CBF = | Close binary, full period. These stars are contact or near-contact
eclipsing binaries for which the Fourier fit has found the correct
period and hence fit the primary and secondary eclipses separately;
|
CBH = | Close binary, half period. These stars are contact or near-contact
eclipsing binaries for which the Fourier fit has settled on half the
correct period and hence has overlapped the primary and secondary
eclipses. Physically, the CBF and CBH stars are expected to differ
in that the primary and secondary eclipses are likely to be more
similar in depth in the latter class;
|
DBF = | Distant binary, full period. These stars are detached eclipsing
binaries for which the Fourier fit has found the correct period and
hence fit the primary and secondary eclipses separately;
|
DBH = | Distant binary, half period. These stars are fully detached
eclipsing binaries for which the Fourier fit has settled on half the
correct period and hence has overlapped the primary and secondary
eclipses;
|
IRR/LPV = | The acronyms stand for "long-period" and "irregular" variables.
These classes serve as "catch-all" bins for objects that do not seem
to fit into any of our more specific categories. The LPV class
contains objects whose variations appear to be dominated by low
frequencies, corresponding to P≳5 days, while the IRR class
contains objects whose dominant frequencies are higher. Most of the
stars classified as LPV or IRR (especially the latter) do not show
coherent variations that can be folded cleanly with a single period.
Hence, both classes are in some sense "irregular," though the
characteristic timescales are different. Among the objects that
cannot be cleanly phased to a single period, the LPV class surely
includes many semiregular red giant variables, while the IRR class
has a large number of cataclysmic binaries;
|
MIRA = | Mira variables. These stars are a subset of the LPV's that have
photometric amplitudes exceeding 2.0 mag in either the cyan or
orange filter. They generally show coherent periodicity, but the
two-year temporal baseline of our data may in many cases be
insufficient to solve for the period accurately;
|
MPULSE = | Stars showing modulated pulsation, such that the Fourier fit has
settled on a period double or triple the actual pulsation, in order
to render multiple pulses of different amplitudes or shapes. These
objects could be multimodal or Blazhko-effect stars, or stars
exhibiting some other kind of variability in addition to their
pulsations;
|
MSINE = | Stars showing modulated sinusoids. These are exactly analogous to
the MPULSE stars, except that instead of a classic sawtooth pulse
light curve, the fundamental waveform being modulated is a simple
sinusoid. Thus, MSINE stars may show two, three, four, five, or even
six cycles through the Fourier fit. Each cycle appears to be a good
approximation to a sine wave, but the amplitude and/or mean
magnitude varies from one to the next. Physically, the MSINE stars
may include spotted ellipsoidal variables, rotating stars with
evolving spots, and sinusoidal pulsators such as RR Lyrae (RRC)
stars that have multiple modes or multiple types of variability;
|
NSINE = | Sinusoidal variables with much residual noise or with evidence of
additional variability not captured in the fit. Many spotted
rotators with evolving spots likely fall into this class, as well as
faint or low-amplitude δ Scuti stars and ellipsoidal
variables;
|
PULSE = | Pulsating stars showing the classic sawtooth light curve, regardless
of period. They are expected to include both RR Lyrae and
δ Scuti stars, and some Cepheids. These classes are resolvable
based on period, color, amplitude, and the phase offsets of the
various Fourier terms;
|
SHAV = | These are the slow high-amplitude variables, an extremely rare class
with long periods and Mira-like amplitudes, but with color
insufficiently red for a true Mira. Only 17 of these were identified
in our entire catalog. They include AGNs, R Coronae Borealis stars,
and at least one apparent nova;
|
SINE = | Sinusoidal variables. These stars exhibit simple sine-wave
variability with little residual noise. Ellipsoidal variables likely
dominate this class;
|
STOCH = | These are the variables that do not fit into any coherent periodic
class, not even IRR. They would be classified as "dubious" except
that they have ddcSTAT=1, meaning that detections on the difference
images demonstrate their genuine variability. Their physical nature
is unclear, but many of them do appear to exhibit highly significant
stochastic variations with very little coherence on the timescales
probed by ATLAS;
|
dubious = | Star might not be a real variable.
|