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The uniform disk (UD) angular diameter measurements of two oxygen-rich Mira variables (AW Aur and BS Aur) and three semiregular (SRb) variables (GP Tau, RS Cap, RT Cap), in near Infrared K-band (2.2 micron) by lunar occultation observations…

Solar and Stellar Astrophysics · Physics 2015-05-30 Tapas Baug , T. Chandrasekhar

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.…

Astrophysics · Physics 2009-11-07 G. T. van Belle , R. R. Thompson , M. J. Creech-Eakman

The angular diameters of six oxygen rich Mira-type long-period variables have been measured at various near-infrared (NIR) wavelengths using the aperture masking technique in an extensive observing program from 1997 Jan to 2004 Sep. These…

Semi-regular variables (SRVs) though closely related to Mira variables, are a less studied class of AGB stars. While asymmetry in the brightness distribution of many Mira variables is fairly well known, it is detected only in a few SRVs.…

Solar and Stellar Astrophysics · Physics 2015-06-22 Tapas Baug , T. Chandrasekhar , Shashikiran Ganesh

We present a possible interpretation for the increase of the angular diameter of the Mira variables o Cet, R Leo, and chi Cyg from the K band to the 11 micron region revealed by the recent interferometric observations using narrow…

Astrophysics · Physics 2009-11-10 Keiichi Ohnaka

We present results from a spectro-interferometric study of the Miras o Cet, R Leo and W Hya obtained with the Keck Aperture Masking Experiment from 1998 Sep to 2002 Jul. The spectrally dispersed visibility data permit fitting with…

Aims: We present J, H, K interferometry with a spectral resolution of 35 for the Mira variable S Orionis. We aim at measuring the diameter variation as a function of wavelength that is expected due to molecular layers lying above the…

Astrophysics · Physics 2008-01-10 M. Wittkowski , D. A. Boboltz , T. Driebe , J. -B. Le Bouquin , F. Millour , K. Ohnaka , M. Scholz

We have used near- and mid-infrared interferometry to investigate the pulsating atmosphere and the circumstellar environment of the Mira variable RR Aql. Observations were taken with the VLTI/AMBER (near infrared) and the VLTI/MIDI (mid…

Astrophysics · Physics 2009-11-13 Iva Karovicova , Markus Wittkowski , David A. Boboltz , Michael Scholz

We present a program of routine lunar occultations, at optical and near-IR wavelengths, recently started at the 1.5m Spanish telescope at the Calar Alto Observatory. Both a CCD and an infrared array detector are used. The program is aimed…

Astrophysics · Physics 2007-05-23 O. Fors , A. Richichi , J. Nunez , A. Prades

We present an update of the lunar occultation program which is routinely carried out in the near-IR at the Calar Alto Observatory. A total of 350 events were recorded since our last report (Fors et al. 2004). In the course of eight runs we…

Astrophysics · Physics 2016-08-30 A. Richichi , O. Fors , M. Merino , X. Otazu , J. Nunez , A. Prades , U. Thiele , D. Perez-Ramirez , F. J. Montojo

(Abridged) Lunar occultations (LO) are a very efficient and powerful technique, that achieves the best combination of high angular resolution and sensitivity possible today at near-infrared wavelengths. Given that the events are fixed in…

Solar and Stellar Astrophysics · Physics 2015-05-19 A. Richichi , O. Fors , W-P. Chen , E. Mason

We report on 26 lunar occultation events observed in the context of a program started at Devasthal in 2017. In addition to the customary observations with the 1.3-m telescope, we report here also the first attempts performed with the…

Solar and Stellar Astrophysics · Physics 2020-09-09 A. Richichi , Saurabh Sharma , T. Sinha , R. Pandey , A. Ghosh , D. K. Ojha , A. K. Pandey , M. B. Naik

We have used the VLA at 43 GHz to image the radio continuum emission from o Ceti, R Leo, and W Hya and to precisely locate their SiO maser emission with respect to the star. The radio continuum emission region for all three stars has a…

Astrophysics · Physics 2009-11-13 M. J. Reid , Karl M. Menten

Dynamic model atmospheres of Mira stars predict variabilities in the photospheric radius and in atmospheric molecular layers which are not yet strongly constrained by observations. Here we measure the variability of the oxygen-rich Mira…

Solar and Stellar Astrophysics · Physics 2018-06-06 M. Wittkowski , G. Rau , A. Chiavassa , S. Hoefner , M. Scholz , P. R. Wood , W. J. de Wit , F. Eisenhauer , X. Haubois , T. Paumard

Based on CHARA Array measurements, we present the angular diameters of 23 nearby, main- sequence stars, ranging from spectral type A7 to K0, five of which are exoplanet host stars. We derive linear radii, effective temperatures, and…

We report on 25 sub-arcsecond binaries, detected for the first time by means of lunar occultations in the near-infrared as part of a long-term program using the ISAAC instrument at the ESO Very Large Telescope. The primaries have magnitudes…

Solar and Stellar Astrophysics · Physics 2015-06-16 A. Richichi , O. Fors , F. Cusano , M. Moerchen

We present new measurements of the millimeter wavelength continuum emission from the long period variable Mira ($o$ Ceti) at frequencies of 46 GHz, 96 GHz, and 229 GHz ($\lambda$~7 mm, 3 mm, and 1 mm) based on observations obtained with the…

Solar and Stellar Astrophysics · Physics 2015-08-06 L. D. Matthews , M. J. Reid , K. M. Menten

We obtained a total of 20 near-infrared K-band spectro-interferometric snapshot observations of the Mira variables o Cet, R Leo, R Aqr, X Hya, W Vel, and R Cnc with a spectral resolution of about 1500. We compared observed flux and…

Solar and Stellar Astrophysics · Physics 2016-02-17 M. Wittkowski , A. Chiavassa , B. Freytag , M. Scholz , S. Hoefner , I. Karovicova , P. A. Whitelock

We present the first coordinated VLBA/VLTI measurements of the stellar diameter and circumstellar atmosphere of a Mira variable star. Observations of the v=1, J=1-0 (43.1 GHz) and v=2, J=1-0 (42.8 GHz) SiO maser emission toward the Mira…

Astrophysics · Physics 2009-11-10 D. A. Boboltz , M. Wittkowski

We present new measurements of the diameter of o Cet (Mira) as a function of wavelength in the 2.2 micron atmospheric window using the adaptive optics system and the infrared camera and spectrograph mounted on the Subaru Telescope. We found…

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