Sunday, 29 December 2019

JJ's 2019 in review...

Well 2019 was okay? I did feel overwhelmed with work load at times but this was just because I was in the state of having too many different things to do at times it was difficult to work out which one to do first! While I haven't been as productive as I think I should have been I have been productive. I've also been able to recover still from 2016/7 that were too busy and stressful. I know I just need to try to not overwork or expect too much of myself again. And I definitely need to be more active, I do a lot of walking everyday but need to do more fun exercise.

In terms of family life that was really the priority this year and another reason I was most stressed at times is a I put being a parent first while also trying to do all my work. This led to working 7 days a week, catching up at the weekends with everything I didn't get done during the week.

But on the other hand the big thing that happened this year is that I applied for promotion to an Associate Professor, which I was successful in! So this just means I need to keep going as I'm doing something right. 

Anyway her is my highlights of the year! And I've probably forgotten something!

Anyway things I’ve done in research. First I’ve been on 6 (+1) refereed (submitted) articles this year:
  • Three first author papers:  
    • Eldridge & Xiao, The distance, supernova rate, and supernova progenitors of NGC6946
    • Eldridge et al, Supernova lightCURVE POPulation Synthesis II: Validation against supernovae with an observed progenitor,
    • Eldridge et al., Weighing in on black hole binaries with BPASS: LB-1 does not contain a 70M(Sun) black hole [Note - currently only submitted but so proud of it, especially as it's a strong team effort, decided to include it! :o) ].
  • Student/close collaborator papers:
  • I'm quite proud of all these papers but Petra Tang's letter on the GW transient event rate deserves a special mention as it's her first paper and the result of her masters thesis work. 

Things I’ve done in Teaching
  • Won the Faculty of Science award for sustained excellence in teaching!
  • Had a second student, John Bray, go through their graduation ceremony!
  • Lectured the 1st year astronomy course twice again which went well but improvements still to be made.
  • Also lectured 2nd year quantum mechanics for the first time. Was quite stressful and I learnt a lot but it was fun in the end.
  • Taught 1 honors project student and 2 masters student.
  • Was "deputy head academic" for first half of the year. This was interesting and contributing to the broader development of teaching across the Faculty of Science. This was a significant time load, especially in putting together course descriptions and amendments as well as creating entirely new courses. But it was a positive experience and unfortunately means I'll probably end up doing the job in a few years.
  • Also a big thing is I lectured as myself consistently for most of my lectures this year. This is a small step but my lecturing was so much better because of it.

Things I’ve done in Service & Leadership

Saturday, 8 December 2018

JJ's 2018 in review...

So 2018… it wasn’t as busy nor as stressful as 2016 and 2017 were. I finally listened to what I was writing! I didn’t necessarily say no so many times to things but ran out of energy and motivation to do many things, which has had some negative impacts on the amount of stuff I’ve done. I’ve also just had many fewer requests for things this year. So, all in all I’ve got to the end of the year with a list of things I could/should have done but didn’t, but I’m not completely stressed out and exhausted. I’ve still got to improve my fitness and that will help with my productivity, but this is good and I can move forward for sure.

Also it’s worth nothing I’ve tried again this year to be a good parent and partner. This is always difficult as anything in life. Especially as I’m also trying to come to understand myself – which is also still difficult – think I’m starting to know who I am but working out how to fit that into life and not impact those I love most.

Anyway things I’ve done in research. First I’ve been on 9 articles this year:

Things I’ve done in Teaching
  • Had one student, Lin Xiao, go through their graduation ceremony!
  • Had another student, John Bray, pass his viava!
  • Only lectured on course, 1st year astronomy which went well, despite some administrative mistakes, but it’s important to learn from those.
  • Finished the text book on the structure and evolution of stars I’ve written with Chris Tout! (Link here: World Scientific Press).
  • Observing my 2nd year redesign from a few years ago really seems to be going well.
  • Taught 4 honors project students and 1 masters student.
  • Ended a student project.

Things I’ve done in Service & Leadership
  • Unfortunately, this year I’ve just had not enough energy to do enough in this space this year and that makes me sad. But I guess it balances with needing a break and trying to get research done. This is something I really see as a failure as there are so many things I should have done.
  • Trans on Campus, had some meetings and did some work with the University giving feedback on transition at work, trans and sporting and travelling guidelines. This needs more effort next year!
  • Rainbow science was also very quiet, but there are a few new interested people around, so we might be able to get it busy again.
  • Was nominated as NZ LGBTI Hero – a controversial event but a fun evening at least.
  • Public talks at continuing education groups in Te Awa Mutu and Thames. The latter was my first talk as myself. Also just about to give a talk at Stardome to the Auckland Astronomical Society. As well as talks at RASNZ annual meeting, Hidden perspectives seminars and for a trans group in London.
  • Curated the Real Scientists account for a week, wow that was fun and busy!

Thursday, 29 November 2018

School question time!

So I just had some questions on twitter and via email from school children about astronomy. So rather than just replying to the people in question I thought I'd put the answers in a blogpost so everyone can read them.

Set one:

Q1 "What would happen if two red giants collided?" - context is discussions about neutron stars colliding and forming a black hole

This happens sometimes in binary stars systems where two stars orbit around one another. If their masses are similar enough they can both become red giants at the same time, grow in radius and eventually touch. To work out what will happen we need to think about the structure of a red giant. In the center is the star's helium core, the remnants of it fusing hydrogen to helium over it's main sequence lifetime (i.e. the phase our Sun is in). The core is then surrounded by the hydrogen envelope that is the material that wasns't hot enough to burn during the main sequence. 

Then in a binary when the two red giants touch one of two things will happen, either they will merge, losing some of the hydrogen and making a supersized helium core. Or all the hydrogen will be removed and the two helium cores will orbit each other in a much shorter orbit. If these are close enough they may eventually merge as they emit gravitational radiation and explode in some way.

If the helium cores were big enough then supernovae might happen and the stars could eventually become neutron stars or black holes and then eventually also merge via gravitational radiation to cause a GW event. Especially in the case where the two stars touching results in the orbit shrinking so the stars are closer together. If they're closer together they'll merge more quickly.

It's also worth noting it's very rare for the two stars to both become red giants at the same time. More typically one star will become a red giant while the other in still a main sequence star. But we're pretty sure they must touch and interact strongly to get close enough to form GW events.

Finally two single stars might me moving around a star cluster and just bump into each other. The same two possible results apply but this would be even rarer as space is big and stars are small.

Q2 - " Is Betelgeuse the only red giant we can see in the night sky? How soon can we expect to see a supernova?"

There are many red giants/supergiants we can see in the sky, for example: Betelgeuse, Aldebaran, Antares and Arcturus. Also a star atlas will definitely contain many more. It's worth noting that many red giants won't go supernova, only those that were more massive than 8 times that of the Sun will explode. Betelgeuse is likely to be above that mass but we really can be sure about when it'll explode as we can't see inside it. It could explode tomorrow or in a few 100,000 years, so we just need to play a waiting game!

We do see many red supergiants explode in other nearby galaxies and they're 60% of all supernovae we see. It's just within our own Galaxy we can only expect 1 supernova every 50 to 100 years.

Q3 - Could the stuff thrown off a supernova go and form another star?

Yes, that's where all the iron in your blood game from as well as many (but not all) the elements in your body that aren't hydrogen came from. The iron comes mostly from a specific type of SN, type Ia which is from exploding white dwarf stars in a binary star. 

What happens is the material formed in the explosion gets through out to get mixed with the material surrounding the star making it richer in heavier elements. We can actually see in more and more distant galaxies that there are less and less heavy elements showing us in reverse how stars have built up all the elements over 13.7 billion years.

Set two:

1. Do you believe we will get to Mars by 2030?

We've been there since the 1960s with space probes so I guess you mean humans. My only answer is maybe. It depends on whether there is the political will to spend that large amount of money that such a large project will require. We could get there before 2030 if we wanted to. Also the other question is whether it is a one-way trip or a return journey. The latter is more tricky.

2. Do you believe there is currently life on Mars?

It's certainly possible but unlikely. Although life on Earth has been found in increasingly extreme environments. This is why it's key to go there and at least check whether there is or ever has been life there.

3. Do you believe we could possibly live on Mars in the future?

It would be hard, recent research has suggested it may be even more difficult to terraform Mars than we thought. There is only a very sparse atmosphere so people will need to use spacesuits and pressure domes to live in and will not be able to walk through the open air on Mars.

Then there is also the problem that the planet has no magnetic field so people would have to live underground rather than on the surface. This is to avoid the solar wind and cosmic rates that are dangerous to life.

So again it's certainly possible just really, really difficult. 

Monday, 8 October 2018

What the 13th Doctor means to me...

So I’ve been meaning to write a short blogpost about what it means as a trans person to see the Doctor change sex and gender. I mean it’s been on the cards for some time now with the Mistress/Master leading to the casting of Jodie Whittaker as the 13th Doctor. My first reaction upon learning this months ago was “hey the Doctor is going to go through the same thing I’m kinda going through”.

As a quick aside it’s worth noting that I am not going to say the Doctor is trans, they’re not they are cisgender. Why? Well we’re talking about aliens here and I’ve got an entire set of blogposts that I need to write about gender and sci-fi but for Timelords we have to treat the fact that a regeneration is like a rebirth (based on this talk here: So while for cisgender humans their sex assigned at birth and gender align, the equivalent for Timelords is that their sex at regeneration and their gender align. This does of course reinforce the idea that sex and gender are both binary which they’re not, for humans at least, but anyway this is the topic for another blogpost not this one, also there are probably intersex regenerations but if it’s a rate of 1% as for humans then we probably have seen enough Timelord characters to know.

a few friends used to jokingly say I did remind people of the 10th Doctor and I may be listened to them too closely, also it was a time when I was still male. But then when the 10th Doctor left it was around the time of my move to New Zealand and that’s when I really began to change and come to understand myself. This has lead me to my journey reaching a moment of me moving over to being more female. It’s a funny coincidence for me to see a character I associate with so strongly reflect my own change.

It’s worth noting that I’m a theoretical astrophysicist which is as close to being a Timelord as possible on Earth. I mean there is the understanding the Universe from one side to the other and running around showing young people the wonders it contains (i.e. lecture undergraduates and teach project students). (Un)fortunately there is a lot less running and no daleks or cybermen.

To not give away any spoilers, the Doctor is still the Doctor. There is that regeneration confusion when she’s still working out who she is but then the moment everything clicks it is as clear as day and I can’t wait to watch more. There is one quote though that I need to share when the Doctor explains her regeneration to her new companions, there are so many aspects of the description that parallel experiences of trans people:

Doctor: “You should have seen me a few hours ago. My whole body’s changed. Every cell in my body burning. Some of them are still at it now, reordering, regenerating”.

Grace: “Sounds painful love.”

Doctor: “You have no idea… there is this moment when you’re sure you’re about to die and then... you’re born, it’s terrifying. Right now I’m a stranger to myself, the’s echos of who I was, and a sort of call towards who I am and I have to hold my nerve and trust all these new instincts, shape myself towards them. I’ll be fine. In the end… hopefully… but I have to be cos you guys need help and if there’s one thing I’m certain of, when people need help I never refuse. Right! This is going to be fun.

Trans people when they transition in some ways do die, that’s why previous names are referred to as “deadnames”. We have to become reborn but then we have our previous lives still with us and we do have to move forwards and reinvent ourselves. There is so much to unlearn, so many habits we have to break that we've had to fit in and go undiscovered. To move forwards and reinvent ourselves we really have to trust instincts and thoughts that for so long we have suppressed to become the person we are.

Also personally I think the wanting to help people in trouble is what the Doctor is all about and it’s one of the things I like most.

So for me at least, and may be other transgender people seeing this change and seeing a popular character go through similar changes to us inspires us a little, who knows, to me at least it’s a big deal.
Anyway personally it’s strange to see past photos of me and remember times from so long ago. I don't hate them and there are aspects of my oldself that I hate but there is a lot I love about my oldself too. Now though I still don’t know where I’m going or who I’m going to be. I really hope it’ll be okay in the end.

Right, time to get on, think I’ll leave you with two last quotes, “Allons-y!” and I just hope my adventure is going to be “Brilliant!”
(And yes sorry this was a rush job but was just toooooooo excited).

Sunday, 31 December 2017

The Holdo Maneuver

So first, ***SPOILERS***, do not read on if you don't want to read a major spoiler about Star Wars: The Last Jedi.

Okay, it's been out for several weeks now but better to be safe than sorry!

Also quick disclaimer before going on, these are just my thoughts around the issue, I've got a PhD in astrophysics and have written about this stuff before (e.g. read and watched more sci-fi than I probably should have and completed X-wing, TIE fighter and X-wing alliance, again, more times than I should have. So I do love Star Wars and really like thinking not of the problems with science fiction but with "how could they possibly happen".

Anyway, one of the main scenes in the movie is when Admiral Holdo takes the Mon Calamari cruiser "Raddus" and rams into Supreme Leader Snoke's ship by sending it to hyperdrive. The second I saw this I thought that it tells us something interesting about how this fictional hyperdrive works. After some thought and googling I found out many people were having similar thoughts, e.g. 

In case you're wondering what the aftermath looks like here's a link:*fNvQQ4vnLNY6M_pnBsEEHw.png

But over doing the washing up I realised something, we've seen starship/starship collisions before. For example in Rogue One, where the collision between two Star Destroyers was "bad" for those ships.

Then even in Return of the Jedi there was the collision of a tiny little A-wing with a super-Star Destroyer (

In both these cases the velocities weren't at "hyperspeed" but the collisions were still bad. In the latter case mainly because of the collision hitting the bridge of the Executor.

A lot of people seem to have latched onto the fact that the Holdo Maneuver is the first to occur at light speed. However when you look at the damage to the mega-ship, it doesn't look so bad. The ship didn't suddenly explode it was just cut through. This looks quite similar to the star destroyer-star destroyer collision but at higher speed.

So here is the sciency bit - why did Admirial Holdo go to lightspeed? It was to make the collision happen quickly rather than allowing time for the First Order to move out the way. The energy of the collision wasn't enhanced due to the lightspeed it was just the time of the collision changed. This fact suggests the hyperdrive in the Star Wars Universe doesn't warp space but time? Or both maybe? So how it allows an object to travel the same distance that would take minutes at sub-light speed in a fraction of a second. Thus when the cruiser collides with the First Order ship rather than taking minutes or seconds as we've seen before it takes fractions of a micro-second. The trailing wake of material from the explosion is then what hits the other destroys behind the mega-ship.

If you want an analogy: think along the lines of someone punching a watermelon (=sublight collision) compared to a sword being slashed at speed through a watermelon and cutting it in half (=hyperdrive speed collision). Same energy (as a person throws the punch or turns the sword) but the speed is different. Actually, thinking on this more, a lot of martial art breaking techniques are more about speed than strength... but that's another post....

Another sciency thing her is that it means by the way that the hyperdrive doesn't remove a ship from spacetime like say the TARDIS does in Dr Who. But it means that there must be a similar solution, that we don't know of, that is how to "disconnect" one bit of spacetime from another, change the passage of time in someway and then "reconnect" them later without problems (this is impossible in our current understanding of the Universe).

Anyway the good news is this removes some of the problems what people have pointed out about the collision, namely "why did no one think of doing this before?". Well first, they have, just not with the hyperdrive engaged. Also let's think about this, a cruiser is an expensive ship, even if it's really old and ready for scrap, using one up as a weapon wouldn't be cost effective. There are many better (more cost effective) weapons that could be deployed.

Also let's think about mass. A tiny little fighter is maybe, 10 or 20 tonnes? A modern aircraft carrier on the Earth is about 100,000 tonnes, lets guesstimate that the Mon Calamari cruise is 1,000,000 tonnes. That's why the collision is so destructive, it's got 500,000 times more mass in that collision than a tiny little fighter would have. And its going to be more often that a person in a fighter would ram another ship in desperation than having a large carrier ship with only one person on board to decide their own fate

Summary: the hyperdrive didn't add destructive power, it just meant the collision (which we know already to be destructive) to just happen much more quickly.

There are other things to bear in mind here why no one developed "hyperdrive suicide robot ships". I think this comes down to cost and how difficult it is to build hyperdrives. The original TIE fighters didn't have hyperdrives or even shields. Even in the prequels the jedi starfighters needed to hook up to a special hyperdrive attachment. Hyperdrives are probably either expensive or difficult to make, if they don't add any destructive power it is probably more cost effective to put your money into making a bigger bang for your bomb.

Also then there are the safe guards that hyperdrives have which stop you if there is a large mass nearby. (I've played X-Wing, TIE Fighter and X-wing Alliance and have died in a mission many times when a star destroyer has blocked my exit vector, grrrrr). But you can always override them because as the article above points out, and suggestions in cannon dialogue gives you a "bad feeling" about collisions in hyperdrive.

One last thought though, if the hyperdrive does change time somehow, it means there might be some equivalence between distance and time taken to travel that distance, there might only be one speed of hyperdrive. This means that when in "A New Hope" Han Solo talks about doing the Kessel run in 12 parsecs, that has some direct meaning to time, not necessarily time, although that's still a complex and loaded statemtent.

Anyway, don't panic, we didn't see any new destructive tactic in "The Last Jedi", just a way of speeding things up.

Tuesday, 26 December 2017

JJ's 2017 in review.

After writing a review like this last year I thought it'd be interesting to write another one!

Looking back to last year's review it was clear that in 2016 I thought I was working at my limit. This year I know I've gone way beyond that limit. Towards the end of the year I was almost unable to keep going. I was finding it impossible to find energy to start anything new and trouble keeping all the different streams of projects going through my mind. I don't think anything I did on it's own was too difficult but just the combination of multiple different projects was tough. Especially things way outside my comfort zone away from science research and teaching.

I could tell this work load did effect my family life too much. Being stressed and not having energy was a bad thing. Part of the issue was changes at home meaning that I needed to be home earlier than before which meant I had to try to be more efficient with my time and trying to juggle too many things.

Anyway, I survived and a number of things have been completed which means I don't need to worry about them any more. On the big plus side I did also get promoted to "Senior Lecturer above the bar" which is reward for doing so much work. While I still need to do more to get my next promotion in a few years it's good to already have a number of acomplishments. I just need to make sure I don't fill up my to-do list with more things that get in the way of research so much. Especially as I have a sabbatical second semester next year.

So anyway here is a (probably incomplete) list of everything I've done this year....

Service (astronomy):
  • Edited and published the proceedings for the IAU Symposium, #NZstars2016 which was run in 2016.
  • Took part in continuing discussions to set up Astro Aotearoa of research astronomers in NZ group. This led to the running of the first PhD summer school at Auckland run by myself with support from Nick Rattenbury and Richard Easther. Also the first science meeting which was also a success.
  • Won the Bronze Pleiades award for Auckland Physics Department in collaboration with the department’s equity working group. 
  • More public outreach talks at Stardome and Thames.
  • Curated @astrotweeps for a week again.
  • Refereed lots and lots of papers again and was named one of Nature's referees of 2016.

Service (University, Academia and wider):

  • Oversaw the redesign and teaching of second year courses in department of physics. This year we concentrated on lectures and examples classes. It will take a few more years to get perfect but we definitely improved all the courses and the students did enjoy the courses and seems to have done better (we still need to look in detail). Next year we'll be restructuring and organizing the labs....
  • Taught 5 courses: 2x 1st year astro (36 lectures), 2nd year classical mechanics (24 lectures, 8 example classes), 3rd year astrophysics (11 lectures) and course coordinated 2nd year electromagnetism. Considering the 2nd yr mechanics and 3rd yr astro meant I had to write two new courses in the same semester it wasn't easy and was quite stressful, especially when I wasn't able to keep so many things in my head at the same time but I made is somehow.
  • Finished of the course in Academic Practice, scoring A- grade overall. Again having to do this on top of everything else was difficult. Especially since my project work concerned trans and gender diverse people in academia which meant a serious amount of challenging self-reflection that made me quite uncomfortable, but I did learn a lot about myself at least. I still need to submit one of these projects to an education journal for publication maybe....
  • My 1st University of Auckland PhD student, Dr Lin Xiao, submitted her thesis, and passed. She has now moved back to China to take up a post-doc and she is finishing papers on the unpublished work in her thesis.
  • I still have 2 other PhD students who are close to finishing and submitting their theses early next year. I also now have a MSc student who is progressing through her project well and she should finish early 2019.
  • I did also apply for a University teaching award, I was unsuccessful in this but I did have to put together a teaching portfolio that allowed me to look at my teaching in detail. It allowed me to being to try to understand what it is I do when teaching that seems to be successful. I'll work out what "it" is one day I hope.

Monday, 16 October 2017

We are all made of stardust but gold, silver and platinum are neutron stardust!

GW170817/GRB170817A/SSS17a was the event many astrophysicists have been waiting for since LIGO made the first detection of gravitational waves in 2015. This time we didn’t just detect the gravitational waves from two merging neutron stars, but have also seen the associated gamma-rays, optical light and radio emission from the possible black hole and from the two exploding stars.

This new discovery shows again the importance of LIGO and VIRGO’s work over decades. The refinement of their highly sensitive work allows us to be able to detect these gravitational waves.

In addition, there have been a large number of dedicated astronomers that have been following up the fading afterglow of the merger. Again showing their practice over many years of following up transient events as quickly as possible have payed off. I offer huge congratulations to everyone that contributed to this stunning discovery. Especially to everyone who wrote and published those papers in the two months since discovery!

Neutron stars are quite different to the black holes that have been detected merging before. They are made of “stuff” so there is material we can see when they do collide. Neutron stars are formed when massive stars (that about 8 times more massive than our Sun) die, in their last gasp these stars crush all the material in their core down into a sphere 10km in radius. This releases a large amount of energy that makes a star explode in a supernova.

If the star was in a binary, and the binary wasn’t destroyed in the two supernovae that much have occurred to make the two neutron stars, then these two neutron stars will slowly orbit closer and closer together as they emit gravitational waves. This can take billions of years until they touch, merge and possibly form a black hole as we’ve seen in GW170817.

We don’t even know the full story yet. The observations are ongoing and only in the coming months and years will we really begin to fully understand how exciting this object is. The fact that we have so much information from so many different sources will allow us to piece together in a way we have never been able to before. It’s going to take a lot of time and a lot of effort!

This event alone has already answered questions on the nature and structure or neutron stars and confirms that merging neutron stars look like we’ve always expected them to, as a short gamma-ray burst and a type of explosion called a “kilonova”.

A short gamma-ray burst is a highly energetic burst of gamma-rays that have the same apparent energy as entire exploding star but spaced over a few seconds. While a kilonova is the explosion powered by the collision, making new heavy elements that are ejected extremely fast, some maybe at close to the speed of light!

The observations of the kilonova, the explosive afterglow, also confirms something else. In the explosion we have seen evidence for large amount of heavy elements. These events mostly create elements such as gold, silver and platinum. In this event it’s likely that 100s or 1000s of Earth masses of gold and other elements were made. If the rate of neutron stars mergers is as high as we now think, these dying stars are now the source of most of these elements in the Universe.
We’re all made of stardust, but gold, silver and platinum are made of neutron stardust!

One funny thought is that in a Doctor Who story called “Revenge of the Cybermen”, there was a planet called “Voga” that was made entirely of gold. Since this is the one element that is lethal to the Cybermen they attempted to destroy the planet. Now after the observations around this event we know that solid-gold planets are not as unlikely as we might have thought before!

Researchers in NZ have not played a role in the detection of this event but we are highly interested in gravitational waves. For example, at the University of Auckland Assoc. Prof. Renate Meyer has worked on the problem of extracting the faint gravitational waves signals from the much larger terrestrial signals that jostle the instrument, a problem that is like trying to hear a whispered conversation in a noisy room.

While in my own group two students PhD student John Bray and MSc student Petra Tang are both working to predict from models what the rate of these events should be, this event is showing that our models need to be improved to match the high rate of such mergers we now expect in the Universe.
The problem comes down to this, for two neutron stars to merge, the binary must have survived two supernovae, these are extremely destructive events. The stars musts also have remained close enough that the two stars only took a few days to orbit around one another. Otherwise the Universe is not old enough for the stars to merge via gravitational radiation. Modelling these in population synthesis depends on many uncertain bits of physics, but now merging neutron stars and black holes will give us a new tool to constrain the evolution of stars. That’s what makes me most excited!