New rotation periods in the open cluster NGC 1039 (M 34), and a derivation of its gyrochronology age

Abstract

Aims. Employing photometric rotation periods for solar-type stars in NGC 1039 [M 34], a young, nearby open cluster, we use its mass-dependent rotation period distribution to derive the cluster's age in a distance independent way, i.e., the so-called gyrochronology method. Methods. We present an analysis of 55 new rotation periods, using light curves derived from differential photometry, for solar type stars in the open cluster NGC 1039 [M 34]. We also exploit the results of a recently-completed, standardized, homogeneous BV Ic CCD survey of the cluster, performed by the Indiana Group of the WIYN open cluster survey, in order to establish photometric cluster membership and assign B − V colours to each photometric variable. We describe a methodology for establishing the gyrochronology age for an ensemble of solar-type stars. Empirical relations between rotation period, photometric colour and stellar age (gyrochronology) are used to determine the age of M 34. Based on its position in a colour-period diagram, each M 34 member is designated as being either a solid-body rotator (interface or I-star), a differentially rotating star (convective or C-star) or an object which is in some transitory state in between the two (gap or g-star). Fitting the period and photometric colour of each I-sequence star in the cluster, we derive the cluster's mean gyrochronology age. Results. Of the photometric variable stars in the cluster field, for which we derive a period, 47 out of 55 of them lie along the loci of the cluster main sequence in V/B − V and V/V − I space. We are further able to confirm kinematic membership of the cluster for half of the periodic variables [21/55], employing results from an on-going radial velocity survey of the cluster. For each cluster member identified as an I-sequence object in the colour-period diagram, we derive its individual gyrochronology age, where the mean gyro age of M 34 is found to be 193 ± 9 Myr. Conclusions. Using differential photometry, members of a young open cluster can be easily identified in a colour−magnitude diagram from their periodic photometric variability alone. Such periodicity can be used to establish a period-colour distribution for the cluster, which for M 34, we have used to derive its gyrochronology age of 193 ± 9 Myr. Formally, our gyro age of M 34 is consistent (within the errors) with that derived using several distance-dependent, photometric isochrone methods (250 ± 67 Myr).

Evaluating Gyrochronology on the Zero-Age-Main-Sequence: Rotation Periods in the Southern Open Cluster Blanco 1 From the Kelt-South Survey

“…Here, we also include in our analysis the I-sequence relationships calibrated in Barnes (2007;B07), Mamajek & Hillenbrand (2008;MH08), and Meibom et al (2009;MMS09). We note that we use an updated age-dependence term given by James et al (2010) for the MMS09 relationship.…”

“…A Skumanich-like spin-down is represented with n = 0.5. Other studies have further calibrated the n parameter using open clusters of known ages, and the solar datum -B07: n = 0.5189, MH08: n = 0.566, and MMS09 with the recalibration from James et al (2010): n = 0.5344.…”

“…Subsequent studies have shown that although the Skumanich relationship encapsulates something fundamental about the process of stellar angular momentum loss, the actual link between a star's rotation rate and its age is a more complex, mass-dependent relationship (Kawaler 1988;Barnes 2003). More recently, many groups have used extensive catalogs of stellar rotation periods for stars in open clusters of known ages to establish empirical calibrations of this age-rotation relationship (Barnes 2003(Barnes , 2007Mamajek & Hillenbrand 2008;Meibom et al 2009;James et al 2010). In addition, there are many studies that attempt to establish a theoretical framework that explains the underlying physics governing how fast a star loses its angular momentum content (Barnes & Kim 2010;Barnes 2010;Matt et al 2012;Reiners & Mohanty 2012).…”

X-ray emission regimes and rotation sequences in the M34 open cluster

“…Detection was made of 189 X-ray sources that are listed in the XMM − Newton Serendipitous Source Catalog (Watson et al 2009). This list of X-ray sources was correlated with lists of M34 cluster members with known rotation periods established by Meibom et al (2011), Irwin et al (2006), and James et al (2010). In total, 41 single stars in the M34 open cluster have been found that have known rotational periods and detected X-ray emissions (Gondoin 2012).…”

Variable Stars in the Region of the Open Cluster NGC 1039 (M34)

“…NGC 1039(M34)는 나이가 약 2억년 (Meynet et al, 1993;Ianna & Schlemmer, 1993;Jones & Prosser, 1996, 이후 JP96; James et al, 2010)인 중년 산개성단이다. 성간소 광량은 E(B − V ) = 0.07 (Canterna, Perry & Crawford, 1979)이며, 거리지수는 (V − M V ) = 8.60(JP96)이다.…”