The Galactic kinematics of cataclysmic variables

Ak, T.; Bilir, S.; Özdönmez, Aykut; Soydugan, F.; Soydugan, E.; Püsküllü, Çağlar; Ak, S.; Eker, Z.

doi:10.1007/s10509-015-2245-3

Cited by 6 publications

(8 citation statements)

References 52 publications

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“…Ak et al (2015) derives a similar result. The donors in longer period CVs appear to have more dramatic abundances anomalies than do the short period systems.…”

mentioning

confidence: 53%

Abundance Derivations for the Secondary Stars in Cataclysmic Variables From Near-Infrared Spectroscopy

Harrison

2016

ApJ

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We derive metallicities for 41 cataclysmic variables (CVs) from near-infrared spectroscopy. We use synthetic spectra that cover the 0.8 µm ≤ λ ≤ 2.5 µm bandpass to ascertain the value of [Fe/H] for CVs with K-type donors, while also deriving abundances for other elements. Using calibrations for determining [Fe/H] from the K-band spectra of M-dwarfs, we derive more precise values for T eff for the secondaries in the shortest period CVs, and examine whether they have carbon deficits. In general, the donor stars in CVs have sub-solar metallicities. We confirm carbon deficits for a large number of systems. CVs with orbital periods > 5 hr are most likely to have unusual abundances. We identify four CVs with CO emission. We use phase-resolved spectra to ascertain the mass and radius of the donor in U Gem. The secondary star in U Gem appears to have a lower apparent gravity than a main sequence star of its spectral type.Applying this result to other CVs, we find that the later-than-expected spectral types observed for many CV donors is mostly an affect of inclination. All of the magnetic CVs, except the low accretion rate polar MQ Dra, have donors with subsolar metallicities. We find that two systems with unusual spectra, EI Psc and QZ Ser, that have large excesses of sodium, and extreme deficits of carbon.Synthetic spectra that have a reduced abundance of hydrogen are best able to explain the spectra of these two objects. The observed dearth of CVs with 2 hr ≤ P orb ≤ 3 hr (see Kolb et al. 1998).unpublished data is presented in Table 1, and it lists the UT date, start and stop times, the length of the exposure times used for each object, the instrument used, the orbital period, the orbital phase at the mid-point of the observational sequence (except for U Gem where full orbits were covered), and the outburst state for each of the CVs.We also present previously unpublished spectra obtained with NIRSPEC 2 on Keck.We used NIRSPEC in low-resolution, single order mode with a 0.38" slit. The grating tilt was set so as to cover the wavelength region 2.04 µm ≤ λ ≤ 2.46 µm, with a dispersion of 4.27Å/pixel. We employed the two-nod script, and used 4 minute exposure times for all of the program CVs. To correct for telluric absorption, we observed bright A0V stars located close to the program objects so as to minimize their relative differences in air mass. These data were reduced using the IDL routine REDSPEC 3 , specially developed for NIRSPEC.Finally, we used TripleSpec 4 (Wilson et al. 2004) on the Apache Point Observatory (APO) 3.5 m telescope to obtain phase-resolved near-IR spectra of U Gem over two orbital periods, and for 50% orbital period coverage of QZ Ser. TripleSpec is similar to SPEX in that it provides cross-dispersed spectra covering the near-IR, from 0.95 µm to 2.46 µm, at a resolution of R ∼ 3500. The 1.1" slit was used, and all exposures were four minutes in length. These data were reduced using "Triplespectool," a version of SPEXTOOL modified by Michael Cushing for use at APO. Nearby A0V stars were used to pr...

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“…Ak et al (2015) derives a similar result. The donors in longer period CVs appear to have more dramatic abundances anomalies than do the short period systems.…”

mentioning

confidence: 53%

Abundance Derivations for the Secondary Stars in Cataclysmic Variables From Near-Infrared Spectroscopy

Harrison

2016

ApJ

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“…Regardless, the majority of the observed CVs in the field seem to be much younger than GC CVs. Ak et al (2015) inferred kinematic ages in a sample of field CVs and concluded that 94 per cent of CVs in the solar neighbourhood belong to the thin-disc component of the Galaxy. Mean kinematical ages of 3.40 ± 1.03 and 3.90 ± 1.28 Gyr were found for the non-magnetic thin-disc CVs below and above the period gap, respectively.…”

Section: Discussion On the Age-dependence Of CV Propertiesmentioning

confidence: 99%

“…For instance, Belloni et al (2016) quantified the observational selection effects that plague the search for CVs in GCs, and concluded that their detection rates could be dramatically increased if detectable during quiescence. Ak et al (2015) inferred the ages of a sample of field CVs from kinematic data, and concluded that 94 per cent of CVs in the solar neighbourhood belong to the thin-disc component of the Galaxy. The corresponding mean kinematical ages are 3.40 ± 1.03 Gyr and 3.90 ± 1.28 Gyr for the non-magnetic thin-disc CVs below and above the period gap, respectively.…”

Section: Agementioning

confidence: 99%

MOCCA-SURVEY database I. Accreting white dwarf binary systems in globular clusters – II. Cataclysmic variables – progenitors and population at birth

Belloni

Giersz

Rocha-Pinto

et al. 2016

Mon. Not. R. Astron. Soc.

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This is the second in a series of papers associated with cataclysmic variables (CVs) and related objects, formed in a suite of simulations for globular cluster evolution performed with the MOCCA Monte Carlo code. We study the properties of our simulated CV populations throughout the entire cluster evolution. We find that dynamics extends the range of binary CV progenitor properties, causing CV formation from binary progenitors that would otherwise not become CVs. The CV formation rate in our simulations can be separated into two regimes: an initial burst ( 1 Gyr) connected with the formation of the most massive white dwarfs, followed by a nearly constant formation rate. This result holds for all models regardless of the adopted initial conditions, even when most CVs form dynamically. Given the cluster agedependence of CV properties, we argue that direct comparisons to observed Galactic field CVs could be misleading, since cluster CVs can be up to 4 times older than their field counterparts. Our results also illustrate that, due mainly to unstable mass transfer, some CVs that form in our simulations are destroyed before the present-day. Finally, some field CVs might have originated from globular clusters, as found in our simulations, although the fraction of such escapers should be small relative to the entire Galactic field CV population.

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“…The constraints are as follows: (i) Z max ⩽ 825 pc and (ii) e p ⩽ 0.10. The first parameter was first used by Ak et al (2015), while the second appeared in Huang et al (2015), who used the range e p < 0.13 to separate the cold thin-disc stars from the thick-disc stars. The vertical distance Z max = 825 pc is the place where space densities of the thin and thick discs are compatible.…”

Section: Discussionmentioning

confidence: 99%

“…We adopted the procedure detailed in Ak et al (2015) to separate the sample stars into different populations. Thus, stars with Z max ⩽ 825 pc are assumed to be thin-disc stars, while those with Z max > 825 pc are categorised as thick disc or perhaps halo stars.…”

Section: The Datamentioning

confidence: 99%

Local Stellar Kinematics from RAVE Data – VI. Metallicity Gradients Based on the F–G Main-Sequence Stars

Plevne

Karaali

et al. 2015

Publ. Astron. Soc. Aust.

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We estimated iron and metallicity gradients in the radial and vertical directions with the F and G type dwarfs taken from the Radial Velocity Experiment Data Release 4 database. The sample defined by the constraints Z max ≤ 825 pc and e p ≤ 0.10 consists of stars with metal abundances and space velocity components agreeable with the thin-disc stars. The radial iron and metallicity gradients estimated for the vertical distance intervals 0 < Z max ≤ 500 and 500 < Z max ≤ 800 pc are d[Fe/H]/dR m = −0.083 ± 0.030 and d[Fe/H]/dR m = −0.048 ± 0.037 dex kpc −1 , and d[M/H]/dR m = −0.063 ± 0.011 and d[M/H]/dR m = −0.028 ± 0.057 dex kpc −1 , respectively, where R m is the mean Galactocentric distance. The iron and metallicity gradients for less number of stars at further vertical distances, 800 < Z max ≤ 1500 pc, are mostly positive. Compatible iron and metallicity gradients could be estimated with guiding radius (R g ) for the same vertical distance intervals 0 < Z max ≤ 500 and 500 < Z max ≤ 800 pc, i.e. d[Fe/H]/dR g = −0.083 ± 0.030 and d[Fe/H]/dR g = −0.065 ± 0.039 dex kpc −1 ; d[M/H]/dR g = −0.062 ± 0.018 and d[M/H]/dR g = −0.055 ± 0.045 dex kpc −1 . F and G type dwarfs on elongated orbits show a complicated radial iron and metallicity gradient distribution in different vertical distance intervals. Significant radial iron and metallicity gradients could be derived neither for the sub-sample stars with R m ≤ 8 kpc, nor for the ones at larger distances, R m > 8 kpc. The range of the iron and metallicity abundance for the F and G type dwarfs on elongated orbits, [−0.13, −0.01), is similar to the thin-disc stars, while at least half of their space velocity components agree better with those of the thick-disc stars. The vertical iron gradients estimated for the F and G type dwarfs on circular orbits are d[Fe/H]/dZ max = −0.176 ± 0.039 dex kpc −1 and d[Fe/H]/dZ max = −0.119 ± 0.036 dex kpc −1 for the intervals Z max ≤ 825 and Z max ≤ 1500 pc, respectively.

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The Galactic kinematics of cataclysmic variables

Cited by 6 publications

References 52 publications

Abundance Derivations for the Secondary Stars in Cataclysmic Variables From Near-Infrared Spectroscopy

Abundance Derivations for the Secondary Stars in Cataclysmic Variables From Near-Infrared Spectroscopy

MOCCA-SURVEY database I. Accreting white dwarf binary systems in globular clusters – II. Cataclysmic variables – progenitors and population at birth

Local Stellar Kinematics from RAVE Data – VI. Metallicity Gradients Based on the F–G Main-Sequence Stars

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