Presentation on theme: "Double Stars Discovered by IOTA and Reported to JDSO (Journal of Double Star Observations) (or in process to be reported) Tony George Presented at IOTA."— Presentation transcript:
Double Stars Discovered by IOTA and Reported to JDSO (Journal of Double Star Observations) (or in process to be reported) Tony George Presented at IOTA 2012 Conference North Las Vegas, NV
JDSO Reports Submitted January 2010 – July 2011 Summary Table JDSO Publish Date Event DateAsteroid (No) Name Target StarSeparation (mas) PA Vol. 8 No.4 Oct1, April 6 (336) Lacadiera 3UC ± ± 6.3
2009 April 16 (336) Lacadiera occults 3UC Carl Bracken, Bob Cadmus, Al Carcich, John Centala, Robert Modic, Doug Slauson The Lacadiera event found a fourth component of a previously known triple star system, making it a quadruple star system. This is an example of an ABAB event with very unequal star magnitudes. This was also the fist time that we used the UCAC3 catalog to report a double star. We used UCAC3 because it contained the other three components of the quadruple star system
Lacadiera Continued Quaternary Star in previously known triple star system
Reports Currently in Progress JDSO Publish Date Event DateAsteroid (No) Name Target StarSeparation (mas) PA Report Discontinued 2010 August 31 (695) Bella TYC ?.? Submitted Not Yet Published 2012 March 11 (57) Mnemosyne BN Orionis TYC SAO HD ± ± 15.2 In Process Not Yet Submitted 2012 August 12 (52) EuropaTYC ± ?.??.?
2010 August 31 (695) Bella occults TYC T Beard, David Dunham, Paul Maley, Walt Morgan, R Stanton The Bella event was originally thought to have found a component so close to the primary star that the secondary occultation was barely detectable. Unfortunately, this event was only observed with mini telescopes using PC164CEX2 cameras. The PC164CEX2 camera uses on-chip integration methods that smears star images across multiple pixels when the target star is drifting across the field of view. The variation in brightness due to the PC164CEX2 on-chip integration is approximately 20%. If this variation occurs during an occultation step transition, it can mimic a brief step event. Since all the data was obtained with PC164CEX2 cameras, no clear unambiguous step event could be evaluated. Therefore, no report has been submitted.
Two chords showed a clear step event in the data, while a third chord showed a partial occultation of only one of the two components – essentially a graze event with only one component occulted. This may be a first for IOTA observers. BN Orionis (TYC ) Duplicity Discovery from an asteroidal occultation by (57) Mnemosyne John Brooks, Steve Conard, Joan Bixby Dunham, David W. Dunham, Robert Jones, Thomas R. Lipka, Wayne Thomas, Wayne H. Warren Jr., Rick Wasson, Jan Wisniewski,
Unknown to the observers at the time of the occultation: TYC is also listed in the General Catalogue of Variable Stars as BN Ori, an INSB eruptive variable. An A7 (Pre Main Sequence) star, 2-5 solar masses, with some surrounding gas and dust (faint emission nebula) and possessing an accretion disk, at a distance of some 400 pc but is rotating at speeds upward of 220 km/sec. Source: The FUOR characteristics of the PMS star BN Orionis inferred from new spectroscopic and photometric observations; Shevchenko, V. S.; Ezhkova, O.; Tjin A Djie, H. R. E.; van den Ancker, M. E.; Blondel, P. F. C.; de Winter, D. Astronomy & Astrophysics Supplement series, Vol. 124, July 1997, The authors of the above referenced paper were contacted about the observation and were very excited to learn that BN Orionis was indeed a double star. This star will likely be the source of much study in the future. BN Orionis (TYC ) by (57) Mnemosyne (continued)
TYC duplicity discovery from occultation by (52) Europa A singe chord observation by Brazilian IOTA observer Breno Loureiro Giacchini
Because there is only one observing chord, there are at least two potential solutions for any ellipsoid major or minor axis assumption – four total combinations!
Conclusions Occultations continue to be an excellent method of finding or verifying double stars. Any time a light curve is obtained from a video record, it should be carefully examined for the presence of step events that could be due to duplicity of the target star The PC164CEX2 camera may produce results that can mimic very short step events in normal instantaneous occultations. As a result, double star claims from very short step events using these cameras must be verified by other non-integrating cameras Single-chord observations can discover double stars, however there is a great deal of uncertainty in the PA and Separation.