A new survey for high velocity HI detections in the
 Southern Hemisphere

Morras, R.; Bajaja, E.; Arnal, E. M.; Pöppel, W. G. L.

doi:10.1051/aas:2000132

Cited by 55 publications

(50 citation statements)

References 12 publications

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“…At the position of HD 156359 no H I is found in the list of Morras et al (2000), but many small, faint HVCs with similar velocities exist nearby (Fig. 11).…”

Section: Complex Wementioning

confidence: 99%

“…These include some clouds previously catalogued on a 2 • ×2 • grid (WW356, WW364, WW373, WW412). With the better view provided by the Morras et al (2000) list, these clouds were swept together into "complex WE", by analogy with the positive-velocity complexes WA through WD defined by Wakker & van Woerden (1991).…”

Section: Complex Wementioning

confidence: 99%

“…Therefore, for each velocity channel a weighted average was constructed using the four gridpoints surrounding the direction to the probe; the weights are given by max(0,0.5−R), where R is the distance to the nearest gridpoint in degrees. VE − For HD 156359 the limit of 2×10 18 cm −2 is based on the fact that Morras et al (2000) & Sembach 1996a) are assumed, an implied N(H I) can be derived from the column densities of Mg II, Al II, Si II, Mn II and Fe II. This yields column densities of 8.0±2.5 and 5.4±1.9×10 18 cm −2 for the components at +120 and +165 km s −1 , respectively, which are consistent with the N(H I) measured half a degree away by McGee & Newton (1986) in the directions toward Sk−69 246 and their position "JM43".…”

Section: Column 10mentioning

confidence: 99%

“…• 5 grid with 1 km s −1 velocity resolution. b) The HVC survey made at the "Instituto Argentina de Radioastronomia" (IAR) (Morras et al 2000) provides a list of H I components with |v LSR |>80 km s −1 for declinations south of −23 • on a 0. • 5 grid, extracted from spectra with 16 km s −1 velocity resolution.…”

Section: Introductionmentioning

confidence: 99%

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Distances and Metallicities of High‐ and Intermediate‐Velocity Clouds

Wakker

2001

ASTROPHYS J SUPPL S

342

573

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A table is presented that summarizes published absorption line measurements for the high-and intermediate velocity clouds (HVCs and IVCs). New values are derived for N(H I) in the direction of observed probes, in order to arrive at reliable abundances and abundance limits (the H I data are described in Paper II). Distances to stellar probes are revisited and calculated consistently, in order to derive distance brackets or limits for many of the clouds, taking care to properly interpret non-detections. The main conclusions are the following. 1) Absolute abundances have been measured using lines of S II, N I and O I, with the following resulting values: ∼0.1 solar for one HVC (complex C), ∼0.3 solar for the Magellanic Stream, ∼0.5 solar for a southern IVC, and ∼ solar for two northern IVCs (the IV Arch and LLIV Arch). Finally, approximate values in the range 0.5−2 solar are found for three more IVCs. 2) Depletion patterns in IVCs are like those in warm disk or halo gas. 3) Most distance limits are based on strong UV lines of C II, Si II and Mg II, a few on Ca II. Distance limits for major HVCs are >5 kpc, while distance brackets for several IVCs are in the range 0.5−2 kpc. 4) Mass limits for major IVCs are 0.5−8×10 5 M ⊙ , but for major HVCs they are >10 6 M ⊙ . 5) The Ca II/ H I ratio varies by up to a factor 2−5 within a single cloud, somewhat more between clouds. 6) The NaI/ H I ratio varies by a factor >10 within a cloud, and even more between clouds. Thus, Ca II can be useful for determining both lower and upper distance limits, but Na I only yields upper limits.

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“…At the position of HD 156359 no H I is found in the list of Morras et al (2000), but many small, faint HVCs with similar velocities exist nearby (Fig. 11).…”

Section: Complex Wementioning

confidence: 99%

Section: Complex Wementioning

confidence: 99%

Section: Column 10mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Distances and Metallicities of High‐ and Intermediate‐Velocity Clouds

Wakker

2001

ASTROPHYS J SUPPL S

342

573

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“…As mentioned above, the present survey will also be useful to build a new database of High Velocity Clouds (HVC), achieving a much better sensitivity, spatial resolution, and spatial coverage than in previous HVC surveys previously conducted (Morras et al 1999). This new Hi survey will also allow to study in much more detail some of the HVC complexes known to date.…”

Section: Main Scientific Driversmentioning

confidence: 91%

A high sensitivity Hi survey of the sky at δ ≤ -25°

Arnal¹,

Bajaja²,

Larrarte³

et al. 2000

Astron. Astrophys. Suppl. Ser.

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Abstract. This paper reports on a high sensitivity λ 21-cm neutral hydrogen survey of the sky south of δ ≤ −25• . A total of 50980 positions lying on a galactic coordinate grid with points spaced by ( l, b) = (0.• 5/cos b, 0.• 5), were observed with the 30 m dish of the Instituto Argentino de Radioastronomía (IAR). The angular resolution of the survey is HPBW = 30 , and the velocity coverage spans the interval −450 km s −1 to +400 km s −1 (LSR). The velocity resolution is 1.27 km s −1 and the final rms noise of the entire database is ∼ 0.07 K. The brightness temperature scale is accurate to 5%.

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High‐Velocity Clouds and the Local Intergalactic Medium

Richter¹

2006

Reviews in Modern Astronomy

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In this article I review recent observations of the gaseous halos of galaxies and the intergalactic medium at low redshift. In the first part I discuss distribution, metal content, and physical properties of the Galactic intermediate- and high-velocity clouds and the hot halo of the Milky Way. Recent absorption and emission measurements show that the Galaxy's tidal interaction with the Magellanic Clouds, the infall of low-metallicity gas, as well as the circulation of gas as part of the galactic fountain contribute to the observed distribution of gas in the halo of the Milky Way. In the second part I give a short overview on the circumgalactic gaseous environment of other nearby spiral galaxies. Multi-wavelength observations demonstrate that neutral and ionized gaseous halos of galaxies are common, and that they extend deep into intergalactic space. These studies suggest that the gaseous material around spiral galaxies is tightly connected to the on-going hierarchical formation and evolution of these galaxies. In the last part of this article I summarize recent quasar absorption-line measurements of the local intergalactic medium. In accordance with cosmological simulations, absorption-line studies in the far-ultraviolet indicate that both the photoionized Ly alpha forest and the shock-heated warm-hot intergalactic medium harbor a substantial fraction of the baryons in the local Universe.Comment: 32 pages, 10 figures; to appear in Reviews in Modern Astronom

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A new survey for high velocity HI detections in the Southern Hemisphere

Cited by 55 publications

References 12 publications

Distances and Metallicities of High‐ and Intermediate‐Velocity Clouds

Distances and Metallicities of High‐ and Intermediate‐Velocity Clouds

A high sensitivity Hi survey of the sky at δ ≤ -25°

High‐Velocity Clouds and the Local Intergalactic Medium

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