≡ Menu

Notes & Queries 10/20/07

South Dakota’s Homestake Gold Mine, famed for the work Ray Davis did on solar electron-neutrinos, may point toward clues in another search, the quest for dark matter. Experiments called LUX and DEAP/CLEAN are aimed at measuring the recoil of dark matter particles off ultra-pure, non-radioactive gases like purified argon and xenon. Robert McTaggart (South Dakota State University) gives the needed background:

“The visible matter that we all know and love only accounts for 4 percent of the total mass in the entire Universe. Furthermore, the gravitational attraction of a spherical halo of dark matter throughout galaxies can explain why they do not fly apart given their measured rotational speeds. Physicists expect the remaining 96 percent to be made of something other than protons, neutrons, electrons, or neutrinos. This ‘dark matter’ should interact with normal matter via gravity and very rarely via a collision.”

Critical to the work is adequate shielding, a more complicated process than you would think. The new laboratory site, announced by the National Science Foundation in July, is taking extraordinary measures, screening out even non-radioactive impurities in water and electroplating copper underground to prevent surface exposure to cosmic rays, which would produce radioactive cobalt. More in this SDSU news release.
It’s a long way to Comet 67P/Churyumov-Gerasimenko, but when ESA’s Rosetta spacecraft arrives in 2014, it will release the Philae lander onto the nucleus, orbiting the comet for the next two years while the lander does its work. Four planetary swing-bys are needed to get it there, each a fuel-saving gravitational assist, the second of which around Earth takes place in November (another will occur in late 2009). Out of all this we should get the most detailed look at a comet ever, with glimpses of two main-belt asteroids (Steins and Lutetia) along the way.
Black holes formed from the remnants of massive stars were thought to be no more than ten times the mass of the Sun or less until astronomers zeroed in on M33 X-7, whose 15.65 solar masses come as a bit of a surprise. But the calculations are the best ever, drawn from measurements of a star orbiting the black hole. Says Charles Bailyn (Yale University): “…an eclipse in the system provided the exact orientation and gave mass information far more accurate than any previous reports. Researchers rarely have such accurate points of reference.”

Black hole M33 X-7

Clearly we have more to learn about how these enigmatic objects form. M33 X-7 is the most distant stellar black hole ever observed, located in the galaxy M33, some three million light years away. Bailyn’s Black Holes Toolbox offers a nice tutorial. The paper on this work appears as Orosz et al., “A 15.65-solar-mass black hole in an eclipsing binary in the nearby spiral galaxy M 33,” Nature 449 (18 October 2007), pp. 872-875, with abstract available.

Image: The main component of this graphic is an artist’s representation of M33 X-7, a binary system in the nearby galaxy M33. In this system, a star about 70 times more massive than the Sun (large blue object) is revolving around a black hole. This black hole is almost 16 times the Sun’s mass, a record for black holes created from the collapse of a giant star. Other black holes at the centers of galaxies are much more massive, but this object is the record-setter for a so-called “stellar mass” black hole. Credit: NASA/CXC/M.Weiss; X-ray: NASA/CXC/CfA/P.Plucinsky et al.; Optical: NASA/STScI/SDSU/J.Orosz et al.

Addendum: The original entry mislabeled M33 as a ‘dwarf’ galaxy, a mistake quickly noted by a reader. See also the comment below re the mass of star vs. black hole.

Comments on this entry are closed.

  • andy October 20, 2007, 11:45

    M33 isn’t a dwarf galaxy – it’s the Triangulum Galaxy, the third largest member of the Local Group

  • Administrator October 20, 2007, 13:32

    Right you are — M33 is indeed mislabeled in the original, which I just corrected.

  • Ron S October 20, 2007, 14:38

    A minor point, but it’s probably better to say the black hole revolves around the star since it is less than 1/4 the star’s mass. I only mention this since there’s a bad meme out there that black holes have bizarre properties like being cosmic vacuum cleaners sucking in everything in sight.

  • Administrator October 20, 2007, 15:48

    Point taken, Ron. I added it to the addendum.

  • Adam October 20, 2007, 21:13

    Hi Paul

    An erratum for the top note… Dark Matter is only the other 23% of the Universe compared to regular Baryonic Matter, not 96% – the other 73% of the mass-energy budget is “dark energy”, whatever it may be. Important to keep the two distinct.

    Thus there’s roughly 6 times as much DM as there is BM. If MOND is correct then there’s somewhere between 2-3 times as much DM as BM.

  • andy October 30, 2007, 18:19

    Even more massive stellar black hole (this time in a dwarf galaxy): IC 10 X-1

    Maybe someone got the two discoveries confused when making the press releases?

  • forrest noble November 4, 2007, 16:30

    Adam, don’t get caught up in these percentages. I realize you have considerable knowledge concerning current theory. In my opinion, be aware that theories in general are somebody’s contructs, that some of these theories, in this case Dark Matter, are wrong. These are only somebody’s ideas/ hypothesis. Just because one is a PHD in Physics or Astronomy doesn’t enable them, in my opinion, to make better theories, often the contrary is true. Most all theories have their basis in observation, but observations may become counter-productive when they are misinterpreted.

    Alternate theory (and I grant you, this also is only a theory): Dark matter, and the energy that this dark matter possesses (i.e. zero point field energy, etc.), makes up roughly 90% of the universe. Dark energy, “the energy that is supposedly causing the accelerated expansion of the universe, is only a theory. Even Einstein commented on this matter. He said this concept was the biggest mistake of his (theoretical) life.

    The remaining amount of dark matter are both baryonic and fermions and is made up of materials such as molecular hydrogen, atomic particles, and voluminous amounts of dust and burned out stellar material and cores, planetary, asteroid size, comets, etc. material which originated both inside and outside the galaxy. Additionally there is both light and neutrinos. Both, according to this theory, have a mass (influenced by gravity and produce influences) when they are traveling at or near C.

    According to this theory, Dark matter is primarily consists of strings of more fundamental particles, 10’s of thousands of different lengths. Dark matter is omni-present throughout the universe. Fields of “Dark matter” not only influence galaxy revolution (non Keplerian), and galaxy cluster rotation, it is also the only cause of gravity everywhere including here on Earth. It has a pushing rather than pulling influence on matter.

    respectfully forrest

  • forrest noble November 4, 2007, 21:22

    correction above. I’ve made this same mistake before! D2598w08, curse, curse.

    “that some of these theories, in this case dark matter, are wrong.”

    should have been: “that some of these theories in this case Dark Energy, I believe to be wrong”.

  • Adam November 5, 2007, 5:14

    Hi forrest

    For now I’m sticking with mainstream ideas in my explorations of these ideas, but if you could point me towards relevant literature on your alternative I’m keen to give it a look.

  • forrest noble November 6, 2007, 1:31

    Hi Adam,

    The literature/ theories that I refer to are my own. An unpublished book of about 150 pages — written a long time ago but updated every couple of years. It is primarily another theory of Relativity but not nearly as complicated as SR or GR– but it would generally change both of them. It consists of field theory concerning dark matter, concerning the creation of all particle matter (primarily protons and electrons) as evidenced by galactic jets during a galaxies formative years. Basically the theory is that galaxies form from the inside out. The black hole forms first from dark matter and the stars form from atomic particles created by the resulting black hole.

    These theories, I believe, can answer nearly any fundamental question that might be asked. No BB, No “a priori forces”, generally no new physics. Just a relatively simple universe from the beginning till now (very large granted, but not infinite in space or time). My background is Engineering.

    I can e-mail you a summary and if you want more I can send you 25 pages at a time. Over the many years I’ve had a few scientific reviews but I’d love to have your opinion or could send out info to anyone who might be interested. Hopefully some day soon I’ll have it published.

    forrest underscore forrest at netzero dot net.

    best regards, forrest

  • Adam November 6, 2007, 9:21

    Hi forrest

    I’m genuinely interested. I get enough spam as it is so I have no compunctions about sharing my email address…


    …summary or bits at a time is fine by me. Years ago I was surprised by Grote Reber’s cosmological predilections – militant “everlasting Universe” believer – but since then I’ve learnt that there’s as many cosmological theories as there are people who care to invest a bit of thought on the matter.


  • forrest noble November 7, 2007, 15:37

    That’s very true Adam. Seemingly countless theories are out there. Some theories like the BB theory it seems could never be “proven”. I wrote mine over 40 years ago. I try to update it every couple of years or so. But well-formulated theories of course shouldn’t require major revisions or they essentially become a different theory, like the BB theory when Inflation was added, dark energy, dark matter, etc. The key to good theories I think is being able to make valid predictions that when observed would also generally contradict competing theories.

    I’m e-mailing you the first installment.

    Your friend forrest

  • george scaglione November 7, 2007, 18:13

    forrest and everybody else: meaning all the respect in the world but it is clear to me that the best theories are just really…the best”guesses” around at any given time!!! they change every couple of years or decades.i have the answer however about the ultimate beginning …and…end of the universe…weDO NOT know yet! yes the big bang seemed correct to me too,but now we ad on stuff that as someone so correctly said – makes it a new theory.if we could talk to those million year old alien technological societes i love to hypothacize about,i wonder if they would have any good acceptable answers!? anybody agree…or disagree…i’d like to hear from you. thank you george ps let me hasten to ad something that i’m pretty sure i heard from a college prof while i was still in school -” any theory you may have is just as valid as anyone elses as long as you can site good valid reasons why you think so”. again,thanks g

  • forrest noble November 8, 2007, 21:08

    Hey George and Adam,

    Sent out a theoretical Synopsis to both of you. Hope you find it interesting. I’m hoping in the not too distant future I will publish the related book in Cosmology and Theoretical Physics. Naturally if you provide input I will give theoretical credits in the book if I use any of your material, and/ or editor’s credits for just your comments (good or bad) or constructive criticisms.

    The advantages to this theory are that it provides “answers” , I believe, to generally “all” the “WHY” questions that nearly all other theories can not and do not address. It also explains a very simple beginning to the universe and relatively simple explanations for its appearance and mechanics which are different from current theory. It also makes a number of predictions.

    That’s an artists conception above isn’t it? Nice!

    all for now, your friend forrest

  • Daniel Scuka November 9, 2007, 9:40

    A quick note on Rosetta: We’re blogging the Rosetta Earth swing-by from ESOC (in Darmstadt, Germany), so if anyone wishes to follow progress, pls. do check for regular updates between now and 15 Nov.

    Rosetta Swing-by Blog:

  • george scaglione November 9, 2007, 10:16

    forrest i am now all the more sorry that,as i told you before,i did not recieve my copy! please try again! sounds good.your friend george