Publications (93)
Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae. IV: The Fourth Year (2011-2012)
Taichi Kato, Franz-Josef Hambsch, Hiroyuki Maehara +85
Continuing the project described by Kato et al. (2009, arXiv:0905.1757), we studied 86 SU UMa-type dwarf novae. We confirmed the general trends such as the relation between period…
The Probable Direct-Imaging Detection of the Stellar Companion to Betelgeuse
Steve B. Howell, David R. Ciardi, Catherine A. Clark +3
Betelgeuse -- the closest M-supergiant to the Sun -- has recently been predicted to host a lower-mass stellar companion that orbits the primary with a period of years. The…
Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae. VII: The Seventh Year (2014-2015)
Taichi Kato, Franz-Josef Hambsch, Pavol A. Dubovsky +89
Continuing the project described by Kato et al. (2009, arXiv:0905.1757), we collected times of superhump maxima for 102 SU UMa-type dwarf novae observed mainly during the 2014-2015…
PM J03338+3320: Long-Period Superhumps in Growing Phase Following a Separate Precursor Outburst
Taichi Kato, Enrique de Miguel, William Stein +12
We observed the first-ever recorded outburst of PM J03338+3320, the cataclysmic variable selected by proper-motion survey. The outburst was composed of a precursor and the main sup…
VaTEST II: Statistical Validation of 11 TESS-Detected Exoplanets Orbiting K-type Stars
Priyashkumar Mistry, Kamlesh Pathak, Aniket Prasad +48
NASA's Transiting Exoplanet Survey Satellite (TESS) is an all-sky survey mission designed to find transiting exoplanets orbiting nearby bright stars. It has identified more than 32…
Return of the King: Time-Series Photometry of FO Aquarii's Initial Recovery from its Unprecedented 2016 Low State
Colin Littlefield, Peter Garnavich, Mark R. Kennedy +28
In 2016 May, the intermediate polar FO~Aqr was detected in a low state for the first time in its observational history. We report time-resolved photometry of the system during its…
The Rise and Fall of the King: The Correlation between FO Aquarii's Low States and the White Dwarf's Spindown
Colin Littlefield, Peter Garnavich, Mark R. Kennedy +45
The intermediate polar FO Aquarii (FO Aqr) experienced its first-reported low-accretion states in 2016, 2017, and 2018, and using newly available photographic plates, we identify p…
The Intriguing Polar EU Cancri in the Eyes of Kepler K2
Katherine Hill, Colin Littlefield, Peter Garnavich +1
We present the light curve of EU Cnc, the first published analysis of a Kepler light curve of a polar. Although EU Cnc was extremely faint during campaign 16 and 18 its light curve…
Study of Negative and Positive Superhumps in ER Ursae Majoris
Tomohito Ohshima, Taichi Kato, Elena Pavlenko +45
We carried out the photometric observations of the SU UMa-type dwarf nova ER UMa during 2011 and 2012, which showed the existence of persistent negative superhumps even during the…
A transiting giant planet in orbit around a 0.2-solar-mass host star
Edward M. Bryant, Andrés Jordán, Joel D. Hartman +56
Planet formation models suggest that the formation of giant planets is significantly harder around low-mass stars, due to the scaling of protoplanetary disc masses with stellar mas…
A magnetic valve at L1 revealed in TESS photometry of the asynchronous polar BY Cam
Paul A. Mason, Colin Littlefield, Lorena C. Monroy +7
We present TESS photometry of the asynchronous polar BY Cam, which undergoes a beat-cycle between the 199.384-min white dwarf (WD) spin period and the 201.244-min orbital period. T…
Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae. III: The Third Year (2010--2011)
Taichi Kato, Hiroyuki Maehara, Ian Miller +75
Continuing the project described by Kato et al. (2009, PASJ 61, S395, arXiv:0905.1757), we collected times of superhump maxima for 51 SU UMa-type dwarf novae mainly observed during…
Classifying optical (out)bursts in cataclysmic variables: the distinct observational characteristics of dwarf novae, micronovae, stellar flares and magnetic gating
Krystian Ilkiewicz, Simone Scaringi, Martina Veresvarska +5
Cataclysmic variables can experience short optical brightenings, which are commonly attributed to phenomena such as dwarf novae outbursts, micronovae, donor flares or magnetic gati…
A 43 day transiting Neptune and two 25 day Saturns from TESS, NGTS and ASTEP
Alicia Kendall, Solène Ulmer-Moll, Samuel Gill +53
Beyond orbital periods of 10 days, there is a dearth of known transiting gas giants. On longer orbits, planets are less affected by their host star, and become ideal probes of plan…
Visual Orbits & Alignments of Planet Hosting Binary Systems
Kathryn Lester, Steve Howell, Rachel Matson +7
Roughly half of Solar-type planet hosts have stellar companions, so understanding how these binary companions affect the formation and evolution of planets is an important componen…
An Improved Spin-Down Rate for the Proposed White-Dwarf Pulsar AR Scorpii
Yadira Gaibor, Peter Garnavich, Colin Littlefield +2
We analyze rapid-cadence, multiwavelength photometry of AR Scorpii from three observatories, covering five observing seasons. We measure the arrival times of the system's beat puls…
An Eccentric Planet Orbiting the Polar V808 Aurigae
McKenna Leichty, Peter Garnavich, Colin Littlefield +4
We analyze 15 years of eclipse timings of the polar V808 Aur. The rapid ingress/egress of the white dwarf and bright accretion region provide timings as precise as a few tenths of…
Paving the Road to the Habitable Worlds Observatory with High-Resolution Imaging I: New and Archival Speckle Observations of Potential HWO Target Stars
Zachary D. Hartman, Catherine A. Clark, Michael B. Lund +15
One of the key goals of the Habitable Worlds Observatory (HWO) is to directly image about 25 potentially habitable exoplanets and determine their properties. This challenge will re…
Confirmation of a Second Propeller: A High-Inclination Twin of AE~Aquarii
Peter Garnavich, Colin Littlefield, R. M. Wagner +4
For decades, AE Aquarii (AE Aqr) has been the only cataclysmic variable star known to contain a magnetic propeller: a persistent outflow whose expulsion from the binary is powered…
A Refined Orbital Ephemeris for the Intermediate Polar FO Aquarii and Evidence for a Period Derivative
Peter Garnavich, Jordan Tweddale, Colin Littlefield
We combine more than 40 years of eclipse timings of the intermediate polar FO Aqr and derive new orbital ephemerides. The eclipse times are best fit with a second order polynomial,…
HIP 33609 b: An Eccentric Brown Dwarf Transiting a V=7.3 Rapidly Rotating B-Star
Noah Vowell, Joseph E. Rodriguez, Samuel N. Quinn +41
We present the discovery and characterization of HIP 33609 b, a transiting warm brown dwarf orbiting a late B star, discovered by NASA's Transiting Exoplanet Survey Satellite TESS…
Superoutburst of WZ Sge-type Dwarf Nova Below the Period Minimum: ASASSN-15po
Kosuke Namekata, Keisuke Isogai, Taichi Kato +38
We report on a superoutburst of a WZ Sge-type dwarf nova (DN), ASASSN-15po. The light curve showed the main superoutburst and multiple rebrightenings. In this outburst, we observed…
Three low-mass companions around aged stars discovered by TESS
Zitao Lin, Tianjun Gan, Sharon X. Wang +42
We report the discovery of three transiting low-mass companions to aged stars: a brown dwarf (TOI-2336b) and two objects near the hydrogen burning mass limit (TOI-1608b and TOI-252…
TESS light curves of two new magnetic cataclysmic variables: an asynchronous polar at the period minimum, and an eclipsing system with a large spin-to-orbit ratio
Colin Littlefield, Krystian Ilkiewicz, Paul A. Mason +2
A recent development in the study of magnetic cataclysmic variable stars (mCVs) has been the identification of asynchronously spinning mCVs with orbital periods <2 h that have sign…
Migration and Evolution of giant ExoPlanets (MEEP) I: Nine Newly Confirmed Hot Jupiters from the TESS Mission
Jack Schulte, Joseph E. Rodriguez, Allyson Bieryla +72
Hot Jupiters were many of the first exoplanets discovered in the 1990s, but in the decades since their discovery, the mysteries surrounding their origins remain. Here, we present n…
An Improved Orbital Period for GY Cancri Based on Two K2 Campaigns
Luis Alberto Canizares, Peter Garnavich, Colin Littlefield +4
GY Cnc is a deeply eclipsing cataclysmic variable star with an orbital period of 4.21 hours that has shown several dwarf nova outbursts. The variable was continuously observed by t…
Nearly a Decade of Groundbreaking Speckle Interferometry at the International Gemini Observatory
Steve B. Howell, Clara E. MartÃnez-Vázquez, Elise Furlan +8
Since its inception, speckle interferometry has revolutionized high-resolution astronomical imaging, overcoming atmospheric challenges to achieve the diffraction limits of telescop…
Validation of TESS Planet Candidates with Multi-Color Transit Photometry and TRICERATOPS+
Jonathan Gomez Barrientos, Michael Greklek-McKeon, Heather A. Knutson +33
We present an upgraded version of TRICERATOPS, a software package designed to calculate false positive probabilities for planet candidates identified by the Transiting Exoplanet Su…
HST Observations of the CV Propeller LAMOST J024048.51+195226.9
Jordan Tweddale, Peter Garnavich, Colin Littlefield +1
We present Hubble Space Telescope (HST) FUV spectra and light curves of the magnetic cataclysmic variable (CV) LAMOST J024048.51+195226.9 (J0240), the second known CV propeller. Th…
Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae. X: The Tenth Year (2017)
Taichi Kato, Keisuke Isogai, Yasuyuki Wakamatsu +67
Continuing the project described by Kato et al. (2009, PASJ, 61, S395, arXiv/0905.1757), we collected times of superhump maxima for 102 SU UMa-type dwarf novae observed mainly duri…
TOI-4562 b: A highly eccentric temperate Jupiter analog orbiting a young field star
Alexis Heitzmann, George Zhou, Samuel N. Quinn +47
We report the discovery of TOI-4562 b (TIC-349576261), a Jovian planet orbiting a young F7V-type star, younger than the Praesepe/Hyades clusters (< Myr). This planet stands o…
High-Amplitude, Rapid Photometric Variation of the New Polar MASTER OT J132104.04+560957.8
Colin Littlefield, Peter Garnavich, Katrina Magno +4
We present photometric and spectroscopic observations of the cataclysmic variable MASTER OT J132104.04+560957.8 which strongly indicate that it is a polar with an orbital period of…
Kepler K2 and TESS observations of two magnetic cataclysmic variables: The new asynchronous polar SDSS J084617.11+245344.1 and Paloma
Colin Littlefield, D. W. Hoard, Peter Garnavich +7
There have been relatively few published long-duration, uninterrupted light curves of magnetic cataclysmic variable stars in which the accreting white dwarf's rotational frequency…
Superoutburst of SDSS J090221.35+381941.9: First Measurement of Mass Ratio in an AM CVn-Type Object using Growing Superhumps
Taichi Kato, Tomohito Ohshima, Denis Denisenko +36
We report on a superoutburst of the AM CVn-type object SDSS J090221.35+381941.9 [J0902; orbital period 0.03355(6) d] in 2014 March-April. The entire outburst consisted of a precurs…
Hitting a New Low: The Unique 28 h Cessation of Accretion in the TESS Light Curve of YY Dra (DO Dra)
Katherine L. Hill, Colin Littlefield, Peter Garnavich +6
We present the Transiting Exoplanet Surveying Satellite (TESS) light curve of the intermediate polar YY Draconis (YY Dra, also known as DO Dra). The power spectrum indicates that w…
Driving the Beat: Time-Resolved Spectra of the White Dwarf Pulsar AR Scorpii
Peter Garnavich, Colin Littlefield, Stella Kafka +4
We obtained high temporal resolution spectroscopy of the unusual binary system AR Sco covering nearly an orbit. The H emission shows a complex line structure similar to that se…
OT J002656.6+284933 (CSS101212:002657+284933): An SU UMa-Type Dwarf Nova with Longest Superhump Period
Taichi Kato, Tamas Tordai, Colin Littlefield +17
We observed the 2016 outburst of OT J002656.6+284933 (CSS101212:002657+284933) and found that it has the longest recorded [0.13225(1) d in average] superhumps among SU UMa-type dwa…
Periodic Variations in the Residual Eclipse Flux and Eclipse Timings of Asynchronous Polar V1432 Aql: Evidence of a Shifting Threading Region
Colin Littlefield, Koji Mukai, Ryan Cain +8
We report the results of a twenty-eight-month photometric campaign studying V1432 Aql, the only known eclipsing, asynchronous polar. Our data show that both the residual eclipse fl…
NGTS-28Ab: A short period transiting brown dwarf
Beth A. Henderson, Sarah L. Casewell, Michael R. Goad +43
We report the discovery of a brown dwarf orbiting a M1 host star. We first identified the brown dwarf within the Next Generation Transit Survey data, with supporting observations f…
SDSS J134441.83+204408.3: A highly asynchronous, short-period magnetic cataclysmic variable with a 56 MG field strength
Colin Littlefield, Paul A. Mason, Peter Garnavich +6
When the accreting white dwarf in a magnetic cataclysmic variable star (mCV) has a field strength in excess of 10 MG, it is expected to synchronize its rotational frequency to the…
Investigating the low-flux states in six Intermediate Polars
Ava E. Covington, Aarran W. Shaw, Koji Mukai +30
We present optical photometry of six intermediate polars that exhibit transitions to a low-flux state. For four of these systems, DW Cnc, V515 And, V1223 Sgr and RX J2133.7+5107, w…
Two Earth-size Planets and an Earth-size Candidate Transiting the Nearby Star HD 101581
Michelle Kunimoto, Zifan Lin, Sarah Millholland +43
We report the validation of multiple planets transiting the nearby ( pc) K5V dwarf HD 101581 (GJ 435, TOI-6276, TIC 397362481). The system consists of at least two Earth-…
Superoutburst of CR Bootis: Estimation of Mass Ratio of a typical AM CVn star by Stage A Superhumps
Keisuke Isogai, Taichi Kato, Tomohito Ohshima +31
We report on two superoutbursts of the AM CVn-type object CR Boo in 2014 April--March and 2015 May--June. A precursor outburst acompanied both of these superoutbursts. During the r…
High-Resolution Imaging of a TESS Control Sample: Verifying a Deficit of Close-In Stellar Companions to Exoplanet Host Stars
Colin Littlefield, Steve B. Howell, David R. Ciardi +6
The large number of exoplanets discovered with the Transiting Exoplanet Survey Satellite (TESS) means that any observational biases from TESS could influence the derived stellar mu…
On the Nature of Long-Period Dwarf Novae with Rare and Low-Amplitude Outbursts
Mariko Kimura, Taichi Kato, Hiroyuki Maehara +35
There are several peculiar long-period dwarf-nova like objects, which show rare, low-amplitude outbursts with highly ionized emission lines. 1SWASP J162117441254, BD Pav, and V3…
Identification of Orbital Eclipses in LAMOST J024048.51+195226.9, a Candidate AE Aqr-type Cataclysmic Variable Star
Colin Littlefield, Peter Garnavich
AE Aqr objects are a class of cataclysmic variable stars in which the rapidly rotating magnetosphere of the white dwarf (WD) primary centrifugally expels most infalling gas before…
Exploring the tilted accretion disc of AQ Men with TESS
Krystian Ilkiewicz, Simone Scaringi, James M. C. Court +8
AQ Men is a nova-like variable which is presumed to have a tilted, precessing accretion disc. Grazing eclipses in this system have been speculated to be useful in exploring the geo…
A Pair of Dynamically Interacting Sub-Neptunes Around TOI-6054
Maxwell A. Kroft, Thomas G. Beatty, Ian J. M. Crossfield +31
We confirm the planetary nature of a pair of transiting sub-Neptune exoplanets orbiting the bright F-type sub-giant star TOI-6054 (, ) as a part of the OrCAS radia…
Long-term photometric variations in the candidate white-dwarf pulsar AR Scorpii from K2, CRTS, and ASAS-SN observations
Colin Littlefield, Peter Garnavich, Mark Kennedy +3
We analyze long-cadence Kepler K2 observations of AR Sco from 2014, along with survey photometry obtained between 2005 and 2016 by the Catalina Real-Time Sky Survey and the All-Sky…
Discovery of a Wolf-Rayet Star Through Detection of its Photometric Variability
Colin Littlefield, Peter Garnavich, G. H. Howie Marion +4
We report the serendipitous discovery of a heavily reddened Wolf-Rayet star that we name WR142b. While photometrically monitoring a cataclysmic variable, we detected weak variabili…
Optical outbursts of the cataclysmic variable 1RXS J140429.5+172352
Jeremy Shears, Pavol Dubovsky, Colin Littlefield +5
We present the nine-year light curve of the cataclysmic variable 1RXS J140429.5+172352 from 2005 April to 2014 July. We identified four dwarf nova-like outbursts, which typically l…
EX Draconis: Using Eclipses to Separate Outside-In and Inside-Out Outbursts
James M. C. Court, Simone Scaringi, Colin Littlefield +8
We present a study of the eclipses in the accreting white dwarf EX Dra during TESS Cycles 14 and 15. During both of the two outbursts present in this dataset, the eclipses undergo…
The POKEMON Speckle Survey of Nearby M dwarfs. IV. Distance-Limited Catalog (POKEMON-DLC)
Catherine A. Clark, Zafar Rustamkulov, Gerard T. van Belle +5
The Solar Neighborhood is dominated by stars smaller, colder, and fainter than the Sun: the M dwarfs. If we are to understand the context in which the Sun formed and evolved, then…
A Phenomenon Resembling Early Superhumps in a New SU UMa-Type Dwarf Nova with a 2-Hour Orbital Period
Rebecca Boyle, Colin Littlefield, Peter Garnavich +4
We investigate K2BS5, an optical transient that we identified in Campaign 13 of the Kepler/K2 archives by the "K2 Background Survey", and classify it as a new SU UMa-type dwarf nov…
Repetitive Patterns in Rapid Optical Variations in the Nearby Black-hole Binary V404 Cygni
Mariko Kimura, Keisuke Isogai, Taichi Kato +65
How black holes accrete surrounding matter is a fundamental, yet unsolved question in astrophysics. It is generally believed that matter is absorbed into black holes via accretion…
WZ Sge-type dwarf novae with multiple rebrightenings: MASTER OT J211258.65+242145.4 and MASTER OT J203749.39+552210.3
Chikako Nakata, Tomohito Ohshima, Taichi Kato +25
We report on photometric observations of WZ Sge-type dwarf novae, MASTER OT J211258.65+242145.4 and MASTER OT J203749.39+552210.3 which underwent outbursts in 2012. Early superhump…
Rapid Evolution of the White Dwarf Pulsar AR Scorpii
Peter Garnavich, Stephen B. Potter, David A. H. Buckley +4
Analysis of AR Sco optical light curves spanning nine years show a secular change in the relative amplitudes of the beat pulse pairs generated by the two magnetic poles of its rota…
TOI-1846b: A super-Earth in the radius valley orbiting a nearby M dwarf
Abderahmane Soubkiou, Khalid Barkaoui, Zouhair Benkhaldoun +42
We present the discovery and validation of a super-Earth planet orbiting the M dwarf star TOI-1846 (TIC 198385543). The host star(Kmag = 9.6)is located 47 pc away and has a radius…
A massive hot Jupiter orbiting a metal-rich early-M star discovered in the TESS full frame images
Tianjun Gan, Charles Cadieux, Farbod Jahandar +41
Observations and statistical studies have shown that giant planets are rare around M dwarfs compared with Sun-like stars. The formation mechanism of these extreme systems remains u…
Multicolour Validation of Two Temperate Mini-Neptunes Around M-dwarf Habitable Zones
Chengzi Jiang, Aleksandra Selezneva, Hannu Parviainen +17
For small planets orbiting within the habitable zones of their host stars, multicolour validation via photometric transit observations offers an efficient alternative to prioritize…
Short-cadence K2 observations of an accretion-state transition in the polar Tau 4
Colin Littlefield, Peter Garnavich, Paula Szkody +5
The Kepler spacecraft observed a total of only four AM Herculis cataclysmic variable stars during its lifetime. We analyze the short-cadence K2 light curve of one of those systems,…
Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae. IX: The Ninth Year (2016-2017)
Taichi Kato, Keisuke Isogai, Franz-Josef Hambsch +76
Continuing the project described by Kato et al. (2009, arXiv:0905.1757), we collected times of superhump maxima for 127 SU UMa-type dwarf novae observed mainly during the 2016--201…
V1006 Cygni: Dwarf Nova Showing Three Types of Outbursts and Simulating Some Features of the WZ Sge-Type Behavior
Taichi Kato, Elena P. Pavlenko, Alisa V. Shchurova +17
We observed the 2015 July-August long outburst of V1006 Cyg and established this object to be an SU UMa-type dwarf nova in the period gap. Our observations have confirmed that V100…
Characteristics of the Permanent Superhumps in V533 Herculis
McKenna Leichty, Peter Garnavich, Colin Littlefield +2
We analyze two sectors of TESS photometry of the nova-like cataclysmic variable star V533 Her. We detect a periodicity consistent with the binary orbital period and estimate a revi…
Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae. VI: The Sixth Year (2013-2014)
Taichi Kato, Pavol A. Dubovsky, Igor Kudzej +83
Continuing the project described by Kato et al. (2009, PASJ, 61, S395, arXiv:0905.1757), we collected times of superhump maxima for 56 SU UMa-type dwarf novae mainly observed durin…
An Examination of Possible Gravitational Perturbations in the Transit Timing Variations of Exoplanet WASP-3b
Colin Littlefield
Maciejewski et al. (2010) claim to have detected a possible sinusoidal variation in the transit timing variations of exoplanet WASP-3b, which is currently the only known planet orb…
A 16 Myr super-Neptune in Upper-Centaurus Lupus and a preliminary survey of transiting planets in Sco-Cen with TESS
Sydney Vach, George Zhou, Andrew W. Mann +25
Measuring the properties of planets younger than about 50 Myr helps to test different planetary formation and evolution models. NASA's Transiting Exoplanet Survey Satellite (TESS)…
Optical Variability Correlated with X-ray Spectral Transition in the Black-Hole Transient ASASSN-18ey = MAXI J1820+070
Keito Niijima, Mariko Kimura, Yasuyuki Wakamatsu +49
How a black hole accretes matter and how this process is regulated are fundamental but unsolved questions in astrophysics. In transient black-hole binaries, a lot of mass stored in…
CoronaGraph Instrument Reference stars for Exoplanets (CorGI-REx) I. Preliminary Vetting and Implications for the Roman Coronagraph and Habitable Worlds Observatory
Justin Hom, Schuyler G. Wolff, Catherine A. Clark +28
The upcoming Roman Coronagraph will be the first high-contrast instrument in space capable of high-order wavefront sensing and control technologies, a critical technology demonstra…
Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae. V: The Fifth Year (2012-2013)
Taichi Kato, Franz-Josef Hambsch, Hiroyuki Maehara +84
Continuing the project described by Kato et al. (2009a, arXiv:0905.1757), we collected times of superhump maxima for SU UMa-type dwarf novae mainly observed during the 2012-2013 se…
TESS spots a mini-neptune interior to a hot saturn in the TOI-2000 system
Lizhou Sha, Andrew M. Vanderburg, Chelsea X. Huang +52
Hot jupiters (P < 10 d, M > 60 ) are almost always found alone around their stars, but four out of hundreds known have inner companion planets. These rare compan…
A New Brown Dwarf Orbiting an M star and An Investigation on the Eccentricity Distribution of Transiting Long-Period Brown Dwarfs
Tianjun Gan, Charles Cadieux, Shigeru Ida +32
The orbital eccentricities of brown dwarfs encode valuable information of their formation and evolution history, providing insights into whether they resemble giant planets or stel…
Fast-Cadence TESS Photometry and Doppler Tomography of the Asynchronous Polar CD Ind: A Revised Accretion Geometry from Newly Proposed Spin and Orbital Periods
Colin Littlefield, Peter Garnavich, Koji Mukai +5
The TESS spacecraft observed the asynchronous polar CD Ind at a two-minute cadence almost continuously for 28 days in 2018, covering parts of 5 consecutive cycles of the system's 7…
TOI-7169 b: A Hot Jupiter Transiting a Metal-Poor Star
Joshua D. Simon, Joseph E. Rodriguez, Jhon Yana Galarza +38
Most known planets are found around metal-rich host stars, which has made it difficult to determine whether a lower metallicity limit for planet formation exists and how the proper…
TOI-7166 b: A Habitable Zone mini-Neptune planet around a nearby low-mass star
Khalid Barkaoui, Francisco J. Pozuelos, Benjamin V. Rackham +41
We present the discovery and validation of TOI-7166b, a 2.01+/-0.05R_Earth planet orbiting a nearby low-mass star. We validated the planet by combining TESS and multi-color high-pr…
Peeking Between the Pulses: The Far-UV Spectrum of the Previously Unseen White Dwarf in AR Scorpii
Peter Garnavich, Colin Littlefield, Maxim Lyutikov +1
The compact object in the interacting binary AR Sco has widely been presumed to be a rapidly rotating, magnetized white dwarf (WD), but it has never been detected directly. Isolati…
TOI-6692b: An eccentric 130 day period giant planet with a single transit from TESS
Allyson Bieryla, Karen A. Collins, George Zhou +46
We report the discovery and characterization of TOI-6692 b, an eccentric (e~0.54) Jupiter on a 130-day orbit. TOI-6692 b was first detected as a community TESS Object of Interest (…
Rapid bursts of magnetically gated accretion in the intermediate polar V1025 Cen
Colin Littlefield, Jean-Pierre Lasota, Jean-Marie Hameury +5
Magnetically gated accretion has emerged as a proposed mechanism for producing extremely short, repetitive bursts of accretion onto magnetized white dwarfs in intermediate polars (…
Spectroscopy of the Proposed White Dwarf Pulsar ASASSN-V J205543.90+240033.5
R. Mark Wagner, Peter Garnavich, John R. Thorstensen +2
We obtained spectra of ASASSN-V J205543.90+240033.5 (J2055), a system that shows photometric variations similar to the white dwarf (WD) pulsar AR Scorpii (Kato et al. arXiv:2109.03…
Analysis of a Century's Worth of AR Scorpii Photometry from DASCH and ASAS-SN
Erik Peterson, Colin Littlefield, Peter Garnavich
AR Scorpii (AR Sco) is a binary star system containing the only known white dwarf (WD) pulsar. Previously reported photometric datasets only provide coverage back to 2005, but we e…
Magnetospheric interaction in white dwarf binaries AR Sco and AE Aqr
Maxim Lyutikov, Maxim Barkov, Matthew Route +3
We develop a model of the white dwarf (WD) - red dwarf (RD) binaries AR Sco and AE Aqr as systems in a transient propeller stage of highly asynchronous intermediate polars. The WDs…
Searching for Diamagnetic Blob Accretion in the 74 day K2 Observation of V2400 Ophiuchi
Andrew Langford, Colin Littlefield, Peter Garnavich +3
Since its discovery in 1995, V2400 Ophiuchi (V2400 Oph) has stood apart from most known intermediate polar cataclysmic variables due to its proposed magnetic field strength (9-27 M…
The TOI-1117 Multi-planetary System: 3 sub-Neptunes, 1 in both the Neptunian Desert and Radius Valley
Isobel S. Lockley, David J. Armstrong, Jorge Fernández Fernández +33
We present the discovery of three sub-Neptune planets around TOI-1117, a Sun-like star with mass , radius , age Gyr and ef…
The Intermediate Polar FO Aquarii Has Not Been the Same Since Recovering from a Series of Low States
Peter Garnavich, Colin Littlefield, Rebecca S. Boyle +1
FO Aqr is a bright intermediate polar that has long displayed large amplitude photometric variations corresponding to the 20.9 min spin period of its white dwarf. Between 2016 and…
MASTER OT J132104.04+560957.8: A Polar with Absorption-Emission Line Reversals
Colin Littlefield, Peter Garnavich, Taylor Hoyt +1
We present time-resolved photometry and spectroscopy of the recently classified polar MASTER OT J132104.04+560957.8. The spectrum shows a smooth, non-thermal continuum at the time…
Quasi-periodic oscillations in the TESS light curve of TX Col, a diskless intermediate polar on the precipice of forming an accretion disk
Colin Littlefield, Simone Scaringi, Peter Garnavich +4
One of the fundamental properties of an intermediate polar is the dynamical nature of the accretion flow as it encounters the white dwarf's magnetosphere. Many works have presumed…
Locating the flickering source in polars
Krystian Ilkiewicz, Simone Scaringi, Colin Littlefield +1
Flickering is a fast variability observed in all accreting systems. It has been shown that in most cataclysmic variables flickering originates in the accretion disc. However, in po…
A Comprehensive K2 and Ground-Based Study of CRTS J035905.9+175034, an Eclipsing SU UMa System with a Large Mass Ratio
Colin Littlefield, Peter Garnavich, Mark Kennedy +2
CRTS J035905.9+175034 is the first eclipsing SU UMa system for which a superoutburst has been observed by Kepler in the short-cadence mode. The light curve contains one superoutbur…
The orbital and superhump periods of the deeply eclipsing dwarf nova PU UMa
Jeremy Shears, Franz-Josef Hambsch, Colin Littlefield +5
We report unfiltered photometry during superoutbursts of PU UMa in 2009 and 2012. The amplitude was 4.5 magnitudes above mean quiescence and lasted at least 9 to 10 days. Superhump…
High-Time-Resolution Photometry of AR Scorpii: Confirmation of the White Dwarf's Spin-Down
Robert A. Stiller, Colin Littlefield, Peter Garnavich +3
The unique binary AR Scorpii consists of an asynchronously rotating, magnetized white dwarf (WD) that interacts with its red-dwarf companion to produce a large-amplitude, highly co…
A Catalogue of Orbital Periods of Cataclysmic Variables and Candidates from TESS Observations
Meryem K. DaÄ, Simone Scaringi, Kieran O'Brien +21
We present a systematic analysis of 2544 cataclysmic variable systems and related candidates observed by the Transiting Exoplanet Survey Satellite (TESS), with the aim of compiling…
Migration and Evolution of giant ExoPlanets (MEEP) II: Super-Jupiters and Lithium-rich Host Stars
Jack Schulte, Joseph E. Rodriguez, David W. Latham +30
Although hot Jupiters were the first exoplanets discovered orbiting main sequence stars, the dominant mechanisms through which they form and evolve are not known. To address the qu…
HD 21520 b: a warm sub-Neptune transiting a bright G dwarf
Molly Nies, Ismael Mireles, François Bouchy +49
We report the discovery and validation of HD 21520 b, a transiting planet found with TESS and orbiting a bright G dwarf (V=9.2, K, $R_{\star} = 1.04\pm 0.02…