Cepheids and other short-period variables near the Galactic Centre

Matsunaga, Noriyuki; Feast, M. W.; Kawadu, T.; Nishiyama, Shogo; Nagayama, Takahiro; Nagata, T.; Tamura, Motohide; Bono, G.; Kobayashi, Naoto

doi:10.1093/mnras/sts343

Cited by 55 publications

(69 citation statements)

References 46 publications

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“…Groenewegen, Udalski & Bono (2008) used NIR data for 39 population II Cepheids in the bulge from the ogle survey; a related work is by Majaess (2010). Matsunaga et al (2011Matsunaga et al ( , 2013 analysed 3 classical Cepheids and 16 type Recent determinations of the distance to the Galactic Center, R0, used for weighted averages and in Fig. 4.…”

Section: Secondary Estimatesmentioning

confidence: 99%

The Galaxy in Context: Structural, Kinematic, and Integrated Properties

Bland-Hawthorn¹,

Gerhard

2016

Annu. Rev. Astron. Astrophys.

1,382

846

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Our Galaxy, the Milky Way, is a benchmark for understanding disk galaxies. It is the only galaxy whose formation history can be studied using the full distribution of stars from faint dwarfs to supergiants. The oldest components provide us with unique insight into how galaxies form and evolve over billions of years. The Galaxy is a luminous (L ) barred spiral with a central box/peanut bulge, a dominant disk, and a diffuse stellar halo. Based on global properties, it falls in the sparsely populated "green valley" region of the galaxy colour-magnitude diagram. Here we review the key integrated, structural and kinematic parameters of the Galaxy, and point to uncertainties as well as directions for future progress. Galactic studies will continue to play a fundamental role far into the future because there are measurements that can only be made in the near field and much of contemporary astrophysics depends on such observations.

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Section: Secondary Estimatesmentioning

confidence: 99%

The Galaxy in Context: Structural, Kinematic, and Integrated Properties

Bland-Hawthorn¹,

Gerhard

2016

Annu. Rev. Astron. Astrophys.

1,382

846

View full text Add to dashboard Cite

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“…The individual distance moduli are listed in Col. 9 of Tables 3 and 4 with their uncertainties. The Galactocentric distances listed in Col. 10 of Tables 3 and 4 were estimated assuming a solar Galactocentric distance of 7.94 ± 0.37 ± 0.26 kpc (Groenewegen et al 2008;Matsunaga et al 2013, and references therein). The final error on R G accounts for errors affecting both the solar Galactocentric and heliocentric distances.…”

Section: Distance Determinationmentioning

confidence: 99%

On the fine structure of the Cepheid metallicity gradient in the Galactic thin disk

Genovali

Lemasle

Bono

et al. 2014

A&A

188

262

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We present homogeneous and accurate iron abundances for 42 Galactic Cepheids based on high resolution (R ∼ 38 000) high signal-to-noise ratio (S /N ≥ 100) optical spectra collected with UVES at VLT (128 spectra). The above abundances were complemented with high-quality iron abundances provided either by our group (86) or available in the literature. We were careful to derive a common metallicity scale and ended up with a sample of 450 Cepheids. We also estimated accurate individual distances for the entire sample by using homogeneous near-infrared photometry and the reddening free period-Wesenheit relations. The new metallicity gradient is linear over a broad range of Galactocentric distances (R G ∼ 5-19 kpc) and agrees quite well with similar estimates available in the literature (-0.060 ± 0.002 dex/kpc). We also uncover evidence that suggests that the residuals of the metallicity gradient are tightly correlated with candidate Cepheid groups (CGs). The candidate CGs have been identified as spatial overdensities of Cepheids located across the thin disk. They account for a significant fraction of the residual fluctuations, and also for the large intrinsic dispersion of the metallicity gradient. We performed a detailed comparison with metallicity gradients based on different tracers: OB stars and open clusters. We found very similar metallicity gradients for ages younger than 3 Gyr, while for older ages we found a shallower slope and an increase in the intrinsic spread. The above findings rely on homogeneous age, metallicity, and distance scales. Finally, by using a large sample of Galactic and Magellanic Cepheids for which accurate iron abundances are available, we found that the dependence of the luminosity amplitude on metallicity is vanishing.

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“…Observations at about 30 epochs were made between 2007 and 2012. The basic data analysis was done in the same manner as in Matsunaga et al (2009Matsunaga et al ( , 2013. In short, point-spreadfunction (PSF) fitting photometry was performed on every image using the IRAF/DAOPHOT package, and variable stars were searched for by considering the standard deviations of time-series photometric data.…”

Section: Observation and Data Analysismentioning

confidence: 99%

“…The variability search was done using the three-band datasets independently, so that we could find variables even if they are visible only in one of the JHKs bands. In addition, we included the variable stars in Matsunaga et al (2013) which are within the fields of this survey even if their variations are slightly smaller than the detection limits of variability. This survey is slightly shallower than that of Matsunaga et al (2013), and as a result many objects are too faint to be detected in J band.…”

Section: Observation and Data Analysismentioning

confidence: 99%

A lack of classical Cepheids in the inner part of the Galactic disc

Matsunaga¹,

Feast²,

Bono³

et al. 2016

Mon. Not. R. Astron. Soc.

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Recent large-scale infrared surveys have been revealing stellar populations in the inner Galaxy seen through strong interstellar extinction in the disk. In particular, classical Cepheids with their period-luminosity and period-age relations are useful tracers of Galactic structure and evolution. Interesting groups of Cepheids reported recently include four Cepheids in the Nuclear Stellar Disk (NSD), about 200 pc around the Galactic Centre, found by Matsunaga et al. and those spread across the inner part of the disk reported by Dékány and collaborators. We here report our discovery of nearly thirty classical Cepheids towards the bulge region, some of which are common with Dékány et al., and discuss the large impact of the reddening correction on distance estimates for these objects. Assuming that the four Cepheids in the NSD are located at the distance of the Galactic Centre and that the near-infrared extinction law, i.e. wavelength dependency of the interstellar extinction, is not systematically different between the NSD and other bulge lines-of-sight, most of the other Cepheids presented here are located significantly further than the Galactic Centre. This suggests a lack of Cepheids in the inner 2.5 kpc region of the Galactic disk except the NSD. Recent radio observations show a similar distribution of star-forming regions.

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Cepheids and other short-period variables near the Galactic Centre

Cited by 55 publications

References 46 publications

The Galaxy in Context: Structural, Kinematic, and Integrated Properties

The Galaxy in Context: Structural, Kinematic, and Integrated Properties

On the fine structure of the Cepheid metallicity gradient in the Galactic thin disk

A lack of classical Cepheids in the inner part of the Galactic disc

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