J/AJ/144/81 Spectroscopy and photometry of CV candidates (Thorstensen+, 2012)
Spectroscopy and photometry of cataclysmic variable candidates from the Catalina
Real Time Survey.
Thorstensen J.R., Skinner J.N.
<Astron. J., 144, 81 (2012)>
=2012AJ....144...81T 2012AJ....144...81T
ADC_Keywords: Binaries, cataclysmic ; Novae ; Photometry, UBVRI ;
Equivalent widths ; Radial velocities
Keywords: binaries: close - stars: dwarf novae - surveys
Abstract:
The Catalina Real Time Survey (CRTS) has found over 500 cataclysmic
variable (CV) candidates, most of which were previously unknown. We
report here on follow-up spectroscopy of 36 of the brighter objects.
Nearly all of the spectra are typical of CVs at minimum light. One
object appears to be a flare star, while another has a spectrum
consistent with a CV but lies, intriguingly, at the center of a small
nebulosity. We measured orbital periods for eight of the CVs, and
estimated distances for two based on the spectra of their secondary
stars. In addition to the spectra, we obtained direct imaging for an
overlapping sample of 37 objects, for which we give magnitudes and
colors. Most of our new orbital periods are shortward of the so-called
period gap from roughly 2 to 3hr. By considering the
cross-identifications between the Catalina objects and other catalogs
such as the Sloan Digital Sky Survey, we argue that a large number of
CVs remain uncataloged. By comparing the CRTS sample to lists of
previously known CVs that CRTS does not recover, we find that the CRTS
is biased toward large outburst amplitudes (and hence shorter orbital
periods). We speculate that this is a consequence of the survey
cadence.
Description:
The Catalina Real Time Survey (CRTS) maintains a catalog of
"Confirmed/Likely" cataclysmic variables (CVs) on the World Wide Web
(http://nesssi.cacr.caltech.edu/catalina/AllCV.html). We downloaded
this catalog on 2012 March 7, when it contained 584 objects, and used
this data set for the present analysis.
All our data are from MDM Observatory on Kitt Peak, Arizona. Nearly
all are from the 2.4m Hiltner telescope, but a single photometric
measurement was kindly taken by J. Halpern at the 1.3m McGraw-Hill
telescope.
For most of the spectra we used the modular spectrograph. The detector
was either "Templeton" a 10242 thinned SITe that gave 2Å/pixel from
4600 to 6700Å, or "Nellie", a thick 20482 CCD that gave 1.7Å/pixel
from 4460 to 7770Å. All of our radial velocity time series were taken
with the modular spectrograph.
For the other spectra, we used the Ohio State Multi-Object
Spectrograph (OSMOS). This versatile instrument images the focal plane
onto a 4k*4k CCD. We used the "inner" slit, which gives coverage from
3960 to 6875Å. We inserted a V filter for the acquisition exposures, and
therefore obtained a rough V magnitude (without a color transformation) for
our targets.
For direct imaging, we mostly used the "Nelie" CCD, which gave
0.24Å/pixel. This detector is insensitive in the ultraviolet, so we
used BVRI filters (although R and B were sometimes slipped).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 56 56 List of the observed objects
table2.dat 52 36 Summary of spectroscopy
table3.dat 37 303 Radial Velocities
table4.dat 67 12 Fits to radial velocities
table5.dat 58 49 Standardized magnitudes
table6.dat 29 285 SDSS classifications and cross-match
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See also:
B/cb : Cataclysmic Binaries, LMXBs, and related objects (Ritter+, 2013)
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
V/123 : Catalog of Cataclysmic Variables (Downes+ 2001-2006)
J/MNRAS/421/2414 : Faint cataclysmic variables from SDSS (Woudt+, 2012)
J/AJ/142/181 : CVs from SDSS. VIII. The final year (Szkody+, 2011)
J/ApJ/696/870 : Catalina Real-time Transient Survey (CRTS) (Drake+, 2009)
J/AJ/134/185 : Cataclysmic variables from SDSS-DR5 (Szkody+, 2007)
http://crts.caltech.edu/ : Catalina Real Time Survey (CRTS)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [CSS]
4- 23 A20 --- CRTS Catalina Real Time Survey (CRTS) name (encodes
the date of outburst before the colon, and the
J2000 celestial coordinates after the colon)
25 A1 --- f_CRTS [b] CSS2029-15 has been named SY Cap
27- 29 A3 --- --- ---
30- 36 A7 --- CSS Cataclysmic variable identifier (JHHMM+DD)
38- 39 I2 --- No [0/15] Number of outbursts (from a perusal of
light curves; see Section 5.2 for more details)
41 A1 --- n_No [a] CSS1219-19 shows a secular increase from
m∼19.5 to m∼17.5, with short-term variability,
but no clearly defined outbursts
43- 46 F4.1 mag mMax Magnitude at maximum from CRTS
48- 51 F4.1 mag mMin Magnitude at minimum from CRTS
53- 54 I2 --- Ns [1/52]? Total number of spectra obtained
56 I1 --- Ni [1/8]? Total number of direct images obtained
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [CSS]
4- 10 A7 --- CSS Catalina Survey Cataclysmic variable identifier
12- 18 F7.2 d JD Observation Julian Date; JD-2450000 (1)
20- 23 I4 d JD2 ? 2nd observation Julian Date; JD-2450000
25 A1 --- f_JD2 [e] CSS1055+09 was observed on two nights
27- 28 A2 --- In Instrument (MN=Modular spectrograph with
detector Nellie; MT=Modular spectrograph with
detector Templeton; OS=OSMOS, Ohio State
Multi-Object Spectrograph)
30- 34 I5 s Exp Exposure time
36- 39 F4.1 mag Vmag ? V magnitudes synthetized from the spectrum
(they are ideally good to ±0.2mag, but larger
errors are possible because of clouds and seeing)
41 A1 --- f_Vmag [d] magnitudes could not be synthesized for the
spectra of CSS2213+17 and CSS2227+28 because of
condensation on the detector window
43- 47 F5.1 0.1nm EWHa Hα equivalent width (positive for emission)
49- 52 A4 --- f_EWHa Flag on EWHa (2)
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Note (1): Times for single visits are given to the hundredth; times given
to the nearest day are averages for multi-night observations.
Note (2): Flag on equivalent widths as follows:
: = Uncertainty flag;
a = CSS0350+35 appears to be a dMe star (see Section 3 for further details);
b = These objects appeared to be in outburst or are possibly novalike
variables;
c = See section 3, the note concerning the cataclysmic variable CSS0545+02.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [CSS]
4- 10 A7 --- CSS Catalina Survey Cataclysmic variable identifier
12- 21 F10.4 d HJD Heliocentric Julian Date of mid-exposure in
UTC time system; HJD-2400000
23- 26 I4 km/s RVa ? Absorption line radial velocity
28- 29 I2 km/s e_RVa ? The 1σ error in RVa
31- 34 I4 km/s RVe ? Emission line radial velocity
36- 37 I2 km/s e_RVe ? The 1σ error in RVe
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [CSS]
4- 10 A7 --- CSS Catalina Survey Cataclysmic variable identifier
12- 15 A4 --- Spec Spectra (emn=emission, absn=absorption,
comb=combined)
17- 26 F10.4 d T0 ? Heliocentric Julian Date; HJD-2400000 (the
epoch is chosen to be near the center of the
time interval covered by the data, and within
one cycle of an actual observation) (1)
28- 32 F5.4 d e_T0 ? Uncertainty in T0
34- 40 F7.5 d Per Period (1)
42- 47 F6.5 d e_Per Uncertainty in Per
49- 51 I3 km/s K ? Ksin parameter (1)
53- 54 I2 km/s e_K ? Uncertainty in K
56- 58 I3 km/s y ? γ parameter (1)
60- 61 I2 km/s e_y ? Uncertainty in y
63- 64 I2 --- N ? Number of spectra used
66- 67 I2 km/s rms ? rms residual of the fit (σ)
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Note (1): Of least-squares sinusoid fits to the radial velocities, of the form
v(t)=γ+K[2π(t-T0)/Per].
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [CSS]
4- 10 A7 --- CSS Cataclysmic variable identifier
12- 19 A8 d JD Observation Julian Date; JD-2450000
21- 25 F5.2 mag B-V ? The (B-V) color index
27- 29 F3.2 mag e_B-V ? Statistical uncertainty in B-V (1)
31- 35 F5.2 mag Vmag V magnitude
37- 39 F3.2 mag e_Vmag Statistical uncertainty in Vmag (1)
41- 45 F5.2 mag V-R ? The (V-R) color index
47- 49 F3.2 mag e_V-R ? Statistical uncertainty in V-R (1)
51- 54 F4.2 mag V-I ? The (V-I) color index
56- 58 F3.2 mag e_V-I ? Statistical uncertainty in V-I (1)
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Note (1): When the uncertainty exceed ∼0.1mag, the value should be considered
somewhat unreliable.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- SDSS SDSS identifier of the cataclysmic variable;
(JHHMMSS.ss+DDMMSS.s)
20 I1 --- r_SDSS Reference (paper number in the SzkodyI-VIII
series in which the object was published) (1)
22- 24 A3 --- CRTS Object also found by Catalina Real Time
Survey (CRTS)? (Yes or No)
26- 29 A4 --- Type Estimate of the cataclysmic variable type (2)
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Note (1): Paper in the SzkodyI-VIII series as follows:
1 = Szkody et al., 2002AJ....123..430S 2002AJ....123..430S;
2 = Szkody et al., 2003AJ....126.1499S 2003AJ....126.1499S;
3 = Szkody et al., 2004AJ....128.1882S 2004AJ....128.1882S;
4 = Szkody et al., 2005AJ....129.2386S 2005AJ....129.2386S;
5 = Szkody et al., 2006AJ....131..973S 2006AJ....131..973S;
6 = Szkody et al., 2007, Cat. J/AJ/134/185;
7 = Szkody et al., 2009AJ....137.4011S 2009AJ....137.4011S;
8 = Szkody et al., 2011, Cat. J/AJ/142/181.
Note (2): Classification scheme as follows:
AM = These objects showed HeII λ4686 similar in strength to Hβ,
or other evidence of a strong magnetic field such as cyclotron humps.
DN = Objects known to be dwarf novae, or objects whose spectra resemble those
of dwarf novae. The spectra classified this way tended to have strong,
broad Balmer emission (with Hα equivalent width usually greater
than 30Å), relatively flat disk continua (in Fλ versus
λ), and weak or absent HeII λ4686;
DN-W = DN objects showing blue continua and white dwarf absorption wings
around Hβ;
DN-2 = DN objects with a K- or M-type secondary;
NCV = We assigned 14 objects to this "non-cataclysmic variable" class. This
heterogeneous group includes objects whose spectra resembled reflection-
effect white dwarf systems, subdwarf B stars, and chromospherically
active M dwarfs. One, SDSS J1023+00, has proven to be a binary
containing a millisecond radio pulsar
(Archibald et al., 2009Sci...324.1411A 2009Sci...324.1411A; Wang et al.,2009ApJ...703.2017W 2009ApJ...703.2017W;
Thorstensen & Armstrong, 2005AJ....130..759T 2005AJ....130..759T);
NL = This class included spectra showing blue continua, without white dwarf
absorption, and relatively weak emission lines, or stronger emission
lines and substantial HeII λ4686 (typically half the strength of
Hβ in those cases). The Balmer absorption wings in a novalike
variable can superficially resemble white dwarf absorption, but with
experience the distinctive white dwarf line profile can usually be
distinguished from the disk absorption lines seen in UX-UMa type
variables;
PEC = Peculiar.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 14-Oct-2013