Tracing the Spiral Structure of the Outer Milky Way with Dense Atomic Hydrogen Gas

Koo, Bon‐Chul; Park, Geumsook; Kim, Woong-Tae; Lee, Myung Gyoon; Balser, Dana S.; Wenger, Trey V.

doi:10.1088/1538-3873/aa7c08

Cited by 41 publications

(45 citation statements)

References 56 publications

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“…by tracing its spiral arms and other substructures. Some overdensities in the face-on distribution of the classical Cepheids are in tentative agreement with the extrapolated locations of the spiral arms from the models of Koo et al (2017) and Hou & Han (2014) (Fig. 23), and the deviations between the KDE maxima and the spiral arm ridges of either model do not exceed the deviations between the different models.…”

Section: Discussionsupporting

confidence: 83%

“…The red dot and circle show the position of the Galactic center and its 2 kpc radius. The blue and red dashed curves denote four-arm logarithmic models of the Milky Way's spiral arms by Hou & Han (2015) and Koo et al (2017), respectively.…”

Section: Discussionmentioning

confidence: 99%

“…The structure of the Galactic disk has been traced with two different approaches: (i) by the velocity map-ral models with both anomalously large pitch angles and signs of a global non-axisymmetric configuration of the spiral structure (Levine et al 2006), and also axisymmetric models with their global configuration being in qualitative agreement with maps based on other tracers (e.g., Koo et al 2017).…”

Section: Introductionmentioning

confidence: 99%

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Into the Darkness: Classical and Type II Cepheids in the Zona Galactica Incognita

Dékány¹,

Hajdu

Grebel³

et al. 2019

ApJ

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The far side of the Milky Way's disk is one of the most concealed parts of the known Universe due to extremely high interstellar extinction and point source density toward low Galactic latitudes. Large time-domain photometric surveys operating in the near-infrared hold great potential for the exploration of these vast uncharted areas of our Galaxy. We conducted a census of distant classical and type II Cepheids along the southern Galactic mid-plane using near-infrared photometry from the VISTA Variables in the Vía Láctea survey. We performed a machine-learned classification of the Cepheids based on their infrared light curves using a convolutional neural network. We have discovered 640 distant classical Cepheids with up to ∼40 magnitudes of visual extinction, and over 500 type II Cepheids, most of them located in the inner bulge. Intrinsic color indices of individual Cepheids were predicted from sparse photometric data using a neural network, allowing their use as accurate reddening tracers. They revealed a steep, spatially varying near-infrared extinction curve toward the inner bulge. Type II Cepheids in the Galactic bulge were also employed to measure robust mean selective-to-absolute extinction ratios. They trace a centrally concentrated spatial distribution of the old bulge population with a slight elongation, consistent with earlier results from RR Lyrae stars. Likewise, the classical Cepheids were utilized to trace the Galactic warp and various substructures of the Galactic disk, and to uncover significant vertical and radial age gradients of the thin disk population at the far side of the Milky Way.

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Section: Discussionsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Into the Darkness: Classical and Type II Cepheids in the Zona Galactica Incognita

Dékány¹,

Hajdu

Grebel³

et al. 2019

ApJ

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“…The large height of KSP-OT-201611a safely rejects the possibility that KSP-OT-201611a is a thin disk component. Considering the Galactic position of KSP-OT-201611a, it is located near the Perseus arm which is warped toward the direction of KSP-OT-201611a (Koo et al 2017). However, the warped disk reaches a height of about −1 kpc (Koo et al 2017;Skowron et al 2018).…”

Section: Halo or Thick Disk Dwarf Novaementioning

confidence: 99%

“…Considering the Galactic position of KSP-OT-201611a, it is located near the Perseus arm which is warped toward the direction of KSP-OT-201611a (Koo et al 2017). However, the warped disk reaches a height of about −1 kpc (Koo et al 2017;Skowron et al 2018). This fact implies that KSP-OT-201611a is well separated from the warped disk and may be halo or thick disk populations (Özdönmez et al 2015;Mateu & Vivas 2018).…”

Section: Halo or Thick Disk Dwarf Novaementioning

confidence: 99%

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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Peering into the Milky Way by FAST: I. Exquisite Hi structures in the inner Galactic disk from the piggyback line observations of the FAST GPPS survey

Hong

Han

Hou

et al. 2022

Sci. China Phys. Mech. Astron.

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Neutral hydrogen (Hi) is the fundamental component of the interstellar medium. The Galactic Plane Pulsar Snapshot (GPPS) survey is designed for hunting pulsars by using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) from the visible Galactic plane within |b| ≤ 10 • . The survey observations are conducted with the L-band 19-beam receiver in the frequency range of 1.0 − 1.5 GHz, and each pointing has an integration time of 5 minutes. The piggyback spectral data simultaneously recorded during the FAST GPPS survey are great resources for studies on the Galactic Hi distribution and ionized gas. We process the piggyback Hi data of the FAST GPPS survey in the region of 33 • ≤ l ≤ 55 • and |b| ≤ 2 • . The rms of the data cube is found to be approximately 40 mK at a velocity resolution of 0.1 km s −1 , placing it the most sensitive observations of the Galactic Hi by far. The high velocity resolution and high sensitivity of the FAST GPPS Hi data enable us to detect weak exquisite Hi structures in the interstellar medium. Hi absorption line with great details can be obtained against bright continuum sources. The FAST GPPS survey piggyback Hi data cube will be released and updated on the web: http://zmtt.bao.ac.cn/MilkyWayFAST/.

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Tracing the Spiral Structure of the Outer Milky Way with Dense Atomic Hydrogen Gas

Cited by 41 publications

References 56 publications

Into the Darkness: Classical and Type II Cepheids in the Zona Galactica Incognita

Into the Darkness: Classical and Type II Cepheids in the Zona Galactica Incognita

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

Peering into the Milky Way by FAST: I. Exquisite Hi structures in the inner Galactic disk from the piggyback line observations of the FAST GPPS survey

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