! Hubble Space Telescope Cycle 5 (1995) Phase II Proposal Template ! $Id: 6071,v 3.1 1995/12/15 20:19:05 pepsa Exp $ ! ! Refer to the HST Phase II Proposal Instructions to fill this out ! ! Anything after a "!" is ignored, and may be deleted ! ! All keywords with multiple entries are comma delimited except the ! Visit_Requirements and Special_Requirements keywords which can be ! delimited with carriage returns or semi-colons, but not commas ! ! For help call your Program Coordinator: Dustin Manning ! Phone: 410 338-4456 , E-mail: manning@stsci.edu ! ! This partially completed template was generated from a Phase I proposal. ! Date generated: Sun Dec 18 19:06:21 EST 1994 ! Proposal_Information ! Section 4 Title: The temperature structure in the wind of the pre-main sequence Herbig Ae star AB Aurigae Proposal_Category: GO Scientific_Category: Hot Stars Cycle: 5 Investigators PI_name: Claude Catala PI_Institution: Observatoire de Paris, Section de Meudon CoI_Name: Theodore Simon CoI_Institution: University of Hawaii Contact: Y ! Y or N (designate at most one contact) CoI_Name: Torsten Boehm CoI_Institution: Landessternwarte Heidelberg Contact: ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) The Herbig Ae/Be stars are pre-main sequence objects of intermediate mass, and, according to standard stellar evolution theory, they are not supposed to possess outer convection zones. Despite this absence of convection, they show evidence for intense activity, which may be magnetic in origin. The model proposed so far to explain the various line profiles observed in these stars includes an extended chromosphere with temperatures of the order of 15,000--20,000 K. A few Herbig Ae/Be stars were recently detected as X-ray sources by ROSAT, but no evidence for temperatures typical of solar-type transition regions has ever been found in these stars. This lack of evidence may be the result of the low sensitivity of the instruments used so far. Using the GHRS, we propose to make a deep search for N V resonance lines near 1240 Angstrom in the spectrum of AB Aur, the star which is the prototype of this class. A non-detection would confirm the moderate temperature chromosphere model, while a positive detection would indicate the presence of temperatures above 100,000 K and would thus impose strong constraints on the mechanisms of nonradiative energy deposition in the atmospheres of these stars. Questions ! Free format text (please update) Observing_Description: We propose to use the GHRS to obtain a spectrum of AB Aur in the region of the N V resonance lines (1238.8, 1242.8) having a S/N in the range of 20--50. We also propose to record a spectrum with comparable S/N ratio in the region of the C IV resonance lines (1548.2, 1550.8), so that we can compare and model the profiles of the two sets of lines. The two spectra must be obtained within a few hours of each other, because we know that the line spectrum of AB Aur varies on a time scale of about one day due to streams in the wind. A spectral resolution of the order of 10--20,000 will be sufficient for our purpose, because the wide C IV lines of AB Aur typically extend to velocities of 300 kms^-1, and because we expect the same type of line width for the N V lines. Such a resolution can be obtained with the G140M grating and the 2 arcsec aperture (LSA), after a 2-pixel sliding mean of the spectra. The G140M grating + D1 detector combination is preferable to the G160M + D2 combination because the G140M grating has 30% higher resolving power than the G160M grating at these short wavelengths, the D1 detector is solar-blind, and its background count rate is lower by 25%. The G160M + D2 combination has the higher sensitivity at 1550 Angstrom, but the resolution and solar-blind response advantages of the G140M + D1 configuration outweigh the savings in exposure time at C IV (which amount to a few minutes at best for the short C IV exposure according to our estimated observing timeline). The observations will be made using the standard observing modes to reduce fixed pattern noise, detector granularity, geomagnetically-induced image motion, and undersampling. From the flux of about 2 * 10^-13 erg cm^-2 s^-1 ang^-1, measured in low (~ 8 Angstrom) dispersion by IUE at 1240 Angstrom for AB Aur, we infer a count rate through the large aperture of about 0.088 count s^-1 diode^-1 with the G140M grating and D1 detector. A two-pixel averaged S/N ratio of 30:1 can be obtained in 98 minutes of integration (which will extend over 3 orbits of the spacecraft). The flux at 1550 Angstrom\ is of the order of 4 * 10^-12 erg cm^-2 s^-1 ang^-1, yielding an expected count rate of 0.94 counts s^-1 diode^-1. A 15 min exposure will result in a S/N ratio = 40:1 for 2 pixel averaging. The 2-pixel sliding mean can be applied to the data without significant loss of resolution for our purposes. Real_Time_Justification: None. Calibration_Justification: ! Move appropriate text from Real_Time_Justification Additional_Comments: Fixed_Targets ! Section 5.1 Target_Number: 1 Target_Name: HD31293 Alternate_Names: AB-AURIGAE Description: STAR, AE, A0-A3 V-IV Position: ! J2000 FROM HIC 22910 RA = 04H 55M 45.9S +/- 1", ! RA=0H 0M 0.00S +/- 0S, DEC=+30D 33' 03.9" +/- 1" ! DEC=0D 0' 0.0" +/- 0", ! PLATE-ID=0000 Equinox: 2000 RV_or_Z: V = 18.0 ! RA_PM: 0.0004 ! Units are seconds of time per year ! Dec_PM: -0.030 ! Units are seconds of arc per year ! Epoch: 2000 !Annual_Parallax: 0.006 Flux: V = 7.05 +/- 0.4, ! Include at least V and B-V B-V = 0.13 +/- 0.2, E(B-V) = 0.2 +/- 0.1, F-CONT(1550) = 3 +/- 1 E-12, F-CONT(1240) = 2 +/- 0.5 E-13 Comments: ! This is a template for a single visit containing a single exposure ! Repeat exposure and visit blocks as needed Visits ! Section 6 Visit_Number: 1 Visit_Requirements: ! Section 7.1 On_Hold_Comments: Visit_Comments: Exposure_Number: 10 ! Section 6.5 Target_Name: HD31293 Config: HRS Opmode: ACQ Aperture: 2.0 Sp_Element: MIRROR-N1 ! Wavelength: Optional_Parameters: SEARCH-SIZE = 3, BRIGHT = RETURN ! STEP-TIME = 1.0s ! EXPECT 4800 COUNTS SCALING BY V=7.1 ! EXPECT 7400 COUNTS SCALING BY Vo = 6.6 Number_of_Iterations: 1 Time_Per_Exposure: 9.0S Special_Requirements: ONBOARD ACQuisition FOR 20-30 Comments: Exposure_Number: 20 ! Section 6.5 Target_Name: HD31293 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G140M Wavelength: 1549 Optional_Parameters: FP-SPLIT = STD, DOPPLER = ON, STEP-PATT = 5 Number_of_Iterations: 1 Time_Per_Exposure: 979.2S Special_Requirements: ! Section 7.2 Comments: Exposure_Number: 30 ! Section 6.5 Target_Name: HD31293 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G140M Wavelength: 1240 Optional_Parameters: FP-SPLIT = STD, DOPPLER = ON, STEP-PATT = 5 Number_of_Iterations: 4 Time_Per_Exposure: 1523.2S Special_Requirements: ! Section 7.2 Comments: Data_Distribution ! Defaults indicated; change if desired Medium: 8MM ! 8MM or 6250BPI or 1600BPI Blocking_Factor: 10 ! 10 or 1 ! Only astronomers with very old 9- ! track tape drives should consider ! a blocking factor of 1 Ship_To: PI_Address ! STSCI or PI_Address or ! PI Address from Phase I is: ! ! 92195 Meudon Principal Cedex, ! France ! ! Ship_Via: UPS ! UPS (2-day) or OVERNIGHT ! Overnight shipping done at PI expense Recipient_Email: ! Needed if Ship_To: is not PI_Address ! ! Let us know what you think of this template and software! ! Please send a list of your likes and dislikes to your Program Coordinator