Far-Ultraviolet Observations of the Spica Nebula and the Interaction Zone

Choi, Youngkyu; Kang, Min; Seon, Kwang‐Il; Lim, Taeho; Jo, Young-Soo; Park, Jae-Woo

doi:10.1088/0004-637x/774/1/34

Cited by 16 publications

(10 citation statements)

References 67 publications

(88 reference statements)

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“…This H II region is associated with the bright binary star Spica (α Vir). The H II region is also observed in far-UV (FUV) spectral line emission (Park et al 2010;Choi et al 2013). With a Hipparcos parallax of 12.44 ± 0.86 mas (Perryman et al 1997), the distance of Spica is 80 ± 5 pc.…”

Section: Loop IVmentioning

confidence: 99%

Revisiting the Distance to Radio Loops I and IV Using Gaia and Radio/Optical Polarization Data

Panopoulou

Dickinson

Readhead

et al. 2021

ApJ

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Galactic synchrotron emission exhibits large angular scale features known as radio spurs and loops. Determining the physical size of these structures is important for understanding the local interstellar structure and for modeling the Galactic magnetic field. However, the distance to these structures is either under debate or entirely unknown. We revisit a classical method of finding the location of radio spurs by comparing optical polarization angles with those of synchrotron emission as a function of distance. We consider three tracers of the magnetic field: stellar polarization, polarized synchrotron radio emission, and polarized thermal dust emission. We employ archival measurements of optical starlight polarization and Gaia distances and construct a new map of polarized synchrotron emission from WMAP and Planck data. We confirm that synchrotron, dust emission, and stellar polarization angles all show a statistically significant alignment at high Galactic latitude. We obtain distance limits to three regions toward Loop I of 112 ± 17 pc, 135 ± 20 pc, and <105 pc. Our results strongly suggest that the polarized synchrotron emission toward the North Polar Spur at b > 30° is local. This is consistent with the conclusions of earlier work based on stellar polarization and extinction, but in stark contrast with the Galactic center origin recently revisited on the basis of X-ray data. We also obtain a distance measurement toward part of Loop IV (180 ± 15 pc) and find evidence that its synchrotron emission arises from chance overlap of structures located at different distances. Future optical polarization surveys will allow the expansion of this analysis to other radio spurs.

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Section: Loop IVmentioning

confidence: 99%

Revisiting the Distance to Radio Loops I and IV Using Gaia and Radio/Optical Polarization Data

Panopoulou

Dickinson

Readhead

et al. 2021

ApJ

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“…In addition to the large scale structure associated with the Galactic dust distribution, there are smaller features such as the halos found around hot stars (Murthy & Henry 2011;Choi et al 2013).…”

Section: Introductionmentioning

confidence: 99%

GALEX DIFFUSE OBSERVATIONS OF THE SKY: THE DATA

Murthy

2014

ApJS

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I present tabulations of the diffuse observations made by the GALEX spacecraft in two UV bands (FUV: 1539Å and NUV: 2316Å) from the (almost) final data release of the GALEX spacecraft (GR6/GR7). This data release includes all the FUV observations and the majority of the NUV observations. I discuss overall trends in the data but the primary purpose is to make the data available to the public. These data files described in this paper are hosted by the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Insitutute from whence they may be downloaded. For ease of use, I have also created maps of the diffuse radiation in both bands over the entire observed sky at 6 resolution.Subject headings: surveys -dust -local interstellar matter -ultraviolet: generalultraviolet: ISM

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“…This H II region is associated with the bright binary star Spica (α Vir). The H II region is also observed in FUV spectral line emission (Park et al 2010;Choi et al 2013). With a Hipparcos parallax of 12.44 ± 0.86 (Perryman et al 1997), the distance of Spica is 77 ± 5 pc.…”

Section: Loop IVmentioning

confidence: 96%

Revisiting the distance to radio Loops I and IV using Gaia and radio/optical polarization data

Panopoulou,

Dickinson,

Readhead

et al. 2021

Preprint

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Galactic synchrotron emission exhibits large-angular-scale features known as radio spurs and loops. Determining the physical size of these structures is important for understanding the local interstellar structure and for modeling the Galactic magnetic field. However, the distance to these structures is either debated or entirely unknown. We revisit a classical method of finding the location of radio spurs by comparing optical polarization angles with those of synchrotron emission as a function of distance. We consider three tracers of the magnetic field: stellar polarization, polarized synchrotron radio emission, and polarized thermal dust emission. We employ archival measurements of optical starlight polarization and Gaia distances, and construct a new map of polarized synchrotron emission from WMAP and Planck data. We confirm that synchrotron, dust emission, and stellar polarization angles all show a statistically significant alignment at high Galactic latitude. We obtain distance limits to three regions towards Loop I of 112±17 pc, 122±32 pc, and < 105 pc. Our results strongly suggest that the polarized synchrotron emission towards the North Polar Spur at b > 30 • is local. This is consistent with the conclusions of earlier work based on stellar polarization and extinction, but in stark contrast with the Galactic center origin recently revisited on the basis of X-ray data. We also obtain a distance measurement towards part of Loop IV (177±17 pc) and find strong evidence that its synchrotron emission arises from chance overlap of structures located at different distances. Future optical polarization surveys will allow the expansion of this analysis to other radio spurs.

show abstract

Far-Ultraviolet Observations of the Spica Nebula and the Interaction Zone

Cited by 16 publications

References 67 publications

Revisiting the Distance to Radio Loops I and IV Using Gaia and Radio/Optical Polarization Data

Revisiting the Distance to Radio Loops I and IV Using Gaia and Radio/Optical Polarization Data

GALEX DIFFUSE OBSERVATIONS OF THE SKY: THE DATA

Revisiting the distance to radio Loops I and IV using Gaia and radio/optical polarization data

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