0Assigned ID: 1208
----- Attempting Submission 1 (Fri Jan 17 12:54:35 GMT 2020) -----In visit 3, in order to avoid brights stars in the grism WFC3/IR observation I have added an ORIENT constraint.
In visits 1 and 2, the STIS observations, WAVECALs have been explicitly included,
In visit 1, the STIS/MAMA observations, I have omitted MAMA monthly offsets as these data are
required for critical flux calibration.-896291312----- Attempting Submission 1 (Wed Mar 11 23:37:51 GMT 2020) -----In order to improve the flux calibration to better than 3%, required by the proposal ,
I need to omit the MAMA monthly offsets and can only include this option
in restricted mode.Does the binary system LB-1 host a Black Hole?It was recently proposed that the Galactic binary system LB-1 hosts an ~8+70 solar mass B-star+black hole (BH) wide binary that is X-ray quiet, strongly challenging the current paradigm for the formation of stellar mass black holes in metal rich environments. This claim was quickly disputed in two ways: The Balmer emission lines originally thought to arise from an accretion disk around the BH have been re-interpreted as a stationary circumbinary disk, hence it is only possible to estimate a minimum mass for the dark companion from the inferred mass of the B-type star. Secondly, detailed non-LTE analyses of the optical spectrum and spectral energy distribution of the B-type star now imply two scenarios for a significantly lower mass of the B-type 'primary': It is found to be either a main sequence B-type star of 3.2+/-2 solar masses or a stripped helium star of 1.1+/-0.5 solar masses, consistent with a 'secondary' mass between approximately 2 and 5 solar masses. The dark secondary could therefore still be a stellar mass BH, making it only the second X-ray quiet star+BH system known, or possibly even a massive neutron star. We propose obtaining an exquisite UV/optical/near-IR flux calibrated spectrum of the system that will provide the pivotal means of discriminating between these two scenarios by tightly constraining the mass and helium abundance of the primary.We follow the standard STIS and WFC3/IR flux calibration configurations, aiming for a s/n of at least 100--200, and a combined spectrum covering the FUV--near-IR with a spectral resolution of 500-1000 in the UV-optical, and 100-200 in the near-IR. For the predicted UV flux we adopt the parameters and extinction law from Simon-Diaz et al (their Appendix C). The source is non-variable and the extinction law is well enough determined to permit a reliable estimate of BOP concerns.
We require a total of 3 orbits/visits as follows:
VISIT O1: For a s/n of approximately 100 with STIS/MAMA using the 52x2 aperture and NUV G140L and FUV G230L configurations we require exposure times of at least 1000 and 800 seconds respectively. Exposure times are auto-adjusted to fill the orbit and improve s/n. We switch off the MAMA monthly offsets as this improves flux calibration to better than 3%, an objective of the proposal. Wavecals are explicitly added.
VISIT 02: For the STIS/CCD G430L and G750L detector/grating combinations exposure times are short, 20 seconds for s/n around 100 and we therefore repeat each x4 times (CRSPLIT=4) to match STIS calibration observations. We will use the 52x2 aperture, the E1 position for the G430L to mimimize CTE losses and the center position for G750L as per the standard calibration configurations. To complete this orbit we will add higher resolution G430M/3680 and G430M/3936 150/50 second exposures with the 52x0.1E1 aperture. These data will permit a very high fidelity view of the Balmer jump and the higher series members of the Balmer lines from Hepsilon onwards. In addition we note that the use of the 2 arcsec wide aperture in the low resolution observations will in effect provide imaging spectroscopy of the disk emission lines. Wavecals are explicitly added.
VISIT 03: With WFC3/IR we require use of the G102 and G141 grisms. We use an 8-point line dither pattern in Y of 10 pixels to improve the total s/n and reduce persistence effects. Using the 512 subarray, we can obtain 2 patterns per grism in a single orbit, for a total exposure time per grism of 102 seconds. A short exposure is added at the end of the sequence to define position of the source for the grism observations. We add short imaging exposures to check the Paschen Beta for extended emission. We use the 256 subarray to avoid saturation of the target.Lennon: Stellar atmospheres of B-type stars, stellar evolution
Maiz-Apellaniz: Spectrophotometry and photometry
Bohlin: Spectrophotometry and flux calibration
Deustua: Spectrophotometry and photometry
Simon-Diaz: Stellar atmopheres and surface abundances of OB stars, stellar pulsation
Dufton: Stellar atmospheres of B-type and post-AGB stars
Smartt: Advanced stages of stellar evolution, SN progenitors
Herrero: Stellar atmospheres and winds of OB stars
Casares; Accretion discs and stellar mass black holes
Munoz Darias: Accretion discs and stellar mass black holes
Allende-Prieto: Stellar atmospheres and chemical abundances
Castro: Stellar atmospheres of OB stars
de Burgos Sierra: B-type stars (PhD student)
Gonzalez-Hernandez: X-ray binariesStellar Physics3falsefalsefalsefalsefalsefalsefalseSUPPORTEDEXT-STARB6-B9.5 III-INOThis object was generated by the targetselector and retrieved from the SIMBAD database.J2000J2000STIS/FUV-MAMASpectroscopicNoNoG140L1425STIS/NUV-MAMASpectroscopicNoNoG230L2376STIS/CCDSpectroscopicNoNoG430L4300STIS/CCDSpectroscopicNoNoG750L7751STIS/CCDSpectroscopicNoNoG430M3680STIS/CCDSpectroscopicNoNoG430M3936WFC3/IRSpectroscopicNoNoG102WFC3/IRSpectroscopicNoNoG141POS-TARGDITHER1.3LINEfalsefalse841.788WFC3-IR-DITHER-LINE1falsePOS-TARGDITHER0.572LINE0.365falsefalse74.653418.528WFC3-IR-DITHER-BOX-MIN2falseThe scheduling data was generated by CASM 28.0.CASM was run in Phase II mode.(Tic-Visit
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:date "11-Mar-2020 23:14:04.0"
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:trans-version "20191203"
:date "11-Mar-2020 23:11:27.0"
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