Photographic photometry of the carbon star RW LMi (CIT6) during 1989-1995

Alksnis, A.

doi:10.1515/astro-1995-0107

Cited by 4 publications

(5 citation statements)

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“…However, the source of blue light is likely to be different from the source of red emission (Alksnis et al 1988). This contention is most securely based on multi-wavelength photometry which shows that the red and infrared flux vary at the ∼626 day period of the carbon star, while the blue flux level is roughly constant (Alksnis 1995). In addition, the blue light has a polarization angle (∼0 • ) roughly orthogonal to that seen in the red and infrared (Cohen & Schmidt 1982;Trammell et al 1994).…”

Section: Discussionmentioning

confidence: 99%

“…The identification of CIT 6 as a carbon star is based on its near-infrared CN bands (Wisniewski et al 1967;Gaustad et al 1969) and its thick carbon-rich dust shell, responsible for the heavy visible obscuration (e.g., Strecker & Ney 1974). Monitoring of the infrared variability, first recognized by Ulrich et al (1966), has led to an established period of ∼628 days for this long-period variable (Alksnis & Khozov 1975;Alksnis 1995;Taranova & Shenavrin 1999). Based on the pulsational period, the distance to CIT 6 has been estimated by Cohen & Hitchon (1996) as 400±50 pc from application of the period-luminosity relations established for O-rich Miras (LMC and galactic) and C-rich Miras (LMC only).…”

Section: Introductionmentioning

confidence: 99%

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Diffraction‐limited Near‐IR Imaging at Keck Reveals Asymmetric, Time‐variable Nebula around Carbon Star CIT 6

Monnier¹,

Tuthill²,

Danchi³

2000

ApJ

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We present multi-epoch, diffraction-limited images of the nebula around the carbon star CIT 6 at 2.2µm and 3.1µm from aperture masking on the Keck-I telescope.The near-IR nebula is resolved into two main components, an elongated, bright feature showing time-variable asymmetry and a fainter component about 60 milliarcseconds away with a cooler color temperature. These images were precisely registered (∼35 milliarcseconds) with respect to recent visible images from the Hubble Space Telescope (Trammell et al. 2000), which showed a bipolar structure in scattered light. The dominant near-IR feature is associated with the northern lobe of this scattering nebula, and the multi-wavelength dataset can be understood in terms of a bipolar dust shell around CIT 6. Variability of the near-IR morphology is qualitatively consistent with previously observed changes in red polarization, caused by varying illumination geometry due to non-uniform dust production. The blue emission morphology and polarization properties can not be explained by the above model alone, but require the presence of a wide binary companion in the vicinity of the southern polar lobe. The physical mechanisms responsible for the breaking of spherical symmetry around extreme carbon stars, such as CIT 6 and IRC+10216, remain uncertain.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Diffraction‐limited Near‐IR Imaging at Keck Reveals Asymmetric, Time‐variable Nebula around Carbon Star CIT 6

Monnier¹,

Tuthill²,

Danchi³

2000

ApJ

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“…Photometry data as a function of (Julian Date -2446000) days. Photometry data taken from: Alksnis (1995); Le ; Cutri et al (2003); Whitelock et al (2006); Shenavrin et al (2011);Henden (2013); Fouque et al (1992); DENIS Consortium (2005); Kerschbaum et al (2006); Price et al (2010); Helou & Walker (1988); Jones et al (1990); Epchtein et al (1990). Maser spectroscopic data taken from: Lucas et al (1986); Guilloteau et al (1987); Goldsmith et al (1988); Lucas et al (1988); Lis et al (1989); Carlstrom et al (1990); Lucas & Guilloteau (1992).…”

Section: Relation To Variabilitymentioning

confidence: 99%

A new HCN maser in IRAS 15082−4808

Smith

Zijlstra

Fuller

2014

Monthly Notices of the Royal Astronomical Society

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We have identified a new vibrational HCN maser at 89.087 GHz in the asymptotic giant branch (AGB) star IRAS 15082−4808, a maser which is thought to trace the innermost region of an AGB envelope. The observations of this maser at three epochs are presented: two positive detections and one null detection. The line profile has varied between the positive detections, as has the intensity of the maser. The major component of the maser is found to be offset by −2.0 ± 0.9 km/s with respect to the systemic velocity of the envelope, as derived from the 88.631 GHz transition of HCN. Similar blueshifts are measured in the other 9 sources where this maser has been detected. Maser variability with pulsation phase has been investigated for the first time using the 10 stars now available. Comparisons with AGB model atmospheres constrain the position of the formation region of the maser to the region between the pulsation shocks and the onset of dust acceleration, between 2 and 4 stellar radii.

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“…It is a long-period-variable star with a period of ∼ 628 days (e.g. Alksnis 1995), and was classified as PPN by Johnson & Jones (1991). However, the estimated photospheric temperature of ∼ 2 800 K (Cohen 1979) implies that the star is still near the AGB.…”

Section: Citmentioning

confidence: 99%

Dust temperature and density profiles in the envelopes of AGB and post-AGB carbon stars from mid-infrared observations

Lagadec¹,

Mékarnia²,

Pacheco³

et al. 2005

A&A

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Abstract. First mid-infrared images of a sample of AGB and post-AGB carbon stars (V Hya, IRC +10216, CIT 6 and Roberts 22) obtained at the ESO-La Silla Observatory (Chile) are reported. CIT 6 presents a cometary-like feature clearly seen in the 9.7 µm image, Roberts 22 shows an envelope slightly elongated in the north-east direction while images of V Hya and IRC +10216 are roughly spherically symmetric. Using an inversion technique, the dust emissivity was derived from the observed intensity profiles, allowing a determination of the grain temperature and density distributions inside the envelope for these stars. Dust masses and mass-loss rates were estimated for V Hya and IRC +10216. Our results are comparable to those obtained in previous studies if dust grains have dimensions in the range ∼0.01-0.2 µm. Color maps suggest the presence of temperature inhomogeneities in the central regions of the dust envelopes. In the case of V Hya, an eccentric hot point, whose direction coincides with the jet previously seen in [S II] emission, suggests that we are observing material ejected in a previous mass-loss event. Bipolar lobes are clearly seen in the color maps of Roberts 22 and IRC +10216.

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Photographic photometry of the carbon star RW LMi (CIT6) during 1989-1995

Cited by 4 publications

References 1 publication

Diffraction‐limited Near‐IR Imaging at Keck Reveals Asymmetric, Time‐variable Nebula around Carbon Star CIT 6

Diffraction‐limited Near‐IR Imaging at Keck Reveals Asymmetric, Time‐variable Nebula around Carbon Star CIT 6

A new HCN maser in IRAS 15082−4808

Dust temperature and density profiles in the envelopes of AGB and post-AGB carbon stars from mid-infrared observations

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