From jop at astro.columbia.edu Mon Jul 4 06:19:20 2022 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 4 Jul 2022 06:19:20 -0400 Subject: (cba:news) v1674 Her and other seasonal stars Message-ID: Hi CBAers, OK, we've sent off our paper on V1674 Her. Pretty amazing target. https://arxiv.org/abs/2207.00181 Co-authors should check their email/address/etc. I know a couple of errors, but there might be more. We'll send off the proper paper ("proper" = for refereeing) in ~5-7 days. V1674 will remain the highest priority in the next few months. But it's around 17.1 now, and the raw light curves look pretty ugly since the 8-minute signal is of such high amplitude as to look like NOISE. I've had no difficulty digging it out, and urge you to keep the faith for the next few months. But some other of our favorites have suffered at its hands, and let's get back to them, too. Our of our common themes, large Porb changes in CVs, needs attention... and in particular these stars: IM Nor V617 Sgr QR And CI Aql WX Cen V Sge These stars don't particularly need FREQUENT coverage, but you must have LONG coverage - at least 3 hrs/night, and preferably 5 or more. The reason is that we seek the *orbital* light curve. Those of you who have been working V2487 Oph should keep that one going too, until Christian and/or Maria calls you off. I haven't said anything about U Sco here, because (a) I haven't studied anything about this latest outburst, and (b) I've been assuming that other people will do it. But so far, not much has appeared about its light curve. Some of you probably know, though - could you share it? joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Sat Jul 9 07:19:39 2022 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 9 Jul 2022 07:19:39 -0400 Subject: (cba:news) Novae with lessons to teach us... Message-ID: <3bd0e1ab-a973-8d14-a321-ea966cebe9e4@astro.columbia.edu> Hi CBAers, There are two classical novae, arguably, which have had a titanic effect on humans' ideas of what novae actually are: DQ Her (1934) and T Pyx (1890 and six more times). The 1954 report that DQ Her was an eclipsing binary with an "incredibly short" orbital period of 4.6 hours changed all our ideas about novae. T Pyx was the first RECURRENT nova found, and showed that a nova was a natural event in the lifetime of a close binary (with a white-dwarf component). I believe that V1674 Her will take a place in this pantheon. Why? We already know that it's the fastest nova in history,which suggests that it erupted from a WD of very high mass. So far, everything about this star announces SPEED: the speed of the ejected shell; the speed of its light-curve evolution, the speed of its spin-period change; the speed of its orbital-period change. Even OUR speed in getting out an initial paper. I had hoped that sending out a preprint of our Paper I would help motivate observers to keep the faith on it. At magnitude 17.0 and with a large-amplitude (0.1 mag) 8-minute signal, it's still within reach for all CBA observers - and easy reach for many. But the flow of data has virtually stopped. Maybe your light curves seem very ratty to you; but this is probably because with the integration times you're probably using to get decent S/N, the data look like noise. But it's very likely SIGNAL. With an 8-minute *coherent* signal, sampling just 4x per cycle is PERFECTLY suited to define its properties, even though the data won't look good (considering counting statistics, background light, etc.) The star is near opposition now, and I'm super-eager to continue work on this star through October - and finish a second paper which will establish a full ephemeris for the rapid pulses (+ the orbit). Until it drops to mag 19 or so, it will remain a GREAT target. joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/