Mapping the interface between the Local and Loop I bubbles   using Strömgren photometry

Reis, Wilson; Corradi, W. J. B.

doi:10.1051/0004-6361:20077946

Cited by 18 publications

(21 citation statements)

References 41 publications

(89 reference statements)

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“…The distance to this interaction region is somewhat uncertain. A recent analysis of the E(b−y) data made by Reis & Corradi (2008) suggests that the western (left) side of the wall is at the distance of 110 ± 20 pc, while the eastern (right) side cannot be seen clearly before 280 ± 50 pc.…”

Section: Interaction Zone Between the Local Bubble And Loop Imentioning

confidence: 99%

Interstellar polarization at high galactic latitudes from distant stars

Berdyugin

Piirola

Teerikorpi

2013

A&A

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Aims. Interstellar polarization of starlight at high galactic latitudes gives information on the direction of the local Galactic magnetic field and the distribution of cosmic dust in wide "windows" perpendicular to the Galactic plane. Polarization data allow us to construct for the first time high-latitude polarization maps with resolution and sky coverage high enough to examine in detail the distribution of the interstellar polarization and the direction of the Galactic magnetic field around Galactic poles. Methods. We measured the polarization for more than 2400 new stars at distances of up to 600 pc and within 60• and 30• from the north and south Galactic poles. Here we describe the measurements and properties of the resulting total sample of about 3600 stars (completeness, radial distribution), and present polarization maps of the regions around the north (b > 30• ) and south (b > 60 • ) poles. Results. The new interstellar polarization maps give wider and higher resolution views around the Galactic poles than previous maps. The major patterns in the maps are significant asymmetries in the polarization, one in the northern sky directly across the local spiral and the second between the northern and southern Galactic hemispheres. We confirm that there is significantly more interstellar polarization at high southern latitudes than at high northern latitudes within the local spiral. A comparison of our optical polarization map with the proposed models using local dust-and gas shells, (i.e., Weaver's Loop I superbubble, Wolleben's two-bubble model, the interaction between the Local Bubble and the Loop I superbubble) reveals interesting features. 1) The optical and radio polarizations are lower in the eastern than in the western branch of Loop I, which may be caused by a weaker effective magnetic field in the eastern part where the diffuse IRAS emission is bright; this illustrates that low optical polarization does not always imply little dust. 2) We can see a clear signature of the western side of Wolleben's S2 shell (at 35 < l < 55), while there is no alignment of the polarization directions along the suggested wall of S2 in the eastern part, though the alignment along S1 is visible. 3) In the upper parts of the suggested interaction zone between the Local Bubble and the Loop I superbubble our data show polarizations aligned along the zone contour. The week and rather randomly directed polarizations measured previously in the eastern part of this region may reflect the shorter distances (<250 pc) in the investigated sample of stars.

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Section: Interaction Zone Between the Local Bubble And Loop Imentioning

confidence: 99%

Interstellar polarization at high galactic latitudes from distant stars

Berdyugin

Piirola

Teerikorpi

2013

A&A

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“…The third model, with a globally similar scenario, explains the radio continuum polarization data with two colliding shells, both generated within about the same region as in the Sco-Cen association. Recently, Reis & Corradi (2008), Santos et al (2011) and Reis et al (2011) have questioned the existence of the interaction ring, which is associated to the first model only (see also Frisch et al 2011).…”

Section: On the Shell Geometrymentioning

confidence: 99%

Distance to northern high-latitude HI shells

Puspitarini

Lallement

2012

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Context. A detailed three-dimensional (3D) distribution of interstellar matter in the solar neighborhood is increasingly necessary. It would allow a more realistic computation of photons and cosmic rays propagation, which is of prime importance for microwave and gamma-ray background emission interpretation, as well as a better understanding of the chain of phenomena that gave rise to the main local structures. Aims. As part of a 3D mapping program, we aim at assigning a precise distance to the high-latitude HI gas, in particular the northern part (b ≥ 55 • ) of the shell associated with the conspicuous radio continuum Loop I. This shell is thought to be the expanding boundary of an interstellar bubble inflated and recently reheated by the strong stellar winds of the nearby Scorpius-Centaurus OB associations. Methods. We recorded high-resolution spectra of 30 A-type target stars located at various distances in the direction of the northern part of Loop I. Interstellar neutral sodium and singly ionized calcium absorptions (NaI 5889-5895 and CaII K-H 3934-3968 Å) are modeled and compared with the HI emission spectra from the LAB Survey. Results. About two-thirds of our stellar spectra possess narrow interstellar lines, while the remaining spectra show no absorption at all. Narrow lines are located at the velocity of the main, low-velocity Loop 1 HI shell ([-6, +1] km s −1 in the LSR). Using Hipparcos distances to the target stars, we show that the closest boundary of the b ≥ +70 • part of this low-velocity Loop I arch is located at of 98 ± 6 pc. The corresponding interval for the lower-latitude part (55 ≤ b ≤ 70 • ) is 95-157 pc. However, since the two structures are apparently connected, the lower limit is more likely. At variance with this shell, the second HI structure (b ≥ +85 • ), which is characterized by LSR Doppler velocities centered at -30 km s −1 , is NOT detected in any of the optical spectra. It is located beyond 200 parsecs or totally depleted in NaI and CaII. Conclusions. We discuss these results in the light of spherical expanding shells and show that they are difficult to reconcile with simple geometries and a nearby shell center close to the plane. Instead, this high-latitude gas seems to extend the inclined local chimney wall to high distances from the plane.

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“…However, Egger & Aschenbach's scenario makes no consideration of the kinematics of the H I. Furthermore, their ringlike feature has been questioned (Reis & Corradi 2008). On the other hand, from a detailed study involving about 3900 OB stars Fernández (2005; concluded that the Sco-Cen association could have formed in the Sgr-Car arm and not in the GB.…”

Section: Introductionmentioning

confidence: 99%

The interstellar medium surrounding the Scorpius-Centaurus association revisited

Pöppel¹,

Bajaja²,

Arnal

et al. 2010

A&A

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Aims. We want to make a large-scale study of the morphology, kinematics, and origin of the H I, which surrounds the Sco-Cen association. Methods. We combine our high-sensitivity southern H I survey with the Leiden/Dwingeloo Survey, considering l = 240 • −400 • , b = −60 • to +60 • , and radial velocities of V = −41.8 to +40.8 km s −1 . We point out the main H I branches surrounding the association and derive their kinematics. Kinematical H I-maps were compared with spatial maps of interstellar (IS) Na I from the literature. Upper limits for distances d were derived from optical IS absorption components from the literature. Models of expanding spherical H I shells were fitted around each stellar subgroup. Results. The expanding ring of H I associated with the Gould Belt (GB) is very prominent. At each l, its radial velocity shifts ∼−7 km s −1 within an interval Δb ∼ 10 • −25 • . On the sky, the shifts occur within a narrow stripe extending between l, b ∼ 250 • , −18 • and 400 • , +50 • . The ranges of distances and radial thicknesses of most H I branches are nearly 70−160 pc and 40−90 pc, respectively. The shell-models fit the main branches. Interactions between the shells built a large expanding bubble with a transverse diameter of nearly 250 pc around the association. The near face is approaching with a mean velocityV ∼ −6.6 km s −1 at d ≤ 76 pc from the Sun, covering about 102 • × 65 • (l, b), forming an "H I-wall". There are streamers atV ∼ −15 to −35 km s −1 , as well as gas presumably overshot into Galactic Quadrant II. The receding gas is more tenuous. Conclusions. The association is traversing the ring since a time comparable to its age producing a significant disturbance on the expanding GB-ring of gas. The latter was almost totally shocked by the association, northerly of the stripe of velocity shifts. Southerly there are large amounts of preshocked gas, as well as smaller more localized shocked regions. Hot gas within the bubble produces most of the 1/4 keV radiation detected toward it by ROSAT. The total mass of the GB gas embedding the Sco-Cen association is estimated at M t ∼ 368 000 M ± 60%, including ∼34 000 M of associated H 2 and 30% of He. About 39% of the embedding gas was shocked by the association. At | b |≥ 35 • , a comparison of the observations with test points moving on ballistic orbits is consistent with the formation of the Sco-Cen association within the gas ring of the GB and the presumable explosive origin of the latter. The rotation of the ring is assumed.

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Mapping the interface between the Local and Loop I bubbles using Strömgren photometry

Cited by 18 publications

References 41 publications

Interstellar polarization at high galactic latitudes from distant stars

Interstellar polarization at high galactic latitudes from distant stars

Distance to northern high-latitude HI shells

The interstellar medium surrounding the Scorpius-Centaurus association revisited

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