From jop at astro.columbia.edu Tue May 6 22:12:59 2014 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 06 May 2014 22:12:59 -0400 Subject: (cba:news) early may stellar menu Message-ID: <536996AB.7070103@astro.columbia.edu> Dear CBAers, The month of AY Sex has come to an end. The HST spectroscopic observation (basically a time-resolved 1100-3000 A spectrum) was beautiful and a humdinger - looked practically like a quasar spectrum (numerous very broad and generally high-excitation lines... and a few weak mystery lines). Thanks for all the coverage! Also time to ring the curtain down on DW UMa and OT1759+25. It would, however, be good to continue observations of T Pyx, HP Lib, and perhaps AM CVn. These are not quite ripe yet in their 2014 coverage. May-June-July is high season for classical novae, and let's go get 'em. I've become ever more fascinated by their orbital light curves over the few decades after eruption. Early in the decay, the light curves look like classic reflection effects, as if the secondary is merely reflecting the incident light from the hot white dwarf ("heating effect"). Then it can acts as a bolometer for the white dwarf, long after the supersoft X-ray source has disappeared. We've tested this out for one nova, and managed to follow T_wd down to 120,000 K. That was a thrill for me; the X-ray telescopes can't detect anything south of 300,000 K. Later on, it seems to get more complex... but anyway, the point is to obtain orbital light curves season by season. Within the first 5-10 years, the changes are most obvious - presumably since the white dwarf cools faster then. We've started similar programs on NR TrA, V1494 Aql, V339 Del, V959 Mon, V2491 Cyg, V382 Vel, V2362 Cyg, and V1500 Cyg. Some of these are off-season, but bear 'em in mind. Also, smapshot estimates of magnitude will be very helpful too. These stars are pretty neglected years after outburst... so we often don't know whether they're feasible targets (until you look). Also, the most recent novae (2013-4) are of great interest too - we'd like to know exactly when the orbital wave first appears. This is probably the exact time the ejected shell goes transparent - out first look at the underlying hot white dwarf. By comparing that to the time the soft X-rays first appear, as seen by the SWIFT satellite, we'll get our theory tested. While we're on the subject of heating, there's *dwarf* novae to think about too. V355 UMa and GW Lib are both WZ Sge - type dwarf novae which had recent outbursts, and both contain pulsating white dwarfs as well. Still well placed in the sky, but somewhat challenging for brightness. For very lengthy runs on northern stars, my #1 recommendation is HS 1813+6122 (J2000: 18 14 29.83 +61 23 34.3) = "Dra" in Downes catalog. Decently bright star, very very likely to show superhumps. And it's time also to do a campaign on UX UMa, which we have criminally avoided all these years. Perfectly placed in the night sky. Scrambling to get my SAS/AAVSO paper in. It's wonderful that so many of you are coming this year. joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Sat May 17 06:45:23 2014 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 17 May 2014 06:45:23 -0400 Subject: (cba:news) NR TrA and IM Nor, recent novae Message-ID: <53773DC3.4070806@astro.columbia.edu> Dear (southern) CBAers, We're getting some great data from Gordon Myers this week on NR TrA, and the seasonal timing is mighty good. The next couple of weeks offer a great opportunity to do a round-the-world sweep on this extremely fascinating star - which Fred Walter has been covering with spectroscopy since its 2008 nova eruption. About mag 16.7. Then there's IM Nor, a recurrent nova and a 2002 erupter - of extra special interest to us because its probable binary period is so short (a likely friend of T Pyx, which urgently needs friends). Quite a challenge, around 18.5... and I believe only Berto has been able to get data on it. But maybe things have changed; probably all of us, except for me, are slightly better photometrists than we were a few years ago. On a good night, can you try to get time series on it? joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Wed May 21 12:36:39 2014 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 21 May 2014 12:36:39 -0400 Subject: (cba:news) QZ Lib = ASAS1536-08 Message-ID: <537CD617.50800@astro.columbia.edu> Hi CBAers, We've started some observations of QZ Lib with the MDM 2.4 m telescope. The light curve looks promising both for a precise Porb (or Pphot) measurement, and a detection of rapid WD pulsations. This is a star I've long wanted to do (a peachy candidate for a "period bouncer"), but never managed to - overly seduced by trying to finish the winter stars before midnight, and start the summer stars after. I still dunno how much time we can devote to it, but it should be a GREAT, if somewhat challenging, target for CBA coverage. That's QZ Lib, not QZ Vir - which is itself pretty confusing, since it's an alias for the famous T Leo, credited as the first dwarf nova ever observed! QZ Lib is about 17.5 and the light curve is pretty quiet, since it's a very intrinsically faint star - just a little bit more than a bare white dwarf. joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Fri May 23 05:44:27 2014 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 23 May 2014 05:44:27 -0400 Subject: (cba:news) Fwd: (cba:chat) V418 Ser, a new ultra-short period DNe? AM CVn type? In-Reply-To: <2FB561B3-03CF-4FC7-BC45-AB646E30CEAF@gmail.com> References: <2FB561B3-03CF-4FC7-BC45-AB646E30CEAF@gmail.com> Message-ID: <537F187B.3020309@astro.columbia.edu> GREAT target for follow-up tonight, and likely all subsequent nights during the outburst! joe -------- Original Message -------- Return-Path: Received: Delivered-To: cba-chat at cbastro.org CRTS detected this object in outburst on May 21 at 15.6 mag (link to the CRTS light curve below) http://nesssi.cacr.caltech.edu/catalina/20010321/103211010824100533p.html No much seems to be known about this object (type UG in VSX; no clue about its periodicities). From the CRTS light curve, outbursts are not infrequent. I've been with this target tonight and the light curve shows a 64-min signal (light curve attached). An ultra-short period DNe? An AM CVn-type star? From inspection of the light curve in Rykoff et al. (2004) IBVS 5559, this eruption is probably fresh and may last another 7-10 days Enrique ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/