Population types of cataclysmic variables in the solar neighbourhood

Ak, T.; Bilir, S.; Güver, T.; Çakmak, Hikmet; Ak, S.

doi:10.1016/j.newast.2012.11.007

Cited by 7 publications

(8 citation statements)

References 34 publications

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“…Although metallicity data is missing in the catalogue of Eker et al (2014), the thin-disk field stars in the solar neighborhood are known to have solar metallicity on average, with upper and lower limits of ±0.5 dex in metallicity (Cox 2000). It is also known that the thin disk stars in the solar neighborhood could be polluted by about 6-8% by thick disk and halo stars (Karaali et al 2003;Karataş et al 2004;Bilir et al 2005Bilir et al , 2006Bilir et al , 2008Ak et al 2010Ak et al , 2013. TAMS lines for zero metallicity, therefore, do not limit the upper border sharply.…”

Section: Calibration Samplementioning

confidence: 99%

Main-Sequence Effective Temperatures From a Revised Mass–luminosity Relation Based on Accurate Properties

Eker

Soydugan

et al. 2015

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The mass-luminosity (M − L), mass-radius (M − R) and mass-effective temperature (M − T ef f ) diagrams for a subset of galactic nearby main-sequence stars with masses and radii accurate to ≤ 3% and luminosities accurate to ≤ 30% (268 stars) has led to a putative discovery. Four distinct mass domains have been identified, which we have tentatively associated with low, intermediate, high, and very high mass main-sequence stars, but which nevertheless are clearly separated by three distinct break points at 1.05, 2.4, and 7M ⊙ within the mass range studied of 0.38 − 32M ⊙ . Further, a revised mass-luminosity relation (MLR) is found based on linear fits for each of the mass domains identified. The revised, mass-domain based MLRs, which are classical (L ∝ M α ), are shown to be preferable to a single linear, quadratic or cubic equation representing as an alternative MLR. Stellar radius evolution within the main-sequence for stars with M > 1M ⊙ is clearly evident on the M − R diagram, but it is not the clear on the M − T ef f diagram based on published temperatures. Effective temperatures can be calculated directly using the well-known Stephan-Boltzmann law by employing the accurately known values of M and R with the newly defined MLRs. With the calculated temperatures, stellar temperature evolution within the main-sequence for stars with M > 1M ⊙ is clearly visible on the M − T ef f diagram.Our study asserts that it is now possible to compute the effective temperature of a mainsequence star with an accuracy of ∼ 6%, as long as its observed radius error is adequately small (< 1%) and its observed mass error is reasonably small (< 6%).A calibration sample was formed by selecting main-sequence stars with the most accurate masses, radii and effective temperatures from Table 2 of "The Catalogue of Stellar Parameters ..." by Eker et al. (2014), which is already reprocessed and homogenized. In the first step, our preliminary criteria involved finding stars where both mass and radius with errors of less than or equal to 3%, and luminosities with errors less than or equal to 30% were available. Among 514 stars (257 binaries), 296 stars were found fulfilling the criteria.In the second step, 25 stars outside of the main sequence were removed.The process of removing non-main-sequence stars was completed by using the mass-radius diagram. Compared to effective temperatures and luminosities, which can only be inferred indirectly, masses and radii provide much more reliable indicators of stellar properties, and a highly improved diagnostic tool for analyzing stellar evolution. Fig. 1 shows 271 main-sequence stars selected for the calibration sample and 25 non main-sequence stars on the M − R diagram. Theoretical ZAMS (Zero Age Main Sequence) and TAMS (Terminal Age Main Sequence) lines for metallicity zero from Bertelli et al. (2008Bertelli et al. ( , 2009 were used as border lines to secure the stars within the main-sequence band.Although metallicity data is missing in the catalogue of Eker et al. (2014), the thin-disk field stars in ...

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Section: Calibration Samplementioning

confidence: 99%

Main-Sequence Effective Temperatures From a Revised Mass–luminosity Relation Based on Accurate Properties

Eker

Soydugan

et al. 2015

Self Cite

145

140

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“…In the same situation, dwarf novae follow the same trend. That is, PopI dwarf novae are more concentrated in the Galactic disk than PopII dwarf novae (Howell & Szkody 1990;Ak et al 2013;Uthas et al 2011;Özdönmez et al 2015). Since PopI dwarf novae are located nearby the Sun, they have been found and well studied (Coppejans et al 2016;Otulakowska-Hypka et al 2016).…”

Section: Halo or Thick Disk Dwarf Novaementioning

confidence: 99%

“…The typical V -band absolute magnitudes of dwarf novae are within a range of 7-9 mag (Warner 1987), and they have been mostly found in the solar neighborhood ( 1 kpc) (Downes et al 2001;Özdönmez et al 2015). These nearby dwarf novae are part of the thin disk of the Milky Way (Ak et al 2013). Their mass donors, i.e., the main sequence secondaries, have relatively high metallicity and low velocity (Ak et al 2013;Harrison & Hamilton 2015;Harrison 2016).…”

Section: Introductionmentioning

confidence: 98%

“…These nearby dwarf novae are part of the thin disk of the Milky Way (Ak et al 2013). Their mass donors, i.e., the main sequence secondaries, have relatively high metallicity and low velocity (Ak et al 2013;Harrison & Hamilton 2015;Harrison 2016). Most of the dwarf novae that have been studied so far, therefore, belong to Population I (PopI) group.…”

Section: Introductionmentioning

confidence: 99%

“…Handful of PopII dwarf novae that have been studied so far, to the best of our knowledge, are those in the globular cluster 47 Tucanae (Edmonds et al 2003) at 4.5 kpc from the Sun (Zoccali et al 2001) with [Fe/H] ≃ −0.78 (Thygesen et al 2014). Furthermore, few dwarf novae are spectroscopically classified as thick disk components (Ak et al 2013). The only spectroscopically confirmed PopII dwarf nova is SDSS J1507+52 of [Fe/H] = −1.2 and d = 250 pc (Uthas et al 2011).…”

Section: Introductionmentioning

confidence: 99%

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KSP-OT-201611a: A Distant Population II Dwarf Nova Candidate Discovered by the KMTNet Supernova Program

Lee

Moon

Kim

et al. 2019

ApJ

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We present a multi-color, high-cadence photometric study of a distant dwarf nova KSP-OT-201611a discovered by the Korea Microlensing Telescope Network Supernova Program. From October 2016 to May 2017, two outbursts, which comprises a super/long outburst followed by a normal/short outburst separated by ∼91 days, were detected in the BV I bands. The shapes and amplitudes of the outbursts reveal the nature of KSP-OT-201611a to be an SU UMa-or U Gem-type dwarf nova. Color variations of periodic humps in the super/long outbutst possibly indicate that KSP-OT-201611a is an SU UMatype dwarf nova. The super and normal outbursts show distinctively different color evolutions during the outbursts due most likely to the difference of time when the cooling wave is formed in the accretion disk. The outburst peak magnitudes and the orbital period of the dwarf nova indicate that it is at a large Galactocentric distance (∼13.8 kpc) and height (∼1.7 kpc) from the Galactic plane. KSP-OT-201611a, therefore, may provide a rare opportunity to study the accretion disk process of Population II dwarf novae.

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The Galactic kinematics of cataclysmic variables

Bilir

Özdönmez

et al. 2015

Astrophys Space Sci

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Kinematical properties of CVs were investigated according to population types and orbital periods, using the space velocities computed from recently updated systemic velocities, proper motions and parallaxes. Reliability of collected space velocity data are refined by removing 34 systems with largest space velocity errors. The 216 CVs in the refined sample were shown to have a dispersion of 53.70 ± 7.41 km s −1 corresponding to a mean kinematical age of 5.29 ± 1.35 Gyr. Population types of CVs were identified using their Galactic orbital parameters. According to the population analysis, seven old thin disc, nine thick disc and one halo CV were found in the sample, indicating that 94% of CVs in the Solar Neighbourhood belong to the thindisc component of the Galaxy. Mean kinematical ages 3.40±1.03 and 3.90±1.28 Gyr are for the non-magnetic thin-disc CVs below and above the period gap, respectively. There is not a meaningful difference between the velocity dispersions below and above the gap. Velocity dispersions of the non-magnetic thin-disc systems below and above the gap are 24.95 ± 3.46 and 26.60 ± 4.18 km s −1 , respectively. This result is not in agreement with the standard formation and evolution theory of CVs. The mean kinematical ages of the CV groups in various orbital period intervals increase towards shorter orbital periods. This is in agreement with the standard theory for the evolution of CVs. Rate of orbital period change was found to be dP/dt = −1.62(±0.15) × 10 −5 sec yr −1 .

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Population types of cataclysmic variables in the solar neighbourhood

Cited by 7 publications

References 34 publications

Main-Sequence Effective Temperatures From a Revised Mass–luminosity Relation Based on Accurate Properties

Main-Sequence Effective Temperatures From a Revised Mass–luminosity Relation Based on Accurate Properties

KSP-OT-201611a: A Distant Population II Dwarf Nova Candidate Discovered by the KMTNet Supernova Program

The Galactic kinematics of cataclysmic variables

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