NGC 6254 / C1654-040 / Messier 10
RA: 16:57:09.05 DEC: -04:06:01.1 (J2000)
(Most recent updates:
Membership probability flag - 2024; Remaining data - April 2022)
============================================================
Bytes Format Explanation
1-8 A8 Star ID
10-32 A11,1x,A11 Position
34-35 A2 Membership probability flag based on data published
by Prudil & Arellano Ferro (2024)
m1: prob >=0.85; m2: prob >=0.7 and <0.85;
m3: prob >= 0.5 and <0.7; f: prob <0.5
u: no data available
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 Mem Period <mag> ampl C Type Notes/
RA Dec Flag Remarks
=========================================================================
1 16:57:10.12 -04:05:36.1 m1 48.94 11.94 1.5 V SR Note
2 16:57:11.74 -04:03:59.7 m1 18.70 12.08 1.2 V CW Note
3 16:56:55.95 -04:04:16.3 m1 7.833 12.78 0.3 V CW Note
4 16:57:11.63 -04:10:37.9 m1 ---- -- -- CST? Note
5 16:57:08.59 –04:06:16.3 u 0.0585 17.079 0.53 V SXP
6 16:57:10.70 –04:05:33.4 u 0.0599 16.717 0.09 V SXP
7 16:57:10.37 –04:07:03.3 u 0.0481 17.592 0.10 V SXP
8 16:57:08.38 –04:05:08.7 u 0.0510 17.012 0.10 V SXP f?;Note
9 16:57:10.57 –04:05:51.8 u 0.0513 17.303 0.60 V SXP f?;Note
10 16:57:08.43 –04:06:54.8 u 0.0223 17.555 0.10 V SXP
11 16:57:10.82 –04:05:55.9 u 0.0480 17.515 0.265 V SXP f
12 16:57:04.05 –04:06:07.3 u 0.0228 17.305 0.04 V SXP
13 16:57:08.80 –04:06:24.5 u 0.0369 16.896 0.04 V SXP Note
14 16:57:09.19 –04:06:05.4 u 0.0382 17.641 0.10 V SXP f?;Note
15 16:57:13.28 –04:05:49.0 u 0.0348 17.496 0.07 V SXP
16 16:57:06.23 –04:06:42.5 u -- 16.904 – V CST? Note
17 16:57:05.52 –04:07:47.3 u 0.0369 17.284 0.10 V SXP
18 16:57:20.23 –04:04:52.2 u 0.0424 17.534 0.07 V SXP
19 16:57:38.66 –04:08:57.4 u 0.0438 –– – V SXP
20 16:57:02.97 –04:04:00.6 u 0.0506 16.987 0.59 V SXP
21 16:57:13.69 –04:07:28.1 u 0.2450 19.682 0.32 V EW
22 16:57:08.32 –04:02:19.8 u 0.4046 14.637 0.39 V RR1
23 16:57:01.15 –04:07:49.7 u 1.4466 17.657 0.09 V sin
24 16:57:07.55 –04:05:42.4 u 2.3075 14.023 0.353 V CW
25 16:57:05.83 –04:03:46.0 u 4.4570 17.322 0.07 V ? Note
26 16:57:13.20 –04:04:11.8 u 21.7847 16.573 0.18 V sin Note
27 16:57:15.07 –04:05:52.4 u 21.040 11.915 0.68 V SR
28 16:57:10.76 –04:04:43.8 u 60.4838 11.87 0.09 V SR
29 16:57:27.38 –04:01:24.7 u 68.3883 11.872 0.20 V SR
30 16:57:07.78 –04:06:06.0 u 71.6680 12.447 0.18 V SR
31 16:57:00.63 –04:04:12.5 u 0.2051 15.882 V Var? Note
32 16:57:26.85 –04:04:31.3 u 0.8480 17.973 – V Var? Note
33 16:57:21.58 –04:02:18.6 u 0.9335 17.581 0.10 V sin Note
34 16:57:08.49 –04:05:55.7 u 3.3391 16.996 – V E Note
35 16:57:08.95 -04:05:44.5 u 0.0553 17.147 0.18 V SXP
36 16:57:10.72 -04:05:58.7 m1 1.0825 14.470 0.025 V sin
37 16:57:21.00 -04:06:38.1 m1 0.1908 14.692 0.02 V sin
PSR -- -- -- -- -- -- u ---- -- -- 2 msPs
=========================================================================
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.
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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 at the Max Planck
Institute in Bonn (July 2024 version), there are
2 millisecond pulsars in NGC 6254 (M10).
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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)
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Pietrukowicz et al. (2008, MNRAS 388, 1111) searched for
dwarf novae in M10 and found none.
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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
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Schroder, K. P., Giridhar, S., Calderson, J. H. 2020, MNRAS, 499, 4026
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Clement, C. M., Hogg, H. S., Wells, T. R. 1985, AJ 90, 1238
Dalessandro, E., Ferraro, F. R., Lanzoni, B., Schiavon, R. P.,
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Harris, W. E. 2010, arXiv:1012.3224
Kaluzny, J., Kubiak, M., Szymanski, M., Udalski, A., Krzeminski, W.,
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Karmakar, P., Smith, H. A., Osborn, W., Stetson, P.B. 2022,
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Sawyer, H. B. 1938, Publ. DAO, 7, no.5
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Shishkovsky, L., Strader, J., Chomiuk, L., Bahramian, A., Tremou, E.,
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Voroshilov, Yu. V. 1971, Astron. Tsirk., 623, 7
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