75 research outputs found
Spectroscopy and Photometry of Cataclysmic Variable Candidates from the Catalina Real Time Survey
The Catalina Real Time Survey (CRTS) has found over 500 cataclysmic variable
(CV) candidates, most of which were previously unknown. We report here on
followup spectroscopy of 36 of the brighter objects. Nearly all 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 3
hours. 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 cataclysmic variables remain uncatalogued. 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.Comment: Accepted for publication in The Astronomical Journal. 35 pages,
including 7 figure
Cataclysmic Variables in the SUPERBLINK Proper Motion Survey
We have discovered a new high proper motion cataclysmic variable (CV) in the
SUPERBLINK proper motion survey, which is sensitive to stars with proper
motions greater than 40 mas/yr. This CV was selected for follow-up observations
as part of a larger search for CVs selected based on proper motions and their
NUV-V and V-K colors. We present spectroscopic observations from the 2.4m
Hiltner Telescope at MDM Observatory. The new CV's orbital period is near 96
minutes, its spectrum shows the double-peaked Balmer emission lines
characteristic of quiescent dwarf novae, and its V magnitude is near 18.2.
Additionally, we present a full list of known CVs in the SUPERBLINK catalog.Comment: Accepted for publication in The Astronomical Journal, 22 pages, 6
figure
Optical Studies of Twenty Longer-Period Cataclysmic Binaries
We obtained time-series radial velocity spectroscopy of twenty cataclysmic
variable stars, with the aim of determining orbital periods P_orb. All of the
stars reported here prove to have P_orb > 3.5 h. For sixteen of the stars,
these are the first available period determinations, and for the remaining four
(V709 Cas, AF Cam, V1062 Tau, and RX J2133+51) we use new observations to
improve the accuracy of previously-published periods. Most of the targets are
dwarf novae, without notable idiosyncracies. Of the remainder, three (V709 Cas,
V1062 Tau, and RX J2133+51) are intermediate polars (DQ Her stars); one (IPHAS
0345) is a secondary-dominated system without known outbursts, similar to LY
UMa; one (V1059 Sgr) is an old nova; and two others (V478 Her and V1082 Sgr)
are long-period novalike variables. The stars with new periods are IPHAS 0345
(0.314 d); V344 Ori (0.234 d); VZ Sex (0.149 d); NSVS 1057+09 (0.376 d); V478
Her (0.629 d); V1059 Sgr (0.286 d); V1082 Sgr (0.868 d); FO Aql (0.217 d); V587
Lyr (0.275 d); V792 Cyg (0.297 d); V795 Cyg (0.181 d); V811 Cyg (0.157 d); V542
Cyg (0.182 d); PQ Aql (0.247 d); V516 Cyg (0.171 d); and VZ Aqr(0.161 d).
Noteworthy results on individual stars are as follows. We see no indication of
the underlying white dwarf star in V709 Cas, as has been previously claimed;
based on the non-detection of the secondary star, we argue that the system is
farther away that had been thought and the white dwarf contribution is probably
negligible. V478 Her had been classified as an SU UMa-type dwarf nova, but this
is incompatible with the long orbital period we find. We report the first
secondary-star velocity curve for V1062 Tau. In V542 Cyg, we find a late-type
contribution that remains stationary in radial velocity, yet the system is
unresolved in a direct image, suggesting that it is a hierarchical triple
system.Comment: P.A.S.P., in press. 34 pages and 8 figure
The New Eclipsing Cataclysmic Variable SDSS 154453+2553
The cataclysmic variable SDSS154453+2553 was recently identified in the Sloan
Digital Sky Survey. We obtained spectra and photometry at the MDM Observatory,
which revealed an eclipse with a 6.03 hour period. The H{\alpha} emission line
exhibits a strong rotational disturbance during eclipse, indicating that it
arises in an accretion disk. A contribution from an M-type companion is also
observed. Time-series photometry during eclipse gives an ephemeris of
2454878.0062(15) + 0.251282(2)E. We present spectroscopy through the orbit and
eclipse photometry. Our analysis of the secondary star indicates a distance of
800 {\pm} 180 pc.Comment: 6 pages, 3 figures, Accepted for publication in PAS
Spectroscopic Orbital Periods for 29 Cataclysmic Variables from the Sloan Digital Sky Survey
We report follow-up spectroscopy of 29 cataclysmic variables from the Sloan Digital Sky Survey (SDSS), 22 of which were discovered by SDSS and seven of which are previously known systems that were recovered in SDSS. The periods for 16 of these objects were included in the tabulation by Gänsicke et al. While most of the systems have periods less than 2 hr, only one has a period in the 80–86 minutes spike found by Gänsicke et al., and 11 have periods longer than 3 hr, indicating that the present sample is skewed toward longer-period, higher-luminosity objects. Seven of the objects have spectra resembling dwarf novae, but have apparently never been observed in outburst, suggesting that many cataclysmics with relatively low variability amplitude remain to be discovered. Some of the objects are notable. SDSS J07568+0858 and SDSS J08129+1911 were previously known to have deep eclipses; in addition to spectroscopy, we use archival data from the Catalina Real Time Transient Survey to refine their periods. We give a parallax-based distance of 195 (+54, −39) pc for LV Cnc (SDSS J09197+0857), which at Porb = 81 m has the shortest orbital period in our sample. SDSS J08091+3814 shows both the spectroscopic phase offset and phase-dependent absorption found in SW Sextantis stars. The average spectra of SDSS J08055+0720 and SDSS J16191+1351 show contributions from K-type secondaries, and SDSS J080440+0239 shows a contribution from an early M star. We use these to constrain the distances. SDSS J09459+2922 has characteristics typical of a magnetic system. SDSS11324+6249 may be a novalike variable, and if so, its orbital period (99 minutes) is unusually short for that subclass
Searching for Exosatellites Orbiting L and T Dwarfs: Connecting Planet Formation to Moon Formation and Finding New Temperate Worlds
L-type and T-type dwarfs span the boundaries between main-sequence stars,
brown dwarfs, and planetary-mass objects. For these reasons, L and T dwarfs are
the perfect laboratories for exploring the relationship between planet
formation and moon formation, and evidence suggests they may be swarming with
close-in rocky satellites, though none have been found to date. The discovery
of satellites orbiting L or T dwarfs will have transformative implications for
the nature of planets, moons and even life in the Universe. These transiting
satellites will be prime targets for characterization with NASA's James Webb
Space Telescope. In this white paper, we discuss the scientific motivations
behind searching for transiting satellites orbiting L and T dwarfs and argue
that robotizing current 1-to-2-meter US optical/infrared (O/IR) facilities and
equipping them with recently developed low-cost infrared imagers will enable
these discoveries in the next decade. Furthermore, robotizing the 1-to-2-meter
O/IR fleet is highly synergistic with rapid follow-up of transient and
multi-messenger events.Comment: Science white paper submitted to the Astro 2020 Decadal Survey on
Astronomy and Astrophysic
Searching for exosatellites orbiting L and T dwarfs:connecting planet formation to moon formation and finding new temperate worlds
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