Models of classical and recurrent novae

The behavior of novae may be divided roughly into two separate stages: quiescence and outburst. However, at closer inspection, both stages cannot be separated. It should be attempted to explain features in both stages with a similar model. Various simple models to explain the observed light and spectral observations during post optical maximum activity are conceivable. In instantaneous ejection models, all or nearly all material is ejected in a time that is short compared with the duration of post optical maximum activity. Instantaneous ejection type 1 models are those where the ejected material is in a fairly thin shell, the thickness of which remains small. In the instantaneous ejection type 2 model ('Hubble Flow'), a thick envelope is ejected instantaneously. This envelope remains thick as different parts have different velocities. Continued ejection models emphasize the importance of winds from the nova after optical maximum. Ejection is supposed to occur from one of the components of the central binary, and one can imagine a general swelling of one of the components, so that something resembling a normal, almost stationary, stellar photosphere is observed after optical maximum. The observed characteristics of recurrent novae in general are rather different from those of classical novae, thus, models for these stars need not be the same

Classical novae and recurrent novae: General properties

We describe the observable characteristics of classical novae and recurrent novae obtained by different techniques (photometry, spectroscopy, and imaging) in all the available spectral ranges. We consider the three stages in the life of a nova: quiescence (pre- and post-outburst), outburst, final decline and nebular phase. We describe the photometric properties during the quiescent phase. We describe the photometric properties during outburst, the classification according the rate of decline (magnitudes per day), which permits us to define very fast, fast, intermediate, slow, and very slow novae and the correlation between luminosity and speed class. We report the scanty data on the spectra of the few known prenovae and those on the spectra of old novae and those of dwarf novae and nova-like, which, however, are almost undistinguishable. We describe the typical spectra appearing from the beginning of the outburst, just before maximum, up to the nebular phase and the correlation between spectral type at maximum, expansional velocity, and speed class of the nova. We report the existing infrared observations, which permit us to explain some of the characteristics of the outburst light curve, and give evidence of the formation of a dust shell in slow and intermediate novae (with the important exception of the very slow nova HR Del 1967) and its absence or quasi-absence in fast novae. The ultraviolet and X-ray observations are described. The X ray observations of novae, mainly from the two satellites EINSTEIN and EXOSAT, are reported. Observations of the final decline and of the envelopes appearing several months after outburst are also reported

Typical examples of classical novae

Because of the very complicated individualistic behavior of each nova, we think it necessary to review the observations of a few well-observed individuals. We have selected a few objects of different speed classes, which have been extensively observed. They are: V1500 Cygni 1975, a very fast nova; V603 Aql 1918, fast nova; CP Pup 1942, fast nova; GK Per 1901, fast nova; V 1668 Cyg 1979, moderately fast nova; FH Ser 1970, slow nova; DQ Her 1934, slow nova; T Aur 1891, slow nova; RR Pic 1925, slow nova; and HR Del 1967, very slow nova

A Catalog and Atlas of Cataclysmic Variables - The Living Edition

The Catalog and Atlas of Cataclysmic Variables (Edition 1 - 1993) and Edition 2 - 1997) has been a valuable source of information for the cataclysmic variable (CV) community. However, the goal of having a central location for all objects is slowly being lost as each new edition is generated. There can also be a long time delay between new information becoming available on an object and its publication in the catalog. To eliminate these concerns, as well as to make the catalog more accessible, we have created a web site which will contain a ``living'' edition of the catalog. We have also added orbital period information, as well as finding charts for novae, to the catalog.Comment: LaTeX, 8 pages, 4 ps-figures, accepted by PAS

A Catalog and Atlas of Cataclysmic Variables: The Final Edition

The Catalog and Atlas of Cataclysmic Variables has been a staple of the CV community for over 10 years. The catalog has grown from 751 CVs in 1993 to 1600 CVs at present. The catalog became a ``living'' edition in 2001, and its contents have been continually updated since that time. Effective 27 January 2006, the catalog will transition to an archival site, with no further updates to its contents. While it is antipicated that the site will remain active, we present the complete contents of the site as a precaution against a loss of the on-line data.Comment: 8 pages, including 6 table

Nova Geminorum 1912 and the Origin of the Idea of Gravitational Lensing

Einstein's early calculations of gravitational lensing, contained in a scratch notebook and dated to the spring of 1912, are reexamined. A hitherto unknown letter by Einstein suggests that he entertained the idea of explaining the phenomenon of new stars by gravitational lensing in the fall of 1915 much more seriously than was previously assumed. A reexamination of the relevant calculations by Einstein shows that, indeed, at least some of them most likely date from early October 1915. But in support of earlier historical interpretation of Einstein's notes, it is argued that the appearance of Nova Geminorum 1912 (DN Gem) in March 1912 may, in fact, provide a relevant context and motivation for Einstein's lensing calculations on the occasion of his first meeting with Erwin Freundlich during a visit in Berlin in April 1912. We also comment on the significance of Einstein's consideration of gravitational lensing in the fall of 1915 for the reconstruction of Einstein's final steps in his path towards general relativity.Comment: 31 p

Optical Imaging of Nova Shells and the Maximum Magnitude-Rate of Decline Relationship

An optical imaging study of recent 30 novae has been undertaken using both ground-based and space-based observations. Resolved shells have been detected around 9 objects in the ground-based data, while another four objects have shells detected by HST observations; for RW UMi, we fail to detect a shell which was observed five years earlier. Images in H-alpha, and when appropriate [O III], are shown, and finding charts for novae without shells are given if no published chart is available. Expansion parallaxes for all systems with shells are derived, and absolute magnitudes for a total of 28 objects are presented, along with a discussion of the maximum magnitude-rate of decline relation. We find that separate linear fits for fast and slow novae may be a better representation of the data than a single, global fit. At minimum, most novae have similar magnitudes as those of dwarf novae at maximum and novalike stars.Comment: 39 pages, 5 ps-figures, 13 jpg-figures. Accepted for publication in the Astronomical Journal (October 2000

Radial Velocity Studies of Southern Close Binary Stars.I

Radial-velocity measurements and sine-curve fits to the orbital velocity variations are presented for nine contact binaries, V1464 Aql, V759 Cen, DE Oct, MW Pav, BQ Phe, EL Aqr, SX Crv, VZ Lib, GR Vir; for the first five among these, our observations are the first available radial velocity data. Among three remaining radial velocity variables, CE Hyi is a known visual binary, while CL Cet and V1084 Sco are suspected to be multiple systems where the contact binary is spectrally dominated by its companion (which itself is a binary in V1084 Sco). Five additional variables, V872 Ara, BD Cap, HIP 69300, BX Ind, V388 Pav, are of unknown type, but most are pulsating stars; we give their mean radial velocities and Vsini.Comment: to appear in AJ October 2006; 3 figure