Comments on: In search of Tidal Tails… http://www.starstryder.com/2007/06/05/in-search-of-tidal-tails/ Blogging one sidereal day at a time Sat, 04 Feb 2012 16:26:45 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Lorne Ipsum http://www.starstryder.com/2007/06/05/in-search-of-tidal-tails/comment-page-1/#comment-2424 Lorne Ipsum Fri, 15 Jun 2007 23:21:51 +0000 http://www.starstryder.com/2007/06/05/in-search-of-tidal-tails/#comment-2424 Gotcha -- thanks! Gotcha — thanks!

]]> By: pamela http://www.starstryder.com/2007/06/05/in-search-of-tidal-tails/comment-page-1/#comment-2342 pamela Fri, 08 Jun 2007 18:37:28 +0000 http://www.starstryder.com/2007/06/05/in-search-of-tidal-tails/#comment-2342 Open clusters are the stars born in a star forming region (a collapsing, fragmenting, molecular cloud) that all have the same chemistry and same age, and they are young. By themselves, they are not rich in dark matter. Dwarf galaxies can have open clusters. Dwarf galaxies are small galaxies that have Mass to Luminous Mass ratios of 50-500 (globular clusters have ratios of <5). The dwarfs in the halo are all old, and are not forming stars. In tidal streams, how the stars move defines if they are shredded globular clusters of shredded dwarf galaxies. It all becomes a question of dynamics. Open clusters are the stars born in a star forming region (a collapsing, fragmenting, molecular cloud) that all have the same chemistry and same age, and they are young. By themselves, they are not rich in dark matter. Dwarf galaxies can have open clusters. Dwarf galaxies are small galaxies that have Mass to Luminous Mass ratios of 50-500 (globular clusters have ratios of <5). The dwarfs in the halo are all old, and are not forming stars. In tidal streams, how the stars move defines if they are shredded globular clusters of shredded dwarf galaxies. It all becomes a question of dynamics.

]]> By: Lorne Ipsum http://www.starstryder.com/2007/06/05/in-search-of-tidal-tails/comment-page-1/#comment-2337 Lorne Ipsum Fri, 08 Jun 2007 16:13:29 +0000 http://www.starstryder.com/2007/06/05/in-search-of-tidal-tails/#comment-2337 Just a quick question here... When the discovery of the remains of a dwarf galaxy is announced, how do the discoverers draw the line between dwarf galaxy remnants and open clusters? Is it a function of morphology (tail = dwarf), or the critter's orbit, or is it a stellar chemistry thing? Just a quick question here…

When the discovery of the remains of a dwarf galaxy is announced, how do the discoverers draw the line between dwarf galaxy remnants and open clusters? Is it a function of morphology (tail = dwarf), or the critter’s orbit, or is it a stellar chemistry thing?

]]> By: pamela http://www.starstryder.com/2007/06/05/in-search-of-tidal-tails/comment-page-1/#comment-2298 pamela Thu, 07 Jun 2007 19:03:11 +0000 http://www.starstryder.com/2007/06/05/in-search-of-tidal-tails/#comment-2298 Hi Vijayaraghaven, To search for black holes you need to be able to measure the velocities of the stars in the bright knots - in the remainders of galaxy cores. Unfortunately, these stars are generally too far away for us to get sufficient measurements of enough of them for anything to be said for certain. This is definately an interesting and open question! Hi Mayonaze, This is a hard question to answer because galaxies come in a range of sizes and have undergone different amounts of mass loss. Think of it this way - If you know the mass and age of a person, can you determin how many meals/calories they've consumed? An educated guess is possible, and you can say "If this, then this..." but an accurate answer requires information that can't be gleaned from a modern snap shot. Cheers, Pamela Hi Vijayaraghaven,

To search for black holes you need to be able to measure the velocities of the stars in the bright knots – in the remainders of galaxy cores. Unfortunately, these stars are generally too far away for us to get sufficient measurements of enough of them for anything to be said for certain. This is definately an interesting and open question!

Hi Mayonaze,

This is a hard question to answer because galaxies come in a range of sizes and have undergone different amounts of mass loss. Think of it this way – If you know the mass and age of a person, can you determin how many meals/calories they’ve consumed? An educated guess is possible, and you can say “If this, then this…” but an accurate answer requires information that can’t be gleaned from a modern snap shot.

Cheers,
Pamela

]]> By: Mayonaze http://www.starstryder.com/2007/06/05/in-search-of-tidal-tails/comment-page-1/#comment-2297 Mayonaze Thu, 07 Jun 2007 18:44:24 +0000 http://www.starstryder.com/2007/06/05/in-search-of-tidal-tails/#comment-2297 Given the age of the universe, an average density of galaxies, and a speed/direction for the Milky Way, would it be possible to predict the number of galaxies that are incorporated into the Milky Way? Given the age of the universe, an average density of galaxies, and a speed/direction for the Milky Way, would it be possible to predict the number of galaxies that are incorporated into the Milky Way?

]]> By: Vijayaraghavan. E http://www.starstryder.com/2007/06/05/in-search-of-tidal-tails/comment-page-1/#comment-2270 Vijayaraghavan. E Thu, 07 Jun 2007 13:42:35 +0000 http://www.starstryder.com/2007/06/05/in-search-of-tidal-tails/#comment-2270 Those bright spots in the trails, I suppose, are the cores of the byegone halaxies. Do they show any trace of black holes? Those bright spots in the trails, I suppose, are the cores of the byegone halaxies. Do they show any trace of black holes?

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