Betelgeuse: The Great Dimming Redux?

0 Assigned ID: 4627 ----- Attempting Submission 1 (Wed May 24 20:46:10 GMT 2023) ----- POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE NO ORIENT POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE POS TARG OUTSIDE OF APERTURE The errors and warnings relate to the offsets that wehave done for several years (5)... and simply offset from the initial peakup... and have received all these warnings before.. We do no specify an orientation but simply take HST where it happens to be oriented. These comments still apply as of this re-submission 2024, December 3. All visits are schedulable between Aug and December 2025. -732486013 ----- Attempting Submission 1 (Thu Sep 14 18:56:42 GMT 2023) ----- ----- Attempting Submission 2 (Mon Aug 12 19:42:06 GMT 2024) ----- ----- Attempting Submission 3 (Thu Nov 14 22:26:08 GMT 2024) ----- ----- Attempting Submission 4 (Tue Dec 03 19:53:25 GMT 2024) ----- These are 64 warnings - not errors. We are carrying out offsets from the peak up position at whatever orientation HST happens to be in. We always get this warning from the APT for the past 5 year when doing these offsets. We are not losing the target. Betelgeuse is large. 44 mas diameter in the optical and 3-4 times that size in the ultraviolet, Betelgeuse: The Great Dimming Redux? The historic Great Dimming of the red supergiant Betelgeuse in 2020 was initiated at a propitious confluence of maximum outflow of the 400-day fundamental mode of pulsation and the 2200-day Long Secondary Period. This condition will occur again sometime between Fall 2024 and Spring 2025. We propose to follow its behavior. Spatially resolved ultraviolet spectra of the star achievable with STIS can provide the connecting link between the convective activity on the stellar surface and the formation of a dust cloud in the outer atmosphere. This campaign will probe the entire atmosphere, from the photosphere to the circumstellar environment, with a combination of ground-based interferometric/AO imaging, radio observations, and optical and UV spectroscopy, creating a comprehensive contemporaneous sampling of the star, its variation with time, and the effects on its extended atmosphere. We should learn whether the event of 2019-2020 was a 'random' occurrence or results from oscillation phase superposition. Two visits are requested during Cycle 31, and 5 visits during Cycle 32 (16 orbits) to obtain spatially resolved ultraviolet spectra at this unique time. We propose to obtain short slit echelle spectra of Betelgeuse with the medium resolution E230M grating in the wavelength range of 2303 to 3111\AA. We will use the small (0.1" x 0.025") slit for maximum spatial resolution. Only with this supported slit can we take full advantage of the STIS/HST resolution. Betelgeuse has no record of flaring and previous STIS observations demonstrate that the STIS detectors are not subject to any danger. We plan 1 orbit in the first visit with the E230H grating to investigate the behavior of blended line features. For 5 visits: 1 visit (4 orbits), 4 visits (3 orbits) TOTAL 16 orbits These visits will take advantage of the small aperture (0.1X0.3 arsec) to obtain spatially resolved ultraviolet spectra of the supergiant Betelgeuse. Chromospheric emission lines reveal dynamics, densities, and emission measures of the chromospheric plasma. We plan to cover the optical diameter of the star (42 mas) with a center pointing, and offsets at +/-25 mas. Then followed by pointing off the optical disk and offset to +/- 50 mas, and +/-75 mas. (Not in this order, but designed to appropriately fill the time available.: sequence of o) We have used the ETC for STIS, assuming a Castelli/Kurucz model of a M2 supergiant, and normalizing it to the observed STIS flux (from MAST) near 2786A (to avoid Mg II emission) for various pointing offsets on the star at different dates. We used spectra from the 'normal' state of Betelgeuse (not the spectra taken during 2019 Sep-Nov). Ideally a range of exposure times would be used in response to the varying stellar flux. However, we cannot predict the ultraviolet flux level a priori, as it is not related to the optical V-magnitude. We therefore have selected an average value. This is a pattern we have used since 2019 and it works. The center exposure requires 7.9 minutes; the offset at +/-25 mas and +/-50 mas require 9-10 minutes, and at +/-75 mas, 20-30 minutes. At the declination of Betelgeuse, each HST orbit allows 49-52 minutes on target. These spectra will require guide star acquisition, target acquisition, and two peak ups with the small slit (0.1" x 0.025") during the first orbit of a visit. This takes 31.7 minutes; then we offset to -75 mas for a 1155 dec exposure. Orbit 2 is followed by offset to -50 mas as for a 606 sec exposure, offset to -25 mas for 530 sec exposure, offset to 0 (center) for a 472 sec exposure,, and to +25 masfor a 569 sec exposure. In the 3rd orbit, we offset to +50 mas for a 606 sec exposure, followed by an offset to +75 mas for a 1944 sec exposure. In the first visit, we are including another orbit which will extend to +/-100 mas where there may be indications of the presence of a companion star. The following 4 visits will only require 3 orbits. Total of 16 orbits. Andrea Dupree (PI): Dupree was PI of the HST proposal that first imaged the surface of Betelgeuse, and subsequent proposals that obtained spatially resolved uv spectra and determined the rotation and the asymmetical motions in the Betelgeuse atmosphere. She used HST/STIS in Cycles 26-30 to document the massive outflow from the chromosphere of the star that led to the formation of dust and subsequent dimming. The HST observations were critical in documenting the Surface Mass Ejection, its progress through the chromosphere, and eventual formation of a dust cloud. She will acquire contemporaneous echelle spectra from TRES to complement the results from STELLA. She leads the program design, analysis of the spectra, and subsequent detailed modeling. All STIS observations under this program (except for 2023 April) have been published. Tom Calderwood is an experienced optical observer with photoelectric photometers and contributes his measurement to the AAVSO database and assists with the validation of other AAVSO contributions. Caroline Huang and Morgan MacLeod are leading the radiative transfer and hydrodynamic calculations to model the surface mass ejection and motion through the chromosphere, to understand the change in pulsation period, and the response of the photosphere to this and other events. Kateryna Kravchenko and Alain Jorissen have developed the tomagraphic techniques that will be used with the photospheric spectrum to diagnose motions in layers of the photosphere. They have arranged for the acquisition of HERMES spectra. Lynn Matthews is an expert in radio interferometric observations of stars and will lead the VLA observations. Miguel Montarges and Pierre Kervella lead the proposals for ESO time on SPHERE and MATISSE and ALMA to image Betelgeuse and perform the reduction and analysis. They are experienced in the interferometric imaging of supergiant stars and Betelgeuse in particular. Klaus Strassmeier, Thomas Granzer, and Michael Weber direct and operate the STELLA automatic telescope and echelle spectrograph on Tiede in the Canary Islands. They will obtain and reduce the echelle spectra to determine photospheric radial velocities. Stellar Physics and Stellar Types 6 false false false false false false false true PRIMARY 4 true SUPPORTED STAR M III-I SUPERGIANT O J2000 J2000 STIS/NUV-MAMA Spectroscopic No No E230M 2707 STIS/NUV-MAMA Spectroscopic No No E230M 2707 STIS/NUV-MAMA Spectroscopic No No E230M 2707 STIS/NUV-MAMA Spectroscopic No No E230M 2707 STIS/NUV-MAMA Spectroscopic No No E230M 2707 STIS/NUV-MAMA Spectroscopic No No E230M 2707 1733246912970 Timing link suitability includes constraints ([02 After 01 by 25.0 to 45.0 days]) The scheduling data was generated by CASM 32.1.1. 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Spiral in 0.1X0.03 aperture.