Southeastern Association for Research in Astronomy SARA OBSERVING TIME Information for Scheduling Observing Time _______________________________________________________________ 1) Program Information: PROGRAM TITLE: Time-Resolved Photometry of Close Binaries with Compact Components Scientific Category (listed below) #___2_______ (1) Solar System Objects (6) SN Remnants, X-ray sources, (2) Stars-Individual, Binaries, Pulsars Cluster Members (7) QSOs, Active Galaxies (3) Galactic Structure (8) Structure & Dynamics (4) Gaseous Nebulae, Interstellar Galaxies Matter (9) Large Scale Structure, (5) Star Formation Cosmology (10) Standardization & Miscellaneous Brief Description of Project: See below 2) PRINCIPAL OBSERVER SECOND OBSERVER THIRD OBSERVER Name: Fred Ringwald Student 1 Student 2 e-mail address: ringwald@astro.fit.edu - - SARA Member (y/n): y n n DATE THIS FORM IS SUBMITTED: 1999 September 7 3) SCHEDULING INFORMATION - OBSERVING RUNS REQUESTED FOR THIS PROJECT ______________________________________________________________________ | Run| Instrument(s)| #Nights | #Days | Range of | Other | | | | | | Preferred | Acceptable| | | | | | Dates | Dates | |____|______________|_________|________|_________________|____________| | | | | | | | | 1 | CCD | ** | | Thursdays & | Any | | | | | | Fridays | | |____|______________|_________|________|_________________|____________| 4) Dates you cannot use for non-astronomical reasons: None. 5) Telescope, auxiliary equipment, and special requirements. If you seek, or are providing, any special instrument or software support, please attach a page with details. Remote observations will be essential: I want to invite students from my observational astronomy class on Thursdays and Fridays nights to sit up with me. (But not use the telesope themselves!) Need to bin the CCD, to ameliorate data storage problems and to improve time resolution. 6) SUBMIT TO: Fred Ringwald by e-mail: ringwald@astro.fit.edu ======================================================================= Description of Projects: I wish to carry out several projects to obtain time-resolved photometry of close binary systems with compact components. In all, the objective is to search for variability on timescales hours or minutes, with amplitudes in V-band photometry of tenths of magnitudes. These projects will lend themselves well to remote observing, since relatively little slewing, setting, or, indeed, any action aside from reading out the CCD is required. Indeed, this type of program will serve as a useful shakedown for eventual operations when fully robotic. More importantly for the immediate future, I wish to observe on Thursday and Friday nights, and invite my sophomore Observational Astronomy (SPS 2010) students to sit up with me, two or three at a time, throughout the semester---much as we did with the REUs last summer. The telescope should therefore serve brilliantly as an educational tool, and the science produced will be excellent for those interested in research projects. The science has a simple appeal, too: they can honestly tell their parents they're searching for black holes, something their parents can understand (or at least, think they do). Weather need not be photometric, although this of course would not hurt. Seeing need not be superb, either: the science will come from photometry of point sources. The data stream can be made more manageable by binning the CCD by 4x4, which worked fine last summer. This would improve the time resolution of the observations, too. However, since these are time-resolved programs, it would definitely help if they were scheduled within a month of when these objects cross the Meridian at midnight. Specific projects include: a) Photometric Searches for Black Holes in Old Novae RA(1950) DEC(1950) V Observable Time needed HR Lyr (1919) 18 51 27.7 +29 09 50 16.0 June 6 - Aug 6 4 nights FS Sct (1952) 18 55 37.0 -05 28 11 17.5 June 6 - Aug 6 4 nights V606 Aql (1899) 19 17 50.1 -00 13 41 17.3 June 6 - Aug 6 4 nights V450 Cyg (1942) 20 56 48.2 +35 44 46 16.8 July 7 - Sep 7 4 nights IV Cep (1971) 22 02 46.8 +53 15 48 16.4 July 22 - Sep 22 4 nights DI Lac (1910) 22 33 46.5 +52 27 26 14.9 July 30 - Sep 29 4 nights BC Cas (1929) 23 48 48.7 +60 01 29 17.4 Aug 15 - Oct 15 4 nights DN Gem (1912) 06 51 39.7 +32 12 19 15.8 Dec 1 - Feb 1 4 nights These classical novae had outbursts in the years listed in parentheses. Their decline light curves were not unlike those shown by most soft X-ray transients, which have proved to be black hole binaries. There were of course no astronomical X-ray satellites when these novae erupted, just photography. Might there be black holes lurking here? There were, in several other binaries once though to be "just" old classical novae. One was V404 Cyg, formerly Nova 1938, now known to have a compact object with a mass function of 6 solar masses---incontestably a black hole. I propose to obtain several nights of differential photometry for each object in a campaign similar to that of Thorstensen (1987), when he found the 9.3-hour orital period of 4U 1957+11. This will be to search for coherent waves in the light curve, either from the system's "bright spot" (where the gas stream hits the accretion disk) moving into and out of the field of view, or from "superhumps", or variations from the accretion disk sloshing around, under the influence from the tides a binary with an extreme mass ratio would have. These are also targets for a spectroscopic project I am carrying out with Roger Romani (Stanford) and Rick Hessman (Goettingen) with the 9.2-m Hobby-Eberly Telescope. Discovering coherent photometric variations first would be a huge help to this program: knowing the periods would show how much scarce 9.2-m time we need, to carry out radial velocity studies, to measure the black hole masses. b) What are the sdBpe Stars? The sdBpe stars are stars that have shown up in my catalog (available at http://www.astro.fit.edu/ringwald/comp2.3lis) of detached binaries with hot, high-gravity stars and cool companions. They are apparently hot subdwarfs, but they show emission lines, which hot, high-gravity stars shouldn ot do, hence the "p", for peculiar. They could be any of several things. They might be cataclysmic variables. They might be CV progenitors (like MT Ser), in which the facing hemisphere of the cool star is so heated it raises emission lines. They might be completely enigmatic high-latitude Be stars, like PG 1002+506 (Ringwald et al. 1998, ApJ, 497, 717). The targets include: RA(1950) DEC(1950) V Observable Time needed PG 1524+439 15 24 09.7 +43 51 53 15.6 Mar 15 - Jul 15 2 hours PG 1632+088 16 32 22 +08 46 05 13.4 Mar 29 - Jul 29 2 hours PG 1656+213 16 56 12.4 +21 15 05 15.1 Apr 6 - Aug 6 2 hours PG 1701+359 17 01 35.0 +35 52 56 13.4 Apr 6 - Aug 6 2 hours PG 2200+085 22 00 51.9 +08 31 06 13.8 Oct 1 - Dec 1 2 hours PG 2244+031 22 44 24.7 +03 08 52 16.0 Oct 1 - Dec 1 2 hours KUV 23012+1702 23 01 13.2 +17 01 44 16.0 Oct 1 - Dec 1 2 hours PG 0322+078 03 22 53 +07 49 20 16.0 Oct 1 - Jan 1 2 hours All that needs to be done with any is to follow each for about two hours apiece. Distinguishing the three cases would be easy. CVs would erratically flicker. Pre-CVs should have sinusoidal light curves. High-latitude Be stars will not vary at all. c) Does the Cataclysmic Variable PG 2337+300 have Eclipses? RA(1950) DEC(1950) V Observable Time needed PG 2337+300 06 54 54.4 +32 08 28 15.8 Dec 1 to Feb 1 4 nights PG 2337+300 was discovered to be a CV by Koen and Orosz (1997). This is the only cataclysmic variable that was missed by my study of a complete sample of CVs from the UV-excess Palomar-Green survey (Green, Schmidt, & Liebert 1986); for completeness, I need to check it for eclipses. CVs have orbital periods of several hours, so 2 nights will suffice for this. d) Three candidate V Sge Stars RA(1950) DEC(1950) V Observable Time needed KUV 23061+1229 23 06 04.6 +12 29 24 14.8 Oct 1 to Nov 1 3 nights KUV 23182+1007 23 18 12.8 +10 07 25 16.8 Oct 1 to Nov 1 3 nights KUV 01584-0939 01 58 24.1 -09 39 01 17.1 Oct 1 to Dec 1 3 nights These appear to be spectroscopically similar to V Sge, the enigmatic, peculiar emission-line object perhaps related to CVs, that for years was thought to be one-of-a-kind, until WX Cen was noticed (see Diaz, M. P., & Steiner, J. E. 1995, MNRAS, 277, 959). The He II 4686 emission line is by far the strongest in the spectrum, and is variable over days or faster. Steiner, J. E., & Diaz, M. P. 1998, PASP, 110, 276 point out that V Sge stars may be related to Galactic supersoft X-ray sources, in which steady nuclear burning of accreted gas is taking place on the white dwarf all the time---not unlike a classical nova, but stuck in outburst all the time. KUV 23061+1229 and KUV 01584-0939 are not in the ROSAT Bright Source Catalog, however. New, deeper ROSAT or AXAF pointed observations may be interesting: but they will not happen unless I observe them and find the characteristic double-humped light curves that SSXSs have. These objects have orbital periods that are long, for cataclysmic variables, of 10 to 12 hours. Three nights apiece should therefore suffice to find any periodicities. e) Do These Detached Binaries Show Reflection Effects? RA(1950) DEC(1950) V Observable Time needed PG 1114+187 11 14 25.6 +18 42 21 15.2 Feb 1 to Apr 15 2 nights PG 1119+147 11 19 36.5 +14 42 48 15.9 Feb 1 to Apr 15 2 nights PG 1316+678 13 16 11.8 +67 47 45 16.0 Mar 7 to Apr 30 2 nights All three stars were classified as cataclysmic variables by the Palomar-Green survey. However, a few minutes of time-resolved photometry of each by Misselt and Shafter (1995) showed that they do not flicker, or show the erratic variations that all cataclysmic variables do (which is thought to be from magnetic reconnection and microflaring in their accretion disks, but a definitive solution has never been found). Their spectra look like those of cataclysmic variables, though (Ringwald 1993), with Balmer (and not forbidden) emission lines on blue continua. They could well be cataclysmic variable progenitors, in which a hot subdwarf or white dwarf irradiates a cool companion star, raising emission lines on its facing hemisphere that vary over the phase. This heating often causes significant broadband variability with a characteristic sinusoidal light curve: BE UMa, for example, shows an orbital variation with a 2-magnitude (!) amplitude. I therefore wish to carry out more extensive campaigns on all three objects, to search for reflection effects or other variations. Two nights apiece should suffice for this, since such objects have orbital periods of just a few hours. f) Reflection Effects in Double Degenerates White dwarf stars with white dwarf companions are the current favorite candidates for Type Ia supernova progenitors. Creating them constrains common envelope evolution, the physics of which are poorly understood. Finding their masses would yield gravitational redshifts and GR tests. Their orbital periods are unknown, but can be as short as 1 minute. It is not known whether these systems are detached or semi-detached, and transferring matter. Semi-detached systems are known to have orbital periods between 17 and 40 minutes; in addition to photometric variations with these periods or less, they would have erratic flickering variations. Detached systems would have reflection effects with periods equal to their orbital periods. P(orb) known or suspected: RA(1950) DEC(1950) V Sp.type P(orb)(d) LB 11146 09 45 56.3 +24 35 29 14.32 DXP+DA long? PG 1101+364 11 01 35.3 +36 26 20 14.76B DA 3 0.1445833 GD 231 20 32 58 +18 49.1 15.34 DA3 2-10: GD 251 23 31 51.5 +29 02 06 15.86B DA3 0.167: P(orb) unknown: RA(1950) DEC(1950) V Sp.type Comments WD 0109-264 01 09 47.92 -26 29 22.2 13.13 DD? with He I MCT 0128-3846 01 28 14.4 -38 46 06 15.32 DAB G 4-34 02 39 26 +10 59.9 16.1B DA+DC WD 0346-011 03 46.3 -01 07 14.05 DD? MCT 0453-2933 04 53 38.5 -29 33 41 15.12 DAB WD 0839-327 08 39 35.9 -32 46 55 12.00 DD? WD 0940+068 09 40 16.4 +06 49 23 13.34B DD? PG 1022+050 10 22 24.1 +05 01 27 14.18 DD? G 62-46 13 30 17 +01 32.7 17.11 DA+DC GD 387 20 03 59 +43 45.7 16.0B DA+DC GD 402 22 16.8 +48 24 16.0B DA+DC =======================================================================