HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4145

PERIOD COVERED: UT June 28, 2006 (DOY 179)

OBSERVATIONS SCHEDULED

FGS 10612

Binary Stars in Cyg OB2: Relics of Massive Star Formation in a Super-Star Cluster

We propose to make a high angular resolution SNAP survey of the massive stars in the nearby, super-star cluster Cyg OB2 We will use FGS1r TRANS mode observations to search for astrometric companions in the separation range of 0 01 to 1 00 arcsec and in the magnitude difference range smaller than 4 magnitudes The observations will test the idea that the formation of very massive stars involves mergers and the presence of nearby companions Discovery of companions to massive stars in this relatively nearby complex will provide guidance in the interpretation of apparently supermassive stars in distant locations The search for companions will also be important for verification of fundamental parameters derived from spectroscopy, adjustments to main sequence fitting and distance estimations, determining third light contributions of eclipsing binaries, identifying wide colliding wind binaries, studying the relationship between orbital and spin angular momentum, and discovering binaries amenable to future mass determinations The massive star environment in Cyg OB2 may be similar to the kinds found in the earliest epoch of star formation, so that a study of the role of binaries in Cyg OB2 will help us understand the formation processes of the first stars in the Universe

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated )

HSTARS: (None)

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: 1595-0 Delivery of ACS Side2 FSW loads (CS 4 02) @ 179/1630z

         SCHEDULED      SUCCESSFUL

FGS GSacq 08 08 FGS REacq 05 05 OBAD with Maneuver 26 26

SIGNIFICANT EVENTS: (None)

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