Browsed by
Author: ktj

New paper: X-ray emission line spectra of main-sequence stars ?>

New paper: X-ray emission line spectra of main-sequence stars

We investigated the X-ray emission line spectra of cool main-sequence stars in order to construct their emission measure distributions and compare them to the Sun: “A Chandra/LETGS Survey of Main-sequence Stars” We analyze the X-ray spectra of 19 main-sequence stars observed by Chandra using its LETGS configuration. Emission measure (EM) distributions are computed based on emission line measurements, an analysis that also yields evaluations of coronal abundances. The use of newer atomic physics data results in significant changes compared to…

Read More Read More

New paper: Unmasking a hot Jupiter in an unresolved binary system ?>

New paper: Unmasking a hot Jupiter in an unresolved binary system

The NGTS planet-search project in which I take part has detected a new planet in an interesting system: “Unmasking the hidden NGTS-3Ab: a hot Jupiter in an unresolved binary system” We present the discovery of NGTS-3Ab, a hot Jupiter found transiting the primary star of an unresolved binary system. We develop a joint analysis of multi-colour photometry, centroids, radial velocity (RV) cross-correlation function (CCF) profiles and their bisector inverse slopes (BIS) to disentangle this three-body system. Data from the Next…

Read More Read More

New paper: Kepler Object of Interest Network ?>

New paper: Kepler Object of Interest Network

I am happy to be part of the Kepler Object of Interest Network, a network of ground-based telescopes to observe transits of exoplanets discovered by the Kepler space telescope in order to figure out their masses through Transit Timing Variations. The first paper about this project is now accepted: “Kepler Object of Interest Network I. First results combining ground and space-based observations of Kepler systems with transit timing variations” During its four years of photometric observations, the Kepler space telescope…

Read More Read More

New paper on the Star Formation Region Serpens South ?>

New paper on the Star Formation Region Serpens South

As part of the Young Stellar Object VARiability project (YSOVAR), I am happy to report that we have published a new paper investigating the mid-infrared variability of young stellar objects in the star-forming region Serpens South. Here’s the title and abstract: “YSOVAR: Mid-infrared Variability among YSOs in the Star Formation Region Serpens South” We present a time-variability study of young stellar objects (YSOs) in the Serpens South cluster performed at 3.6 and 4.5 μm with the Spitzer Space Telescope; this…

Read More Read More

New paper: X-ray line coincidence photopumping in a solar flare ?>

New paper: X-ray line coincidence photopumping in a solar flare

This is somewhat unusual research for me, but it was good fun – some recent work about identifying an emission line in the X-ray regime which is excited by photons from a different atomic species which just happens to have the correct wavelength for that. This can be used as an independent density diagnostics for plasma in flaring loops, for example. The paper has just been published, here is the title and abstract: “X-ray line coincidence photopumping in a solar…

Read More Read More

New paper and press release: Discovery of a monster planet ?>

New paper and press release: Discovery of a monster planet

A timely discovery for Halloween: Our NGTS collaboration has discovered a “monster planet”, a giant planet around a very small star. This is very surprising, because barely any of those huge planets have been found close to tiny stars. We will have to re-think some of our planet formation theories. A neat press release has been published by Queen’s University Belfast: Monster planet discovery challenges formation theory, which gives the key points about the discovery in layperson’s terms. And here…

Read More Read More

New paper: Next Generation Transit Survey (2) ?>

New paper: Next Generation Transit Survey (2)

The mission paper about the Next Generation Transit Survey (NGTS), a ground-based telescope network to search for transiting exoplanets, has just been published. I’m happy to be part of this project, which is a collaboration between several universities in the UK, Germany, Chile, and Switzerland – lots of exciting discoveries to come soon! Here’s some more info about the paper: We describe the Next Generation Transit Survey (NGTS), which is a ground-based project searching for transiting exoplanets orbiting bright stars….

Read More Read More

Musings on scientific discoveries, luck, and being prepared ?>

Musings on scientific discoveries, luck, and being prepared

I’ve been thinking about the relationship between luck and good preparation lately. We have published a paper on the discovery of three plus one small planets around a small star recently, and we basically did the work for that in one day. The way that worked out got me thinking. From the outside, what happened was this: Data from the latest Kepler-K2 campaign was publicly released. My student Rob Wells looked through some light curves and found something that looked…

Read More Read More

New paper: Discovery of three (plus one) small planets around a small star ?>

New paper: Discovery of three (plus one) small planets around a small star

Happy to report that we have discovered three small planets, plus one additional candidate planet, around a small cool star. This is some very nice work by my PhD student Rob Wells. The planets were discovered using data from the Kepler K2 space telescope. The planets are in fairly close orbits around their host star; the candidate planet, for which we need some more data to be certain it is really a planet, might be in the habitable zone of…

Read More Read More

Conference: “Ages^2 – Taking stellar ages to the next power” ?>

Conference: “Ages^2 – Taking stellar ages to the next power”

I spent some time at a fantastic conference, “Ages^2 – Taking stellar ages to the next power” on Elba, Italy. It was a great meeting, with people from very different areas of astronomy coming together to share progress on measuring how old different kinds of stars are, which is a very fundamental and very difficult to solve question. I gave an invited talk on the topic of “Precise stellar ages as the key to exoplanet evolution”, and my PhD student…

Read More Read More