The infrared angular diameter of Omicron Ceti near maximum light

Ridgway, Stephen T.; Benson, J. A.; Dyck, H. M.; Townsley, L. K.; Hermann, R. A.

doi:10.1086/116397

Cited by 15 publications

(14 citation statements)

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“…Measurements of the angular size of Mira at a variety of wavelengths by other groups appears to support this hypothesis. At 2.2 µm, the 36.1 ± 1.4 mas size measured by Ridgway et al (1992) is in agreement with a similar recent measurement of 31.6 mas at 2.26 µm by Tuthill et al (1999b) (no error or phase was given in this promising but preliminary result). However, at 11.15 µm, Weiner et al (2000) find an angular size of 47.8 ±0.5 mas.…”

Section: Discussion: Size and Pulsation Modesupporting

confidence: 92%

Angular Size Measurements of Mira Variable Stars at 2.2 Microns. II.

Belle¹,

Thompson²,

Creech‐Eakman³

2002

The Astronomical Journal

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We present angular size measurements of 22 oxygen-rich Mira variable stars. These data are part of a long term observational program using the Infrared Optical Telescope Array (IOTA) to characterize the observable behavior of these stars. Complementing the infrared angular size measurements, values for variable star phase, spectral type, bolometric flux and distance were established for stars in the sample; flux and distance led to values for effective temperature (T EF F ), and linear radius, respectively. Additionally, values for the K − [12] color excess were established for these stars, which is indicative of dusty mass loss. Stars with higher color excess are shown to be systematically 120 R ⊙ larger than their low color excess counterparts, regardless of period. This analysis appears to present a solution to a long-standing question presented by the evidence that some Mira angular diameters are indicative of first overtone pulsation, while other diameters are more consistent with fundamental pulsation. A simple examination of the resultant sizes of these stars in the context of pulsation mode is consistent with at least some of these objects pulsating in the fundamental mode.

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Section: Discussion: Size and Pulsation Modesupporting

confidence: 92%

Angular Size Measurements of Mira Variable Stars at 2.2 Microns. II.

Belle¹,

Thompson²,

Creech‐Eakman³

2002

The Astronomical Journal

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“…These values agree with the interferometric UD diameters within the K band of Ridgway et al (1992) ( phase 0.8) and Woodruff et al (2004) ( phases 0.1Y 0.4; see Table 10). Our UD angular diameters are generally larger than those measured by Mennesson et al (2002) (phases 0.9 Y0.0).…”

Section: Individual Starssupporting

confidence: 90%

The Keck Aperture Masking Experiment: Multiwavelength Observations of Six Mira Variables

Woodruff

Tuthill

Monnier

et al. 2008

ApJ

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International audienceThe angular diameters of six oxygen-rich Mira-type long-period variables have been measured at various NIR wavelengths using the aperture-masking technique in an extensive observing program from 1997 January to 2004 September. These data sets span many pulsation cycles of the observed objects and represent the largest study of multiwavelength, multiepoch interferometric angular diameter measurements on Mira stars to date. The calibrated visibility data of ο Cet, R Leo, R Cas, W Hya, χ Cyg, and R Hya are fitted using a uniform disk brightness distribution model to facilitate comparison between epochs, wavelengths, and with existing data and theoretical models. The variation of angular diameter as a function of wavelength and time is studied, and cyclic diameter variations are detected for all objects in our sample. These variations are believed to stem from time-dependent changes of density and temperature (and hence varying molecular opacities) in different layers of these stars. The similarities and differences in behavior between these objects are analyzed and discussed in the context of existing theoretical models. Furthermore, we present time-dependent 3.08 μm angular diameter measurements, probing for the first time these zones of probable dust formation, which show unforeseen sizes and are consistently out of phase with other NIR layers shown in this study. The S-type Mira χ Cyg exhibits significantly different behavior compared to the M-type Mira variables in this study, in both its NIR light curves and its diameter pulsation signature. Our data show that the NIR diameters predicted by current models are too small and need to incorporate additional and/or enhanced opacity mechanisms. Also, new tailored models are needed to explain the behavior of the S-type Mira χ Cyg

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“…Observations of the dust have been made at mid-infrared wavelengths by the ISI using short baselines (Bester et al 1991;Danchi et al 1994;Lopez et al 1997), as well as longer, single-baseline measurements of the star by Weiner et al (2000Weiner et al ( , 2003a to track changes in its diameter over time. Observations have also been made by the Infrared Optical Telescope Array (IOTA; Ragland et al 2006), the Mid-Infrared Array Camera (MIRAC3) at the NASA-IRTF ( Marengo et al 2001), and the Infrared Michelson Array (IRMA; Ridgway et al 1992). Measurements using aperture mask interferometry have been performed at visible to near-IR wavelengths ( Haniff et al 1995;Ireland et al 2004).…”

Section: O Cetimentioning

confidence: 99%

The Evolving Shapes ofoCeti and R Leonis

Tatebe

Wishnow

Ryan

et al. 2008

Astrophysical Journal

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The sizes and shapes of the stars o Ceti and R Leonis have been measured in the mid-infrared. The observations were made using the UC Berkeley Infrared Spatial Interferometer (ISI ), and they reveal details about the size, shape and asymmetry of both stars over several epochs in 2006. The star o Ceti appears to be rather symmetric, while the shape of R Leonis appears more consistent with a uniform disk plus a point source that provides approximately 9% additional intensity somewhere in the southern half of the star.

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The infrared angular diameter of Omicron Ceti near maximum light

Cited by 15 publications

References 0 publications

Angular Size Measurements of Mira Variable Stars at 2.2 Microns. II.

Angular Size Measurements of Mira Variable Stars at 2.2 Microns. II.

The Keck Aperture Masking Experiment: Multiwavelength Observations of Six Mira Variables

The Evolving Shapes ofoCeti and R Leonis

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