Multi-epoch Optical Images of IRC+10216 Tell About the Central Star And the Adjacent Environment

Abstract

Six images of IRC+10216 taken by the Hubble Space Telescope at three epochs in 2001, 2011, and 2016 are compared in the rest frame of the central carbon star. An accurate astrometry has been achieved with the help of Gaia Data Release 2. The positions of the carbon star in the individual epochs are determined using its known proper motion, defining the rest frame of the star. In 2016, a local brightness peak with compact and red nature is detected at the stellar position. A comparison of the color maps between 2016 and 2011 epochs reveals that the reddest spot moved along with the star, suggesting a possibility of its being the dusty material surrounding the carbon star. Relatively red, ambient region is distributed in an $\Omega$ shape and well corresponds to the dusty disk previously suggested based on near-infrared polarization observations. In a larger scale, differential proper motion of multiple ring-like pattern in the rest frame of the star is used to derive the average expansion velocity of transverse wind components, resulting in $\sim$ 12.5 km s${}^{-1}$ ($d$/123 pc), where $d$ is the distance to IRC+10216. Three dimensional geometry is implied from its comparison with the line-of-sight wind velocity determined from half-widths of submillimeter emission line profiles of abundant molecules. Uneven temporal variations in brightness for different searchlight beams and anisotropic distribution of extended halo are revisited in the context of the stellar light illumination through a porous envelope with postulated longer-term variations for a period of $\lesssim 10$ years.

20 pages, 12 figures, 1 table, accepted for publication in The Astrophysical Journal

References in corpus (10)

• The Gaia mission
• The Catalina Surveys Periodic Variable Star Catalog
• Unexpectedly large mass loss during the thermal pulse cycle of the red giant R Sculptoris!
• ALMA data suggest the presence of a spiral structure in the inner wind of CW Leo
• Molecular shells in IRC+10216: tracing the mass loss history
• The circumstellar envelope of IRC+10216 from milli-arcsecond to arcmin scales
• Discovery of multiple dust shells beyond 1 arcmin in the circumstellar envelope of IRC+10216 using Herschel/PACS
• The Formation of Crystalline Dust in AGB Winds from Binary Induced Spiral Shocks
• HST Images Reveal Dramatic Changes in the Core of IRC+10216
• Rings and arcs around evolved stars. II. The Carbon Star AFGL 3068 and the Planetary Nebulae NGC 6543, NGC 7009 and NGC 7027

Cited by in corpus (3)

• Investigating Anomalous Photochemistry in the Inner Wind of IRC+10216 Through Interferometric Observations of HC${}_3$N
• Atmospheric molecular blobs shape up circumstellar envelopes of AGB stars
• Near-infrared Integral-field Spectroscopy of the Wind Forming Region of CW Leo