TCP J21040470+4631129 - a highly evolved cataclysmic variable unmasked?

0 Assigned ID: 1228 ----- Attempting Submission 1 (Fri Jan 17 23:07:30 GMT 2020) ----- HST Phase I Proposal 1228 (tcpj2104.apt) successfully submitted. Receipt: # 1228-1 ----- Attempting Submission 2 (Fri Jan 17 23:10:06 GMT 2020) ----- HST Phase I Proposal 1228 (tcpj2104.apt) successfully submitted. Receipt: # 1228-2 ----- Attempting Submission 3 (Sat Jan 18 00:33:29 GMT 2020) ----- HST Phase I Proposal 1228 (tcpj2104.apt) successfully submitted. Receipt: # 1228-3 ----- Attempting Submission 4 (Sat Jan 18 01:26:19 GMT 2020) ----- The number of orbits used exceeds the number allocated 0 ----- Attempting Submission 1 (Wed Mar 18 11:56:48 GMT 2020) ----- TCP J21040470+4631129 - a highly evolved cataclysmic variable unmasked? The cataclysmic variable TCP J21040470+4631129 has been laying dormant in our backyard until July 12th, 2019, when it brightened from V=17.8 to V=8.4 in a matter of days, undergoing its first recorded dwarf nova outburst. TCP J2104+4631 is literally in our backyard: The accurate Gaia parallax places the system at 109.2+-1.5 pc, making it one of the closest of > 5000 known CVs. How did it manage to remain hidden to the intense scrutiny of the northern hemisphere by both the vast array of time-domain surveys and countless amateur observers? The only valid explanation is that its outburst recurrence time is extremely long, implying an exceptionally low mass loss rate of the donor, and that in turn suggests that this system may be an example of the predicted, but so far missing population of highly evolved and inconspicuous interacting binaries. We propose to obtain COS far-ultraviolet spectroscopy of TCP J2104+4631 spanning the full binary orbit to determine the masses of both stellar components, the chemical composition of the donor star, and to measure the effective temperature of the white dwarf as it emerges from the recent accretion eposide. Using these quantities, we will establish the evolutionary state of the system. Confirming that TCP J2104+4631 is one of the long sought-after highly evolved CVs that are predicted to dominate the Galactic population of these interacting binaries would provide strong support that these systems are effectively hiding from our view, alleviating the stark contrast between current theoretical and observational population studies. The goal of these observations is to obtain high signal-to-noise far-ultraviolet spectra of the white dwarf in the dwarf nova TCPJ21040470+4631129, which was heated during a recent dwarf nova outburst. The planned COS spectroscopy will be used to measure the effictive temperature, and the abundances of the accreted material from the sharp photospheric metal lines. We use the G130M grating with two central wavelengths to maximise the wavelength covered by these observations, and to achieve gap-less coverage. We make use of all permitted FP-POS positions, i.e. 3 & 4 for @1291A, and 1,2,3,4 @ 1222A. The @1291A and @1222A observations are split into two separate visits to facilitate the scheduling. We use a dispersed light target acquisition, and for the ETC simulations we adopted a white dwarf temperature of 25000K. Scaled to the (Gaia-based) distance of 109pc, this corresponds to a flux of 1e-13erg/cm2/s/AA @ 1300A. This program should not be affected in case that HST moves to a 2-gyro mode. Neustroev, Kim, Echevarria, Zharikov and Osborne have obtained large amounts of optical and X-ray follow-up data of TCPJ2104+4631, and will continue to closely monitor the system in preparation for the HST observations. Gaensicke, Toloza and Knigge have detailed experience in planning and analyzing HST far-ultraviolet spectroscopy. Toloza and Knigge have detailed experience in modelling the evolution of CVs, including the use of MESA. Townsley has developed models for the accretion-heating of the white dwarf and will lead the determination of the accreted mass. Marsh is an expert in the observational study of close white dwarf binaries. Stellar Physics 3 false false true false false false false AVAILABLE STAR DWARF NOVA NO J2000 J2000 Swift UVW1=13.0 UNIDENTIFIED BLANK FIELD NO This target is a blank piece of sky which is the bright object safe pointing and is 9.845 arcseconds away at a PA 172.8 degrees from TCP-J21040470+4631129. J2000 UNIDENTIFIED BLANK FIELD NO This target is a blank piece of sky which is the bright object safe pointing and is 9.941 arcseconds away at a PA of 210.1 degrees from TCP-J21040470+4631129. J2000 COS/FUV Spectroscopic No No G130M 1222 1584527491612 The scheduling data was generated by CASM 28.0. CASM was run in Phase II mode. Only two FP-POS settings allowed for the 1291A central wavelength. This should be scheduled in evening-local time. Flags need to be cleared during the work day. 1599894997000 121.0 (Tic-Visit :proposal-id 16069 :visit-id "01" :proposal-version -1 :trans-version "20191203" :date "18-Mar-2020 10:31:31.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 3539728 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16069 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16069 :visit-id "01" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2892 :al-overhead-at-end 0 :internal-dur-at-end 143 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16069 :visit-id "01" :orbit-number 2 :pcs-time 302 :si-vis-utilization 2983 :al-overhead-at-end 0 :internal-dur-at-end 95 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16069 :visit-id "01" :orbit-number 3 :pcs-time 302 :si-vis-utilization 2983 :al-overhead-at-end 0 :internal-dur-at-end 114 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16069 :visit-id "01" :orbit-number 4 :pcs-time 302 :si-vis-utilization 2983 :al-overhead-at-end 0 :internal-dur-at-end 407 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) false 4 0 We have good orbital phase coverage with Swift UVW1 (2600A) and SDSS u (3650A), amplitude and flux in the two bands are identical, so we adopt a flat spectrum in Flambda. At orbital minimum, the flux in Swift UVW1 is 2e-15 erg/cm2/s/AA, and we set up the target acquisition to achieve a S/N of 40 at that faintest phase. At orbital maximum, the system reaches 1.2e-14 erg/cm2/s/AA. This is a factor ~30 below the COS bright limit for the chosen setup. This visit allocates and sets up the safeposition offset slot for science visit 01 which will use that slot. This S/C visit should go earlier in the week while science visit 01 will be at least 3 days later. Note: weekends are to be avoided since the CS must clear the target within 24 hours of HST execution. 1599542803000 124.0 false -1 -1 1584527491612 This visit is for BOP checking the safetarget only and should not execute onboard HST. (Tic-Visit :proposal-id 16069 :visit-id "01" :proposal-version -1 :trans-version "20191203" :date "18-Mar-2020 10:31:31.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 3539728 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16069 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16069 :visit-id "01" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2892 :al-overhead-at-end 0 :internal-dur-at-end 143 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16069 :visit-id "01" :orbit-number 2 :pcs-time 302 :si-vis-utilization 2983 :al-overhead-at-end 0 :internal-dur-at-end 95 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16069 :visit-id "01" :orbit-number 3 :pcs-time 302 :si-vis-utilization 2983 :al-overhead-at-end 0 :internal-dur-at-end 114 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16069 :visit-id "01" :orbit-number 4 :pcs-time 302 :si-vis-utilization 2983 :al-overhead-at-end 0 :internal-dur-at-end 407 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) false 4 0 We have good orbital phase coverage with Swift UVW1 (2600A) and SDSS u (3650A), amplitude and flux in the two bands are identical, so we adopt a flat spectrum in Flambda. At orbital minimum, the flux in Swift UVW1 is 2e-15 erg/cm2/s/AA, and we set up the target acquisition to achieve a S/N of 40 at that faintest phase. At orbital maximum, the system reaches 1.2e-14 erg/cm2/s/AA. This is a factor ~30 below the COS bright limit for the chosen setup. 1603989303629 The scheduling data was generated by CASM 28.2. CASM was run in Phase II mode. /private/var/folders/bl/s7q0tqnn5gbcbyvcfnrhj2rh0004nc/T/OPVisit14953609587086586330.xml This should be scheduled in evening-local time.Flags need to be cleared during the work day. This is a HOPR for failed visit 01 Only two FP-POS settings allowed for the 1291A central wavelength. This should be scheduled in evening-local time. Flags need to be cleared during the work day. (Tic-Visit :proposal-id 16069 :visit-id "04" :proposal-version -1 :trans-version "20200619" :date "29-Oct-2020 12:35:02.0" :trans-errors '(:WARNINGS 4 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 3539728 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16069 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16069 :visit-id "04" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2892 :al-overhead-at-end 0 :internal-dur-at-end 143 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16069 :visit-id "04" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2983 :al-overhead-at-end 0 :internal-dur-at-end 95 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16069 :visit-id "04" :orbit-number 3 :pcs-time 392 :si-vis-utilization 2983 :al-overhead-at-end 0 :internal-dur-at-end 114 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16069 :visit-id "04" :orbit-number 4 :pcs-time 392 :si-vis-utilization 2983 :al-overhead-at-end 0 :internal-dur-at-end 407 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) false 4 4 We have good orbital phase coverage with Swift UVW1 (2600A) and SDSS u (3650A), amplitude and flux in the two bands are identical, so we adopt a flat spectrum in Flambda. At orbital minimum, the flux in Swift UVW1 is 2e-15 erg/cm2/s/AA, and we set up the target acquisition to achieve a S/N of 40 at that faintest phase. At orbital maximum, the system reaches 1.2e-14 erg/cm2/s/AA. This is a factor ~30 below the COS bright limit for the chosen setup. This visit allocates and sets up the safe position offset slot for science visit 04 which will use that slot. This S/C visit should go earlier in the week while visit 04 will be at least 3 days later.The S/C visit will contain only 1 exposure. Note: weekends are to be avoided since the CS must clear the target within 24 hours of HST execution. false -1 -1 1601563569630 This visit is for BOP checking the safe target only and should not execute onboard HST. (Tic-Visit :proposal-id 16069 :visit-id "04" :proposal-version -1 :trans-version "20200619" :date "01-Oct-2020 10:46:09.0" :trans-errors '(:WARNINGS 3 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 3539728 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16069 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16069 :visit-id "04" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2892 :al-overhead-at-end 0 :internal-dur-at-end 143 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16069 :visit-id "04" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2983 :al-overhead-at-end 0 :internal-dur-at-end 95 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16069 :visit-id "04" :orbit-number 3 :pcs-time 392 :si-vis-utilization 2983 :al-overhead-at-end 0 :internal-dur-at-end 114 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16069 :visit-id "04" :orbit-number 4 :pcs-time 392 :si-vis-utilization 2983 :al-overhead-at-end 0 :internal-dur-at-end 407 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) false 4 3 We have good orbital phase coverage with Swift UVW1 (2600A) and SDSS u (3650A), amplitude and flux in the two bands are identical, so we adopt a flat spectrum in Flambda. At orbital minimum, the flux in Swift UVW1 is 2e-15 erg/cm2/s/AA, and we set up the target acquisition to achieve a S/N of 40 at that faintest phase. At orbital maximum, the system reaches 1.2e-14 erg/cm2/s/AA. This is a factor ~30 below the COS bright limit for the chosen setup.