11, Sz14, Sz21, Sz22, Sz30, SZ60 (=V8), Sz72 (=V15) and Sz75 (=V10) are all too faint to be cluster members. Also, the candidate Cepheids Sz25 and Sz76 are probably not cluster members. Sz25 is too faint and Sz76 is too red. R16 had difficulty producing a light curve for Sz25, but they were certain that it is not a Cepheid. R16 did not detect any variability in Sz76. SXPhe The Delta Scuti/SX Phe variable Sz79 is too faint for cluster membership. Sz52 and Sz63 seem too bright, but both stars are close to the cluster centre and their excessive brightness is attributed to the effects of crowding. They are probably members and are included in the table. Sz3, with r=11.1 arcmin, lies beyond the tidal radius, 10.6 arcmin, but its position in the CMD is appropriate for membership in NGC 362. It is a possible member and is therefore included in the table. Eclipsing The eclipsing variables Sz9, Sz13 and Sz28 all have CMD locations that make them unlikely cluster members. Furthermore, Sz9 and Sz13 are located ~10.4 and ~15 arcmin respectively from the cluster centre - close to or beyond the tidal radius. R16 observed Sz9 and Sz28 confirmed that they are not cluster members based on proper motion. Sz2, an Algol type eclipsing system, is located in the blue straggler region of the CMD, but it lies 17 arcmin from the cluster centre, well beyond the tidal radius. Sz82 and Sz83 are also beyond the tidal radius. None of these stars are considered to be cluster members. Sz18 is located at ~3 arcmin from the cluster centre. Its position on the CMD is not known, but given its location in the central region of the cluster, it is assumed to be a cluster member. R16 (2016) were unable to derive reliable magnitudes for this star because its image was partly blended with an overexposed star. Long period The long period variables Sz19 and Sz84 are not considered to be cluster members. Sz19 is too faint and Sz84 is well beyond the tidal radius. R16 confirmed the variability of Sz19 and concluded that the star belongs to the SMC based on its proper motion and CM diagram location. Sz17, Sz36 (=LW1), Sz51 (=V16) and Sz61 are all considered plausible cluster members and are listed in the above table. However, R16 did not detect any variability in Sz61. Unclassified Sz4, Sz24, Sz59, Sz66, Sz70, Sz77 were not classified by S07. These stars were all observed by R16 and consequently none of them are listed in the above table for the following reasons. Sz4 was not observed by R16 and not enough information is currently available to list it in the table of variables. Sz24, Sz59, Sz66, Sz77: R16 did not detect any variability in any of these stars. Thus it is unlikely that any of them are variable. Sz70: R16 concluded that this star is an SMC RR Lyrae variable. =================================================================== References Bailey, S. I. 1902, Harv. Ann., 38 Dalessandro, E., Ferraro, F. R., Massari, D., Lanzoni, B., Miocchi, P., Beccari, G., Bellini, A. and 4 coauthors, 2013, ApJ, 778, 135 Fourcade, C. R., Laborde, J. R., Albarracin, J. 1966, Atlas y Catalogue de Estrellas Variables en Cumulos Globulares al sur de -29 degrees, Cordoba Harris, W. E. 1996, AJ, 112, 1487 Lebzelter, T. & Wood, P. R. 2011, A&A, 529, 137 Lloyd Evans, T. 1983, MNRAS, 204, 961 Margon, B., Beck-Winchatz, B., Homer, L., Pooley, D., Bassa, C. G., Anderson, S. F., Lewin, W. H. G. et al. 2010, AIP Conf. Proc. 1314, 163 Monella, R. 1985, Gli ammassi globulari:II, Coelum, 53, No. 6, 287 Pietrukowicz, P., Kaluzny, J., Schwarzenberg-Czerny, A., Thompson, I. B., Pych, W., Krzeminski, W., Mazur, B. 2008, MNRAS, 388, 1111 Rozyczka, M., Thompson, I. B., Narloch, W., Pych, W., Schwarzenberg-Czerny, A.. 2016, Acta A., 66, 307 (R16) Samus, N. N., Kazarovets, E. V., Pastukhova, E. N., Tsvetkova, T. M., Durlevich, O. V. 2009, PASP, 121, 1378 Sawyer, H. 1931, Harv. Circ., 366 Sawyer Hogg, H. 1973, Publ. DDO, 3, No. 6 Soszynski, I., Udalski, A., Szymanski, M. K., Wyrzykowski, L., Ulaczyk, K., Poleski, R., Pietrukowicz, P. and 5 coauthors, 2016, Acta A., 66, 131 Szekely, P. 2006, ASP Conf., 349, 343 Szekely, P., Kiss, L. L., Jackson, R., Derekas, A., Csak, B., Szatmary, K. 2007, A&A, 463, 589 (S07) ======================================================================