122 citations · 3.4k across the 145 of their papers we have counts for
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Magnetically guided accretion and extremely slow rotation in a metal-enriched white dwarf
S. Bagnulo, M. A. Stroet, C. P. Folsom +3
White dwarfs that show atmospheric metal enrichment offer a direct window into the bulk composition of exoplanetary material and provide some of the most direct constraints on the…
NGTS clusters survey V: Rotation in the Orion Star-forming Complex
Gareth D. Smith, Edward Gillen, Simon T. Hodgkin +16
We present a study of rotation across 30 square degrees of the Orion Star-forming Complex, following a 200 d photometric monitoring campaign by the Next Generation Transit Su…
NGTS clusters survey IV. Search for Dipper stars in the Orion Nebular Cluster
Tyler Moulton, Simon T Hodgkin, Gareth D Smith +13
The dipper is a novel class of young stellar object associated with large drops in flux on the order of 10 to 50 per cent lasting for hours to days. Too significant to arise from i…
LISA Galactic binaries with astrometry from Gaia DR3
Thomas Kupfer, Valeriya Korol, Tyson B. Littenberg +11
Galactic compact binaries with orbital periods shorter than a few hours emit detectable gravitational waves at low frequencies. Their gravitational wave signals can be detected wit…
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…
Short Duration Accretion States of Polars as seen in TESS and ZTF data
C. Duffy, G. Ramsay, Kinwah Wu +4
Polars are highly magnetic cataclysmic variables which have been long observed to have both high and low brightness states. The duration of these states has been previously seen to…
A TESS search for donor-star pulsations in High-Mass X-ray Binaries
Gavin Ramsay, Pasi Hakala, Philip A. Charles
Ground-based optical photometry of the counterparts of High-Mass X-ray Binaries (HMXBs) has revealed the presence of periodic modulations on timescales of ~0.3-0.5 d. More recent s…
Searching for stellar flares from low mass stars using ASKAP and TESS
Jeremy Rigney, Gavin Ramsay, Eoin P. Carley +7
Solar radio emission at low frequencies (<1 GHz) can provide valuable information on processes driving flares and coronal mass ejections (CMEs). Radio emission has been detected fr…
Doubling of minute-long Quasi-Periodic Pulsations from super-flares on a low mass star
J. Gerry Doyle, Puji Irawati, Dmitrii Y. Kolotkov +5
Using the ULTRASPEC instrument mounted on the 2.4-m Thai National Telescope, we observed two large flares, each with a total energy close to 10^34 erg with sub-second cadence. A co…
Circular Polarimetry of Suspect Wind-accreting Magnetic pre-Polars
Pasi Hakala, Steven G. Parsons, Thomas R. Marsh +4
We present results from a circular polarimetric survey of candidate detached magnetic white dwarf - M dwarf binaries obtained using the Nordic Optical Telescope, La Palma. We obtai…
The OmegaWhite Survey for Short-Period Variable Stars VII: High amplitude, short period blue variables
G. Ramsay, P. A. Woudt, T. Kupfer +11
Blue Large Amplitude Pulsators (BLAPs) are a relatively new class of blue variable stars showing periodic variations in their light curves with periods shorter than a few tens of m…
The OmegaWhite Survey for Short Period Variable Stars VI. Open Clusters
R. Toma, G. Ramsay, C. S. Jeffery +3
Using light curves with 3 min cadence and a duration of 2 hrs made using the OmegaWhite survey, we present the results of a search for short-period variable stars in the fiel…
The Puzzling Story of Flare Inactive Ultra Fast Rotating M dwarfs. I. Exploring their Magnetic Fields
Lauren Doyle, Stefano Bagnulo, Gavin Ramsay +2
Stars which are rapidly rotating are expected to show high levels of activity according to the activity-rotation relation. However, previous TESS studies have found Ultra Fast Rota…
The Puzzling Story of Flare Inactive Ultra Fast Rotating M dwarfs. II. Searching for radial velocity variations
Gavin Ramsay, Pasi Hakala, J. Gerry Doyle +2
Observations made using TESS revealed a sample of low mass stars which show a periodic modulation on a period ~d. Surprisingly many of these Ultra Fast Rotating (UFR) stars s…
The return of the spin period in DW Cnc and evidence of new high state outbursts
C. Duffy, G. Ramsay, D. Steeghs +16
DW Cnc is an intermediate polar which has previously been observed in both high and low states. Observations of the high state of DW Cnc have previously revealed a spin period at ~…
TESS observations of flares and quasi-periodic pulsations from low mass stars and potential impact on exoplanets
Gavin Ramsay, Dmitrii Kolotkov, J. Gerry Doyle +1
We have performed a search for flares and Quasi-Periodic Pulsations (QPPs) from low mass M dwarf stars using TESS 2 min cadence data. We find seven stars which show evidence of QPP…
Detection of an energetic flare from the M5V secondary star in the Polar MQ Dra
Gavin Ramsay, Pasi Hakala, Matt Wood
MQ Dra is a strongly magnetic Cataclysmic Variable whose white dwarf accretes material from its secondary star through a stellar wind at a low rate. TESS observations were made of…
Evidence that short period AM CVn systems are diverse in outburst behaviour
C. Duffy, G. Ramsay, D. Steeghs +12
We present results of our analysis of up to 15 years of photometric data from eight AM CVn systems with orbital periods between 22.5 and 26.8 min. Our data has been collected from…
Power-law energy distributions of small-scale impulsive events on the active Sun: Results from IRIS
Nived Vilangot Nhalil, Chris J. Nelson, Mihalis Mathioudakis +2
Numerous studies have analysed inferred power-law distributions between frequency and energy of impulsive events in the outer solar atmosphere in an attempt to understand the predo…
TESS observations of southern ultra fast rotating low mass stars
G. Ramsay, J. G. Doyle, L. Doyle
In our previous study of low mass stars using TESS, we found a handful which show a periodic modulation on a period <1 d but also displayed no flaring activity. Here we present the…
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,…
Observations and 3D MHD Modeling of a Confined Helical Jet Launched by a Filament Eruption
Lauren Doyle, Peter F. Wyper, Eamon Scullion +3
We present a detailed analysis of a confined filament eruption and jet associated with a C1.5 class solar flare. Multi-wavelength observations from GONG and SDO reveal the filament…
TESS observations of the asynchronous polar CD Ind: mapping the changing accretion geometry
Pasi Hakala, Gavin Ramsay, Stephen B. Potter +3
We present the results of near continuous TESS optical observations of the asynchronous polar CD Ind (RX J2115-5840). The 27.9 d long light curve, with 2 min resolution, reveals re…
Identifying Blue Large Amplitude Pulsators in the Galactic Plane using Gaia DR2: a case study
Gavin Ramsay
Blue Large Amplitude Pulsators (BLAPs) are blue stars showing high amplitude (>0.2 mag) pulsations on a timescale of a few tens of mins. They form a new class of variable star rece…