D. M. Rowan
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View article: ASASSN-24fw: An 8-month long, 4.1 mag, optically achromatic and polarized dimming event
ASASSN-24fw: An 8-month long, 4.1 mag, optically achromatic and polarized dimming event Open
We discuss ASASSN-24fw, a 13th-magnitude star that optically faded by mag starting in September 2024 after over a decade of quiescence in ASAS-SN. The dimmimg lasted $$8 months before returning to quiescence in late May 2025. The spectral…
View article: ASASSN-24fw: An 8-month long, 4.1 mag, optically achromatic and polarized dimming event
ASASSN-24fw: An 8-month long, 4.1 mag, optically achromatic and polarized dimming event Open
We discuss ASASSN-24fw, a 13th-magnitude star that optically faded by mag starting in September 2024 after over a decade of quiescence in ASAS-SN. The dimmimg lasted $$8 months before returning to quiescence in late May 2025. The s…
View article: Astronomical Cardiology: A Search For Heartbeat Stars Using <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mtext mathvariant="italic">Gaia</a:mtext> </a:math> and <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:mtext mathvariant="italic">TESS</c:mtext> </c:math>
Astronomical Cardiology: A Search For Heartbeat Stars Using Gaia and TESS Open
Heartbeat stars are a subclass of binary stars with short periods, high eccentricities, and phase-folded light curves that resemble an electrocardiogram. We start from the catalogs of spectroscopic binaries and use photometry to identi…
View article: Weighing The Options: The Unseen Companion in LAMOST J2354 is Likely a Massive White Dwarf
Weighing The Options: The Unseen Companion in LAMOST J2354 is Likely a Massive White Dwarf Open
LAMOST J235456.73+335625 (J2354) is a binary system hosting a K dwarf and a dark companion, supposedly a neutron star, in a 0.48d orbit. Here we present high- and low-resolution spectroscopy to better constrain the properties of the system…
View article: Hidden in Plain Sight: Searching for Dark Companions to Bright Stars with the Large Binocular Telescope and SHARK-VIS
Hidden in Plain Sight: Searching for Dark Companions to Bright Stars with the Large Binocular Telescope and SHARK-VIS Open
We report the results from a pilot study to search for black holes and other dark companions in binary systems using direct imaging with SHARK-VIS and the iLocater pathfinder “Lili” on the Large Binocular Telescope. Starting from known sin…
View article: Precise and Accurate Mass and Radius Measurements of Fifteen Galactic Red Giants in Detached Eclipsing Binaries
Precise and Accurate Mass and Radius Measurements of Fifteen Galactic Red Giants in Detached Eclipsing Binaries Open
Precise and accurate mass and radius measurements of evolved stars are crucial to calibrating stellar models. Stars in detached eclipsing binaries (EBs) are excellent potential calibrators because their stellar parameters can be measured w…
View article: Weighing The Options: The Unseen Companion in LAMOST J2354 is Likely a Massive White Dwarf
Weighing The Options: The Unseen Companion in LAMOST J2354 is Likely a Massive White Dwarf Open
LAMOST J235456.73+335625 (J2354) is a binary system hosting a $\sim 0.7~\rm M_\odot$ K dwarf and a $\sim 1.4~\rm M_\odot$ dark companion, supposedly a neutron star, in a 0.48d orbit. Here we present high- and low-resolution spectroscopy to…
View article: High mass function ellipsoidal variables in the Gaia Focused Product Release: searching for black hole candidates in the binary zoo
High mass function ellipsoidal variables in the Gaia Focused Product Release: searching for black hole candidates in the binary zoo Open
The recent Gaia Focused Product Release contains radial velocity time-series for more than 9,000 Gaia long-period photometric variables. Here we search for binary systems with large radial velocity amplitudes to identify candidates with ma…
View article: A hidden population of massive white dwarfs: two spotted K + WD binaries
A hidden population of massive white dwarfs: two spotted K + WD binaries Open
The identification and characterization of massive (≳ 0.8 M⊙) white dwarfs is challenging in part due to their low luminosity. Here, we present two candidate single-lined spectroscopic binaries, Gaia DR3 4014708864481651840 and 58112374031…
View article: Seven classes of rotational variables from a study of 50 000 spotted stars with ASAS-SN, <i>Gaia</i>, and APOGEE
Seven classes of rotational variables from a study of 50 000 spotted stars with ASAS-SN, <i>Gaia</i>, and APOGEE Open
We examine the properties of ∼50 000 rotational variables from the ASAS-SN survey using distances, stellar properties, and probes of binarity from Gaia DR3 and the SDSS APOGEE survey. They have higher amplitudes and span a broader period r…
View article: Constraining stellar and orbital co-evolution through ensemble seismology of solar-like oscillators in binary systems
Constraining stellar and orbital co-evolution through ensemble seismology of solar-like oscillators in binary systems Open
Context. Binary systems constitute a valuable astrophysics tool for testing our understanding of stellar structure and evolution. Systems containing at least one oscillating component are interesting in this regard because asteroseismology…
View article: A hidden population of massive white dwarfs: two spotted K+WD binaries
A hidden population of massive white dwarfs: two spotted K+WD binaries Open
The identification and characterization of massive ($\gtrsim 0.8~M_\odot$) white dwarfs is challenging in part due to their low luminosity. Here we present two candidate single-lined spectroscopic binaries, Gaia DR3 4014708864481651840 and…
View article: Constraining stellar and orbital co-evolution through ensemble seismology of solar-like oscillators in binary systems -- A census of oscillating red-giants and main-sequence stars in Gaia DR3 binaries
Constraining stellar and orbital co-evolution through ensemble seismology of solar-like oscillators in binary systems -- A census of oscillating red-giants and main-sequence stars in Gaia DR3 binaries Open
Binary systems constitute a valuable astrophysics tool for testing our understanding of stellar structure and evolution. Systems containing a oscillating component are interesting as asteroseismology offers independent parameters for the o…
View article: The value-added catalogue of ASAS-SN eclipsing binaries – III. Masses and radii of <i>Gaia</i> spectroscopic binaries
The value-added catalogue of ASAS-SN eclipsing binaries – III. Masses and radii of <i>Gaia</i> spectroscopic binaries Open
Masses and radii of stars can be derived by combining eclipsing binary light curves with spectroscopic orbits. In our previous work, we modelled the All-Sky Automated Survey for Supernovae (ASAS-SN) light curves of more than 30 000 detache…
View article: Seven Classes of Rotational Variables From a Study of 50,000 Spotted Stars with ASAS-SN, Gaia, and APOGEE
Seven Classes of Rotational Variables From a Study of 50,000 Spotted Stars with ASAS-SN, Gaia, and APOGEE Open
We examine the properties of $\sim50,000$ rotational variables from the ASAS-SN survey using distances, stellar properties, and probes of binarity from $\textit{Gaia}$ DR3 and the SDSS APOGEE survey. They have high amplitudes and span a br…
View article: A Multiwavelength Study of the Massive Colliding Wind Binary WR 20a: A Possible Progenitor for Fast-Spinning LIGO Binary Black Hole Mergers
A Multiwavelength Study of the Massive Colliding Wind Binary WR 20a: A Possible Progenitor for Fast-Spinning LIGO Binary Black Hole Mergers Open
WR 20a is the most massive close-in binary known in our Galaxy. It is composed of two $\approx$80 M$_\odot$ Wolf-Rayet stars with a short period of $\approx$3.7 days in the open cluster Westerlund 2. As such, WR 20a presents us with a uniq…
View article: The value-added catalogue of ASAS-SN eclipsing binaries: parameters of 30 000 detached systems
The value-added catalogue of ASAS-SN eclipsing binaries: parameters of 30 000 detached systems Open
Detached eclipsing binaries are a fundamental tool for measuring the physical parameters of stars that are effectively evolving in isolation. Starting from more than 40 000 eclipsing binary candidates identified by the All-Sky Automated Su…
View article: The ‘Giraffe’: discovery of a stripped red giant in an interacting binary with an ∼2 M⊙ lower giant
The ‘Giraffe’: discovery of a stripped red giant in an interacting binary with an ∼2 M⊙ lower giant Open
We report the discovery of a stripped giant + lower giant Algol-type binary, 2M04123153+6738486 (2M0412), identified during a search for non-interacting compact object – star binaries. 2M0412 is an evolved (Teff, giant ≃ 4000 K), luminous …
View article: High tide: a systematic search for ellipsoidal variables in ASAS-SN
High tide: a systematic search for ellipsoidal variables in ASAS-SN Open
The majority of non-merging stellar mass black holes are discovered by observing high energy emission from accretion processes. Here, we pursue the large, but still mostly unstudied population of non-interacting black holes and neutron sta…
View article: High Tide: A Systematic Search for Ellipsoidal Variables
High Tide: A Systematic Search for Ellipsoidal Variables Open
The majority of non-merging stellar mass black holes are discovered by observing high energy emission from accretion processes. These interacting systems have masses of 5—10 Msun with a low mass gap from ~ 2—5 Msun that separates the neutr…
View article: ASASSN-21co: A Detached Eclipsing Binary with an 11.9 yr Period
ASASSN-21co: A Detached Eclipsing Binary with an 11.9 yr Period Open
We use ASAS V -band and ASAS-SN g -band observations to model the long-period detached eclipsing binary ASASSN-21co. ASAS observations show an eclipse of depth V ∼ 0.6 mag in 2009 April. ASAS-SN g -band observations from 2021 March show an…
View article: A unicorn in monoceros: the 3 M⊙ dark companion to the bright, nearby red giant V723 Mon is a non-interacting, mass-gap black hole candidate
A unicorn in monoceros: the 3 M⊙ dark companion to the bright, nearby red giant V723 Mon is a non-interacting, mass-gap black hole candidate Open
We report the discovery of the closest known black hole candidate as a binary companion to V723 Mon. V723 Mon is a nearby ($d\sim 460\, \rm pc$), bright (V ≃ 8.3 mag), evolved (Teff, giant ≃ 4440 K, and Lgiant ≃ 173 L⊙) red giant in a high…
View article: A NICER View of Spectral and Profile Evolution for Three X-ray Emitting Millisecond Pulsars
A NICER View of Spectral and Profile Evolution for Three X-ray Emitting Millisecond Pulsars Open
We present two years of Neutron star Interior Composition Explorer (NICER) X-ray observations of three energetic rotation-powered millisecond pulsars (MSPs): PSRs B1937+21, B1821-24, and J0218+4232. We fit Gaussians and Lorentzians to the …
View article: Detections and constraints on white dwarf variability from time-series GALEX observations
Detections and constraints on white dwarf variability from time-series GALEX observations Open
We search for photometric variability in more than 23 000 known and candidate white dwarfs (WDs), the largest ultraviolet survey compiled for a single study of WDs. We use gphoton, a publicly available calibration/reduction pipeline, to ge…