The Galfa-Hi Survey: Data Release 1

Peek, J. E. G.; Heiles, Carl; Douglas, K. A.; Lee, Min Young; Grcevich, Jana; Stanimirović, Snežana; Putman, Mary E.; Korpela, E. J.; Gibson, Steven J.; Begum, Ayesha; Saul, Destry; Robishaw, Timothy; Krčo, Marko

doi:10.1088/0067-0049/194/2/20

Cited by 218 publications

(225 citation statements)

References 27 publications

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“…H i 21 cm observations in the vicinity of Betelgeuse were extracted from the results of the Galactic Arecibo L-Band Feed Array H i (GALFA-H i) survey (Peek et al 2011). GALFA-H i is a survey of the Galactic interstellar medium with a spatial resolution of ∼4 , covering a large area (13 000 deg 2 ) with a high spectral resolution (0.18 km s −1 ) from −700 < v LSR < +700 km s −1 in the 21-cm line hyperfine transition of neutral hydrogen conducted at the Arecibo Observatory.…”

Section: Galfa Hi 21 CM Observationsmentioning

confidence: 99%

“…Each beam is slightly elliptical along the zenith-angle direction, approximately 3.3 × 3.8 FWHM, with a gain of ∼11 K/Jy for the central beam and ∼8.5 K/Jy for the six other beams. Details on the data reduction are given in Peek et al (2011). Typical noise levels are 80 mK rms in an integrated 1 km s −1 channel, corresponding to an integration time of 30 s.…”

Section: Galfa Hi 21 CM Observationsmentioning

confidence: 99%

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The enigmatic nature of the circumstellar envelope and bow shock surrounding Betelgeuse as revealed byHerschel

Decin

Cox

Royer

et al. 2012

A&A

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Context. The interaction between stellar winds and the interstellar medium (ISM) can create complex bow shocks. The photometers on board the Herschel Space Observatory are ideally suited to studying the morphologies of these bow shocks. Aims. We aim to study the circumstellar environment and wind-ISM interaction of the nearest red supergiant, Betelgeuse. Methods. Herschel PACS images at 70, 100, and 160 μm and SPIRE images at 250, 350, and 500 μm were obtained by scanning the region around Betelgeuse. These data were complemented with ultraviolet GALEX data, near-infrared WISE data, and radio 21 cm GALFA-HI data. The observational properties of the bow shock structure were deduced from the data and compared with hydrodynamical simulations. Results. The infrared Herschel images of the environment around Betelgeuse are spectacular, showing the occurrence of multiple arcs at ∼6-7 from the central target and the presence of a linear bar at ∼9 . Remarkably, no large-scale instabilities are seen in the outer arcs and linear bar. The dust temperature in the outer arcs varies between 40 and 140 K, with the linear bar having the same colour temperature as the arcs. The inner envelope shows clear evidence of a non-homogeneous clumpy structure (beyond 15 ), probably related to the giant convection cells of the outer atmosphere. The non-homogeneous distribution of the material even persists until the collision with the ISM. A strong variation in brightness of the inner clumps at a radius of ∼2 suggests a drastic change in mean gas and dust density ∼32 000 yr ago. Using hydrodynamical simulations, we try to explain the observed morphology of the bow shock around Betelgeuse. Conclusions. Different hypotheses, based on observational and theoretical constraints, are formulated to explain the origin of the multiple arcs and the linear bar and the fact that no large-scale instabilities are visible in the bow shock region. We infer that the two main ingredients for explaining these phenomena are a non-homogeneous mass-loss process and the influence of the Galactic magnetic field. The hydrodynamical simulations show that a warm interstellar medium, reflecting a warm neutral or partially ionized medium, or a higher temperature in the shocked wind also prevent the growth of strong instabilities. The linear bar is probably an interstellar structure illuminated by Betelgeuse itself.

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Section: Galfa Hi 21 CM Observationsmentioning

confidence: 99%

Section: Galfa Hi 21 CM Observationsmentioning

confidence: 99%

The enigmatic nature of the circumstellar envelope and bow shock surrounding Betelgeuse as revealed byHerschel

Decin

Cox

Royer

et al. 2012

A&A

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“…Also shown in Figure 4 are the sensitivities and resolutions of the GALFA-HI (Stanimirović et al 2008;Peek et al 2011a) seven-beam single-dish survey and the lower resolution, all-sky, EBHIS survey. The GASS survey Table 3).…”

Section: Comparison With Other Surveysmentioning

confidence: 99%

GASKAP—The Galactic ASKAP Survey

Dickey

McClure-Griffiths

Gibson

et al. 2013

Publ. Astron. Soc. Aust.

Self Cite

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A survey of the Milky Way disk and the Magellanic System at the wavelengths of the 21-cm atomic hydrogen (H i) line and three 18-cm lines of the OH molecule will be carried out with the Australian Square Kilometre Array Pathfinder * Hubble Fellow. telescope. The survey will study the distribution of H i emission and absorption with unprecedented angular and velocity resolution, as well as molecular line thermal emission, absorption, and maser lines. The area to be covered includes the Galactic plane (|b| < 10°) at all declinations south of δ = +40 • , spanning longitudes 167 • through 360 • to 79 • at b = 0 • , plus the entire area of the Magellanic Stream and Clouds, a total of 13 020 deg 2 . The brightness temperature sensitivity will be very good, typically σ T 1 K at resolution 30 arcsec and 1 km s −1 . The survey has a wide spectrum of scientific goals, from studies of galaxy evolution to star formation, with particular contributions to understanding stellar wind kinematics, the thermal phases of the interstellar medium, the interaction between gas in the disk and halo, and the dynamical and thermal states of gas at various positions along the Magellanic Stream.

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“…These telescopes give the highest resolution possible for surveys of the entire sky, but the Arecibo telescope can give higher resolution over a significant portion of the sky (36 • > > 4 • ), and the GALFA survey has made very sensitive spectral line cubes of most of this area with beamwidth 3.5. Stanimirovic et al (2006); Peek et al (2011). The Arecibo data has not been fully corrected for stray radiation to the same level as the LAB, GASS, and EBHIS surveys.…”

Section: What We Have Nowmentioning

confidence: 99%

Surveys of the Milky Way and Magellanic System in the λ21-cm line of atomic hydrogen

Dickey

2012

EPJ Web of Conferences

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Abstract. In the next three years, surveys of the Northern and Southern skies using focal plane arrays on aperture synthesis radio telescopes will lead to a breakthrough in our knowledge of the warm and cool atomic phases of the interstellar medium and their relationship with the diffuse molecular gas. The sensitivity and resolution of these surveys will give an order of magnitude or more improvement over existing interstellar medium data. The GASKAP (South) and GAMES (North) projects together constitute a complete survey of the Milky Way plane and the Magellanic Clouds and Stream in both emission and absorption in the H I 21-cm line and the OH 18-cm lines. The overall goal of this project is to understand the mechanism of galaxy evolution, through a detailed tracing of the astrophysical processes that drive the cycle of star formation in very different environments. Comparison of 21-cm emission and absorption highlights the transition from the warm, diffuse medium to cool clouds. Tracing turbulence in the Magellanic Stream shows how extra-galactic gas makes the difficult passage through the halo to replenish the disk. Finally, high resolution images of OH masers trace outflows from evolved stars that enrich the medium with heavy elements. To understand how the Milky Way was assembled and how it has evolved since, the speed and efficiency of these processes must be measured, as functions of Galactic radius and height above the plane. Observations of similar processes in the Magellanic Clouds show how differently they might have worked in conditions typical of the early universe.

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The Galfa-Hi Survey: Data Release 1

Cited by 218 publications

References 27 publications

The enigmatic nature of the circumstellar envelope and bow shock surrounding Betelgeuse as revealed byHerschel

The enigmatic nature of the circumstellar envelope and bow shock surrounding Betelgeuse as revealed byHerschel

GASKAP—The Galactic ASKAP Survey

Surveys of the Milky Way and Magellanic System in the λ21-cm line of atomic hydrogen

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