From jop at astro.columbia.edu Mon Jan 12 08:12:48 2015 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 12 Jan 2015 08:12:48 -0500 Subject: (cba:news) t pyx and v455 and, mainly Message-ID: <54B3C850.2060905@astro.columbia.edu> Dear CBAers, Some comments on two of our oldest friends. It has now been 3.5 years since T Pyx's eruption, and that's enough baseline to get a good measure of its post-eruption orbital period - increased by 1 part in 10^^4. But it's not quite enough to decide whether the steady period increase IN QUIESCENCE still continues now. That's plausible, but not yet certified (or refuted) by observation. To test this, we mainly need a very precise measure of minimum light in the 0.07622 d wave *now*. Just one - if sufficiently precise - would now provide a sensitive test. But "sufficiently precise" means about 10-15 orbits (6-7 nights), because the weakness of T Pyx's orbital wave makes the job somewhat challenging. It's prime observing season, and observations tightly nested in time have somewhat greater value. Go for it! In the first paper on V455 And, it was advertised as "the star that has everything". Even including some mystery periods which still haven't been successfully interpreted ("explained"). Enrique and I have done separate analyses of this year's data, and V455 seems to have one more period - a *negative superhump* at quiescence. There's still some life left in the observing season, and if we can stitch together European and USA data, we can define this phenomenon pretty well. It does require moving on this project right away, because it may be a transient phenomenon - and also because we lose 4 minutes a day. Unlike the 67-seconf pulse tracking project - our usual interest in V455 And - this one is not sensitive to time resolution, since the candidate period is 80 minutes. With the star at mag 15.8 and the Moon out of the way, it should be a feasible target for all northern observers. Of course, HZ Puppis and ASASSN-14mv continue to be very attractive targets! *MOre* than CP Puppis at present, since that star requires back-to-back lengthy time series. joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Thu Jan 29 06:46:55 2015 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 29 Jan 2015 06:46:55 -0500 Subject: (cba:news) t pyx, finis Message-ID: <54CA1DAF.90602@astro.columbia.edu> 1/29/15 Dear CBAers, Thanks mostly to the great watchfulness of Berto and Gordon, the year's T Pyx campaign - in fact the ten-year campaign - is over. Not only did we (Arto being the main player then) document in much detail the return of the orbital signal after eruption, but the coverage since then (2012-3-4/5) demonstrates that the orbital period continues to increase - at about the same rate as pre-eruption. This supports the idea that the oddities of T Pyx (the great luminosity and Pdot) represent a true evolutionary phase, rather than something transient and essentially recovery-from-eruption. So we're finished with it. I hope people (mostly southern) will give HZ Pup a try. That one hasn't elicited interest this year. It's 2.5 mag fainter, so I can understand why... but it's the "new kid on our block", and any good time series you manage to get would have high impact. Then there's CP Pup. Same part of the sky, pretty bright (15.0), and usually with a high-amplitude signal. The fascinating thing about CP Pup is that this strong signal isn't stable in phase or amplitude, and isn't a superhump either. It's something new, related to the 90-minute Porb in some way not yet known. I have a working hypothesis (the 2:1 cousin of the normal 3:1 superhump), but it's hard to test because the signal is so damn SLIPPERY. But February is surely the right time to try! Bob Rea has been going strong on it; it would be great to have help from others. Finally - for the southern novae - can someone have a look at V382 Vel? How bright is it now? Of course the DWARF NOVAE have started off the year just great - especially the various ASAS guys: 14mv, 15bu, 15bp. I'm going to need a lot of help with these guys, because: 1. They're so numerous. 2. I broke my hand recently, and everything I do with my hands ranges from twice-as-hard to twice-as-long to impossible. This message will take 1-2 hours to type. I hope other people, esp. those of you doing analysis, will help with the information flow. (I can still manage the quickie things, but longer messages are intimidating.) Some of the dwarf novae are really striking, practically unique: 14mv and 14ei are definitely in that category, and the other two might be (I haven't studied them yet). It's awfully weird to use a word like "unique" for a class with already about 700 members! Is this the "tip of an iceberg"? Have a great ol' February! joe p ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/