J/A+A/583/A73 Color-period diagram for M48 (NGC2548) (Barnes+, 2015)
A color-period diagram for the open cluster M 48 (NGC 2548) and its
rotational age.
Barnes S.A., Weingrill J., Granzer T., Spada F., Strassmeier K.G.
<Astron. Astrophys. 583, A73 (2015)>
=2015A&A...583A..73B 2015A&A...583A..73B (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open; Photometry, CCD
Keywords: stars: activity - stars: rotation - stars: late-type -
stars: evolution - open clusters and associations: individual: M 48 -
stars: variables: general
Abstract:
Rotation periods are increasingly being used to derive ages for cool
single field stars. Such ages are based on an empirical understanding
of how cool stars spin down, acquired by constructing color-period
diagrams (CPDs) for a series of open clusters. Our main aims here are
to construct a CPD for M48, to compare this with other clusters of
similar age to check for consistency, and to derive a rotational age
for M48 using gyrochronology. We monitored M48 photometrically for
over 2months with AIP's STELLA.I 1.2m telescope and the WiFSIP 4K
imager in Tenerife. Light curves with 3mmag precision for bright
(V∼14mag) stars were produced and then analysed to provide rotation
periods. A cluster CPD has then been constructed. We report 62
rotation periods for cool stars in M48. The CPD displays a clear
slow/I-sequence of rotating stars, similar to those seen in the
625Myr-old Hyades and 590Myr-old Praesepe clusters, and below both,
confirming that M48 is younger. A similar comparison with the
250Myr-old M34 cluster shows that M48 is older and does not possess
any fast/C-sequence G or early K stars like those in M34, although
relatively fast rotators do seem to be present among the late-K and M
stars. A more detailed comparison of the CPD with rotational evolution
models shows that the cluster stars have a mean age of 450Myr, and its
(rotating) stars can be individually dated to ±117Myr (26%). Much of
this uncertainty stems from intrinsic astrophysical spread in initial
periods, and almost all stars are consistent with a single age of
450Myr. The gyro-age of M48 as a whole is 450±50Myr, in agreement
with the previously determined isochrone age of 400±100Myr.
Description:
The photometry of M48 (NGC 2548) is based on CCD frames taken in
Johnson B and V spanning 40' by 40' centered on M48. Overexposed
stars are excluded from the sample, as well as stars with an
incomplete PSF e.g. on the edge of the frames. Only targets with both
B and V available are listed. Astrometric positions were averaged from
the time series with a precision of typically 0.04". All coordinates
are in the ICRS reference frame epoch J2000.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 52 62 V magnitudes, color index and rotation periods
tablea1.dat 76 5120 Photometry and coordinates for all stars
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See also:
J/A+A/381/464 : Proper motions and membership in NGC 2548 (Wu+, 2002)
J/AJ/127/2210 : u'g'r'i'z' photometry in NGC 2548 (M48) (Rider+, 2004)
J/A+A/437/457 : NGC2548 uvbyHβ & proper motions (Balaguer-Nunez+, 2005)
J/PASP/118/1104 : M48 (NGC 2548) BATC photometry and membership (Wu+, 2006)
J/MNRAS/411/2530 : UBVRIJHK photometry in NGC1624 (Jose+, 2011)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Id Star identification number
6- 11 F6.3 mag Vmag V band magnitude
13- 16 F4.2 mag B-V (B-V) color index
18- 22 F5.2 d Per Rotation period
24- 27 F4.2 d e_Per Mean error of the rotation period
29- 33 F5.3 mag Amp Amplitude
35- 39 F5.3 mag e_Amp Mean error of the amplitude
41 A1 --- Memb [MN-] Member flag (1)
43 A1 --- Prov [cp] Provisional flag (2)
45- 52 A8 --- Name Cross-identification with BJG05, BJG NNNN (3)
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Note (1): Membership flag as follows:
M = cluster member according to BJG05
N = no cluster member
- = undetermined cluster membership
Note (2): Provisional flag as follows:
p = provisional cluster member
c = confirmed cluster member
Note (3): From Balaguer-Nunez et al., 2005A&A...437..457B 2005A&A...437..457B, Cat. J/A+A/437/457,
Cl* NGC 2548 BJG NNNN in Simbad.
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Id [1/5120] Star identification number
6- 14 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
16- 23 F8.5 deg DEdeg Declination in decimal degrees (J2000)
25- 30 F6.3 mag Vmag V band magnitude
32- 36 F5.3 mag e_Vmag Mean error in V band magnitude
38- 43 F6.3 mag B-V (B-V) color index
45- 49 F5.3 mag e_B-V Mean error in (B-V) color index
51- 52 I2 h RAh Hour of Right Ascension (J2000)
54- 55 I2 min RAm Minute of Right Ascension (J2000)
57- 61 F5.2 s RAs Second of Right Ascension (J2000)
63 A1 --- DE- Declination sign (J2000)
64- 65 I2 deg DEd Degree of Declination (J2000)
67- 68 I2 arcmin DEm Arcminute of Declination (J2000)
70- 74 F5.2 arcsec DEs Arcsecond of Declination (J2000)
76 A1 --- Memb Member flag (1)
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Note (1): Membership flag as follows:
M = cluster member according to Balaguer-Nunez et al., 2005A&A...437..457B 2005A&A...437..457B
N = no cluster member
- = undetermined cluster membership
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Acknowledgements:
Joerg Weingrill, jweingrill(at)aip.de
(End) Joerg Weingrill [AIP], Patricia Vannier [CDS] 18-Sep-2015