There needs to be much more information on BOT field/target clearance in cases where GSC colors are lacking/inadequate. Along these lines, tools for HST-approved color-color transformations, color-spectral type conversions, and reddening would be very helpful. ----- Attempting Submission 1 (Fri May 11 22:17:20 GMT 2007) ----- ----- Attempting Submission 2 (Mon Oct 22 21:27:54 GMT 2007) ----- Assigned ID: 1539 ----- Attempting Submission 1 (Sat Feb 10 01:01:11 GMT 2007) ----- Phase I Proposal 1539 (tr_acs) successfully submitted. Exploring the Early FUV History of Cool Stars: Transition Regions at 30 Myr Stellar magnetic activity derives from the so-called "dynamo," a hydromagnetic interplay between overturning plasma motions and differential rotation in stars cool enough to support significant surface convection zones. The magnetic fields resulting from dynamo action are in turn are responsible for a wide range of high-energy emissions, including the spectacular outbursts called flares. Dynamo powered magnetic activity is not confined solely to stars, but also must occur, for example, in accretion disks of all descriptions, and in some planets. A great deal is known about magnetic activity in middle-aged G dwarfs like our Sun, thanks to its proximity. Less is known, however, about the much younger stars, newly emerged from the T-Tauri stage. Yet, it is during this phase that they reach the peak of their magnetic activity, and subsidiary influences, such as the impact of ionizing radiation and strong coronal winds on developing solar systems, also are maximum. One of the key missing ingredients in our current understanding are measurements of FUV emissions of such stars, to complement the extensive collections of coronal (1-10 MK) X-ray measurements, particularly from recent ROSAT, Chandra and XMM-Newton surveys. We propose to conduct sensitive ACS/SBC prism ultraviolet spectroscopy of selected fields in two young (30 Myr) Galactic clusters--IC 2391 and IC 2602--to inventory the key C IV emission index (~0.1 MK) over a much larger and more diverse sample of coeval objects than has been possible hitherto. A key question is whether the FUV emissions also suffer the "saturation" and "super-saturation" at short rotation periods seen in coronal X-rays, or whether they continue to rise in the fastest rotating stars. The saturation behavior of the different temperature regimes holds important clues to the organization of the surface active regions on these very young stars, and should allow us to distinguish among several competing models.
There are no previous measurements of our targets in the FUV. The large FOV of GALEX puts too many UV bright OBA stars on the detector, making observations of these clusters impossible (S/N in any case would be much lower). Thus, only HST can make these observations. We choose the SBC PR130L prism (spectra) and F140LP (pre-image) to limit geocoronal Ly alpha. To test the feasibility of our proposed observations, we have estimated fluxes using HST GHRS spectra of three nearby rapid rotators with saturated activity as proxies: EK Dra (G1V, P_{rot} ~ 3 d, D = 33.9 pc, R ~ 1.05 R_sun), LQ Hya (K2V, P_{rot} ~ 1.8 d, D = 18.3 pc, R 0.75 R_sun), and YZ CMi (M4Ve, P_{rot} ~ 2.8 d, D = 5.1 pc, R ~0.40 R_sun). These stars nicely bracket our targets in temperature and radius. The spectra are scaled to the distances of our clusters (IC 2391, 175 pc, redenning 0.008 mag; IC 2602, 160 pc, redenning 0.024 mag). Figure 2 shows the result for IC 2391, rebinned to the resolution of PR130L data, together with the scaled but un-rebinned spectrum of LQ Hya. The major UV lines in this, the highest efficiency section of the PR130L, can be clearly distinguished from the nearby (pseudo)-continuum with little blending of the major lines (except with others of like type, e.g., C IV with C IV). Indeed, we find (remarkably) that we can recover the measured high resolution fluxes for Si IV, C IV, and He II from the PR130L data within ~5%. Target star fluxes are interpolated from these model spectra fluxes (Table 1) by scaling the stellar radius and distance (for IC 2602); SS stars are assumed to have a factor of 2.0 less flux (a bit less than the factor of ~2.5 mean drop in X-rays). For the ETCs we extend the GHRS spectra beyond 1660 A at constant flux (an underestimate) to account for additional continuum, and used average backgrounds. For the SBC direct image we use F140LP to exclude Ly alpha. We aim for S/N = 10 in C IV, and S/N = 5 in the direct image; this gives the exposure times and S/N for other lines given in table 2. With overheads of 6 min per guide star acquisition and 1.7 per exposure, we can fit one preimage and at least 2 spectra with S/N in C IV S/N_CIV ~ 10 of each of our targets, allowing some variation discrimination. For four of the targets, we can fit 5 to 7 spectra iof higher quality (S/N_CIV ~ 14 - 20) into an orbit, permitting 2 sigma detection of 10% and 14% variations on short timescales, respectively, sufficient to detect moderate size flares. Using the NOMAD photometric database through Vizier, we estimated the V and B-V magnitudes and/or spectral types for most of the unknown stars which turned up in the ACS BOT. The ETC shows none of the targets posing any problem for the detector. (In several cases the BOT did not have enough information on our targets, and labeled them O5 stars... with additional photometric data, they prove entirely safe.) N/A N/A Note that the above description has been modified from the phase one version. Note also that spectra of two stars are obtained in the observation of V372 Vel (see Table 2, owever, V375 Vel will not be possible). The spectra V372 and V373 Vel (a wide binary) will overlap to some extent, but for most roll angles the positional offset (~4") will be sufficient to make at least partial separation possible. In the limited range where overlap is strong, the 4" offset will still displace the emission lines in the merged spectrum, permitting separate measurement against a common (low, M star) continuum. V376 Vel has been added as a substitute for V557 Car, which had nearby B0 star being assertively blue. COOL STARS 12 false 0 0.0 0 false false false false false false SUPPORTED STAR CORONA EMISSION LINE STAR M V-IV This object was generated by the targetselector and retrieved from the SIMBAD database. GSC08569-00072 J2000 08 43 27.8000 -52 57 41.00 J2000 STAR CORONA EMISSION LINE STAR M V-IV This object was generated by the targetselector and retrieved from the SIMBAD database. GSC08569-00696 J2000 08 42 18.4000 -53 01 58.00 J2000 STAR CORONA EMISSION LINE STAR K V-IV This object was generated by the targetselector and retrieved from the SIMBAD database. Aimpoint slightly offset from target star to move overbright blue star out of FOV. GSC08569-01122 J2000 08 45 26.9000 -52 52 3.00 J2000 STAR CORONA EMISSION LINE STAR K V-IV This object was generated by the targetselector and retrieved from the SIMBAD database. GSC08965-00386 J2000 10 40 51.3000 -64 42 48.00 J2000 STAR CORONA EMISSION LINE STAR G V-IV GSC08965-00163 J2000 10 44 59.6000 -65 02 19.00 J2000 STAR CORONA EMISSION LINE STAR G V-IV GSC08569-00678 J2000 00 00 0.0000 +00 00 0.00 J2000 ACS/SBC Imaging No No F140LP ACS/SBC Spectroscopic No No PR130L ACS/SBC Imaging No No F140LP ACS/SBC Spectroscopic No No PR130L ACS/SBC Imaging No No F140LP ACS/SBC Spectroscopic No No PR130L ACS/SBC Imaging No No F140LP ACS/SBC Spectroscopic No No PR130L ACS/SBC Imaging No No F140LP ACS/SBC Spectroscopic No No PR130L ACS/SBC Imaging No No F140LP ACS/SBC Spectroscopic No No PR130L ACS/SBC Imaging No No F140LP ACS/SBC Spectroscopic No No PR130L ACS/SBC Imaging No No F140LP ACS/SBC Spectroscopic No No PR130L /data/kdata1/saar/hst16/11116b/OP-cache/11116b-v01.xml (Tic-Visit :proposal-id 11116 :visit-id "01" :proposal-version -1 :trans-version "20070325" :date "15-Oct-2007 17:14:44.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 55552 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11116 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11116 :visit-id "01" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2843 :al-overhead-at-end 0 :internal-dur-at-end 99 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3200 :pcs-gap 0 ) true 1 0 /data/kdata1/saar/hst16/11116b/OP-cache/11116b-v01.xml pre-image v372 vel exposure /data/kdata1/saar/hst16/11116b/OP-cache/11116b-v02.xml (Tic-Visit :proposal-id 11116 :visit-id "02" :proposal-version -1 :trans-version "20070325" :date "15-Oct-2007 17:39:31.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 55552 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11116 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11116 :visit-id "02" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2845 :al-overhead-at-end 0 :internal-dur-at-end 99 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3200 :pcs-gap 0 ) true 1 0 /data/kdata1/saar/hst16/11116b/OP-cache/11116b-v02.xml v371vel preimage v371vel exposure /data/kdata1/saar/hst16/11116b/OP-cache/11116b-v03.xml (Tic-Visit :proposal-id 11116 :visit-id "03" :proposal-version -1 :trans-version "20070325" :date "15-Oct-2007 15:25:41.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 111088 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11116 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11116 :visit-id "03" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2841 :al-overhead-at-end 0 :internal-dur-at-end 160 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3200 :pcs-gap 0 ) true 1 0 /data/kdata1/saar/hst16/11116b/OP-cache/11116b-v03.xml v379vel preimage v379 exposure /data/kdata1/saar/hst16/11116b/OP-cache/11116b-v04.xml (Tic-Visit :proposal-id 11116 :visit-id "04" :proposal-version -1 :trans-version "20070325" :date "18-Oct-2007 15:14:24.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 129600 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11116 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11116 :visit-id "04" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2886 :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 3243 :pcs-gap 0 ) true 1 0 /var/tmp/OPVisit29240.xml v552car (rsp) preimage v552car (rsp) exposure /data/kdata1/saar/hst16/11116b/OP-cache/11116b-v06.xml (Tic-Visit :proposal-id 11116 :visit-id "06" :proposal-version -1 :trans-version "20070325" :date "18-Oct-2007 15:14:29.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 148112 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11116 :visit-id "06" :obset-id "06" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11116 :visit-id "06" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2926 :al-overhead-at-end 0 :internal-dur-at-end 200 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3281 :pcs-gap 0 ) true 1 0 /var/tmp/OPVisit29241.xml v561car preimage v561car exposures (flare study) /data/kdata1/saar/hst16/11116b/OP-cache/11116b-v07.xml (Tic-Visit :proposal-id 11116 :visit-id "07" :proposal-version -1 :trans-version "20070325" :date "15-Oct-2007 18:12:32.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 111088 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11116 :visit-id "07" :obset-id "07" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11116 :visit-id "07" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2843 :al-overhead-at-end 0 :internal-dur-at-end 160 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3200 :pcs-gap 0 ) true 1 0 /data/kdata1/saar/hst16/11116b/OP-cache/11116b-v07.xml v376vel preimage (temp) v376vel exposure (temp)