Counting M dwarfs in the Digital Sky Survey Era

When I started in astronomy, we were publishing luminosity functions for M dwarfs based on a few photographic sky survey plates. That is, we would count hundreds or perhaps a few thousand stars in a few hundred square degrees. This was just the 1990's, not that long ago. I was reflecting on how quickly things have changed. Here's John Bochanski et al.'s new paper on Sloan Digital Sky Survey K and M dwarfs:

The analysis incorporates ~15 million low-mass stars

I was really taken by their Figure 13 where you see how beautifully they can measure how the density of stars drops above the Galactic Plane (that distance is called Z here) and radial distance from the Galactic Center (R).

It's just a wonderful analysis, one of many coming out of the digital sky surveys. Of course, the luminosity and mass functions -- that is the number of stars that have a given luminosity or mass -- is not that very different from the old analyses.

Hubble's Twentieth Anniversary

This fabulous picture released to celebrate Hubble Space Telescope's 20th anniversary just blows me away. It looks like a painting. They call it "Mystic Mountain:"

This turbulent cosmic pinnacle lies within a tempestuous stellar nursery called the Carina Nebula, located 7,500 light-years away in the southern constellation Carina. The image celebrates the 20th anniversary of Hubble's launch and deployment into an orbit around Earth.

Scorching radiation and fast winds (streams of charged particles) from super-hot newborn stars in the nebula are shaping and compressing the pillar, causing new stars to form within it. Streamers of hot ionized gas can be seen flowing off the ridges of the structure, and wispy veils of gas and dust, illuminated by starlight, float around its towering peaks. The denser parts of the pillar are resisting being eroded by radiation much like a towering butte in Utah's Monument Valley withstands erosion by water and wind.

Nestled inside this dense mountain are fledgling stars. Long streamers of gas can be seen shooting in opposite directions off the pedestal at the top of the image. Another pair of jets is visible at another peak near the center of the image. These jets (known as HH 901 and HH 902, respectively) are the signpost for new star birth. The jets are launched by swirling disks around the young stars, which allow material to slowly accrete onto the stars' surfaces.

It's been my privilege to use HST from time to time to study binary star systems.

Solar Dynamics Observatory

NASA has put out "first light movies" from the new Solar Dynamics Observatory. Here's a youtube that puts them all together (along with some music I don't like.)

Skip ahead to 2:40 to see the most spectacular bit (in my humble opinion.)

Yankees win first four series for first time since Coolidge

I've been really happy the Yankees took two out of three from three very strong teams (Red Sox, Ray, Angels) to start the season and now the first two fro the Rangers. What I didn't know was this amazing Yankees statistic yesterday:

When the Yankees last won their first four series, Lou Gehrig and Babe Ruth anchored the middle of the batting order, Earle Combs and Tony Lazzeri provided the power and Bob Shawkey was on the mound. That was in 1926 and even without extraordinarily fast starts since then in many years, New York dominated baseball.

I remember that even in the wonderful 1998 season they had a bad start against the Angels, but this is incredible. You have to figure the chance of winning a series for the Yankees is 50% (if not better.) Winning the first four should then happen on average once every eight seasons. It should have happened about ten times since 1926. Of course with enough statistics -- and baseball has enough statistics -- something improbable will come up, but I'm really surprised.

An exciting new brown dwarf planetary system

The discovery of a planetary-mass system to a brown dwarf in Taurus has just been announced complete with a explanatory press release for the public. The new system reminds me of my favorite 2M1207AB system in TW Hya except this one is much younger -- just a million years old -- and somewhat closer (15AU) together. Like 1207A, the primary (2MASS J04414489+2301513) has a circumstellar disk and secondary is 5-10 times the mass of Jupiter. However, since this system is less than a million years old, it's clear that the "planet" must have formed from a collapse like a "star" or "brown dwarfs" rather than being slowly accumulated in a disk. Above is an artist's conception of the system. Here's the actual Hubble Space Telescope discovery image:

I talked to Kevin Luhman about the system and he was excited the possibility that this is actually a quadruple system. Not too far away (12.4 arcseconds) there's a pair of stars. Many brown dwarfs that are distant (>1000AU) companions to stars are doubles so perhaps this fits in. Here's a 2MASS survey image (in J band) of the field -- the brown dwarf is inside the magenta circle and the possibly related star is the brighter object to the upper left. They both look single because you need Hubble-quality resolution to tell they are binaries. The other star to the lower right is not related.

President Obama on NASA's future

President Obama's April 15th, 2010 speech on NASA's future:

More here. I think an asteroid mission makes a lot more sense than returning to the Moon. The space station will be continued which also makes a lot of sense. More thoughts later.

Delaware: the MUSICAL

Oh my:

My Governor, Chris Christie, is an alumnus of the University of Delaware, but I guess he's not famous enough yet to attract students.

Update: One of my college friends points out our college did it first: That's Why I Chose Yale: