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  • I do love a good Cornu spiral! DeForest+ on “A Simplified Theory of External Occulters for Solar Coronagraphs” might work for exoplanet imaging - occulters are simple in concept, but typical numerical approximations we commonly use in astronomy don’t work: this paper looks at new ones. πŸ”­πŸͺ #astrodon

    A lovely Cornu spiral - a blue line curls out from an impossibly tight spiral, from the bottom left corner, across as single line, to form a mirror image spiral.
    β†’ 10:53 AM, Dec 31

  • After spending a week in England under a permanent fog layer, flying back yesterday and seeing the sun as we broke through the cloud deck was “Trinity seeing the Sun for the first time” levels of epic.

    Trinity looking out of a spaceship towards the sun, with an emotional look on her face. Neo is blind and wrapped in a red bandage. Bright sunlight is shining into the cabin, as seen in one of the Matrix movies.
    β†’ 10:36 AM, Dec 30

  • 50% gray - Boxing Day, South coast of England

    Gray featureless cloud down to the horizon, where it meets the gray sea. There is one sultry wave sloshing in reluctantly. ON the left is a concrete pier extending about 20 metres into the ocean, with a red metal basket on a pole indicating it's a rain outflow pipe. There is nothing else moving or colourful in the image.
    β†’ 1:52 PM, Dec 26

  • One of the graduate students I work with had access to my office whilst I was away, and I have been discovering photos of me hidden around my office. Apparently I haven’t even found half of them yet… they have been very creative in the hiding spots!

    A photo of me looking grumpy, stuck onto the bottom of my coffee mug.
    β†’ 4:53 PM, Dec 17

  • The tilt of the bulge is the thing: Poon et al. on “A potential exomoon from the predicted planet obliquity of Ξ² Pictoris b” showing that if upcoming JWST observations confirm a suspected obliquity then there may be a massive exomoon to detect! Keep calm and carry on observing…. πŸ”­πŸͺ #astrodon

    A cartoon of the orbits of the exoplanets Beta Pic b and c around the central star, with a zoom in of Beta Pic b showing the geometry of the spin axis of the planet with respect to the orbital plane of an exomoon orbiting around it. We Like The Mooooooon!
    β†’ 12:20 PM, Dec 10

  • End of this teaching semester vibe.

    A Duolingo screen saying "Ik ben helemaal uitgeput" which translates to "I am completely exhausted"
    β†’ 11:21 AM, Dec 8

  • Wow, imagine how differently astronomy would have developed if you had planets orbiting in completely different planes in the sky… Yu+ on “A possible misaligned orbit for the young planet AU Mic c” and the coincidence that we see BOTH transits is astonishing. The Universe is weird. πŸ”­πŸͺ #astrodon

    A circle representing the surface of the star MU Mic, with two lines representing the mean orbits of the planets b and c. Underneath the two lines are a bundle of grety lines representing the draws of the underlying distributions, looking like spaghetti dropped in a pan of water. A blue to red colour gradient on the star represents its rotation in velocity space, and the c orbit is almost at right angles to the b orbit and rotation axis of the star, and the debris disk alignment.
    β†’ 9:44 AM, Nov 27

  • Merc and Boffin show an “Unequivocal detection of the tidal deformation of a red giant in a binary system via interferometry” with reconstruction from PIONIER fringes - their Roche-lobe filling model fits better than a symmetric model. An amazing result! πŸ”­πŸͺ #astrodon

    A teardrop shaped model image of a red giant star, which is a star with a companion that distorts it and makes the star fill the Roche lobe. The lobe is slightly larger than about half the diameter of the star, making it look more like a cam in an engine. The point of the lobe is at the seven o'clock position.
    β†’ 7:10 AM, Nov 25

  • They Might Be Giants in #London at the #Roundhouse tonight - sold out gig and they pulled an amazing trick - they sang a song backwards and recorded it, and after the intermission, the video was played backwards to reveal it was “Sapphire Bullets of Pure Love”! #TMBG #Flood

    The two Johns, one in a plaid shirt, the other with a rocking guitar, on a blue lit stage with one othe band member. The heads of enthusiastic fans are along the bottom.
    β†’ 12:54 AM, Nov 18

  • A masters student working on high resolution spectra of Beta Pictoris made river plots of the circumstellar absorption from several hundred epochs…. the human brain is fantastic at spotting trends in these plots, I love them! πŸ”­πŸͺ #astrodon

    Several pieces of paper, with red lines drawn one on top of another, spread out down the page, exactly like the cover of the album "lost Pleasures" by Joy Division. ~There are several plots laid next to each other on the table, speaking volumes if only we can hear them.
    β†’ 4:35 PM, Nov 14

  • Fascinating paper by Ma+ on Temporal and chromatic variation of polarized scattered light in the outer disk of PDS 70 indicating that shadows are being cast by an (unseen) tilted inner disk, giving us more dynamical information on this system πŸ”­πŸͺ #astrodon

    Images of polarized light taken at several differnt times and wavelengths. It looks like a cereal bowl with a red outer rim and blue inner circle, tilted to our line of sight. The illumination of the rings changes brightness between the different images.
    β†’ 9:53 AM, Nov 7

  • WOndering out loud, how long before the AI image algorithms drum up a Langford Parrot and we’ll

    β†’ 4:37 PM, Nov 5

  • An auspicious start to the week in #Leiden at the Science faculty and Leiden Observatory this morning #astrodon πŸ”­πŸͺ

    A purple sky with a rainbow generated just aster sunrise, with the rainbow touching a long white building with the blue sign "Leiden Univsrsity Faculty of Science". The rainbow terminates at the top floor where the Leiden Observatory is housed.
    β†’ 8:43 AM, Oct 28

  • Monday evening on the 14 October was the first chance to see Comet Tsuchinshan-ATLAS in the evening sky in #Leiden. A 10 second exposure on my ancient DSLR picked it up (along with the 19:15 from LHR to AMS). Barely visible with the naked eye as this is towards playing fields. #astrodon πŸ”­πŸͺ

    A twilight sky with the silhouettes of an electrical transmission tower and buildings. A smeared out plane trail can be seen, and the white head and fuzzy tail points upwards away from the direction of the setting sun.
    β†’ 10:59 AM, Oct 15

  • StrΓΈm with a short review on “Exocomets, exoasteroids and exomoons” featuring a nice review of the exocomet orbital properties and models. #astrodon πŸ”­πŸͺ

    Exocomet models showing a sudden deep drop, followed by a gradual recovery back to pre-eclipse levels. Different parameters leads to different depth and recovery times.
    β†’ 8:55 AM, Oct 14

  • super puff == ringed planet. Lu+ speaking truth with “The Dynamical History of HIP-41378 f – Oblique Exorings Masquerading as a Puffy Planet”. ‘Nuff said. πŸ”­πŸͺ #astrodon

    β†’ 6:05 PM, Oct 8

  • Our department servers are down, #ADS and #arXiv are down, many people I know have head colds and are incapacitated, and there is a majestic naked eye comet in our skies. I am stubbornly refusing to draw any conclusions between these events and ‘harbingers of doom’ here… #astrodon πŸͺπŸ”­β˜„️

    β†’ 10:51 AM, Oct 1

  • Damn straight! πŸ”­πŸͺ #astrodon

    A duolingo Dutch prompt that translates as "The discovery of new planets is important"
    β†’ 6:14 AM, Sep 27

  • A clever idea: use the area covered by a transiting exoplanet to get a narrow band stellar spectrum from a rapidly rotating star! Secrets in the shadow: High precision stellar abundances of fast-rotating A-type exoplanet host stars through transit spectroscopy by Lam+ πŸͺπŸ”­ #astrodon

    A combination of broad line spectra from a rotationally broadened star and the narrow emission from the area of the star blocked by the exoplanet in transit.A figure showing the star blocked by the planet, and the resultant spectrum, and then a figure with a Doppler shifted stellar surface showing how the velocity shift moves the planet selected spectrum of the star to one side.

    β†’ 8:51 AM, Sep 25

  • Absolutely spectacular results from Soummer, Por and their team using the “High-contrast imager for complex aperture telescopes (HiCAT)" testbed, showing coronagraphs with closed loop mirror control making dark holes down to 1e-8 contrast, crucial for terrestrial exoplanet imaging. πŸ”­πŸͺ #astrodon

    An image of an artifical star, where diffraction has been suppressed in a dark D shaped region to the right of the star. The light in the dark hole is a hundred million times fainter than the star.
    β†’ 9:55 AM, Sep 23

  • Good luck to everyone writing #JWST #Cycle4 proposals! #astrodon πŸ”­πŸͺ

    A model of the JWST telescope against a white background, with my screaming face reflected in all the mirrors of the primary segments.
    β†’ 9:34 AM, Sep 13

  • Opening an email on Friday morning:

    A spam email from a predatory journal saying "Dear Professor, May your day be filled with joy!"The dad from the movie Coraline, sitting slumped in front of his computer screen, looking surprised with his hand poised over the computer keyboard.

    β†’ 9:59 AM, Sep 6

  • In our new offices, there is a motion sensor which activates the room lights. After about four hours, the lights dim for no discernible reason, and waving like a nineties raver does nothing - multiple requests to Facilities Management result in “Out of cheese error πŸ€–” messages.

    I miss the future πŸ˜₯

    A strip of LED lights in a white ceiling, shining brightly for another two hours before they will dim by ninety percent and plunge my office into twilight.
    β†’ 9:32 AM, Sep 4

  • Limbach+ present The MIRI Exoplanets Orbiting White Dwarfs (MEOW) Survey: Mid-Infrared Excess Reveals a Giant Planet Candidate around a Nearby White Dwarf with a mass of 3 Jupiters! Very exciting to see this result and it bodes well for the rest of the survey 😺 πŸ”­πŸͺ #astrodon

    False color image from JWST showing several stars on a black background. The WD is a blue speck in the middle of the image.Graph of wavelength versus infrared excess, showing a black body fit to the data. Two histograms show a temperature of 275K and radius of 1 Jupiter.

    β†’ 8:16 PM, Sep 2

  • With astronomy job season approaching, if you’re a PhD or early postdoc, PLEASE make a webpage and put your current contact details on it, so that searching for “< your name > astronomer” finds you first - more explanation how and why here: Unsolicited Advice #astrodon πŸ”­πŸͺ

    β†’ 12:39 PM, Aug 30

  • Sanghi+ on Efficiently Searching for Close-in Companions around Young M Dwarfs using a Multi-year PSF Library where using a super large RDI star atlas as your basis set gives better sensitivity within 0.4 arcseconds on Keck with a Vortex coronagraph for M star survey. #astrodon πŸ”­πŸͺ

    A plot of angular separation in arcseconds versus the difference in delta magnitude between RDI and ADI methods. If the delta is greater than zero, then RDI is the better method. The graph shows tha RDI is better for distances smaller than 0.4 arcseconds.An image of a star with a companion next to it, processed using the new method. The companion is to the lower right of the star, which is itself masked.

    β†’ 9:07 AM, Aug 28

  • Travis and Hamish Hawk (Ian Curtis via Talking Heads) at #Paradiso last night. Most excellent. #Travis

    Four members of Travis standing on the stage at Paradiso, with lead singer with very orange dyed hair and another styled in fifties throwback Mark Lamar. All looking very happy with the first night of their tour.Hamish Hawk with clutched fist looking up at the sky, rest of the band playing guitars. THe picture is badly streaked due to the camera moving, so it looks like everyone is melting, or zooming up into headen.

    β†’ 9:47 AM, Aug 27

  • Horstman and collaborators go hunting for exomoons in “RV measurements of directly imaged brown dwarf GQ Lup B to search for exo-satellites” and get interesting upper limits - we’re not down to the mass ratio of the Galilean satellites (yet!) #astrodon πŸ”­πŸͺ

    A graph of semi-major axis distance from GQ Lup B versus mass ratio between planet and possible moon. The measured limit is about 100 times higher than for the Galilean moons.
    β†’ 3:47 PM, Aug 22

  • ASASSN-21js: A multi-year transit of a ringed disc

    Student paper day! I’ve been looking at the light curves that the ASAS-SN survey releases on their transients page - these are light curves that show curious dimmings caused by stellar variability or by something moving in front of the star. One of these light curves, named ASASSN-21js, showed a sudden dimming in 2021, and over the past three years, has faded and then brightened up again. Theo worked on analyzing this light curve with me as a Masters thesis project here in Leiden: after some experimentation, the light curve is exactly matched by a highly tilted and inclined disk with two rings with different transmissions. What’s particularly impressive is that the residuals after the model fit are consistent with noise. This model explains the data almost perfectly.

    Using a MCMC fitting package, he was able to determine the confidence intervals on the parameters, with the outermost ring about 1.12 au in radius. Due to the geometry of the eclipse, we only see these two rings - there may be more material interior to this radius, but the star’s motion will not reveal this. What’s more amazing is that the eclipse is still ongoing, finishing only in May 2027!

    Okay, so what are the challenges here? First, the star itself is very large star with a mass of 4.5 times that of the Sun. Those are relatively rare, but are seen long distances across the Galaxy. Second, the transverse velocity is less than one kilometre per second! If this is orbiting around this star, then it’s at a distance of over 13000 au from the star! Deep into Oort Cloud territory. This means that the chance of seeing such an eclipse is tiny, around one in ten thousand for all the solar type stars in the ASAS-SN survey size and duration. That’s an uncomfortable problem and we don’t know the answer as to why we’re seeing this now.

    What’s tantalizing is that the MCMC fitting also found solutions with a cleared ring gap between the two main rings (squint at around 59200 days to see this additional gap in the rings). It’s compelling, but not confirmed. There is also multi band data coming in as well, so in future research we can see if the material is sub-micron sized or not. More of these unusual systems are being discovered in ASAS-SN, and with other large survey telescopes coming online soon (think the Vera C. Rubin Observatory) many more of these systems might be discovered. Watch this space!

    The paper is published in A&A as ASASSN-21js: A multi-year transit of a ringed disc by Pramono, Kenworthy and van Boekel. #astrodon πŸ”­πŸͺ

    photometry of the star showing model fits with a single disk, a ring and a double ring system model. The double ring system model works the best.An image of a star moving behind a tilted ring/disk system, showing the light curve geometry at different parts of the eclipse. When the star moves behind the ring edges, the light curve changes shape.

    β†’ 2:28 PM, Aug 14

  • Aurora seen over #Leiden right now… you can see a red glow with your night adjusted eyes but the camera phone easily picks it up along with some green structure too. #astrodon

    Red aurora seen in darkened skies above Leiden.
    β†’ 2:39 AM, Aug 13

  • It doesn’t mean much, but I was delighted to see these two ‘likes’ on a social media post.

    Two 'loves' from Beth Gibbons and Geoff Barrow, the two people behind the amazing group "Portishead", on a social media post I'd made.
    β†’ 6:54 AM, Aug 12

  • As seen around #Caen

    A graffiti wall showing 28 different faces all with different expressions and different colours of the rainbow and the words β€œbims anrione!!!” In one corner. Several metal tripods sticking up out of a stone wall. The wall is covered in moss and on the right is a cathedral gargoyle and on the left is a leafy tree all against a blue sky.

    β†’ 11:49 AM, Aug 8

  • Currently watching small birds fly in and out from under the eaves, drinking a coffee and reading a book. Bliss.

    A wooden gabled roof looked at from the ground looking up. Pale yellow sandstone frames two tall windows, one square and one arched. The sunshine lights up the stonework and the red bricks. The sky is deep blue with no clouds above.
    β†’ 9:36 AM, Aug 6

  • I am sensitive to optical aberrations

    Fortunately it hasn’t impacted my friends and relatives directly, but they know something’s not right. They catch me with one eye closed, staring furiously at an otherwise innocent appliance, be it a computer screen, a phone surface, or the kitchen counter illuminated by the light shining through a plastic container. I reluctantly bought a refurbished iPhone 13, because the 8 was dying and I wanted a better camera for photos (Ask me about how I obsessed over comatic aberrations in the blue channel of early 2000’s Canon cameras!) and the phone I received works perfectly…. but I can very clearly see that the front glass plate is bowed in around the edges. Out of the corner of my eye I can see the distortion of distant parallel lines take on the distinctive S shape of a bowl-like distortion, and it distracts me no end. I can’t help myself. It’s not disruptive enough to go and fix it, partially because it gives me inspiration in my daily work too. There have been a few times where I’ve made a casual observation about some optical phenomenon and then had quizzical looks from fellow academics - “What, you haven’t seen the diffraction pattern from a sodium street lamp though a net curtain before?” and I keep my observations to myself. My point is that there is a tremendous amount of wonder in the physical world, if you look for it. Putting on a protective screen on the curved iPhone surface meant that it did not adhere correctly…. but then I could use the pressure my fingers to get the air gap within a few wavelengths of light and treat myself to Newton’s fringes first hand, transient colours under white light. What’s not to love about that?

    An iPhone sits on top of a copy of Charles Stross' The Fuller Memorandum, which itself is on a green garden table. The blue sky and part of a building are reflected in the phone screen, and the straight white lines of the building roof are distorted into a sinuous S shape in the reflection of the phone screen.
    β†’ 8:04 PM, Jul 29

  • Exocomets in Bern πŸ”­πŸͺ #astrodon

    Last week I was in Bern participating in a Workshop on #exocomets, at the #ISSI on top of the hill behind the University. We discussed chemistry, the number of detections, and what to expect in the next decade or so. I gave a review on detection methods - transit, spectroscopy and maybe direct detection in the not too distant future! I’m interested in setting up ground based observations during the upcoming PLATO mission which will stare at Beta Pictoris for two to three years. This is a unique opportunity to get spectra from the ground during a large exocomet transit towards this famous star.

    A panoramic photo of the crowd at the Exocomets meeting. A laptop sits on the lectern in the middle of the photo. The room is white with windows along the left wall.
    β†’ 10:55 AM, Jul 29

  • Busy week: #ALMA observations of #J1407 just happened, one student let me know they got a PhD position they were hoping for, and a new long period eclipser was announced by the ASAS-SN network, https://www.astronomerstelegram.org/?read=16715 where it looks like a disk system! #astrodon πŸ”­πŸͺ

    Light curve showing a flat portion for three years, then a sudden dip followed by a slower rise.
    β†’ 10:38 AM, Jul 18

  • The radio dish stood mute in the soft rain. The Visitors had responded to its call, leaving behind only their Message. The builders of the dish looked at each other and wondered what the meaning was behind the Message. Two words:

    PARTY HARD

    #astrodon #SETI #JodrellBank πŸ”­πŸͺ

    A giant radio telescope dish points up towards a cloudy grey sky. Stell girders painted white and stained with rust are seen supporting the dish, and in the foreground, a modern green painted metal fences with a small white sticker on it that says "party hard" in a simple black font on a white sticker.
    β†’ 9:29 PM, Jul 13

  • I’ve been putting in references into a review paper I’m coauthoring, and the new ADS website keeps blocking me - apparently searching continuously for over two days is setting off some robot or other! A definite first for me… 🀣 #astrodon #AcademicWriting πŸ”­πŸͺ

    β†’ 3:29 PM, Jul 9

  • I ran a splinter session at #Exoplanets5 last week and there was a discussion to have a conference about Beta Pictoris and AU Mic exoplanets and it is taking all the willpower in my British soul not to call it the “Pic ‘n’ Mics” conference #DadJoke #BetaPic #Astrodon πŸ”­πŸͺ

    β†’ 10:06 PM, Jun 27

  • Summer months at high latitudes are the best time for seeing noctilucent clouds: they look like wisps of blue/white smoke and change over tens of minutes - in #Leiden we’ve just started our season, and I always look to the North at midnight for these high altitude (60km!) ice crystal clouds.

    Thin white clouds over electrical pyolons against a midnight sky, deep twilight from black to deep orange at the bottom.Bluish white noctilucent clouds showing bright mackarel patterns against a dark twilight midnight sky.

    β†’ 8:19 AM, Jun 25

  • Direct Imagers at #exoplanets5 can be identified in these images taken at two different epochs - common proper motion measurements suggest they are bound to the cafe tables! #astrodon πŸ”­πŸͺ

    First epoch establishing what may or may not be 30 astronomers sitting in sun shaded tables in Leiden.Second epoch showing significant positional change from the first epoch, but the candidate astronomers appear to be on the same tables. The hypothesis is tentatively confirmed.

    β†’ 1:35 PM, Jun 20

  • Oh, now this is a beautiful introductory tutorial by Tim Brandt on Astrometry as a Tool for Discovering and Weighing Faint Companions to Nearby Stars - the figures are clear and the text is an excellent introduction to a complex subject. πŸ”­πŸͺ #astrodon

    Proper motion plus parallax motion equals exciting epicyclic squiggles on the sky.
    β†’ 9:30 AM, Jun 18

  • For astronomers missing #SPIE by coming to #Leiden for Exoplanets 5, you can get your #astroninstrumentation fix by visiting the Boerhaave museum and amongst the science exhibits, you can see several lenses hand ground by the Huygens brothers from the 1600’s πŸ”­πŸͺ #astrodon #exo5

    A signature by Christiaan Huygens scratched in cursive script into the edge of one of his lenses. The handwriting is beautiful cursive script, with the date 1666.
    β†’ 9:48 AM, Jun 16

  • It’s Exoplanets 5 in #Leiden next week, so I’ll be using the #exo5 hashtag on Bluesky and on Mastodon - it will be great to catch up with old friends and colleagues, and to see the new and exciting science about planets in our Galaxy #astrodon πŸ”­πŸͺ

    β†’ 11:35 AM, Jun 15

  • I’ve had a weird bug occasionally appear when keeping my laptop and desktop computer synchronised. This morning I was irritated enough to dig in and find the problem: it was me. I’d effectively set a preference option to ‘keep the older file’. I have no idea why I did that! #PEBCAK #academiclife

    β†’ 9:15 AM, Jun 13

  • Zieba, Zwintz, Kenworthy++ use the internal Delta Scuti-like pulsation modes (which are very stable) in Beta Pictoris to search for the presence of the exoplanets Beta Pic b and c but additional modes appear and disappear, unfortunately hiding the signal - a very impressive effort! #astrodon πŸ”­πŸͺ

    An image with time along the x axis and pulsation frequency on the y-axis. A strong signal is seen for most of the time covered, but then about halfway through the time axis, a new pulsational mode appears at a lower frequency.
    β†’ 8:59 AM, Jun 10

  • Bonse+ present a new high contrast imaging algorithm “4S - Signal-Safe Speckle Subtraction” demonstrated with the pre-recovery of the exoplanet AF Lep b from 2011 NaCo data. The software webpage has an interactive figure where you can play with and see the improvement over PCA. Nice! #astrodon πŸ”­πŸͺ

    Three images showing the planetary system of AF Lep b with 20 component PCA, 60 component PCA and the paper's 4S algorithm. The planet is not visible or obscured by speckle noise in the PCA images, but in the 4S image the planet is clearly seen to the lower right of the star at the 4 o'clock position.
    β†’ 8:50 AM, Jun 5

  • Watching the sci-fi film “When Worlds Collide!” and this notice caught my eye in the background. Words for all academics to live by. #astrodon πŸ”­πŸͺ

    A sign that reads "Waste anything except time. Time is our shortest material." The sign is hanging inside a laboratory with men and women standing underneath it in 1950's clothing.
    β†’ 10:55 AM, May 31

  • Oh now THIS is very intriguing! Bernhard and Lloyd with ZTF J185259.31+124955.2: A new evolved disc-eclipsing binary system where the shape of the transit is evolving significantly on every eclipse - look at how much it changes… just wow. πŸ”­πŸͺ #astrodon

    Six light curves showing broader and broader eclipses with the bottom of the eclipse being flat, but expanding each eclipse.
    β†’ 9:50 AM, May 27

  • Ex-student paper day! Sutlieff et al. (2024) using a gvAPP coronagraph to suppress diffraction from the primary star so that the variability of a faint substellar companion can be measured to 3% precision and a 3.2 hour periodic variability detected one night but disappears the next! πŸ”­πŸͺ #astrodon

    A noisy image showing a primary star as a yellow circle with the brown dwarf companion to the lower right of the star as a smaller yellow circle.Many light curves showing the change in brightness of the BD companion as a function of wavelength. Some wavelengths don't change at all over the 32 hours of monitoring, whilst other wavelengths show very large variations from hour to hour.

    β†’ 10:08 AM, May 22

  • As noted by Arttu Sainio it looks as if #ASASSN-24cf is climbing back to pre-eclipse levels - since the ingress and egress look as if they have the same gradient, I’m guessing this is a large, faint star eclipsing a smaller, hotter star. There’s always something interesting in #ASAS-SN πŸ”­πŸͺ #astrodon

    A light curve looking like a trapezium - coloured points from different instruments show the flux going down linearly, staying constant, then rising back up. A classic binary star eclipse.
    β†’ 9:35 AM, May 21

  • One of this morning’s posts on arXiv πŸ”­ had quite a sobering lede: β˜€οΈβ˜ οΈ #astrodon

    A clip from an email saying "In seven billion years, the Sun will be dead."
    β†’ 8:52 AM, May 16

  • Limbach+ on “Occurrence Rates of Exosatellites Orbiting 3-30MJup Hosts from 44 Spitzer Light Curves” with some very intriguing measurements that are suggesting exomoon eclipses around free floating low mass objects and occurrence rates of ~0.6 for short period terrestrial exosatellites πŸ”­πŸͺ #astrodon

    A grey line representing the light curve of an isolated 7 Jupiter mass object, with a dip in the light curve that is modelled as a single eclipsing transit by a 0.7 radius companion.
    β†’ 2:56 PM, May 15

  • On Friday 12 July in the evening I’ll be giving a talk about “Rocks, Rubble and Rings” a.k.a. colliding exoplanets at #SpaceLates at the National Space Centre in Leicester! There are several talks and workshops, ideal for families, so go and book your tickets πŸ”­πŸͺ #astrodon #outreach

    Photos of three scientists and descriptions of the talks for Space Lates.
    β†’ 1:51 PM, May 14

  • There’s an old castle in a suburb of #Leiden that I take a walk through, and sometimes the water is calm enough to get the reflection.

    A castle with grey bulbous turrets against a blue sky with fluffy white clouds. It is a reflection in the lake in front of the castle, rotated the correct way up.
    β†’ 9:02 PM, May 12

  • Deal and Espinoza present Spelunker: A quick-look Python pipeline for JWST NIRISS FGS Guide Star Data - I love astronomy projects which open up new science from previously unconsidered data streams: it will be very interesting to see what someone discovers with this #JWST data. πŸ”­πŸͺ #astrodon

    A three dimensional grid shows the image from the JWST telescope fine guidance sensor, including the FWHM and peak values.
    β†’ 2:27 PM, May 10

  • Student paper day! Kleisioti+ on “Direct detectability of tidally heated exomoons by photometric orbital modulation” where she shows that a tidally locked #exomoon with a volcano can be detected with #JWST and two IR bands, even if it’s NOT transiting its parent exoplanet πŸ”­πŸͺ #astrodon

    A periodogram showing a large peak due to the rotational modulation of clouds on the exoplanet, and much smaller but significant peaks due to an orbiting exomoon with one or more volcanes on it.
    β†’ 4:41 PM, May 6

  • Tschudi+ on SPHERE RefPlanets: Search for epsilon Eridani b and warm dust with an absolutely heroic 38.5 hour cumulative integration looking for reflected light from the RV detected planet πŸ”­πŸͺ around this nearby star, but no joy, even with nearly eight decades of sensitivity at 1 arcsec! #astrodon

    Polarization sensitivity maps around Epsilon Ericani looking for point sources or a circumstellar disk. The four panels show the Q and U limits. The figures show no point sources, but a smooth scatter of speckles that represent noise.
    β†’ 11:25 AM, May 6

  • In my astronomy career I have had my foot run over by Stephen Hawking, had Neil deGrasse Tyson come to my seminar and promptly fall asleep, and stood in an elevator with Roger Penrose where he was wearing exactly the same clothing as the publicity poster on the elevator wall behind his shoulder.

    Timothy Dalton in "Hot Fuzz" as the supermarket manager. He's wearing a white shirt, jacket and tie, with a creepy insincere smile, and is standing front of a framed photo which has exactly the same clothing and pose.
    β†’ 12:13 PM, May 4

  • To sell a telescope

    I’m now blogging at micro.blog which cross posts to my accounts on mattkenworthy@mastodon and mattkenworthy@bluesky - so far, so good, but I don’t know how it works breaking up longer posts, so to test this, I’ll tell an #astroinstrumentation story.

    Many many years ago, as a young postdoc, I went to a talk given by Roger Angel, a professor at the University of Arizona. Among many discoveries and innovations, he’s perhaps most famous for pioneering ‘spin casting’ of giant primary telescope mirrors, built underneath the football stadium on the U of A campus.

    In a packed lecture hall he talked about the need for a wide field, eight metre optical telescope to do cosmological and time domain astronomy, something called the “Dark Matter Telescope”. His talk laid out the science requirements, and the associated optical components and first order estimates of what you would need. The telescope would have to be an all reflective, three mirror design - a challenge in itself, but Roger cut to the chase and said the real issue would be the camera required.

    For starters, all astronomy cameras have to be cryogenically cooled to minimize noise from thermal sources, and to prevent condensation on any electronics, you typically have to build a container that can have the air removed, leaving a vacuum that both prevents damage to the detectors and thermal heating by convection. He quickly pointed out that the dewar would be huge - something shaped like a soda can but the size of a large desk, containing millions of dollars of detectors, complete with filter exchange mechanisms that work in cryogenic conditions.

    He then dropped the bombshell - you’d need a giant glass window across the front of the dewar, at least one metre in diameter.

    I was at the back of the audience, and at this point there was a ripple of amusement and disbelief - this was an incredible, almost impossible design to achieve, challenging engineering limits.

    Roger was unperturbed by this, and continued his argument. This wasn’t impossible, he said, this was necessary. It might not be possible today, but we have to address this challenge in order to enable science in the next twenty years. He carried on for another five minutes, and by the end of the presentation, people were nodding in agreement and the round of applause was huge.

    I’ve never in my professional life seen someone sway an audience from huge skepticism to agreement in a single talk. It was a masterclass in storytelling, something which I’ve since tried to emulate when talking about my science ideas.

    So, how did it all work out?

    The camera and dewar were completed last month ready for installation on the telescope Roger proposed, now called the Vera C. Rubin Telescope and it should see first light early 2025.

    A photo of the Vera C. Rubin telescope, next to a photo of a person in clean room overalls standing next to a giant glass eye that has over a hundred dark blue squares in it - each one a giant cooled detector. This is the dewar, it looks like a black cylinder with a transparent lens on the top, allowing you to see the bare aluminum inside. Picture is from the SLAC news website at https://www6.slac.stanford.edu/news/2024-04-03-slac-completes-construction-largest-digital-camera-ever-built-astronomy
    β†’ 1:55 PM, May 1

  • Cotton+ have discovered that “Deneb is a Large Amplitude Polarimetric Variable” - it’s very rare that something new is found out about a named star, but this shows that you just never know…very cool! Observations were taken with the HIPPI-2 and PICSARR polarimeters πŸ”­πŸͺ #astrodon

    Graph showing the change in brightness of Deneb as seen by the TESS satellite, and the measured linear polarizations. The polarization seems lagged behind the optical variability.
    β†’ 8:47 AM, Apr 30

  • Astronomical photographic plates enable time domain science, including searches for transiting #exoring systems such as #J1407b, so I was happy to see Enke+ “Archives of Photographic PLates for Astronomical USE (APPLAUSE)" that includes a light curve for Boyajian’s star #astrodon πŸͺπŸ”­

    Light curve of Bojajian's star, showing no variability from 1920 to 1980.Inverted photos of white on black images of GK Per, showing the expansion of a shell of ejected material over 1914 to 1953.

    β†’ 8:57 AM, Apr 29

  • Today is #koningsdag here in the Netherlands, and #Leiden is as busy as all the other cities today, despite the cold weather. The #HooglandseKerk had an amazing paper craft exhibition, providing a small respite from the celebrations that are ramping up for tonight.

    The Breestraat in Leiden, looking down the middle of the street which has the City Hall on the left and the street is filled with revellers wearing orange under grey skies.Black and grey paper sculpture with tesselated diamonds and stars, in bas relief illuminated from above.

    β†’ 4:50 PM, Apr 27

  • A paper by TUD student Allard Veenstra on “A general polarimetric model for transiting and non-transiting ringed exoplanets” featuring the Python package Pryngles. It will be very cool to see this tested with the Habitable Worlds Observer, but maybe sooner than that…? #astrodon πŸ”­πŸͺ

    Cartoon of a ringed planet under different illuminations.Three orientations of a ringed planet and the calculated phase and polarization curves.

    β†’ 10:03 AM, Apr 26

  • Oh no, they found me!

    β†’ 9:49 AM, Apr 26

  • Hello world, giving this a try.

    β†’ 7:58 AM, Apr 26
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