Is NGC 2419 a wayward globular or the Milky Way's own?

June 10, 2015 by David Dickinson, Universe Today
NGC 2419 as imaged by the Hubble Space Telescope. Credit: NASA/STScl

Turns out, we may not know our extragalactic neighbors as well as we thought.

One of the promises held forth with the purchase of our first GoTo telescope way back in the late 1990s was the ability to quickly and easily hunt down ever fainter deep sky fuzzies. No more juggling star charts and red headlamps, no more star-hopping. Heck, it was fun to just aim the scope at a favorable target field, hit 'identify,' and see what it turned up.

One of our more interesting 'discoveries' on these expeditions was NGC 2419, a globular cluster that my AstroMaster GoTo controller (featuring a 10K memory database!) triumphantly announced was an 'Intergalactic Wanderer…'

Or is it? The case for NGC 2419 as a lonely globular wandering the cosmic void between the galaxies is a romantic and intriguing notion, and one you see repeated around the echo chamber that is the modern web. First observed by Sir William Herschel in 1788 and re-observed by his son John in 1833, the debate has swung back and forth as to whether NGC 2419 is a true globular or—as has been also suggested of the magnificent southern sky cluster Omega Centauri—the remnant of a dwarf spheroidal galaxy torn apart by our Milky Way. Lord Rosse also observed NGC 2419 with the 72-inch Leviathan of Parsonstown, and Harlow Shapley made a distance estimate of about 163,000 to NGC 2419 in 1922.

Today, we know that NGC 2419 is about 270,000 light years from the Sun, and about 300,000 light years from the core of our galaxy. Think of this: we actually see NGC 2419 as it appeared back in the middle of the Pleistocene Epoch, a time when modern homo sapiens were still the new hipsters on the evolutionary scene of life on Earth. What's more, photometric studies over the past decade suggest there is a true gravitational link between NGC 2419 and the Milky Way. This would mean at its current distance, NGC 2419 would orbit our galaxy once every 3 billion years, about 75% the age of the Earth itself.

The relative distances of NGC 2419, the LMC, SMC and M31.  Created by author using NASA graphics.

This hands down makes NGC 2419 the distant of the more than 150 globular clusters known to orbit our galaxy.

At an apparent magnitude of +9 and 6 arc minutes in size, NGC 2419 occupies an area of the sky otherwise devoid of globulars. Most tend to lie towards the galactic core as seen from our solar vantage point, and in fact, there are no bright globulars within 60 degrees of NGC 2419. The cluster sits 7 degrees north of the bright star Castor just across the border of Gemini in the constellation of the Lynx at Right Ascension 7 Hours, 38 minutes and 9 seconds and declination +38 degrees, 52 minutes and 55 seconds. Mid-January is the best time to spy NGC 2419 when it sits roughly opposite to the Sun , though June still sees the cluster 20 degrees above the western horizon at dusk before solar conjunction in mid-July.

We know globular clusters (say 'globe' -ular, not "glob' -ular) are some of the most ancient structures in the universe due to their abundance of metal poor, first generation stars. In fact, it was a major mystery up until about a decade ago as to just how these clusters could appear to be older than the universe they inhabit. Today, we know that NGC 2419 is about 12.3 billion years old, and we've refined the age of the Universe as per data from the Planck spacecraft down to 13.73 (+/-0.12) billion years.

What would the skies look like from a planet inside NGC 2419? Well, in addition to the swarm of hundreds of thousands of nearby stars, the Milky Way galaxy itself would be a conspicuous object extending about 30 degrees across and shining at magnitude -2. Move NGC 2419 up to 10 parsecs distant, and it would rival the brightness of our First Quarter Moon and be visible in the daytime shining at magnitude -9.5.

And ironically, another 2007 study has suggested that the relative velocity of Large and Small Magellanic Clouds suggest that they may not be bound to our galaxy, but are instead first time visitors passing by.

The location of NGC 2419 in the night sky. Credit: Starry Night Education software

And speaking of passing by, yet another study suggests that the Milky Way and the Andromeda galaxy set on a collision course billions of years hence may be in contact… now.

Mind not blown yet?

The view of the Milky Way galaxy as seen from NGC 2419. Credit: Starry Night Education Software

A 2014 study looking at extragalactic background light during a mission known as CIBER suggests that there may actually be more stars wandering the universe than are bound to galaxies…

But that's enough paradigm-shifting for one day. Be sure to check out NGC 2419 and friends and remember, everything you learned about the universe as a kid, is likely to be false.

The view of the Andromeda galaxy as seen from NGC 2419. Credit: Starry Night Education software

Explore further: Image: Hubble sees an ancient globular cluster

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Tuxford
1 / 5 (4) Jun 10, 2015
We know globular clusters are some of the most ancient structures in the universe due to their abundance of metal poor, first generation stars. In fact, it was a major mystery up until about a decade ago as to just how these clusters could appear to be older than the universe they inhabit. Today, we know that NGC 2419 is about 12.3 billion years old, and we've refined the age of the Universe as per data from the Planck spacecraft down to 13.73 (+/-0.12) billion years.


Assumption followed by a patch. Globulars are growing from the inside-out, much more rapidly than much less dense matter regions of space. Hence, the stars are metal poor, with newly formed matter therein dominating.

For more details, see my comments within the references in my final comment herein:

http://phys.org/n...tml#nRlv

Bigbangcon
1 / 5 (2) Jun 10, 2015
@JeanTate:
Sorry to pop in and out of a discussion, which I hardly can afford. But you seem to be quite serious about astrophysics and cosmology; so I popped in again just to give you some more references about the dialectical view of the universe; an exact opposite of the official view and hence a crank cosmology a la Arp!

This item about NGC 2419 and the one about "Lost in space, NGC 6503" and the whole range of cosmological phenomena in astrophysics so far, has a better fit if you reverse the Big Bang narrative to the narrative expressed in the article "The Breeding Galaxies" I referred before. It was endorsed and highly praised by Chip Arp himself. This globular cluster, the Magallanic clouds and other objects in the Local Group are all most likely ejecta from the Milky Way. If these were formed from the "universal condensation after the Big Bang" they could not be moving away from the strong gravity pull of Milky Way. More below..
Bigbangcon
1 / 5 (2) Jun 10, 2015
@ JeanTate, cntd.

Aside from the book I mentioned before and aside from some other references by this author, the following three would give you a quantum mechanical basis, a concrete example of matter/antimatter annihilation as a basis for cosmic dynamics and a philosophical basis: Regards.
1. http://www.ptep-o...9-03.PDF
2. http://redshift.v...2MAL.pdf
3. http://www.ptep-o...9-04.PDF

yyz
5 / 5 (3) Jun 11, 2015
Although NGC 2419 was found to be a gravitationally bound cluster in the outer halo of the Milky Way galaxy, it is still reasonable to assume that unbound 'intergalactic' globular clusters(IGCs) exist in the Local Group. IGCs have been found in other galaxy groups and clusters(e.g. Fornax, Virgo, Coma, Abell 1689) so a search of the Local Group may turn up a few.

Recently, a dedicated search of the Sloan Digital Sky Survey 'footprint', covering a third of the sky, turned up twelve candidate IGCs in the Local Group that were not close to any members of the LG or galaxies within 3 megaparsecs of the LG. If confirmed, these objects would represent the first of what appears to be a small number of globular clusters wandering around the LG, unbound to any galaxies. Details of the search can be found here:

http://fr.arxiv.o...03.02963
Bigbangcon
1 / 5 (1) Jun 13, 2015
@JeanTate;
Thanks for your response and most of all for the fact that you cared to go through the references I gave you. This in itself is a great favour to me. Whether or not you agree with these views is a different thing. Most people would dismiss these outright without even caring to read them, because the word "dialectics" would turn them all, Moreover these are not published in elite mainstream journal, with famous names behind these publications and hence trash stuff etc. The view expressed in these publications, suffers from the obvious great limitations that these are ideas of a single person based on some of the most general aspects of astrophysics known so far and based on s different (opposite) philosophical perspective.

You are averse to philosophy; but remember that you ( as well as New Physics, religion, old materialism, rationalism) do have a philosophy on which you base your judgement It is called causality, the opposite of dialectic. Cntd. below:
Bigbangcon
1 / 5 (1) Jun 13, 2015
Cntd.
Please see my comment as "futurehuman" in the Guardian article as a criticism of modern theoretical physics: http://www.thegua...collider
The main differences are: Causality can work in a limited universe, has to depend on a first cause or impulse (a perpetual mystery) for any motion, change development etc at every step and needs the incorporation of new mysteries, BB, Black/Dark things etc. Allows no contradiction, is deterministic etc. and needs a creator for first cause and for all other mysteries.
Dialectics is based on contradiction (unity of the opposites), the primary basis for eternal motion, change, evolution etc. mediated by chance and necessity, under given circumstances. No external intervention needed, but it can influence the course of evolution, development etc.
Bigbangcon
1 / 5 (1) Jun 13, 2015
@ JeanTate, from above:

Only a detailed analysis of all the empirical facts known so far and continuously evolving new one in the light of these general ideas can judge whether these ideas have any merit or not. This is the task of whole of physics and no single or limited people can ever accomplish it. Just to give you an example. I was thinking of analyzing ALL the GRB data recorded so far to test the hypothesis that matter/antimatter annihilation is the source of most gamma rays in the observable universe; by looking for electron/positron, proton/antiproton etc. annihilation peaks as well as by analysing the antimatter clouds (at least three are known) in the Milky Way . Official science have nothing to do with it at all! All my efforts to seek collaboration from some scientists working in this area were either ignored or rebuffed! There are broad peaks for example at ~ 1 MeV corresponding to e+/e-. But are complicated due to secondary emissions after the initial burst. So long!

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