current targets slavek rucinski & michael siwak halifax 2010
DESCRIPTION
Current targets Slavek Rucinski & Michael Siwak Halifax 2010. TW Hya: MOST 2008. Wavelet analysis: Evolving single periodicities. Tendency towards shorter periods: Keplerian orbital evolution within the disk. Time-scales 2 – 9 days; shot noise outside. - PowerPoint PPT PresentationTRANSCRIPT
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Current targets
Slavek Rucinski & Michael Siwak
Halifax 2010
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TW Hya: MOST 2008
•Wavelet analysis: Evolving single periodicities.
•Tendency towards shorter periods: Keplerian orbital evolution within the disk.
•Time-scales 2 – 9 days; shot noise outside.
•Within an envelope of the “flicker noise”, a~1/√f spectrum; an extension to several years (ASAS).
Published: MNRAS, 391, 1913 (2008)
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TW Hya: MOST 2009
Siwak et al. 2010, to be published. Spectroscopy from LCO.
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Unstable accretionin young stars:
FU Ori & Z CMa
Slavek Rucinski & Michael Siwak
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FU OriFU Orionis = GSC 00715 00159(2000): 05:45:22 +09:04:12 , V ≈ 8.9
•Prototype of “FUors” (about a dozen).
•FUors: Sudden brightening by 3 – 5 mag in 1 – 10 years.
•Accretion events in the disk surrounding a pre-MS star.
•Random fluctuations ~0.035 mag, “shorter than a day” (2000, ApJ, 531, 1028)
•Extensive variability in various time scales. No continuous record so far.
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FU Ori
Complex theoretical models, e.g. from arXiv:0906.1595v1, June 2009:
“… outbursts can be explained by a slow accumulation of matter due to gravitational instability. Eventually this triggers the magneto-rotational instability, which leads to rapid accretion. The thermal instability is triggered in the inner disk but this instability is not necessary the reason for the outburst”.
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Currently FU Ori
ASAS results for the 8 years (V-filter):
A slow decline and day-to-day fluctuations by ±0.035 mag.
Proposed MOST monitoring for ~30 days. Expect results similar to TW Hya & HD37806, but for a star with photometrically dominant accretion.
Spring 2009
ASAS (V)
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Z CMaZ Canis Majoris = HD 53179 =GSC 05389 01211
(2000): 07:03:43 -11:33:06 V ≈ 9.85 (8.5?)
•Similar to FU Ori, but earlier type: Bpe
•Large fluctuations: ASAS data (V-filter)
•More unstable accretion; probed at 1d time scale: ±0.2 mag(!).
•Unknown for shorter time scales.
Spring 2009
ASAS (V)