Betelgeuse scope: single-mode-fibers-assisted optical interferometer design for dedicated stellar activity monitoring

Betelgeuse has experienced a sudden shift in its brightness and dimmed mysteriously. This is likely caused by a hot blob of plasma ejected from Betelgeuse and then cooled to obscuring dust. If true, it is a remarkable opportunity to directly witness the formation of dust around a red supergiant star. Today's optical telescope facilities are not optimized for monitoring the Betelgeuse surface, so in this work, we propose a low-cost optical interferometer. The facility will consist of 12 x 4 inch optical telescopes mounted to the surface of a large radio dish for model-independent aperture synthesis imaging; polarization-maintaining single-mode fibers will carry the coherent beams from the individual optical telescopes to an all-in-one beam combiner. A fast steering mirror assisted fiber injection system guides the flux into fibers. A metrology system senses vibration-induced piston errors in optical fibers, and these errors are corrected using fast-steering delay lines. We will present the design.

[1]  Pierre Kervella,et al.  The close circumstellar environment of Betelgeuse - II. Diffraction-limited spectro-imaging from 7.76 to 19.50 μm with VLT/VISIR , 2011, 1106.5041.

[2]  A. Amorim,et al.  Methods for multiple-telescope beam imaging and guiding in the near-infrared , 2018, 1801.10596.

[3]  A. Michelson,et al.  Measurement of the diameter of α Orionis with the interferometer , 1991 .

[4]  B. Plez,et al.  Radiative hydrodynamics simulations of red supergiant stars - II. Simulations of convection on Betelgeuse match interferometric observations , 2010, 1003.1407.

[5]  S. T. Ridgway,et al.  The close circumstellar environment of Betelgeuse - IV. VLTI/PIONIER interferometric monitoring of the photosphere , 2016, 1602.05108.

[6]  David F. Buscher,et al.  THE CONCEPTUAL DESIGN OF THE MAGDALENA RIDGE OBSERVATORY INTERFEROMETER , 2013, 1307.0391.

[7]  Wesley A. Traub,et al.  FLUOR fibered instrument at the IOTA interferometer , 1998, Astronomical Telescopes and Instrumentation.

[8]  K.-H. Hofmann,et al.  Vigorous atmospheric motion in the red supergiant star Antares , 2017, Nature.

[9]  Éric Thiébaut,et al.  MIRA: an effective imaging algorithm for optical interferometry , 2008, Astronomical Telescopes + Instrumentation.

[10]  J. Armstrong,et al.  The Navy Prototype Optical Interferometer , 1998 .

[11]  J. Sturmann,et al.  No Sun-like dynamo on the active star ζ Andromedae from starspot asymmetry , 2016, Nature.

[12]  Philip Massey,et al.  Betelgeuse Just Is Not That Cool: Effective Temperature Alone Cannot Explain the Recent Dimming of Betelgeuse , 2020, 2002.10463.

[13]  John D. Monnier,et al.  Contemporaneous Imaging Comparisons of the Spotted Giant σ Geminorum Using Interferometric, Spectroscopic, and Photometric Data , 2017, 1709.10109.

[14]  Klaus G. Strassmeier,et al.  Spatially Resolved Ultraviolet Spectroscopy of the Great Dimming of Betelgeuse , 2020, The Astrophysical Journal.

[15]  Guy Perrin,et al.  AGILIS: Agile Guided Interferometer for Longbaseline Imaging Synthesis - Demonstration and concepts of reconfigurable optical imaging interferometers , 2017, 1703.03919.

[16]  John D. Monnier,et al.  MIRC-X/CHARA: sensitivity improvements with an ultra-low noise SAPHIRA detector , 2018, Astronomical Telescopes + Instrumentation.

[17]  S. T. Ridgway,et al.  First Results from the CHARA Array. II. A Description of the Instrument , 2005 .

[18]  J. Monnier.  Optical interferometry in astronomy , 2003, astro-ph/0307036.

[19]  Boris Safonov,et al.  Differential Speckle Polarimetry of Betelgeuse in 2019-2020: the rise is different from the fall , 2020, 2005.05215.

[20]  J. Hron,et al.  Large granulation cells on the surface of the giant star π1 Gruis , 2017, Nature.

[21]  Christophe Dupuy,et al.  The Very Large Telescope Interferometer v2012+ , 2012, Other Conferences.

[22]  P. Mathias,et al.  Convective cells in Betelgeuse: imaging through spectropolarimetry , 2018, Astronomy & Astrophysics.

[23]  Matthew J. Richter,et al.  SOFIA-EXES Observations of Betelgeuse during the Great Dimming of 2019/2020 , 2020, The Astrophysical Journal.

[24]  John D. Monnier,et al.  A novel image reconstruction software for optical/infrared interferometry , 2010, Astronomical Telescopes + Instrumentation.

[25]  P. R. Lawson,et al.  New views of Betelgeuse: multi‐wavelength surface imaging and implications for models of hotspot generation , 2000 .

[26]  Jacob W. M. Baars,et al.  Evaluation of the ALMA Prototype Antennas , 2006 .

[27]  Iain McDonald,et al.  Betelgeuse Fainter in the Submillimeter Too: An Analysis of JCMT and APEX Monitoring during the Recent Optical Minimum , 2020, The Astrophysical Journal.

[28]  Arancha Castro-Carrizo,et al.  High-resolution observations of the symbiotic system R Aqr , 2018 .

[29]  John D. Monnier,et al.  Monte-Carlo imaging for optical interferometry , 2020, SPIE Astronomical Telescopes + Instrumentation.

[30]  J. Alcolea,et al.  High-resolution observations of the symbiotic system R Aqr , 2018, Astronomy & Astrophysics.

[31]  John D. Monnier,et al.  MIRC-X: A Highly Sensitive Six-telescope Interferometric Imager at the CHARA Array , 2020, The Astronomical Journal.

[32]  S. Meimon,et al.  Imaging the spotty surface of Betelgeuse in the H band , 2009, 0910.4167.