MULTIBAND PHOTOMETRIC AND SPECTROSCOPIC ANALYSIS OF HV Cnc

Gökay, G.; Gürol, B.; Derman, E.

doi:10.1088/0004-6256/146/5/123

Cited by 7 publications

(6 citation statements)

References 23 publications

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“…We find the average seismic mass of stars below the RGB bump to be M sc = 1.39±0.02 M ⊙ , M corr = 1.34±0.02 M ⊙ , and M grid = 1.36 ± 0.02 M ⊙ . These are all in agreement with the expected lower-RGB mass, which we derive by extrapolating the dynamic mass, M EB = 1.31 ± 0.05 M ⊙ (Gökay et al 2013), of the eclipsing binary HV Cnc/S986/WOCS4007 (Sanders 1977;Geller et al 2015) located near the cluster turn-off (V = 12.73, B − V = 0.55; Figure 1). To extrapolate, we add the mass difference between the location of the eclipsing binary and that of the RGB along the BaSTI isochrone, which is 0.05-0.09M ⊙ for the RGB below the bump, hence resulting in expected masses of about 1.36-1.40M ⊙ .…”

Section: Average Cluster Propertiessupporting

confidence: 87%

The K2 M67 Study: Revisiting Old Friends With K2 Reveals Oscillating Red Giants in the Open Cluster M67

Stello

Vanderburg

Casagrande

et al. 2016

ApJ

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Observations of stellar clusters have had a tremendous impact in forming our understanding of stellar evolution. The open cluster M67 has a particularly important role as a calibration benchmark for stellar evolution theory due to its near solar composition and age. As a result, it has been observed extensively, including attempts to detect solar-like oscillations in its main sequence and red giant stars. However, any asteroseismic inference has so far remained elusive due to the difficulty in measuring these extremely low amplitude oscillations. Here we report the first unambiguous detection of solar-like oscillations in the red giants of M67. We use data from the Kepler ecliptic mission, K2, to measure the global asteroseismic properties. We find a model-independent seismic-informed distance of 816±11 pc, or (m − M ) 0 = 9.57 ± 0.03 mag, an average red-giant mass of 1.36 ± 0.01 M ⊙ , in agreement with the dynamical mass from an eclipsing binary near the cluster turn-off, and ages of individual stars compatible with isochrone fitting. We see no evidence of strong mass loss on the red giant branch. We also determine seismic log g of all the cluster giants with a typical precision of ∼ 0.01 dex. Our results generally show good agreement with independent methods and support the use of seismic scaling relations to determine global properties of red giant stars with near solar metallicity. We further illustrate that the data are of such high quality, that future work on individual mode frequencies should be possible, which would extend the scope of seismic analysis of this cluster.

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Section: Average Cluster Propertiessupporting

confidence: 87%

The K2 M67 Study: Revisiting Old Friends With K2 Reveals Oscillating Red Giants in the Open Cluster M67

Stello

Vanderburg

Casagrande

et al. 2016

ApJ

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“…The primary is hotter than the majority of the cluster MSTO stars, which suggests that it is either a blue straggler or undergoing the overall contraction phase along the Henyey hook. Gökay et al (2013) provided an updated set of parameters by adding in the JHKs photometry, confirming the spectroscopic detection of a third component. They combined the radial velocity solution of the primary with the mass ratio inferred from the light curves in order to obtain the full solution of the binary system, shown in purple points.…”

Section: Ngc6819mentioning

confidence: 81%

“…The MIST CMDs, shown in black, adopt m − M = 9.73, [Fe/H] = −0.01, log(Age) [yr] = 9.58, and A V = 0.18 (see text for more details). The left panel in the middle row shows two measurements of the stellar parameters of HV Cnc (Sandquist & Shetrone 2003;Gökay et al 2013) with the MIST mass-radius relation. The open symbols indicate that the system is a single-lined (SB1) spectroscopic binary system.…”

Section: Ngc6819mentioning

confidence: 99%

“…Moreover, DEBs can be used to measure stellar ages without the knowledge of distance and interstellar reddening if they are near the MSTO. DEBs in star clusters are especially useful because they can be combined with CMDs to provide complementary constraints on the models (e.g., Stetson et al 2003;Brogaard et al 2012;Yakut et al 2015;Brewer et al 2016;Gökay et al 2013).…”

Section: Asteroseismologymentioning

confidence: 99%

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Star Cluster Ages in the Gaia Era

Choi

Conroy

Ting

et al. 2018

ApJ

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We use the framework developed as part of the MESA Isochrones and Stellar Tracks (MIST) project to assess the utility of several types of observables in jointly measuring the age and 1D stellar model parameters in star clusters. We begin with a pedagogical overview summarizing the effects of stellar model parameters, such as the helium abundance, mass-loss efficiency, and the mixing length parameter, on observational diagnostics including the color-magnitude diagram, mass-radius relation, and surface abundances, amongst others. We find that these parameters and the stellar age influence observables in qualitatively distinctive, degeneracy-breaking ways. To assess the current state of affairs, we use the recent Gaia Data Release 2 (DR2) along with data from the literature to investigate three well-studied old open clusters-NGC6819, M67, NGC6791-as case studies. Although there is no obvious tension between the existing observations and the MIST models for NGC6819, there are interesting discrepancies in the cases of M67 and NGC6791. At this time, parallax zero point uncertainties in Gaia DR2 remain one of the limiting factors in the analysis of these clusters. With a combination of exquisite photometry, parallax distances, and cluster memberships from Gaia at the end of its mission, we anticipate precise and accurate ages for these and other star clusters in the Galaxy.

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“…The M67 MSTO is 1.3 M ⊙ (1.31±.05 M ⊙ ; Gokay et al 2013;Stello et al 2016b), and would have been only slightly more massive 450 Myr ago. Mass transfer between two such stars would not create a star within the 1σ uncertainty on the mass of S1237 (2.97 ± 0.24 M ⊙ ).…”

Section: Mass Transfermentioning

confidence: 98%

The K2 M67 Study: An Evolved Blue Straggler in M67 From K2 Mission Asteroseismology*

Leiner¹,

Stello²,

Vanderburg³

et al. 2016

ApJL

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Yellow straggler stars (YSSs) fall above the subgiant branch in optical color-magnitude diagrams, between the blue stragglers and the red giants. YSSs may represent a population of evolved blue stragglers, but none have the direct and precise mass and radius measurements needed to determine their evolutionary states and formation histories. Here we report the first asteroseismic mass and radius measurements of such a star, the yellow straggler S1237 in the open cluster M67. We apply asteroseismic scaling relations to a frequency analysis of the Kepler K2 light curve and find a mass of 2.9 ± 0.2 M ⊙ and a radius of 9.2 ± 0.2 R ⊙ . This is more than twice the mass of the mainsequence turnoff in M67, suggesting S1237 is indeed an evolved blue straggler. S1237 is the primary in a spectroscopic binary. We update the binary orbital solution and use spectral energy distribution (SED) fitting to constrain the color-magnitude diagram (CMD) location of the secondary star. We find that the secondary is likely an upper main-sequence star near the turnoff, but a slightly hotter blue straggler companion is also possible. We then compare the asteroseismic mass of the primary to its mass from CMD fitting, finding the photometry implies a mass and radius more than 2σ below the asteroseismic measurement. Finally, we consider formation mechanisms for this star and suggest that S1237 may have formed from dynamical encounters resulting in stellar collisions or a binary merger.

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MULTIBAND PHOTOMETRIC AND SPECTROSCOPIC ANALYSIS OF HV Cnc

Cited by 7 publications

References 23 publications

The K2 M67 Study: Revisiting Old Friends With K2 Reveals Oscillating Red Giants in the Open Cluster M67

The K2 M67 Study: Revisiting Old Friends With K2 Reveals Oscillating Red Giants in the Open Cluster M67

Star Cluster Ages in the Gaia Era

The K2 M67 Study: An Evolved Blue Straggler in M67 From K2 Mission Asteroseismology*

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