13714( 3) - 08-Sep-2014 13:23:30 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13714 Version: 3 Check-in Time: 08-Sep-2014 13:23:30 STScI Edit Number: 1 Title Tracing Hot Plasma in the RY Tau Jet ------------------------------------------------------------------------------------ Type Cycle GO 22 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Stephen L. Skinner University of Colorado at Boulder Y CoI: Dr. Marc Audard Observatoire de Geneve N CoI: Prof. Manuel Guedel University of Vienna N CoI: Dr. Peter Christian Schneider Universitat Hamburg, Hamburger Sternwarte N ------------------------------------------------------------------------------------ Abstract The accreting T Tauri star RY Tau drives a spectacular bipolar jet whose blueshifted component is traced optically at separations of 1.3" - 30" from the star. Optical studies probe cool jet plasma (T ~ 1e4 K) but evidence for much hotter plasma (T ~ 1e5 - 1e6 K) is seen in UV spectral lines and Chandra X-ray images. We propose to obtain STIS UV spectra of RY Tau with the slit aligned along the jet. HST's high spatial resolution and UV spectral line diagnostics will determine the spatial extent and properties of the hot plasma in the inner jet and will test jet-heating models. Only HST provides the capabilities needed to study conditions in the hot dense plasma in the physically important inner jet where launching and collimation occur. ------------------------------------------------------------------------------------ Observations Description ------------------------ Observations: We will obtain 1st-order STIS/MAMA UV grating spectra of the RY Tau jet with the 52" x 0.2" slit, which is well-matched to the jet dimensions. The brightest knots lie within 15" of the star (Fig. 1) and the jet width is FWHM = 0.2" - 0.3" (AA09). We request G140L (2 orbits), G140M (5 orbits), and G230L (1 orbit) gratings. G140L and G230L will provide complete spectral coverage of the FUV and NUV including several important emission lines as specified below. The higher spectral resolution of G140M (1523 - 1577 Ang. ) will fully resolve the C IV doublet at 1548.2/1550.7 Ang . G140M will provide accurate measurements of jet velocity (resolution delta_V = 25 km s^-1) and will allow any weak contribution from fluorescent H2 lines to be discerned (Fig. 6). STIS is clearly preferred over COS since STIS provides spatially-resolved spectra along the jet. Stellar Parameters: RY Tau is a F8-G1 TTS with Teff =5945 K (C04) and variable 13714( 3) - 08-Sep-2014 13:23:30 - [ 2] V = 10.3 +- 0.9 mag. The most recent AAVSO photometry in April 2014 give a range V = 10.5 - 11. Target MAMA brightness limits are not exceeded. The extinction toward the disked star is AV = 2.2 +- 0.2 mag (C04) but may well be lower toward the jet offset from the star. No companion has yet been found (e.g. Leinert et al. 1993; Pott et al. 2010). Observed (absorbed) UV continuum flux densities are Fcont(1760 Ang.) = 1.9e-15 and Fcont(1958 Ang.) = 2.07e-15 ergs cm^-2 s^-1 Ang.^-1 (Valenti et al. 2000 [V00]; C04). Previous STIS G140L/230L observations with the slit nearly perpendicular to the jet (Fig. 5; C04) give observed (absorbed) line fluxes in units of 10^-14 ergs cm^-2 s^-1: C IV = 5.93; Si III] = 7.70; C III] = 5.37. ETC predicts S/N = 35 - 50 for G140L/230L in these lines. Sensitivity: Allowing for overheads (Sec. 6.4 of the Primer), we estimate usable exposures of 13080 s (G140M), 4800 s (G140L), and 2040 s (G230L). Our requested exposures (orbits) are driven by the need to obtain adequate sensitivity and SNR in faint emission lines for flux measurement and line analysis. As a benchmark, we use the C IV flux detected in the DG Tau jet during a 14 ksec STIS G140M slit observation (S13). The observed (absorbed) jet flux is F1548+1551 = 2.0 e-14 erg cm^=2 s^-1 at offsets of 0.15" - 0.3" from the star, of which 2/3 comes from the 1548 Ang. line (Fig. 6-left). Continuum emission in the jet is expected to be very low (Fig. 6-left). Assuming a similar C IV flux for RY Tau's jet, the ETC predicts SNR = 10 in C IV for G140M (Fig. 6-right) and SNR = 30 for G140L. G140L will reach a line detection threshold (SNR = 10) at C IV for absorbed line fluxes 10 times lower than that measured for DG Tau's jet. For G230L, ETC predicts an absorbed line flux detection threshold of Fline (3.0-3.6) e-15 erg cm^-2 s^-1 for Si III] (1892Ang. ) and C III] (1909 Ang. ), more than an order of magnitude fainter than the stellar line fluxes. UV Line Diagnostics: The most important spectral lines for diagnosing physical conditions in the jet will be the C IV doublet at 1548/1551 (G140L, G140M) and the optically thin Si III] 1892 and C III] 1909 lines (G230L). The C IV line traces hotter plasma. The flux ratio of the Si III] and C III] lines provides density information and can diagnose higher densities (n_e = 10^10 cm^-3) that are present in shock regions near the star (Lamzin 13714( 3) - 08-Sep-2014 13:23:30 - [ 3] 2000b; GV07). Other useful G140L lines are: Si IV 1394/1403, He II 1640 (tracers of intermediate-T plasma), C III 1176 and Si III 1206 (densities; C04). Special Requirements Since our primary goal is to study emission from the jet, we require that the 52" x 0.2" slit be oriented along the jet axis, so PA APER = 114 deg. or PA APER = 294 deg. is requested. These values correspond to ORIENT = 159.35 deg. and ORIENT = 339.35 deg.. The Visit Planner shows that the observations are schedulable in Cycle 22 at ORIENT = 159.35 deg. The first available window occurs from 28 Nov. - 6 Dec. 2014 and a second window on similar dates in 2015. ------------------------------------------------------------------------------------ 13714( 3) - 08-Sep-2014 13:23:30 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 RYTAU STAR, F3-F9, G III-I, RA=04H21M57.4100S, J2000 V = 10.3 +/- 1.0 JET, T TAURI STAR DEC=+28D26'35.57" Reference Frame: ICRS Comments: Variable star. AAVSO gives V magnitudes in range V = 9.6 - 11.2 from April 2013 - April 2014. During the same period, B ranged from B = 10.75 - 12.1. Most recent AAVSO values in April 2014 are V = 10.8 +- 0.2 and B = 11.8 +- 0.2. During the period 1983 - 2004 the range was V = 9.3 - 11.6 (Ref. Ismailov & Adygezalzade 2012). Colors are: U-B = +0.48, B-V = +1.03 (Herbig and Bell catalog). U-B = +0.49, B-V = +1.11 (Schegerer et al. 2008). Field star search: A search of GSCv2.3.2 with the HEASARC Browse utility using a circular search region of radius 30 arcsecs centered on RY Tau returns only one object: RY Tau. A search of the USNO B1 catalog using the same search region returns 7 objects of which RY Tau is the brightest (B1 = 11.34) and the second brightest is USNO 1184-0061103 (B1 = 16.69, offset 16.6 arcsec from RY Tau). ------------------------------------------------------------------------------------------------------------------------------------ 13714( 3) - 08-Sep-2014 13:23:30 - [ 5] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type STIS-ALONG-SLIT Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.275 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 90.0 Angle_Between_Sides Center_Pattern NO Pattern_Comments: 0.275 arcsec spacing is approximaely 11 native pixels ------------------------------------------------------------------------------------------------------------------------------------ 13714( 3) - 08-Sep-2014 13:23:30 - [ 6] Visit: 01 Visit Requirements: SCHED 30%; ORIENT 157.8D TO 160.9 D; ORIENT 337.8D TO 340.9 D; GROUP 01, 02 WITHIN 30D On Hold Comments: Additional Comments: Visit schedulability is very sensitive to science target exposure times. Exposure times have been set to allow scheduling in either Nov. 2014 or Nov. 2015. Ref. Email discussion between S. Skinner and Miranda Link on 7-14-2014. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 RYTAU STIS/CCD ACQ F28X50OII MIRROR 1 20. S (20 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 RYTAU STIS/FUV ACCUM 52X0.2 G140M 1550 1 600 S PATTERN 1 2 -MAMA (1800 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 RYTAU STIS/FUV ACCUM 52X0.2 G140M 1550 1 815 S PATTERN 1 3 -MAMA (2445 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 RYTAU STIS/FUV ACCUM 52X0.2 G140M 1550 1 815 S PATTERN 1 4 -MAMA (2445 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 RYTAU STIS/FUV ACCUM 52X0.2 G140M 1550 1 815 S PATTERN 1 5 -MAMA (2445 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 RYTAU STIS/FUV ACCUM 52X0.2 G140M 1550 1 815 S PATTERN 1 6 -MAMA (2445 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ RYTAU 1 STIS/CCD ACQ F28X50OI MIRROR none none none none 1 N/A I RYTAU 2 STIS/FUV ACCUM 52X0.2 G140M 1550 1 none none none 1 N/A -MAMA RYTAU 2 STIS/FUV ACCUM 52X0.2 G140M 1550 2 none none none 1 N/A -MAMA RYTAU 2 STIS/FUV ACCUM 52X0.2 G140M 1550 3 none none none 1 N/A -MAMA RYTAU 3 STIS/FUV ACCUM 52X0.2 G140M 1550 1 none none none 2 N/A -MAMA RYTAU 3 STIS/FUV ACCUM 52X0.2 G140M 1550 2 none none none 2 N/A -MAMA RYTAU 3 STIS/FUV ACCUM 52X0.2 G140M 1550 3 none none none 2 N/A -MAMA RYTAU 4 STIS/FUV ACCUM 52X0.2 G140M 1550 1 none none none 3 N/A -MAMA 13714( 3) - 08-Sep-2014 13:23:30 - [ 7] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ RYTAU 4 STIS/FUV ACCUM 52X0.2 G140M 1550 2 none none none 3 N/A -MAMA RYTAU 4 STIS/FUV ACCUM 52X0.2 G140M 1550 3 none none none 3 N/A -MAMA RYTAU 5 STIS/FUV ACCUM 52X0.2 G140M 1550 1 none none none 4 N/A -MAMA RYTAU 5 STIS/FUV ACCUM 52X0.2 G140M 1550 2 none none none 4 N/A -MAMA RYTAU 5 STIS/FUV ACCUM 52X0.2 G140M 1550 3 none none none 4 N/A -MAMA RYTAU 6 STIS/FUV ACCUM 52X0.2 G140M 1550 1 none none none 5 N/A -MAMA RYTAU 6 STIS/FUV ACCUM 52X0.2 G140M 1550 2 none none none 5 N/A -MAMA RYTAU 6 STIS/FUV ACCUM 52X0.2 G140M 1550 3 none none none 5 N/A -MAMA 13714( 3) - 08-Sep-2014 13:23:30 - [ 8] Visit: 02 Visit Requirements: SCHED 30%; ORIENT 157.8D TO 160.9 D; ORIENT 337.8D TO 340.9 D On Hold Comments: Additional Comments: Visit schedulability is very sensitive to science target exposure times. Exposure times have been set to allow scheduling in either Nov. 2014 or Nov. 2015. Ref. Email discussion between S. Skinner and Miranda Link on 7-14-2014. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 RYTAU STIS/CCD ACQ F28X50OII MIRROR 1 20. S (20 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 RYTAU STIS/FUV ACCUM 52X0.2 G140L 1425 1 620 S PATTERN 1 2 -MAMA (1860 S) Comments: ETC simulation uses archived STIS G140L spectrum as input spectrum (dataset O5EX01020). ------------------------------------------------------------------------------------------------------------------------------------ 3 RYTAU STIS/FUV ACCUM 52X0.2 G140L 1425 1 820 S PATTERN 1 3 -MAMA (2460 S) Comments: ETC simulation uses archived STIS G140L spectrum as input spectrum (dataset O5EX01020). ------------------------------------------------------------------------------------------------------------------------------------ 4 RYTAU STIS/NUV ACCUM 52X0.2 G230L 2376 1 850 S PATTERN 1 4 -MAMA (2550 S) Comments: ETC simulation uses archived STIS G230L spectrum as input spectrum (dataset O5EX01010). ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ RYTAU 1 STIS/CCD ACQ F28X50OI MIRROR none none none none 1 N/A I RYTAU 2 STIS/FUV ACCUM 52X0.2 G140L 1425 1 none none none 1 N/A -MAMA RYTAU 2 STIS/FUV ACCUM 52X0.2 G140L 1425 2 none none none 1 N/A -MAMA RYTAU 2 STIS/FUV ACCUM 52X0.2 G140L 1425 3 none none none 1 N/A -MAMA RYTAU 3 STIS/FUV ACCUM 52X0.2 G140L 1425 1 none none none 2 N/A -MAMA RYTAU 3 STIS/FUV ACCUM 52X0.2 G140L 1425 2 none none none 2 N/A -MAMA 13714( 3) - 08-Sep-2014 13:23:30 - [ 9] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ RYTAU 3 STIS/FUV ACCUM 52X0.2 G140L 1425 3 none none none 2 N/A -MAMA RYTAU 4 STIS/NUV ACCUM 52X0.2 G230L 2376 1 none none none 3 N/A -MAMA RYTAU 4 STIS/NUV ACCUM 52X0.2 G230L 2376 2 none none none 3 N/A -MAMA RYTAU 4 STIS/NUV ACCUM 52X0.2 G230L 2376 3 none none none 3 N/A -MAMA 13714( 3) - 08-Sep-2014 13:23:30 - [ 10] Summary Form for Proposal 13714 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X0.2, F28X50OII ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/FUV-MAMA, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GROUP 01, 02 WITHIN 30D, ORIENT 157.8D TO 160.9 D, ORIENT 337.8D TO 340.9 D, PATTERN 1 2, PATTERN 1 3, PATTERN 1 4, PATTERN 1 5, PATTERN 1 6, SCHED 30% ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, G140M, G230L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names RYTAU ------------------------------------------------------------------------------------------------------------------------------------