Jets from young stellar objects play an important role for star formation as they can regulate the angular momentum balance of the system. The jet from the classical T Tauri star DG Tau stands out due to its stationary very high temperature plasma (T>10^6 K) very close to the driving source observed in deep multi-epoch X-ray observations. This X-ray emitting jet material is significantly hotter than previously studied material and not predicted by current jet theories. Our HST observations during Cycle 18 reveal intermediate temperature FUV C IV emission (T~10^5 K) co-spatial with the X-rays and indications for a further stationary low temperature component (T~10^4 K). In order to investigate the nature of the stationary component(s), we propose to obtain new epoch STIS long-slit spectra with the slit oriented along the jet axis. By studying the evolution of the individual emission components we will determine if C IV and X-ray emission are physically connected and constrain their respective heating processes. We will also test if further stationary components exist in addition to the known moving emission regions which result from episodic mass-loss events. The goal of the proposed observations is to spatially resolve the kinematics of the intermediate (T = 10^5 K) and low temperature (T = 10^4 K) material within the DG Tau jet. No stellar FUV emission has been detected in the previous observations, so that all FUV emission comes from the jet. The interemediate temperature plasma will be traced by C IV emission at ~1550 A and we dedicate three orbits for the associated STIS G140M exposures. For the comparison of the C IV emission with the lower temperature ionic emission one additional orbit with the STIS G750M grating is needed to measure the current forbidden line emission. The position angle of the jet (PA=226 deg) is known from previous observations (HST and ground based AO). A tolerance of ±1deg in position angle is acceptable for this jet. The 52 × 0. 2 slit will include virtually all of the relevant high-velocity emission. Setting the G140M grating to the wavelength range 1513–1567 ̊ includes the C iv emission line doublet (1548 and 1551 A) and ro-vibrationally excited H2 emission at 1521 A and 1525 A. The FUV exposures will be dithered along the slit to identify hot pixel (dither amplitude of 0.5"). A short ACQ exposure (STIS CCD with F28X50LP filter) is needed to center the jet in the slit. As the target is acquired with the CCD, we will take a short G430L exposure prior to the FUV observations in order to check the current accretion state of DG Tau. The two visits (optical and FUV) should be performed within 15 days to ensure that the jet evolution is negligible between the exposures. Detector Safety: We know from our last FUV observations of DG Tau that the expected global (< 200 counts s−1 ) and local count-rates (<0.1 counts/sec/pix) are significantly below the STIS brighness limits. The slit orientation is identical to our last program and no other (bright) sources will illuminate the slit. Further information on surrounding sources can be found in the observation description of Prop 12199. In particular, no other bright sources are known. As discussed for Prop-ID 12199, the two unknown BOT sources (N9QL001759, N9QL009269) do not violate any brightness limit. STAR FORMATION 12 false 0.0 0.0 false false false false SUPPORTED STAR JET T TAURI STAR YSO This object was generated by the targetselector and retrieved from the SIMBAD database. The alternate name is also from the SIMBAD database. The target uncertainties pertain to the difference between the expected, proper-motion corrected position from Ducourant et al. (2005) and the 2MASS position for epoch 2012 given here. We regard this as the uncertainty since both values do not agree for the same epoch. GSC01820-00330 J2000 J2000 The C IV is about 2e-14 erg/s/cm^2. STIS/CCD Spectroscopic No No G430L 4300 STIS/FUV-MAMA Spectroscopic No No G140M 1540 STIS/CCD Spectroscopic No No G750M 6581 POS-TARG DITHER 0.5 This pattern is applied to the FUV observations to dither the emission along the slit. The dither amplitude of 0.5" places the emission (size about 0.5") at disjunct regions on the detector during the three dither positions. Each dither position should be applied to a different orbit. Centering the pattern places the emission at the nominal center of the detector during the longer exposure of the second orbit. LINE false false 3 90.0 STIS-ALONG-SLIT 1 false Timing link suitability includes constraints ([Group (01 02) Within 15.0 days]) The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. This visit is dedicated to the FUV MAMA exposures (G140M) and the short G430L optical spectrum. (Tic-Visit :proposal-id 12907 :visit-id "01" :proposal-version -1 :trans-version "20120604" :date "11-Jul-2012 15:27:52.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 664432 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12907 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12907 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2680 :al-overhead-at-end 0 :internal-dur-at-end 178 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3013 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12907 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2791 :al-overhead-at-end 0 :internal-dur-at-end 385 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3013 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12907 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2791 :al-overhead-at-end 0 :internal-dur-at-end 647 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3013 :pcs-gap 0 ) false 3 0 CR-SPLIT=2 should be sufficient for cosmic ray removal since the exposure time is sufficiently short. The FUV observations will be dithered along the slit (dither amplitude 0.5") for an improved hot pixel removal. Timing link suitability includes constraints ([Group (01 02) Within 15.0 days]) The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. This visit is dedicated to the G750M long-slit spectrum. No dithering is applied to these exposures. (Tic-Visit :proposal-id 12907 :visit-id "02" :proposal-version -1 :trans-version "20120604" :date "11-Jul-2012 15:27:53.0" :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 74032 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12907 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12907 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2680 :al-overhead-at-end 0 :internal-dur-at-end 380 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3013 :pcs-gap 0 ) false 1 0