Explanipedia

A 43 day transiting Neptune and two 25 day Saturns from TESS, NGTS and ASTEP Open

Alicia Kendall, Soléne Ulmer-Moll, Samuel Gill, M. R. Burleigh, M. R. Goad , et al. · 2025

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 planet formation, migration and evolution. We report the discov…

TOI-333b: A Neptune Desert planet around a F7V star Open

Douglas R. Alves, J. S. Jenkins, José I Vines, Maximiliano Moyano, D. R. Anderson , et al. · 2025

Observations have shown that planets similar to Neptune are rarely found orbiting Sun-like stars with periods up to ~4 days, defining the so-called Neptune desert region. Therefore, the detection of each individual planet in this region ho…

Continuum Reverberation Mapping of 18 AGN Over Four Years Open

Misty C. Bentz, M. R. Goad, I. M. McHardy · 2025

Continuum reverberation mapping probes the size scale of the optical continuum-emitting region in active galactic nuclei (AGN). The source of this emission has long been thought to originate from the accretion disk, but recent studies sugg…

The variability of active galaxies – I. Broad-band noise X-ray power spectra from XMM–Newton and Swift Open

Mehdy Lefkir, S. Vaughan, M. R. Goad, Daniela Huppenkothen, P. Uttley · 2025

Accreting supermassive black holes at the centres of galaxies are the engine of active galactic nuclei (AGNs). X-ray light curves of unabsorbed AGNs show dramatic random variability on time-scales ranging from seconds to years. The power s…

Detection and characterisation of a 106-day transiting Jupiter: TOI-2449 b/NGTS-36 b Open

Solène Ulmer-Moll, Samuel Gill, R. Brahm, Alastair B Claringbold, M. Lendl , et al. · 2025

Context . Only a handful of transiting giant exoplanets with orbital periods longer than 100 days are known. These warm exoplanets are valuable objects, as their radius and mass can be measured and lead to an in-depth characterisation of t…

UV/optical active galactic nuclei reverberation mapping: using a SmallSat to trade time resolution for spatial resolution to study accretion disks around supermassive black holes at the centers of galaxies Open

Varoujan Gorjian, D. R. Ardila, Aaron J. Barth, Edward M. Cackett, Gisella De Rosa , et al. · 2025

Detection and characterisation of a 106-day transiting Jupiter : TOI-2449 b / NGTS-36 b Open

Solène Ulmer-Moll, Samuel Gill, R. Brahm, Alastair B Claringbold, M. Lendl , et al. · 2025

Only a handful of transiting giant exoplanets with orbital periods longer than 100 days are known. These warm exoplanets are valuable objects as their radius and mass can be measured leading to an in-depth characterisation of the planet's …

Departures from standard disc predictions in intensive ground-based monitoring of three AGNs Open

D. González–Buitrago, Aaron J. Barth, Rick Edelson, J V Hernández Santisteban, Keith Horne , et al. · 2025

We present ground-based multiband light curves of the AGN Mrk 509, NGC 4151, and NGC 4593 obtained contemporaneously with Swift monitoring. We measure cross-correlation lags relative to Swift UVW2 (1928 Å) and test the standard prediction …

Echo mapping of the black hole accretion flow in NGC 7469 Open

Raj Prince, J V Hernández Santisteban, Keith Horne, J. M. Gelbord, Ian McHardy , et al. · 2025

Reverberation mapping (RM) can measure black hole accretion disc sizes and radial structure through observable light travel time lags that should increase with wavelength as $\tau \propto \lambda ^{4/3}$ due to the disc’s $T\propto r^{-3/4…

Investigating the Variable Continuum Lags in PG 2130+099 Open

Jake Miller, Edward M. Cackett, M. R. Goad, K. T. Korista · 2025

Broadband photometric reverberation mapping (RM) provides a measure of the size of the continuum-emitting region in active galactic nuclei (AGN). Previous monitoring campaigns of PG 2130+099 disagree as to whether the continuum-emitting re…

NGTS-EB-7, an eccentric, long-period, low-mass eclipsing binary Open

Toby Rodel, C. A. Watson, Solène Ulmer-Moll, Samuel Gill, P. F. L. Maxted , et al. · 2024

Despite being the most common types of stars in the Galaxy, the physical properties of late M dwarfs are often poorly constrained. A trend of radius inflation compared to evolutionary models has been observed for earlier type M dwarfs in e…

NGTS-31b and NGTS-32b: two inflated hot Jupiters orbiting subgiant stars Open

José I Vines, J. S. Jenkins, D. R. Anderson, D. R. Alves, Maximiliano Moyano , et al. · 2024

We present the discoveries of NGTS-31b(= TOI-2721), and NGTS-32b, two hot Jupiters from the Next Generation Transit Survey (NGTS) transiting slightly evolved stars. The orbital periods, radii, and masses are 4.16 and 3.31 d, 1.61 and 1.42 …

NGTS-33b: a young super-Jupiter hosted by a fast-rotating massive hot star Open

D. R. Alves, J. S. Jenkins, José I Vines, Matthew P. Battley, M. Lendl , et al. · 2024

In the last few decades, planet search surveys have been focusing on solar-type stars, and only recently the high-mass regimes. This is mostly due to challenges arising from the lack of instrumental precision, and more importantly, the inh…

NGTS-33b: A Young Super-Jupiter Hosted by a Fast Rotating Massive Hot Star Open

Douglas Alves, J. S. Jenkins, José I Vines, Matthew P. Battley, M. Lendl , et al. · 2024

In the last few decades planet search surveys have been focusing on solar type stars, and only recently the high-mass regimes. This is mostly due to challenges arising from the lack of instrumental precision, and more importantly, the inhe…

AGN STORM 2. X. The Origin of the Interband Continuum Delays in Mrk 817* Open

H. Netzer, M. R. Goad, Aaron J. Barth, Edward M. Cackett, K. Horne , et al. · 2024

The local ( z = 0.0315) active galactic nucleus (AGN) Mrk 817 was monitored over more than 500 days with space-borne and ground-based instruments as part of a large international campaign, AGN STORM 2. Here, we present a comprehensive anal…

AGN STORM 2: X. The origin of the interband continuum delays in Mrk 817 Open

H. Netzer, M. R. Goad, Aaron J. Barth, Edward M. Cackett, K. Horne , et al. · 2024

The local (z=0.0315) AGN Mrk 817, was monitored over more than 500 days with space-borne and ground-based instruments as part of a large international campaign AGN STORM 2. Here, we present a comprehensive analysis of the broad-band contin…

AGN STORM 2. VII. A Frequency-resolved Map of the Accretion Disk in Mrk 817: Simultaneous X-Ray Reverberation and UVOIR Disk Reprocessing Time Lags Open

Collin Lewin, Erin Kara, Aaron J. Barth, Edward M. Cackett, Gisella De Rosa , et al. · 2024

X-ray reverberation mapping is a powerful technique for probing the innermost accretion disk, whereas continuum reverberation mapping in the UV, optical, and infrared (UVOIR) reveals reprocessing by the rest of the accretion disk and broad…

AGN STORM 2. IX. Studying the Dynamics of the Ionized Obscurer in Mrk 817 with High-resolution X-Ray Spectroscopy Open

Fatima Zaidouni, Erin Kara, Peter Kosec, M. Mehdipour, Daniele Rogantini , et al. · 2024

We present the results of the XMM-Newton and NuSTAR observations taken as part of the ongoing, intensive multiwavelength monitoring program of the Seyfert 1 galaxy Mrk 817 by the AGN Space Telescope and Optical Reverberation Mapping 2 (AGN…

Intensive Broadband Reverberation Mapping of Fairall 9 with 1.8 yr of Daily Swift Monitoring Open

Rick Edelson, B. M. Peterson, J. M. Gelbord, K. Horne, M. R. Goad , et al. · 2024

We present 1.8 yr of near-daily Swift monitoring of the bright, strongly variable Type 1 active galactic nucleus (AGN) Fairall 9. Totaling 575 successful visits, this is the largest such campaign reported to date. Variations within the UV/…

AGN STORM 2. VII. A Frequency-resolved Map of the Accretion Disk in Mrk 817: Simultaneous X-ray Reverberation and UVOIR Disk Reprocessing Time Lags Open

Collin Lewin, Erin Kara, Aaron J. Barth, Edward M. Cackett, Gisella De Rosa , et al. · 2024

X-ray reverberation mapping is a powerful technique for probing the innermost accretion disk, whereas continuum reverberation mapping in the UV, optical, and infrared (UVOIR) reveals reprocessing by the rest of the accretion disk and broad…

AGN STORM 2. VIII. Investigating the Narrow Absorption Lines in Mrk 817 Using HST-COS Observations* Open

Maryam Dehghanian, Nahum Arav, G. A. Kriss, M. Mehdipour, Doyee Byun , et al. · 2024

We observed the Seyfert 1 galaxy Mrk 817 during an intensive multiwavelength reverberation mapping campaign for 16 months. Here, we examine the behavior of narrow UV absorption lines seen in the Hubble Space Telescope/Cosmic Origins Spectr…

TOI-2490b – the most eccentric brown dwarf transiting in the brown dwarf desert Open

Beth A Henderson, S. L. Casewell, Andrés Jordán, Rafael Brahm, Thomas Henning , et al. · 2024

We report the discovery of the most eccentric transiting brown dwarf in the brown dwarf desert, TOI-2490b. The brown dwarf desert is the lack of brown dwarfs around main-sequence stars within $\sim 3$ au and is thought to be caused by diff…

TOI-2490b- The most eccentric brown dwarf transiting in the brown dwarf desert Open

Beth A Henderson, S. L. Casewell, Andrés Jordán, Rafael Brahm, Thomas Henning , et al. · 2024

We report the discovery of the most eccentric transiting brown dwarf in the brown dwarf desert, TOI02490b. The brown dwarf desert is the lack of brown dwarfs around main sequence stars within $\sim3$~AU and is thought to be caused by diffe…

Intensive broadband reverberation mapping of Fairall 9 with 1.8 years of daily Swift monitoring Open

R. Edelson, B. M. Peterson, J. M. Gelbord, K. Horne, M. R. Goad , et al. · 2024

We present 1.8 years of near-daily Swift monitoring of the bright, strongly variable Type 1 AGN Fairall 9. Totaling 575 successful visits, this is the largest such campaign reported to date. Variations within the UV/optical are well-correl…

TOI-2447 b / NGTS-29 b: a 69-day Saturn around a Solar analogue Open

Samuel Gill, Daniel Bayliss, Solène Ulmer-Moll, P. J. Wheatley, Rafael Brahm , et al. · 2024

Discovering transiting exoplanets with relatively long orbital periods (>10 d) is crucial to facilitate the study of cool exoplanet atmospheres (Teq < 700 K) and to understand exoplanet formation and inward migration further out than…

AGN STORM 2: VIII. Investigating the Narrow Absorption Lines in Mrk 817 Using HST-COS Observations Open

Maryam Dehghanian, Nahum Arav, G. A. Kriss, M. Mehdipour, Doyee Byun , et al. · 2024

We observed the Seyfert 1 galaxy Mrk817 during an intensive multi-wavelength reverberation mapping campaign for 16 months. Here, we examine the behavior of narrow UV absorption lines seen in HST/COS spectra, both during the campaign and in…

Photo-dynamical characterisation of the TOI-178 resonant chain Open

A. Leleu, J. -B. Delisle, L. Delrez, Edward M. Bryant, A. Brandeker , et al. · 2024

Context . The TOI-178 system consists of a nearby, late-K-dwarf with six transiting planets in the super-Earth to mini-Neptune regime, with radii ranging from to 2.9 R ⊕ and orbital periods between 1.9 and 20.7 days. All the planets, but t…

AGN STORM 2: IX. Studying the Dynamics of the Ionized Obscurer in Mrk 817 with High-resolution X-ray Spectroscopy Open

Fatima Zaidouni, Erin Kara, Peter Kosec, M. Mehdipour, Daniele Rogantini , et al. · 2024

We present the results of the XMM-Newton and NuSTAR observations taken as part of the ongoing, intensive multi-wavelength monitoring program of the Seyfert 1 galaxy Mrk 817 by the AGN Space Telescope and Optical Reverberation Mapping 2 (AG…

TOI-2447 b / NGTS-29 b: a 69-day Saturn around a Solar analogue Open

Samuel Gill, Daniel Bayliss, Solène Ulmer-Moll, P. J. Wheatley, Rafael Brahm , et al. · 2024

Discovering transiting exoplanets with relatively long orbital periods ($>$10 days) is crucial to facilitate the study of cool exoplanet atmospheres ($T_{\rm eq} < 700 K$) and to understand exoplanet formation and inward migration further …

Planet Hunters NGTS: New Planet Candidates from a Citizen Science Search of the Next Generation Transit Survey Public Data Open

Sean O'Brien, Megan E. Schwamb, Samuel Gill, C. A. Watson, M. R. Burleigh , et al. · 2024

We present the results from the first two years of the Planet Hunters Next Generation Transit Survey (NGTS) citizen science project, which searches for transiting planet candidates in data from the NGTS by enlisting the help of members of …

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