Erik Dennihy
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View article: The Origins of Lithium Enhancement in Polluted White Dwarfs
The Origins of Lithium Enhancement in Polluted White Dwarfs Open
The bulk abundances of exoplanetesimals can be measured when they are accreted by white dwarfs. Recently, lithium from the accretion of exoplanetesimals was detected in relatively high levels in multiple white dwarfs. There are presently t…
View article: Simultaneous emission from dust and gas in the planetary debris orbiting a white dwarf
Simultaneous emission from dust and gas in the planetary debris orbiting a white dwarf Open
There is increasing evidence for the presence and variability of circumstellar dust and gas around white dwarfs that are polluted with exoplanetary material, although the origin of this dust and gas remains debated. This paper presents the…
View article: The Origins of Lithium Enhancement in Polluted White Dwarfs
The Origins of Lithium Enhancement in Polluted White Dwarfs Open
The bulk abundances of exoplanetesimals can be measured when they are accreted by white dwarfs. Recently, lithium from the accretion of exoplanetesimals was detected in relatively high levels in multiple white dwarfs. There are presently t…
View article: Simultaneous emission from dust and gas in the planetary debris orbiting a white dwarf
Simultaneous emission from dust and gas in the planetary debris orbiting a white dwarf Open
There is increasing evidence for the presence and variability of circumstellar dust and gas around white dwarfs that are polluted with exoplanetary material, although the origin of this dust and gas remains debated. This paper presents the…
View article: Modeling Circumstellar Gas Emission around a White Dwarf Using cloudy
Modeling Circumstellar Gas Emission around a White Dwarf Using cloudy Open
The chemical composition of an extrasolar planet is fundamental to its formation, evolution, and habitability. In this study, we explore a new way to measure the chemical composition of the building blocks of extrasolar planets by measurin…
View article: Modeling Circumstellar Gas Emission around a White Dwarf Using Cloudy
Modeling Circumstellar Gas Emission around a White Dwarf Using Cloudy Open
The chemical composition of an extrasolar planet is fundamental to its formation, evolution and habitability. In this study, we explore a new way to measure the chemical composition of the building blocks of extrasolar planets, by measurin…
View article: WD 0141−675: a case study on how to follow-up astrometric planet candidates around white dwarfs
WD 0141−675: a case study on how to follow-up astrometric planet candidates around white dwarfs Open
This work combines spectroscopic and photometric data of the polluted white dwarf WD 0141−675, which has a now retracted astrometric super-Jupiter candidate, and investigates the most promising ways to confirm Gaia astrometric planetary ca…
View article: WD0141-675: A case study on how to follow-up astrometric planet candidates around white dwarfs
WD0141-675: A case study on how to follow-up astrometric planet candidates around white dwarfs Open
This work combines spectroscopic and photometric data of the polluted white dwarf WD0141-675 which has a now retracted astrometric super-Jupiter candidate and investigates the most promising ways to confirm Gaia astrometric planetary candi…
View article: An emerging and enigmatic spectral class of isolated DAe white dwarfs
An emerging and enigmatic spectral class of isolated DAe white dwarfs Open
Two recently discovered white dwarfs, WD J041246.84 + 754942.26 and WD J165335.21 − 100116.33, exhibit Hα and Hβ Balmer line emission similar to stars in the emerging DAHe class, yet intriguingly have not been found to have detectable magn…
View article: An emerging and enigmatic spectral class of isolated DAe white dwarfs
An emerging and enigmatic spectral class of isolated DAe white dwarfs Open
Two recently discovered white dwarfs, WDJ041246.84$+$754942.26 and WDJ165335.21$-$100116.33, exhibit H$α$ and H$β$ Balmer line emission similar to stars in the emerging DAHe class, yet intriguingly have not been found to have detectable ma…
View article: Disk or Companion: Characterizing Excess Infrared Flux in Seven White Dwarf Systems with Near-infrared Spectroscopy
Disk or Companion: Characterizing Excess Infrared Flux in Seven White Dwarf Systems with Near-infrared Spectroscopy Open
Excess infrared flux from white dwarf stars is likely to arise from a dusty debris disk or a cool companion. In this work, we present near-infrared spectroscopic observations with Keck/MOSFIRE, Gemini/GNIRS, and Gemini/Flamingos-2 of seven…
View article: Disk or Companion: Characterizing Excess Infrared Flux in Seven White Dwarf Systems with Near-Infrared Spectroscopy
Disk or Companion: Characterizing Excess Infrared Flux in Seven White Dwarf Systems with Near-Infrared Spectroscopy Open
Excess infrared flux from white dwarf stars is likely to arise from a dusty debris disk or a cool companion. In this work, we present near-infrared spectroscopic observations with Keck/MOSFIRE, Gemini/GNIRS, and Gemini/Flamingos-2 of seven…
View article: Faro: A framework for measuring the scientific performance of petascale Rubin Observatory data products
Faro: A framework for measuring the scientific performance of petascale Rubin Observatory data products Open
The Vera C. Rubin Observatory will advance many areas of astronomy over the next decade with its unique wide-fast-deep multi-color imaging survey, the Legacy Survey of Space and Time (LSST). The LSST will produce approximately 20TB of raw …
View article: Velocity-imaging the rapidly precessing planetary disc around the white dwarf HE 1349–2305 using Doppler tomography
Velocity-imaging the rapidly precessing planetary disc around the white dwarf HE 1349–2305 using Doppler tomography Open
The presence of planetary material in white dwarf atmospheres, thought to be accreted from a dusty debris disc produced via the tidal disruption of a planetesimal, is common. Approximately 5 per cent of these discs host a co-orbital gaseou…
View article: Infrared Excesses Around Bright White Dwarfs from Gaia and unWISE. II
Infrared Excesses Around Bright White Dwarfs from Gaia and unWISE. II Open
Infrared excesses around white dwarf stars indicate the presence of various astrophysical objects of interest, including companions and debris disks. In this second paper of a series, we present follow-up observations of infrared excess ca…
View article: Collisions in a gas-rich white dwarf planetary debris disc
Collisions in a gas-rich white dwarf planetary debris disc Open
WD 0145+234 is a white dwarf that is accreting metals from a circumstellar disc of planetary material. It has exhibited a substantial and sustained increase in 3–5 $\mu$m flux since 2018. Follow-up Spitzer photometry reveals that emission …
View article: White dwarfs with planetary remnants in the era of <i>Gaia</i> – I. Six emission line systems
White dwarfs with planetary remnants in the era of <i>Gaia</i> – I. Six emission line systems Open
White dwarfs with emission lines from gaseous debris discs are among the rarest examples of planetary remnant hosts, but at the same time they are key objects for studying the final evolutionary stage of planetary systems. Making use of th…
View article: When flux standards go wild: white dwarfs in the age of Kepler
When flux standards go wild: white dwarfs in the age of Kepler Open
White dwarf stars have been used as flux standards for decades, thanks to their staid simplicity. We have empirically tested their photometric stability by analysing the light curves of 398 high-probability candidates and spectroscopically…
View article: A Volume-limited Sample of Cataclysmic Variables from Gaia DR2: Space Density and Population Properties
A Volume-limited Sample of Cataclysmic Variables from Gaia DR2: Space Density and Population Properties Open
We present the first volume-limited sample of cataclysmic variables (CVs), selected using the accurate parallaxes provided by the second data release (DR2) of the European Space Agency Gaia space mission. The sample is composed of 42 CVs w…
View article: Strategic Scientific Plan for Gemini Observatory
Strategic Scientific Plan for Gemini Observatory Open
We present the Strategic Scientific Plan (SSP) for the direction and activities of the Gemini Observatory in the 2020s. The overarching goal is to ensure that Gemini best uses the available resources to serve the needs of its international…
View article: A White Dwarf with Transiting Circumstellar Material Far Outside Its Tidal Disruption Radius
A White Dwarf with Transiting Circumstellar Material Far Outside Its Tidal Disruption Radius Open
We report the discovery of a white dwarf exhibiting deep, irregularly shaped transits, indicative of circumstellar planetary debris. Using Zwicky Transient Facility DR2 photometry of ZTF$\,$J013906.17+524536.89 and follow-up observations f…
View article: Explorations of the Remnant Exoplanetary Debris Disks around White Dwarf Stars
Explorations of the Remnant Exoplanetary Debris Disks around White Dwarf Stars Open
Always amenable to modern astrophysical needs, the compact degenerate remnants of stars like our Sun known as white dwarf stars have recently been put into service as exoplanetary laboratories. Their nominally pure hydrogen or helium atmos…
View article: The Space Density of Cataclysmic Variables from $\mathit{Gaia}$ DR2
The Space Density of Cataclysmic Variables from $\mathit{Gaia}$ DR2 Open
We present the first volume-limited sample of cataclysmic variables (CVs), selected using the accurate parallaxes provided by the second data release (DR2) of the ESA $\mathit{Gaia}$ space mission. The sample is composed of 42 CVs within 1…
View article: Astro 2020 Science White Paper: Evolved Planetary Systems around White Dwarfs
Astro 2020 Science White Paper: Evolved Planetary Systems around White Dwarfs Open
Practically all known planet hosts will evolve into white dwarfs, and large parts of their planetary systems will survive this transition - the same is true for the solar system beyond the orbit of Mars. Spectroscopy of white dwarfs accret…
View article: Dust production and depletion in evolved planetary systems
Dust production and depletion in evolved planetary systems Open
The infrared dust emission from the white dwarf GD 56 is found to rise and fall by 20 per cent peak-to-peak over 11.2 yr, and is consistent with ongoing dust production and depletion. It is hypothesized that the dust is produced via collis…
View article: A 15.7-Minute AM CVn Binary Discovered in K2
A 15.7-Minute AM CVn Binary Discovered in K2 Open
We present the discovery of SDSS J135154.46−064309.0, a short-period variable observed using 30-mincadence photometry in K2 Campaign 6. Follow-up spectroscopy and high-speed photometry support a classification as a new member of the rare c…
View article: Rapid Evolution of the Gaseous Exoplanetary Debris around the White Dwarf Star HE 1349–2305
Rapid Evolution of the Gaseous Exoplanetary Debris around the White Dwarf Star HE 1349–2305 Open
Observations of heavy metal pollution in white dwarf stars indicate that metal-rich planetesimals are frequently scattered into star-grazing orbits, tidally disrupted, and accreted onto the white dwarf surface, offering direct insight into…
View article: The first sub-70 min non-interacting WD–BD system: EPIC212235321
The first sub-70 min non-interacting WD–BD system: EPIC212235321 Open
We present the discovery of the shortest-period, non-interacting, white\ndwarf-brown dwarf post-common-envelope binary known. The K2 light curve shows\nthe system, EPIC 21223532 has a period of 68.2 min and is not eclipsing, but\ndoes show…
View article: Dusty Exoplanetary Debris Disks in the Single-Temperature Blackbody Plane
Dusty Exoplanetary Debris Disks in the Single-Temperature Blackbody Plane Open
We present a bulk sample analysis of the metal polluted white dwarfs which also host infrared bright dusty debris disks, known to be direct signatures of an active exoplanetary accretion source. We explore the relative positions of these s…
View article: Destroying Aliases from the Ground and Space: Super-Nyquist ZZ Cetis in K2 Long Cadence Data
Destroying Aliases from the Ground and Space: Super-Nyquist ZZ Cetis in K2 Long Cadence Data Open
With typical periods of the order of 10 minutes, the pulsation signatures of ZZ Ceti variables (pulsating hydrogen-atmosphere white dwarf stars) are severely undersampled by long-cadence (29.42 minutes per exposure) K2 observations. Nyquis…