Unveiling the Mass of Galaxies with Vera Rubin
This week I am attending a conference at Queen’s University in Kingston (Ontario, Canada) with I think the longest name I have ever seen. It’s called “A Celebration of Vera Rubin’s Life. Unveiling the Mass: Extracting an Interpreting Galaxy Masses.” I was very excited to attend this conference. Vera Rubin has always been a role model of mine (hard to avoid as a women studying galaxies) and as well as her the list of speakers includes many people who’s work I know and respect. It also has the advantage of being held in Kingston where a close friend (and fellow astronomer) from graduate school is now living with her very new baby.
This morning the introductory talks did not disappoint. We heard anecdotes from Vera Rubin about her work as a young scientist just trying to interpret the observations she was making on the rotation curves of galaxies (observations that provided the first strong evidence for dark matter in galaxies). She talked about a 1962 paper she did with students measuring the rotation curve of the Milky Way, and her regrets on not noticing that dark matter must have been present when she measured a similar “flat” rotation curve for the Andromeda galaxy 13 years later. She further impressed me by dating another anecdote (about discovering a galaxy in which the stars rotated in two directions) by the year her youngest child learned to walk (1961). Not only is Vera Rubin an incredibly successful and famous astronomer, but she managed to have 4 children (at least one of whom followed her into astronomy) during the period she did most of her famous work. Wow! I got to talk with her a little bit this morning at coffee, and she’s also a very nice person.
As well as enjoying the many talks by leaders in the field of galaxy evolution, I am presenting a poster on my work on dust reddening of Galaxy Zoo spirals which you have heard about several times before (eg. Blue Sky and Red Spirals, and from when I presented it at the 2009 European Week of Astronomy). This work has relevance to the masses of galaxies as dust is a significant source of error on estimates of the total mass of stars in a galaxy – at the simplest level dust hides the stars.
I was encouraged to share my poster on this blog, so if you wish to have a closer look at it you can download it (pdf). Of course this poster is aimed at explaining my work to other astronomers not to a general audience. If you have questions about it I encourage you to first look at my more general explanation of the work Blue Sky and Red Spirals and I am also happy to answer questions in the comments below.
One little details which is not explained in the poster is that the images of galaxies on both the right and left are not random. On the right I show edge-on spiral galaxies ordered from bluest (at the bottom) to reddest (at the top). On the left I show all face-on galaxies, also ordered in the same way. My definition of blue versus red comes from a measured difference in the brightness seen through 2 filters (in this case the SDSS g and z filters), so is not always obvious to the eye – also remember that it is the average colour of the whole galaxy, and some have significantly different colours in their centres to in the outskirts. However one of the interesting results coming from this work is that even though on average dust reddens galaxies as they become more inclined (as they go from face-on to edge-on) some face-on galaxies are much redder than some edge-on galaxies. This shows that while dust is important to the colour of a spiral galaxy it is clearly not the most important factor. This is very good news for those of us interested in red spirals as an evolutionary stage!
If anyone is in the Kingston area there will be a public lecture at 8pm tomorrow night given by Prof. Sandy Faber. It’s on the Queen’s Campus in the Biosciences Building, Room 1101. I include the poster below. Sandy Faber was a student of Vera Rubin’s and gave a very nice review talk this morning about her early work on dark matter during this time. I encourage you to attend if you are able – I think it will be a very nice public astronomy talk.