J/A+A/674/A152 Cool star rotation periods in NGC 2281 (Fritzewski+, 2023)
A rotational age for the open cluster NGC 2281. The possibility of using the
fast rotator sequence for accurate cluster age determinations.
Fritzewski D.J., Barnes S.A., Weingrill J., Granzer T., Cole-Kodikara E.,
Strassmeier K.G.
<Astron. Astrophys. 674, A152 (2023)>
=2023A&A...674A.152F 2023A&A...674A.152F (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Stars, late-type; Stars, variable;
Photometry; Optical
Keywords: stars: rotation - stars: late-type - starspots -
stars: variables: general - techniques: photometric -
open clusters and associations: individual: NGC 2281
Abstract:
Cool star rotation periods have become an important tool in
determining ages of open clusters.
We aim to estimate the age of the open cluster NGC 2281 based on the
rotational properties of its low-mass members. Previous age estimates
for this open cluster range from 275Myr to 630Myr.
Based on an eight month-long photometric time series obtained at the
1.2 m robotic STELLA telescope in Tenerife, we measured rotation
periods for 126 cool star members (70% of the observed members) of NGC
2281.
The large set of rotation periods allows us to construct a rich
colour-period diagram for NGC 2281 with very few outliers above the
slow rotator sequence. We identify an evolved fast rotator sequence
which can be used to accurately age date the open cluster relative to
other open clusters. Comparisons with M37 and M48 show that all three
open clusters are roughly coeval, and we estimate the age of NGC 2281
to be 435Myr. Through comparisons with the younger NGC 3532 and the
older Praesepe, we determine the spin down rates of mid-K and early-M
fast rotators to be significantly lower than for early-K stars. We
suspect that the spin down of early-K fast rotators might be governed
by an additional mass dependence.
Finally, we show the path towards an empirical description of the
evolved fast rotator sequences in open clusters.
Description:
The members table includes the full membership for NGC 2281 based on
Gaia DR3. We provide 405 members, their Gaia photometry and the
variability amplitude as measured from our photometry.
The periods table gives rotation periods measured for cool star
members of NGC 2281. We further provide period uncertainties and the
Rossby number.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
members.dat 72 405 Membership for NGC 2281 (table 1)
periods.dat 75 128 Rotation periods for members of NGC 2281 (table 2)
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
J/AJ/158/122 : Local structure & star formation history of the MW
(Kounkel+, 2019)
Byte-by-byte Description of file: members.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID ? ID number for STELLA photometry (1)
6- 13 A8 --- --- [Gaia DR3]
15- 32 I18 --- GaiaDR3 Gaia DR3 designation (Cat. I/355)
34- 42 F9.5 deg RAdeg Right ascension from Gaia DR3
(ICRS) at Ep=2016.0 (Cat. I/355)
44- 51 F8.5 deg DEdeg Declination from Gaia DR3
(ICRS) at Ep=2016.0 (Cat. I/355)
53- 57 F5.2 mag Gmag G-band mean magnitude from Gaia DR3
(Cat. I/355)
59- 64 F6.3 mag (G-RP)0 ? Dereddened Gaia Gmag-RPmag based on Gaia DR3
(Cat. I/355) (2)
66 A1 --- KC19 [ny] Member in Kounkel et al.,
2019AJ....158..122K 2019AJ....158..122K, Cat. J/AJ/158/122
68- 72 F5.3 mag Rvar ? Variability amplitude in STELLA photometry
measured from V 120s light curves
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Note (1): Not assigned for stars outside the FoV of STELLA,
Note (2): Dereddened with E(B-V)=0.11mag.
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Byte-by-byte Description of file: periods.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID ID number for STELLA photometry
6- 13 A8 --- --- [Gaia DR3]
15- 32 I18 --- GaiaDR3 Gaia DR3 designation (Cat. I/355)
34- 42 F9.5 deg RAdeg Right ascension from Gaia DR3
(ICRS) at Ep=2016.0 (Cat. I/355)
44- 51 F8.5 deg DEdeg Declination from Gaia DR3
(ICRS) at Ep=2016.0 (Cat. I/355)
53- 58 F6.3 mag (G-RP)0 Dereddened Gaia Gmag-RPmag based on Gaia DR3
(Cat. I/355) (1)
60- 64 F5.2 d Per Photometric rotation period
66- 69 F4.2 d e_Per Uncertainty on rotation period
71- 75 F5.3 --- Ro ? Rossby number Prot/tauc with tauc
based on Barnes & Kim (2010ApJ...721..675B 2010ApJ...721..675B)
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Note (1): Dereddened with E(B-V)=0.11mag.
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Acknowledgements:
Dario Fritzewski dario.fritzewski(at)kuleuven.be
(End) Patricia Vannier [CDS] 10-May-2023