Convection and mass loss through the chromosphere of Betelgeuse

Assigned ID: 579 ----- Attempting Submission 1 (Fri Feb 25 20:00:54 GMT 2011) ----- HST Phase I Proposal 579 (Betelgeuse_APT.apt) successfully submitted. We changed the buffer time to 400s, and replaced the F25NDQ1 filter by the F25NDQ2 filter both for Betelgeuse and our PSF calibrator ----- Attempting Submission 1 (Wed Jul 06 09:58:23 GMT 2011) ----- HST Phase II Proposal 12610 (2011-07-04_Betelgeuse_APT.apt) successfully submitted. ----- Attempting Submission 2 (Wed Dec 28 10:16:56 GMT 2011) ----- Convection and mass loss through the chromosphere of Betelgeuse Betelgeuse is well suited for detailed study of the mass loss process in a massive red supergiant. We have engaged in a multi-scale, multi-color study to trace the ejected material from the photosphere to the interstellar medium, and understand its chemical evolution (formation of molecules and dust). Infrared interferometry already gave us a detailed image of the photosphere, compatible with large convective cells. Adaptive optics spectro-imaging (1.0-2.2 microns) allowed us to detect the presence of the CN molecule and mass loss plume structures up to at least 6 R*. At larger distances, we observed silicate-rich dust in thermal IR (8-20 microns). From the surface to 100 R*, we therefore have a continuous coverage with multicolor imagery. The chromosphere lies at a key location, between the photosphere and the molecular envelope. As shown by STIS spatially resolved spectroscopy (Lobel & Dupree 2001), it contains rising and falling gases. Such structure is supported by our 3D modeling of the convection. In order to probe the dynamics of the envelope and its relation to photospheric spots and mass loss plumes, we propose to obtain UV imaging with STIS at 3 epochs to complement our coordinated ground-based effort as well as the earlier HST UV snapshots. We will use this imagery to correlate structures at different radii and temperatures, and to explore the time-scales of evolution. With the support of our 3D models, this information will answer specific questions including deciding between convective and polar explanations for bright spots and plumes. Our infrared imaging observations will be repeated contemporaneously with the requested HST/STIS images.

We will observe Betelgeuse: - at two epochs with STIS-MAMA in three filters (FUV-F25LYA, FUV-F25NDQ1, NUV-F25ND5), - at one epoch with STIS-MAMA in two filters (FUV-F25NDQ1, NUV-F25ND5) We will also observe a PSF calibrator, HD 38393, at one epoch, in three filters (FUV-F25LYA, FUV-F25NDQ1, NUV-F25ND5). The observations of Betelgeuse and the PSF calibrator in the F25NDQ1 and F25ND5 filters will be dithered with 1.5-pixel steps to obtain a better PSF sampling. COOL STARS 12 false 0.0 0.0 false false false false SUPPORTED STAR CIRCUMSTELLAR MATTER HOTSPOT M III-I Betelgeuse is an irregular, moderately variable star. Its current (Dec 2011) V band magnitude according to the AAVSO, is mV=0.45, i.e. slightly above its average brightness over the last 10 years (mV ~0.5, with an evolution range between 0.3 and 1.0). ALPHA-ORI HD39801 J2000 J2000 magU = 4.38, magB = 2.27, E(B-V)=0.4699 CALIBRATION PHOTOMETRIC POINT SPREAD FUNCTION This star (Gamma Lep) is a PSF calibrator. GAMMA-LEP HR1983 J2000 J2000 magU=4.08, magB=4.07 STIS/FUV-MAMA Imaging No No F25LYA STIS/FUV-MAMA Imaging No No F25NDQ1 STIS/NUV-MAMA Imaging No No F25ND5 STIS/FUV-MAMA Imaging No No F25LYA STIS/FUV-MAMA Imaging No No F25NDQ1 STIS/NUV-MAMA Imaging No No F25ND5 STIS/FUV-MAMA Imaging No No F25LYA STIS/FUV-MAMA Imaging No No F25NDQ1 STIS/NUV-MAMA Imaging No No F25ND5 STIS/FUV-MAMA Imaging No No F25NDQ1 STIS/NUV-MAMA Imaging No No F25ND5 POS-TARG DITHER 0.0369 This pattern is intended to improve the sampling of the STIS-MAMA PSF by combining four exposures with offsets of 1.5 pixel (1 pixel = 0.0246"). It will be used for following filter configurations: FUV-F25NDQ1 and NUV-F25ND5. LINE 0.0369 false false 143.130102 4 26.6 STIS-MAMA-BOX 1

false

1325067198188 /private/var/folders/qt/z1svn8xm8xjcxr006s6mg_6h0000gn/T/OPVisit3105512208247754447.xml Timing link suitability includes constraints ([02 After 01 by 15.0 to 45.0 days] [03 After 01 by 300.0 to 430.0 days]) The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. This is a three-filter exposure on Betelgeuse (FUV-F25LYA, FUV-F25NDQ2, NUV-F25ND5), spread over 2 orbits. (Tic-Visit :proposal-id 12610 :visit-id "01" :proposal-version -1 :trans-version "20110509" :date "28-Dec-2011 11:13:16.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 1043696 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12610 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12610 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2909 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3242 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12610 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3019 :al-overhead-at-end 0 :internal-dur-at-end 452 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3242 :pcs-gap 0 ) true 2 0 For the ETC computation, we assembled a spectrum of Betelgeuse from past STIS observations using the E140M and E230M settings. This exposure is similar to a STIS-MAMA F25LYA exposure in TIME-TAG mode (EXPTIME=2300s) obtained on 2000-03-14 on Betelgeuse with STIS in the same configuration (exposure id: o55001d7q), that gave a maximum flux of 200 counts/s on the star, and a total flux of 1450 counts/s on the MAMA array. This figure is comparable to out result using the STIS imaging ETC (1870 counts/s). The corresponding BUFFER-TIME parameter is therefore 2e6/1870 = 1070 s. With a further safety margin of 20%, we obtain a BUFFER-TIME value of 855 s. For the ETC computation, we assembled a spectrum of Betelgeuse from past STIS observations using the E140M and E230M settings. This exposure is split in four sub-exposures to allow dithering with an amplitude of 1.5 pixels. For the ETC computation, we assembled a spectrum of Betelgeuse from past STIS observations using the E140M and E230M settings. This exposure is split in four sub-exposures to allow dithering with an amplitude of 1.5 pixels. 1325067201642 /private/var/folders/qt/z1svn8xm8xjcxr006s6mg_6h0000gn/T/OPVisit4212023956415230441.xml Timing link suitability includes constraints ([02 After 01 by 15.0 to 45.0 days]) The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. Two-filter exposure on Betelgeuse, over a 1 orbit visit. (Tic-Visit :proposal-id 12610 :visit-id "02" :proposal-version -1 :trans-version "20110509" :date "28-Dec-2011 11:13:20.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 556624 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12610 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12610 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2909 :al-overhead-at-end 0 :internal-dur-at-end 452 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3242 :pcs-gap 0 ) true 1 0 For the ETC computation, we assembled a spectrum of Betelgeuse from past STIS observations using the E140M and E230M settings. This exposure is split in four sub-exposures to allow dithering with an amplitude of 1.5 pixels. For the ETC computation, we assembled a spectrum of Betelgeuse from past STIS observations using the E140M and E230M settings. This exposure is split in four sub-exposures to allow dithering with an amplitude of 1.5 pixels. 1325067208210 /private/var/folders/qt/z1svn8xm8xjcxr006s6mg_6h0000gn/T/OPVisit6472061438729587754.xml Timing link suitability includes constraints ([03 After 01 by 300.0 to 430.0 days]) The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. This is a three-filter exposure on Betelgeuse (FUV-F25LYA, FUV-F25NDQ2, NUV-F25ND5), spread over 2 orbits. (Tic-Visit :proposal-id 12610 :visit-id "03" :proposal-version -1 :trans-version "20110509" :date "28-Dec-2011 11:13:27.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 1043696 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12610 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12610 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2909 :al-overhead-at-end 0 :internal-dur-at-end 180 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3242 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12610 :visit-id "03" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3019 :al-overhead-at-end 0 :internal-dur-at-end 452 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3242 :pcs-gap 0 ) true 2 0 For the ETC computation, we assembled a spectrum of Betelgeuse from past STIS observations using the E140M and E230M settings. This exposure is similar to a STIS-MAMA F25LYA exposure in TIME-TAG mode (EXPTIME=2300s) obtained on 2000-03-14 on Betelgeuse with STIS in the same configuration (exposure id: o55001d7q), that gave a maximum flux of 200 counts/s on the star, and a total flux of 1450 counts/s on the MAMA array. This figure is comparable to out result using the STIS imaging ETC (1870 counts/s). The corresponding BUFFER-TIME parameter is therefore 2e6/1870 = 1070 s. With a further safety margin of 20%, we obtain a BUFFER-TIME value of 855 s. For the ETC computation, we assembled a spectrum of Betelgeuse from past STIS observations using the E140M and E230M settings. This exposure is split in four sub-exposures to allow dithering with an amplitude of 1.5 pixels. For the ETC computation, we assembled a spectrum of Betelgeuse from past STIS observations using the E140M and E230M settings. This exposure is split in four sub-exposures to allow dithering with an amplitude of 1.5 pixels. 1325067210761 /private/var/folders/qt/z1svn8xm8xjcxr006s6mg_6h0000gn/T/OPVisit8759772420854393795.xml The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. Three-filter exposure on the PSF calibrator HD 38393, 1 orbit. (Tic-Visit :proposal-id 12610 :visit-id "04" :proposal-version -1 :trans-version "20110509" :date "28-Dec-2011 11:13:30.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 765312 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12610 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12610 :visit-id "04" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2916 :al-overhead-at-end 0 :internal-dur-at-end 452 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3249 :pcs-gap 0 ) true 1 0 This exposure is similar to a STIS-MAMA F25LYA exposure in TIME-TAG mode (EXPTIME=2300s) obtained on 2000-03-14 on HD38393 with STIS in the same configuration (exposure id: o55003dhq), that gave a maximum flux of 1867 counts in central pixel on the star. For the ETC computation, we assembled a flux-calibrated spectrum of HD38393 from archival IUE spectra. The STIS ETC gives a total count rate on the detector of 1990 counts/s, which is comparable to the observed total count rate of 1960 counts/s in the o55003dhq exposure. We rely on this 2000 counts/s figure, with a safety margin of 20% to estimate the corresponding BUFFER-TIME parameter a being 800 s. For the ETC computation, we assembled a flux-calibrated spectrum of HD38393 from archival IUE spectra. For the ETC computation, we assembled a flux-calibrated spectrum of HD38393 from archival IUE spectra.