Falling out of a Cluster: The history of the Sun

Falling out of a Cluster: The history of the Sun

One of my favorite things to do with students in the late fall is to take them outside and point first to the Orion nebula, then to the Pleiades, and finally to the Hyades cluster, saying “these are snap shots in the evolution of open clusters.” Each of these systems is the home of young stars, but while the Orion nebula is very much a stellar nursery, with stars just 10 million years old or younger, the Pleiades, is more like a day care center with stars 100 million years old or younger. At the same time, Hyades is more like an afterschool program for stars 730 million years old or younger. All these systems are filled with celestial children. In their youth these stars still gather in clumps. But, as they age, the stars will drift apart until, as...

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BAA / AAVSO Day 2: Novae & Supernovae for all

The word Novae generally refers to a “New Star,” or a “Guest Star” – An object that springs up in the sky quite suddenly as a new but non-permanent object. Today we give these non permanent sky features a dozen or more names: Supernovae (types I & II with all sorts of extra letters), Recurrent Novae, Cataclysmic Variables and more. While observed and documented for about 2000 years, only for the last 100 years have we known that novae and supernovae are different objects, and that supernovae are stars blowing themselves to bits. Only in my lifetime have we known Novae are white dwarfs surrounded by accretion disks that periodically blow (some of) themselves to bits. These dynamic objects change dramatically in brightness. For...

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AAVSO/BAA Day 1: Binary Adventures

AAVSO/BAA Day 1: Binary Adventures

Variable stars come in many forms – there are happy little regular stars, widely separated and merrily circling ones dancing an eon long dance. Some white dwarfs – dead stars, cooling into stellar embers of stars – become vampires as they gravitationally suck mass from their companion and heat themselves back out of the stellar grave. There are stars with touching atmospheres that are merging, spiraling, reheating in a marriage of materials, and stars where one covers the other in a layer of stellar soot as it exhales its spoke thin atmosphere as it sighs at its planetary nebula fate. Binary stars form beautiful, dynamic systems that provide astronomers some of their most necessary data (masses can only be measured in binary systems) and some of...

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AAVSO/BAA Day 1: Paula and Pulsating White Dwarfs

AAVSO/BAA Day 1: Paula and Pulsating White Dwarfs

After several days of travel, I’ve settled into the front row of the BAA/AAVSO meeting in New Hall, in Cambridge, UK. Dr. Paula Skody is giving an excellent talk on pro-am collaboration to make Hubble Space Telescope observations of cataclysmic variables. She studies pulsating white dwarfs – stars whose outer 99% have oscillations that can be seen as high speed, slight changes in brightness. The most interesting of these pulsating stars are in binary systems and are gravitationally stripping mass from their companions. This process changes the mass, temeperature, and composition of the white dwarf, and it is possible to observe how the star’s pulsations change as their mass, temp, and composition change. WhiteDwarf.org has movies of these stars....

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Star Formation in the Center of the Galaxy

Star Formation in the Center of the Galaxy

I saw a really cool paper (to me) on the pre-print server today. Astronomers Kuzic et al. have made detailed measurements of two groups objects in the center of the galaxy within half a parsec of the center of the Milky Way. These objects, named IRS 13E and IRS 13N (aren’t those exciting names?) are each composed of very young stars (less then 1 million years). The objects in 13E are Wolf-Rayet and O-Type giant stars that will quickly blow themselves out and the stars in 13N are still embedded in dust and gas. This paper caught my attention for one simple, stupid reason.  Every read Ringworld by Niven? It depicts a bunch of stars all going Nova at once in the center of the galaxy. Well, O-stars that are sufficiently large enough can do just that! The...

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Tau Boo Back Flips (magnetically)

Tau Boo Back Flips (magnetically)

As some of you may know, my favorite favorite star to bring up when discussing binaries is Tau Boo B (Go ahead, say it out loud. Giggle. Join me in the giggling. Wasn’t that fun?). This little red dwarf star is the companion star to the much more famous, but no where near as fun to say, bigger Tau Boo A. Tau Boo A is a solar (sorta) twin, with similar temps (it’s a bit hotter) and a similar mass (its a bit bigger) to the Sun. Now, we have one new characteristic to add to the list of similarities. Astronomers using the awkwardly names Canada-France-Hawaii Telescope atop Mauna Kea have observed the flip of Tau Boo A’s magnetic field. Tau Boo A’s flip might not be entirely identical to Sol’s back flipping behavior, however. While the...

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