The interface between the stellar wind and interstellar medium around R Cassiopeiae revealed by far-infrared imaging

Ueta, Toshiya; Stencel, R. E.; Yamamura, I.; Geise, Kathleen; Karska, A.; Izumiura, Hideyuki; Nakada, Y.; Matsuura, M.; Ita, Yoshifusa; Tanabé, Toshihiko; Fukushi, H.; Matsunaga, Noriyuki; Mito, Hiroyuki; Speck, A. K.

doi:10.1051/0004-6361/200913455

Cited by 19 publications

(25 citation statements)

References 33 publications

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“…If U Hya is moving through an interstellar medium stationary to the sun, the offset should be opposite to the proper motion, PA at −48 • . An additional PA offset of −37 • may suggest a flow of interstellar matter in the plane of the sky with respect to the Sun (see Ueta et al 2008Ueta et al , 2010. If so, a downstream wake should appear, not around PA = −48 • , but around PA = −85 • ± 15 • .…”

Section: Offset Of the Shell Centermentioning

confidence: 99%

Extended dust shell of the carbon star U Hydrae observed with AKARI

Izumiura

Ueta

Yamamura

et al. 2011

A&A

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Context. Low-to intermediate-mass stars lose a significant fraction of their mass while they are on the asymptotic giant branch (AGB). This mass loss is considered to determine the final stages of their evolution. The material ejected from the stellar photosphere forms a circumstellar envelope in its surroundings. Layers of circumstellar envelope constitute the footprint of mass-loss history. Aims. Our aim is to probe the mass-loss history in the carbon star U Hya in the last ∼10 4 years by investigating the distribution of dust in the circumstellar envelope with high spatial resolution. Methods. We observed U Hya in the far-infrared (FIR) at 65, 90, 140, and 160 μm simultaneously, using the slow scan observing mode of the far-infrared surveyor (FIS) aboard the infrared astronomical satellite AKARI. It produced a map of ∼10 × 40 in size in each band. Results. The FIS maps reveal remarkably circular, ring-like emission structure almost centered on the star, showing the presence of a detached, spherical dust shell. A hollow dust shell model gives the inner radius R in of 101-107 [(2.5-2.6) × 10 17 cm], thickness that covers a half of the total dust mass ΔR hm of 16-23 [(3.8-5.6) × 10 16 cm], which gives ΔR hm /R in ∼ 0.2, and the power-law index of the dust opacity distribution of 1.10-1.15. The dust mass in the shell is well-constrained to be (0.9-1.4) × 10 −4 (κ 100 /25) −1 M , where κ 100 is the dust absorptivity at 100 μm in units of cm 2 g −1 . The dust mass-loss rate at R in is found to be (1.8-9.6) × 10 −8 (κ 100 /25) −1 (v e /15) M yr −1 , which shows that the total mass-loss rate in the shell is at least an order of magnitude higher than the current rate, where v e is the outflow velocity at R in in units of km s −1 . An extension of FIR emission along PA ∼ −70 • is found out to ∼5 from the star, which is probably a ram-stripping wake by the ISM wind. We also find excess FIR emission that might indicate the earliest departure from spherical symmetry in the AGB mass loss inside the shell. Conclusions. The dust shell of U Hya is a hollow sphere and has an effective width that is narrower than the spatial resolution of the FIS. It could be formed as either a direct consequence of a thermal pulse, a result of two-wind interaction induced by a thermal pulse, a termination shock, or any combination of these processes.

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Section: Offset Of the Shell Centermentioning

confidence: 99%

Extended dust shell of the carbon star U Hydrae observed with AKARI

Izumiura

Ueta

Yamamura

et al. 2011

A&A

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“…Sahai and Trauger 1998). Ueta et al (2009) reported an extended far-infrared shell around the AGB star R Cassiopeia and suggested that the interaction with the interstellar medium is responsible for shaping.…”

Section: Introductionmentioning

confidence: 99%

Planetary nebulae NGC 6826 and NGC 2899: early aspherical mass loss?

Aryal

Rajbahak

Weinberger

2009

Astrophys Space Sci

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By systematically searching regions around planetary nebulae (PNe) for signs of interactions of their precursors' wind with ambient matter we found a number of huge IRAS dust structures. Some of them may be chance projections, but a few appear to be real, like those around NGC 6826 and NGC 2899. In the case of NGC 6826 we noticed a giant (∼2°) bipolar dust emission, whose axis is along the proper motion of the central star. The PN itself is offset in the direction of motion both as to the center of this ∼30 pc large dust structure and to the center of a similarly large new Hα nebula. NGC 2899 was found in the center of a 14 × 11 pc quadrupolar cavity, whose directions of axes coincide with the directions of the main axes of the optical PN. In both cases, the formation of these structures appears to have commenced in the asymptotic giant branch (AGB) phase.

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“…I mention here only an example of R Cas, which is one of the strong SiO maser sources (Cotton et al 2004). In the far infrared images between 60 and 160 microns, this star exhibts an extended far-IR emission of the size of about a few arcminutes (Ueta et al 2010). In their FIR images, the stellar position does not fall at the center of the emission, but slightly shifted to the East.…”

Section: Discussionmentioning

confidence: 88%

“…This occurs due to the motion of the star relative to interstellar medium. From a number of these observations, we can obtain the stellar motions in the interstellar medium (Ueta et al 2011). We can also obtain the proper motions of the central star from VLBI measurements.…”

Section: Discussionmentioning

confidence: 99%

SiO Maser Surveys of Nearby Miras and their Kinematics in the Galaxy

Deguchi

2012

Proc. IAU

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Abstract. I review recent developments of SiO maser observations of miras, and discuss their kinematics in the Galaxy. They are deeply related to problems in other fields, such as the noncircular motion of Galactic spiral arms, streaming motions of stars in the solar neighborhood, and the interface between the interstellar and circumstellar medium revealed by Far-IR imaging of some miras, as well as the bar structure of the Galaxy. Recent automated surveys of variable stars in optical bands have increased the number of red variables enormously. Most of these stars were not observed in the radio before because of their blue colors. We have obtained radial velocities of these long-period variables with SiO masers. The longitude-velocity diagrams have revealed interesting deviations of stellar motions from the circular motion of the Galaxy, some of which show spatial motion similar to that of the Hercules group of stars. Important developments of SiO maser observations have been made for symbiotic stars, one of which showed a nova eruption with concurrent γ ray emission in 2010 (V407 Cyg). SiO masers have been monitored for this star after the nova eruption. I summarize the SiO maser observations of individual stars also.

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The interface between the stellar wind and interstellar medium around R Cassiopeiae revealed by far-infrared imaging

Cited by 19 publications

References 33 publications

Extended dust shell of the carbon star U Hydrae observed with AKARI

Extended dust shell of the carbon star U Hydrae observed with AKARI

Planetary nebulae NGC 6826 and NGC 2899: early aspherical mass loss?

SiO Maser Surveys of Nearby Miras and their Kinematics in the Galaxy

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