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Duration of R CRB's Current Minimum

BRJ
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Joined: 2010-07-24

I noted last evening that R CRB's recent attempt at a recovery from its long current minimum clearly has failed once more. A quick check of century-plus lightcurve makes it look like the current minimum is decidedly the longest in duration ever recorded for this odd variable. Plus, there seems little real indication that there could be any return to maximum light in the near future (even though these stars are known for being highly unpredictable).

I'm unsure just what the record is for the duration of the longest minimum state of any confirmed R CRB-type star, but I would think that in the current instance R CRB itself likely is close to, or presently setting it.

J.Bortle    (BRJ)

R CrB current decline
MDAV
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Joined: 2010-07-23

There was a 10 year protracted minimum around 1880 documented cin Burnham Vol. 2. That one was characterized by periods where it rose nearly to maximum before fading again.

I couldn't locate the AAVSO Monograph 4 which had a 1843-1990 curve.

The ligtcurve generator
uis01
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Joined: 2010-07-25

The ligtcurve generator contains the visual observations from the late 19th century minium.  There is a 10-year gap in there so it is hard to accurately judge the length of that mininmum but it appears to have been from 6 to 16 years long (with many "false" recoveries).  

RCB Minima
ocn
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Joined: 2010-07-25

Other RCBs probably lack the observational record of the prototype. R CrB's current long duration active state may well hold the record. I'd like to know whether the ejected material is simply taking a really long time to disperse or is the star throwing off huge multiple globs of stuff in separate events over a protracted period of time. Perhaps both scenarios are playing out concurrently. Great class of variable star !

ocn

Other RCBs
roe
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Joined: 2010-07-25

As I noted earlier, Z UMi has changed its historic behavior too.  The recent minima have been deeper (~ 2 mag) and longer than earlier measurements but also the recoveries are not coming up to the historic levels.

U Aqr is also currently demonstrating its deepest minimum on record - by some 3-4 mags.

Fun stars!

Jim Roe [ROE]

AAVSO 49 Bay State Rd. Cambridge, MA 02138 aavso@aavso.org 617-354-0484