7287( 3) - 05/12/99 11:54 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7287 Version: 3 Check-in Date: 22-Jul-1997 13:10:58 1.Proposal Title: Recovery and Characterization of Old Novae in the Globular Clusters M80 and M14 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Michael Shara Space Telescope Science Institute CoI: David Zurek Space Telescope Science Institute N CoI: Laurent Drissen Laval University N ------------------------------------------------------------------------------------ 5. Abstract A few very close binaries in the core of a globular cluster can drive the dynamical evolution of the 10^5 - 10^6 stars in the cluster. Tidal capture theory predicts that tens of cataclysmic variables should be present in most globulars. Thus these close binaries may be the engines which drive globular cluster dynamical evolution. Despite intensive searches, very few cataclysmic candidates have been sighted - only two are classical novae. Using WFPC2 imagery we have located a UV-bright candidate which coincides with the position of the classical nova T Sco which erupted in 1860 A.D. in the globular cluster M80. Only one other UV-bright star (out of 8000 in the cluster core) was found. We propose to use the long slit of STIS with the modest resolution G430L grating to simultaneously obtain spectra of both UV-bright stars. This would provide the first confirmed, recovered old nova in a globular; the first spectrum of a high mass transfer rate binary in a globular core; and a determination of whether the second UV-bright object is also a cataclysmic binary. We also propose to recover the nova of 1938 in M14 with F336W and F555W Planetary Camera images. ------------------------------------------------------------------------------------ 7287( 3) - 05/12/99 11:54 - [ 2] Observations Description ------------------------ We plan to observe two candidate CVs in M80. We will use the 0.2" slit and orient the telescope such that both objects fall on the slit. Note from Figure 2 that the field of the old nova candidate is crowded. However, we have carefully checked that both it and the second candidate are sufficiently distant from any other cluster star that the 0.2" slit will cleanly isolate the spectra of both objects. The orientation of the STIS slit (approximately 45^o East of North to encompass both CV candidates) fortuitously misses any stars closer than 0.5" to either object. We have checked with STSCI instrument scientists Stefi Baum, George Hartig and Olivia Lupie; they assure us that the calibrated STIS slit can be oriented with the required 0.5^o angular accuracy (corresponding to 0.1" over a lever arm 11" long). We will first acquire an isolated bright star in the periphery of M80. We will then peak up on a second bright star, approximately half way between our two candidates. We will use the grating G430L which will cover the spectral region 2900-5700 angstroms. This will encompass HeII 4686 and the Balmer lines, the usual spectral indicators of CVs. We've carried out S/N calculations with the exposure calculator of STIS to determine that we need five orbits to obtain S/N = 10 at HGamma. Even if the old nova emission lines are as unexpectedly weak as a few angstroms E.W. (indicative of non magnetic CVs) we will be able to measure them. We've thought of imaging the two candidates (instead of using STIS) in narrow band HeII 4686 and HAlpha filters, and nearby continuum filters, to search for emission lines. This will work IF the emission lines are stronger than 10-20 Angstroms E.W. (the filters' FWHM are slightly larger than this). If the emission lines are weaker (as in canonical old novae) then we will see no differences in the narrow band - broadband image pairs. While spectroscopy is more expensive (5 orbits instead of 2 or 3) it guarantees us a definitive answer. Our long slit CCD observations will pick up the spectra of dozens of stars along the line joining our two CV candidates. (None are bright enough or close enough to our two primary candidates for saturation effects to degrade the desired data.) These extra spectra are purely a bonus, and may allow us to get relative abundance ratios for giants, subgiants and main sequence stars. beginfigurehb putplotTSco.ps2.5in0100100-300-300 captionUV-bright object at the position of T Sco 1860 A.D. endfigure We will also obtain Planetary Camera images of the field of nova Oph 1938 in M14. The position of the nova is known to better than 1". The F336W and F555W images will allow us to detect any UV-bright object down to M_u = 7.0, i.e. an order of magnitude fainter than canonical old novae, and slightly fainter than our candidate old nova in M80. Real Time Justification ----------------------- A specific orientation angle will be necessary so that both objects fall on the slit. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 7287( 3) - 05/12/99 11:54 - [ 3] Data Distribution Paper Products: Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7287( 3) - 05/12/99 11:54 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6093-RGB- STAR RA=16H 17M 3.130S +/- 0.005S, J2000 V = 14.049+/-0.05 OFFSET DEC=-22D 58' 41.5515" +/- 0.005" B = 15.049+/-0.02 U-B = 2.108+/-0.05 E(B-V) = 0.20 Comments: This is the brightest star within 100 PC (WFPC2) pixels (a box 200x200 pixels or 9" sqaure) by about 0.3 mags. 2 TSCO-1860 STAR, CLASSICAL NOVA RA-OFF=-0.32295S+/- 0.005S, DEC- J2000 V = 22.7+/-0.2 OFF=10.0065"+/- 0.005", FROM 1 B = 22.2+/-0.2 U-B = -1.0+/-0.2 E(B-V) = 0.20 Comments: This is the position of the nova TSco-1860. I was originally going to position the slit half way between the nova and the UV-object. However, I'm a little nervous doing this so I will place the slit on the nova and hope we get the correct orientation so that the UV-object lands on the slit as well. The central position is RA-OFF = 0.684S, DEC-OFF = 0.6155" Both objects should fall on the slit if the orientation is correct. TSco - RA = 16H 17M 2.807S, Dec = -22D 58' 31.545" and the UV obj - RA = 16H 17M 2.085S, Dec = - 22D 58' 52.789". 3 NGC6402 STAR, CLASSICAL NOVA RA=17H 35M 1.0S +/- 0.1S, DEC=- J2000 V = 23.0+/-0.5 3D 12' 58.0" +/- 0.5" B-V = -0.5+/-0.1 E(B-V) = 0.59 7287( 3) - 05/12/99 11:54 - [ 5] Visit: 01 Visit Priority: Visit Requirements: PCS MODE FINE ORIENT 70.26423D TO 70.50837D On Hold Comments: Additional Comments: Note that this visit requires a specific orientation because we would like to place two objects on the slit. I have calculated the orientation in two ways. First I choose to calculate the orientation using the RA and DEC of the two objects I'd like to place on the slit. The RA and DEC for TSco is 16H 17M 02.8072S and -22D 58' 31.545". The RA and DEC for the other UV object is 16H 17M 02.0850S and -22D 58' 52.789". Using these numbers and the fact the STIS slit is nominally 45D from the U3 axis I arrive at an orientation of 70.149D. The other method which is the eventual numbers I chose above is using the x, y positions on the WFPC2 images (Data set U2J10101T PI is SHARA) and calculting the offset from the orientation in the WFPC2 header. The X, Y position for TSco is 574.0057, 430.231 and the X, Y position for the other UV object is 126.8084, 696.2311. The orientation of the WFPC2 images is 101.1311 (U3 axis). I thus arrive at an orientation of 70.3863. If we place the nominal peaked up center of the slit on TSco this will allow a lever arm of 23.4687" and using the 0.2" slit we require an accuracy of the orientation of 0.24414 Degrees. If we however choose to postion exactly half way between the two objects we require an accuracy of 0.48826 Degrees.I have chosen to place the slit on the nova and hope that the orientation will be acurate to within 0.2 Degrees or better. This will ensure that at least the primary target will be obtained. I would appreciate it if someone would please check these values of the orientation. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6093-RGB STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 0.5 S ONBOARD ACQ FOR 2 to 5 -OFFSET CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6093-RGB STIS/C ACQ/PEA 52X0.2 MIRROR 1 0.5 S ONBOARD ACQ FOR 3 to 5 -OFFSET CD K ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6093-RGB STIS/C ACQ/PEA 52X0.1 MIRROR 1 0.5 S ONBOARD ACQ FOR 4 to 5 -OFFSET CD K ------------------------------------------------------------------------------------------------------------------------------------ 4 TSCO-1860 STIS/C ACCUM 52X0.2 G430L 4300 GAIN=1,CR-SPLIT=NO 1 1800 S EXPAND CD ------------------------------------------------------------------------------------------------------------------------------------ 5 TSCO-1860 STIS/C ACCUM 52X0.2 G430L 4300 GAIN=1,CR-SPLIT=NO 4 2400 S EXPAND CD ------------------------------------------------------------------------------------------------------------------------------------ 7287( 3) - 05/12/99 11:54 - [ 6] Visit: 02 Visit Priority: Visit Requirements: PCS MODE FINE On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6402 WFPC2 IMAGE PC1 F555W 5398 CR-SPLIT=0.5 1 800 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6402 WFPC2 IMAGE PC1 F336W 3342 CR-SPLIT=0.0 2 600 S EXPAND MAX DUR 1000 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6402 WFPC2 IMAGE PC1 F336W 3342 CR-SPLIT=0.0 3 600 S ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC6402 WFPC2 IMAGE PC1 F555W 5398 CR-SPLIT=0.0 1 300 S EXPAND MAX DUR 1000 S ------------------------------------------------------------------------------------------------------------------------------------ 7287( 3) - 05/12/99 11:54 - [ 7] Summary Form for Proposal 7287 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 52X0.2 52X0.1 PC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAK ACCUM IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT CR-SPLIT=NO GAIN=1 CR-SPLIT=0.5 CR-SPLIT=0.0 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE FINE ORIENT 70.26423D TO 70.50837D ONBOARD ACQ FOR 2 to 5 ONBOARD ACQ FOR 3 to 5 ONBOARD ACQ FOR 4 to 5 EXPAND PCS MODE FINE EXPAND MAX DUR 1000 S ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G430L F555W F336W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC6093-RGB-OFFSET TSCO-1860 NGC6402 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 4300 5398 3342 ------------------------------------------------------------------------------------------------------------------------------------