Chemical properties of the central part of the Galactic nuclear stellar disc. Abundances in four classical Cepheids revisited

Kovtyukh, V. V.; Коротин, С. А.; Andrievsky, S. M.; Matsunaga, Noriyuki; Fukue, Kei

doi:10.1093/mnras/stac2468

Cited by 4 publications

(4 citation statements)

References 52 publications

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“…Two stars, SU Cas and ASAS 181024−2049.6, were suggested to be Cepheids located at R GC as small as 2.5-3 kpc (Martin et al 2015;Andrievsky et al 2016). However, the parallax-based distances in Bailer-Jones et al (2021) indicate that these stars are within 3 kpc of the Sun, and thus their R GC are not smaller than 5 kpc (see also Kovtyukh et al 2022). Note that the PLR-based distances are accurate only if the classification as classical Cepheids is correct.…”

Section: Appendixmentioning

confidence: 99%

“…In Figure 2, four Cepheids from Kovtyukh et al (2022) are located in the Galactic center region. As discussed by Matsunaga et al (2011Matsunaga et al ( , 2015, they are located within the Nuclear Stellar Disk (Launhardt et al 2002), with a radius of 200-300 pc, but the line-of-sight locations have not been determined.…”

Section: Connection With Cepheids In the Galactic Center?mentioning

confidence: 99%

“…To separate the markers in Figure 2, they are plotted at around R GC = 0, but with artificial horizontal offsets added. Although the precision in [Fe/H] is not high, Kovtyukh et al (2022) concluded that the metallicities of these central Cepheids are close to solar (see also Kovtyukh et al 2019), but are potentially outliers having slightly higher [Fe/H]. It is tempting to combine these Cepheids with our sample at 3 < R GC < 5.6 kpc to discuss whether the metallicity gradient is flat or slightly positive (i.e., the [Fe/H] being lower at R GC < 300 pc).…”

Section: Connection With Cepheids In the Galactic Center?mentioning

confidence: 99%

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Metallicities of Classical Cepheids in the Inner Galactic Disk

Matsunaga,

Taniguchi,

Elgueta

et al. 2023

ApJ

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Metallicity gradients refer to the sloped radial profiles of the metallicities of gas and stars and are commonly seen in disk galaxies. A well-defined metallicity gradient of the Galactic disk is observed particularly well with classical Cepheids, which are good stellar tracers thanks to their period–luminosity relation, allowing precise distance estimation and other advantages. However, the measurement of the inner-disk gradient has been impeded by the incompleteness of previous samples of Cepheids and the limitations of optical spectroscopy in observing highly reddened objects. Here we report the metallicities of 16 Cepheids measured with high-resolution spectra in the near-infrared YJ bands. These Cepheids are located at 3–5.6 kpc in Galactocentric distance, R GC, and reveal the metallicity gradient in this range for the first time. Their metallicities are mostly between 0.1 and 0.3 dex in [Fe/H] and more or less follow the extrapolation of the metallicity gradient found in the outer part, R GC > 6.5 kpc. The gradient in the inner disk may be shallower or even flat, but the small sample does not allow the determination of the slope precisely. More extensive spectroscopic observations would also be necessary for studying minor populations, if any, with higher or lower metallicities that were reported in previous literature. In addition, the 3D velocities of our inner-disk Cepheids show a kinematic pattern that indicates noncircular orbits caused by the Galactic bar, which is consistent with the patterns reported in recent studies on high-mass star-forming regions and red giant branch stars.

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Section: Appendixmentioning

confidence: 99%

Section: Connection With Cepheids In the Galactic Center?mentioning

confidence: 99%

Section: Connection With Cepheids In the Galactic Center?mentioning

confidence: 99%

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Metallicities of Classical Cepheids in the Inner Galactic Disk

Matsunaga,

Taniguchi,

Elgueta

et al. 2023

ApJ

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“…Indeed, these observations are difficult to apply for faint stars which are distant or in the line of sight of significantly reddened environment such as the Galactic Center. However, this limitation can be overcome owing to medium-and high-resolution near-infrared spectroscopy (Inno Article number, page 1 of 29 arXiv:2301.00229v1 [astro-ph.SR] 31 Dec 2022Dec et al 2019Kovtyukh et al 2019Kovtyukh et al , 2022c). An interesting alternative to spectroscopy is to estimate the metallicity of the Cepheids using the shape of the light-curve since it contains the information on its physical properties such as pulsation period, temperature and chemical composition.…”

Section: Introductionmentioning

confidence: 99%

Metallicity estimations of MW, SMC, and LMC classical Cepheids from the shape of the V- and I-band light curves

Hocdé

Smolec

Moskalik

et al. 2023

A&A

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Context. Estimating metallicity of classical Cepheids is of prime importance for studying metallicity effect on stellar evolution, chemical evolution of galaxies, and ultimately its impact on period-luminosity relation used in the extragalactic distance scale. Aims. We aim first at establishing new empirical relations for estimating the iron content of classical Cepheids for short and longperiods based on Fourier parameters from the V-and I-band light curves. Then we apply these relation to Cepheids from Milky Way (MW), Small and Large Magellanic Clouds (SMC and LMC) available in the literature. Methods. We retrieved metallicity of 586 fundamental mode Cepheids from spectroscopic determinations in the literature and we found well sampled light-curves for 545 of them in different V-band catalogues. We then describe the shape of these light curves by applying Fourier decomposition and we fit empirical relations between the Fourier parameters and the spectroscopic metallicities, separately for short-(2.5 < P < 6.3 days) and for long-period Cepheids (12 < P < 40 days). We verify the accuracy of these relations by applying them to V-band light curves of Cepheids from the Small and Large Magellanic Clouds and comparing the derived metallicities to the literature. We calibrate new interrelations of Fourier parameters to convert these empirical relations into the I-band. We then use these I-band relations to derive the metallicity of fundamental mode Cepheids from OGLE-IV for MW, SMC and LMC (486, 683 and 1678 stars respectively). Last, we map the metallicity distribution in these galaxies for investigating potential application in galactic archeology. Results. For short-period Cepheids, our best fit is given for a relation based on explicit amplitude terms A 1 and A 2 of the first and second harmonic respectively. In the V and I band these empirical relations are found with an intrinsic scatter (rms) of 0.12 dex. This relation performs well for estimating [Fe/H] between about −0.5 and 0.1 dex but remains uncertain outside this range because of the lack of spectroscopic metallicity for the calibration. For the long-period Cepheids we found a metallicity dependence on the Fourier parameters A 1 , φ 21 and R 41 . We found an intrinsic scatter of 0.25 dex when using this relation. These empirical relations in V and I bands are able to derive the mean metallicity of a sample of MW, SMC and LMC Cepheids in agreement with literature values within 1σ. We also show that these relations are precise enough to reconstruct the radial metallicity gradients within the MW from OGLE data. Conclusions. The empirical relations in the V and I bands calibrated in this paper for short and long-period Cepheids provide a new useful tool to estimate the metallicity of Cepheids which are not accessible by spectroscopy. The calibration can be improved with further high-resolution spectroscopic observations of metal-poor Cepheids and homogeneous photometries in V and I bands.

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Cepheids as distance indicators and stellar tracers

Bono,

Braga,

Pietrinferni

2024

Astron Astrophys Rev

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We review the phenomenology of classical Cepheids (CCs), Anomalous Cepheids (ACs) and type II Cepheids (TIICs) in the Milky Way (MW) and in the Magellanic Clouds (MCs). We also examine the Hertzsprung progression in different stellar systems by using the shape of I-band light curves (Fourier parameters) and observables based on the difference in magnitude and in phase between the bump and the minimum in luminosity. The distribution of Cepheids in optical and in optical–near infrared (NIR) color–magnitude diagrams is investigated to constrain the topology of the instability strip. The use of Cepheids as tracers of young (CCs), intermediate (ACs) and old (TIICs) stellar populations are brought forward by the comparison between observations (MCs) and cluster isochrones covering a broad range in stellar ages and in chemical compositions. The different diagnostics adopted to estimate individual distances (period–luminosity, period–Wesenheit, period–luminosity–color relations) are reviewed together with pros and cons in the use of fundamental and overtones, optical and NIR photometric bands, and reddening free pseudo magnitudes (Wesenheit). We also discuss the use of CCs as stellar tracers and the radial gradients among the different groups of elements (iron, $$\alpha $$ α , neutron-capture) together with their age-dependence. Finally, we briefly outline the role that near-future space and ground-based facilities will play in the astrophysical and cosmological use of Cepheids.

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Chemical properties of the central part of the Galactic nuclear stellar disc. Abundances in four classical Cepheids revisited

Cited by 4 publications

References 52 publications

Metallicities of Classical Cepheids in the Inner Galactic Disk

Metallicities of Classical Cepheids in the Inner Galactic Disk

Metallicity estimations of MW, SMC, and LMC classical Cepheids from the shape of the V- and I-band light curves

Cepheids as distance indicators and stellar tracers

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