A three-dimensional map of the Milky Way using classical Cepheid variable stars

Skowron, D. M.; Skowron, J.; Mróz, P.; Udalski, A.; Pietrukowicz, P.; Soszyński, I.; Szymański, M. K.; Poleski, R.; Kozłowski, S.; Ulaczyk, K.; Rybicki, K.; Iwanek, P.

doi:10.1126/science.aau3181

Cited by 175 publications

(225 citation statements)

References 59 publications

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“…It is common to simplify the Galactic disc as an exponential or hyperbolic secant form, but there are many asymmetries such as the flare and warp that need to be taken into account. These structures can be seen from 3D distribution of stars, as shown by Liu et al (2017), who mapped the Milky Way using the LAMOST (The Large Sky Area Multi-Object Fibre Spectroscopic Telescope) RGB (red-giant branch) stars; Skowron et al (2019a), who constructed a map of the Milky Way from classical Cepheids; or Anders et al (2019), who used the second Gaia data release (DR2).…”

Section: Introductionmentioning

confidence: 99%

Structure of the outer Galactic disc with Gaia DR2

Chrobáková

Nagy

López-Corredoira

2020

A&A

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Context. The structure of outer disc of our Galaxy is still not well described, and many features need to be better understood. The second Gaia data release (DR2) provides data in unprecedented quality that can be analysed to shed some light on the outermost parts of the Milky Way. Aims. We calculate the stellar density using star counts obtained from Gaia DR2 up to a Galactocentric distance R=20 kpc with a deconvolution technique for the parallax errors. Then we analyse the density in order to study the structure of the outer Galactic disc, mainly the warp. Methods. In order to carry out the deconvolution, we used the Lucy inversion technique for recovering the corrected star counts. We also used the Gaia luminosity function of stars with MG < 10 to extract the stellar density from the star counts. Results. The stellar density maps can be fitted by an exponential disc in the radial direction hr = 2.07 ± 0.07 kpc, with a weak dependence on the azimuth, extended up to 20 kpc without any cut-off. The flare and warp are clearly visible. The best fit of a symmetrical S-shaped warp gives zw ≈ z + (37 ± 4.2(stat.) − 0.91(syst.))pc · (R/R ) 2.42±0.76(stat.)+0.129(syst.) sin(φ + 9.3 • ± 7.37 • (stat.) + 4.48 • (syst.)) for the whole population. When we analyse the northern and southern warps separately, we obtain an asymmetry of an ∼ 25% larger amplitude in the north. This result may be influenced by extinction because the Gaia G band is quite prone to extinction biases. However, we tested the accuracy of the extinction map we used, which shows that the extinction is determined very well in the outer disc. Nevertheless, we recall that we do not know the full extinction error, and neither do we know the systematic error of the map, which may influence the final result. The analysis was also carried out for very luminous stars alone (MG < −2), which on average represents a younger population. We obtain similar scale-length values, while the maximum amplitude of the warp is 20 − 30% larger than with the whole population. The north-south asymmetry is maintained.

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Section: Introductionmentioning

confidence: 99%

Structure of the outer Galactic disc with Gaia DR2

Chrobáková

Nagy

López-Corredoira

2020

A&A

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“…1 here. Figure 4 shows the young open star clusters Waterloo 1 (the asterisk near Also, mapping of the Milky Way disk with Classical Cepheid variable stars was done recently by Skowron et al (2019 -their Fig.1b), showing many Cepheids in between the Perseus arm and the Cygnus arm -see their interarm in Galactic Quadrant II (some Cepheids) and Quadrant III (twice more Cepheids) near the Galactic Meridian. These interarm Cepheids overlap well, in quantity ratio and in angular size, the interarm island sketched in Figure 1 here, in Galactic Quadrant III.…”

Section: Legitimacy Of a Short Interarm Island Between Cygnus And Pementioning

confidence: 93%

Interarm islands in the Milky Way – the one near the Cygnus spiral arm

Vallée

2020

Monthly Notices of the Royal Astronomical Society

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This study extends to the structure of the Galaxy. Our main goal is to focus on the first spiral arm beyond the Perseus arm, often called the Cygnus arm or the 'Outer Norma' arm, by appraising the distributions of the masers near the Cygnus arm. The method is to employ masers whose trigonometric distances were measured with accuracy. The maser data come from published literaturesee column 8 in Table 1 here, having been obtained via the existing networks ( US VLBA , the Japanese VERA, the European VLBI, and the Australian LBA). The new results for Cygnus are split in two groups: those located near a recent CO-fitted global model spiral arm, and those congregating within an 'interarm island' located halfway between the Perseus arm and the Cygnus arm. Next, we compare this island with other similar interarm objects near other spiral arms. Thus we delineate an interarm island (6x2 kpc) located between the two long spiral arms (Cygnus and Perseus arms); this is reminiscent of the small 'Local Orion arm' (4x2 kpc) found earlier between the Perseus and Sagittarius arms, and of the old 'Loop' (2x0.5 kpc) found earlier between the Sagittarius and Scutum arms. Various arm models are compared, based on observational data (masers, HII regions, HI gas, young stars, CO 1-0 gas).

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“…This corresponds to where the projected position of the lens is slightly interior to the projected source surface. We calculated the magnification factor with finite source size using the RT-model developed by V. Bozza (Bozza et al 2018;Bozza 2010;Skowron & Gould 2012). The magnification factor decreases for ρ /u > 1.1 and the calculation approaches that of the point-lens with point-source as the finite size of the star becomes diminishingly relevant.…”

Section: General Characterizationsmentioning

confidence: 99%

“…Identifying pulsating stars requires intensive observations over several decades (Udalski et al 1999;Soszynski et al 2008;Skowron et al 2019). However, some of variable stars, e.g., lowamplitude variables, short period ones and irregular variables, are difficult to identify and classify.…”

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confidence: 99%

Microlensing of radially pulsating stars

Sajadian

Ignace

2020

Monthly Notices of the Royal Astronomical Society

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Here, we study the microlensing of radially pulsating stars. Discerning and characterizing the properties of distant, faint pulsating stars is achievable through high-cadence microlensing observations. Combining stellar variability period with microlensing gives the source distance, type, and radius and helps better determine the lens parameters. Considering periodically variations in their radius and surface temperature, their microlensing light curves are resulted from multiplication of the magnification factor with variable finite size effect by the intrinsic brightness curves of pulsing source. The variable finite source size due to pulsation can be significant for transit and single microlensing and while caustic-crossing features. This kind of deviation in the magnification factor is considerable when the ratio of the source radius to the projected lens-source distance is in the range of ρ /u ∈ [0.4, 10] and its duration is short and in the same order of the time of crossing the source radius. Other deviations due to variable source intensity and its area make colored and periodic deviations which are asymmetric with respect to the signs of pulsation phase. The positive phases makes deviations with larger amplitude that negative phase. These deviations dominate in filters with short wave lengths (e.g., B−band). The position of magnification peaks in microlensing of variable stars varies and this displacement differs in different filters.

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A three-dimensional map of the Milky Way using classical Cepheid variable stars

Cited by 175 publications

References 59 publications

Structure of the outer Galactic disc with Gaia DR2

Structure of the outer Galactic disc with Gaia DR2

Interarm islands in the Milky Way – the one near the Cygnus spiral arm

Microlensing of radially pulsating stars

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