Lenticular Galaxy - Formula for Probable Location of Stars

[leto]

I bought a nexstar 114gt a few months ago, and I have been unable to use the auto align features, which would allow me to use the tracking and goto features on the telescope. I am not certain if the telescope itself is flawed, or if I am simply doing something wrong. I sent two emails to Celestron over the months, and they have not responded at all. I have read their faqs and setup instructions and do not believe the error lies in what was covered.

I try to be as precise as possible in giving the computer its information, using a gps for long/at, a level to perfectly level and pointing the scope to true north in relation to the north star to a picture I have. I even use atomic time. However, when the scope goes to slew towards the two alignment stars, it is totally off. I don't know what I could be missing, or what I might need to change, and I'm looking for input. Thankyou.

 

[Orion1]

When in a supernova a star collapses to a neutron star, its magnetic field increases dramatically in strength. Duncan and Thompson calculated that the magnetic field of a neutron star, normally an already enormous 10^12 tesla could under certain circumstances grow even larger, to about 10^15 tesla. Such a highly magnetic neutron star is called a magnetar.

In the outer layers of a magnetar, which consist of a plasma of heavy elements (mostly iron), this causes tension which leads to 'starquakes'. These seismic vibrations are extremely energetic, and result in a burst of X-ray and gamma ray radiation. To astronomers, such an object is known as a soft gamma repeater.

It is estimated that about 1 in 10 supernova explosions results in a magnetar rather than a more standard neutron star or pulsar.

The energy of these explosions slows the rotation (causing magnetars to rotate much more slowly than other neutron stars of a similar age) and lessens the electric field, and after only about 10,000 years the starquakes are over.

Reference:
http://www.wordiq.com/definition/Magnetar
http://science.nasa.gov/newhome/headlines/mag_pix/TV-graphics/xsection.tnl.jpg
http://science.nasa.gov/newhome/headlines/mag_pix/TV-graphics/xsection.jpg
http://science.nasa.gov/newhome/headlines/ast20may98_1.htm
http://science.nasa.gov/newhome/headlines/ast29sep98_1.htm

 

[wolram]

http://xxx.sf.nchc.gov.tw/abs/astro-ph/0504038
The fist generation of star forming halos
We model gas cooling in high-resolution N-body simulations in order to investigate the formation of the first generation of stars. We follow a region of a LCDM universe especially selected to contain a rich cluster by the present day. The properties of the dark haloes that form in these sub-solar mass resolution simulations are presented in a companion paper by Gao et al. The first gas clouds able to cool by molecular hydrogen line emission collapse at extremely high redshift, z ~ 47, when the mass of the dark halo is 2.4 x 10^5 Msun/h. By z ~ 30, a substantial population of haloes are capable of undergoing molecular hydrogen cooling although their ability to form stars is dependent on the efficiency of feedback processes such as dissociating Lyman-Werner radiation. The mass of the main halo grows extremely rapidly and, by z ~ 36, its virial temperature has reached 10^4K, at which point gas cooling becomes dominated by more effective atomic line processes. By z ~ 30, a small ``group'' of galaxies will have formed unless prevented from doing so by feedback processes. By this redshift, massive population III stars are able to ionise gas well beyond their own host halo and neighbouring HII regions can percolate to form an ionized superbubble. Such patches would be too widely separated to contribute significantly to reionisation at this time. The large number density of early cooling haloes in the pre-reionised universe raises the exciting prospect that this ultra-early generation of stars may be observable as gamma-ray bursts or supernovae.

 

[wolram]

http://arxiv.org/abs/astro-ph/0506745

Title: The Frequency of Carbon Rich Stars Among Extremely Metal Poor Stars
Authors: Judith G. Cohen, Stephen Shectman, Ian Thompson, Andrew McWilliam, Norbert Christlieb, Jorge Melendez, Franz-Josef Zickgraf, Solange Ramírez, Amber Swenson
Comments: Submitted to the proceedings of the IAU Symposium 228, From Lithium to Uranium: Elemental Tracers of Early Cosmic Evolution (Paris, 23--27 May 2005), Cambridge University Press, ed: Vanessa Hill, Patrick Francois & Francesca Primas

We demonstrate that there are systematic scale errors in the [Fe/H] values determined by the Hamburg/ESO Survey (and by the HK Survey by inference) for certain extremely metal poor (EMP) highly C-enhanced giants. The consequences of these scale errors are that a) the fraction of carbon stars at extremely low metallicities has been substantially overestimated in several papers in the recent literature b) the number of EMP stars known is somewhat lower than has been quoted in the recent literature c) the yield for EMP stars by the HK and the HES Survey is somewhat lower than is stated in the recent literature. A preliminary estimate for the frequency of Carbon stars among the giants in the HES sample with -4 < [Fe/H] < -2.0 dex is 7.4 \pm 2.9%, and for C-rich giants with [C/Fe] > +1.0 dex is 14.4 \pm 4%.
Here we present the key results of detailed abundance analyses of 14 C-stars selected from the HES as candidate EMP stars, of ~50 such stars analyzed. About 80% of such C-stars show highly enhanced Ba as well, with C enhanced by a factor of about 100, and [Ba/C] roughly Solar. These stars often show prominent lead lines, The remaining 20% of the C-stars do not show an enhancemement of the s-process neutron capture elements around the Ba peak. They tend to be the most metal-poor stars studied. We suggest that all these EMP C-stars are the remnants of the secondary in a mass transfer binary system where the former primary was an AGB star, which transferred substantial mass at that evolutionary stage.

 

[wolram]

http://arxiv.org/PS_cache/astro-ph/pdf/0508/0508526.pdf

Title: The effects of Population III stars and variable IMF on the chemical evolution of the Galaxy
Authors: Silvia Kuna Ballero, Francesca Matteucci, Cristina Chiappini
Comments: 30 pages, 10 figures, accepted for publication in New Astronomy

We studied the effects of a hypothetical initial stellar generation (PopIII) of only massive and very massive stars (VMS) on the chemical evolution of the Galaxy. We adopted the two-infall chemical evolution model of Chiappini et al. and tested several sets of yields for primordial VMS (Pair-Creation SNe), which produce different amounts of heavy elements than lower mass stars. We focused on the evolution of alpha-elements, C, N, Fe. The effects of PopIII stars on the Galactic evolution of these elements is negligible if a few generations of such stars occurred, whereas they produce different results from the standard models if they formed for a longer period. Also the effects of a more strongly variable IMF were discussed, making use of suggestions appeared in the literature to explain the lack of metal-poor stars in the Galactic halo with respect to model predictions. The predicted variations in abundances, SN rates, G-dwarf [Fe/H] distribution are here more dramatic and in contrast with observations; we concluded that a constant or slightly varying IMF is the best solution. Our main conclusion is that if VMS existed they must have formed only for a very short period of time (until the halo gas reached the threshold metallicity for the formation of very massive objects); in this case, their effects on the evolution of the studied elements was negligible also in the earliest phases. We thus cannot prove or disprove the existence of such stars on the basis of the available data. Due to their large metal production and short lives, primordial VMS should have enriched the halo gas beyond the metallicity of the most metal poor stars known in a few Myrs. This constrains the number of Pair-Creation SNe: we find that a number of 2-20 of such SNe occurred in our Galaxy depending on the stellar yields.

 

[Spin_Network]

There is a long standing issue with Gravistars, recent paper here:
http://arxiv.org/abs/gr-qc/0509087

gives a good overview, and has links therein.

One can understand that the 'Gravitational Vacuum Star', above has evolved from a certain paramiters contained in the above paper, for instance ordinary Stellar Stars, have their own intertwined/embedded processes, a [fusion-core] embedded within a [fission-outer shell[fusion-core]fission-outer shell] nuclear structure.

The paper details 'gravistar signals' to be of a certain type.

In this paper:http://arxiv.org/abs/gr-qc/0509090

they have extended also has a 'chosen' type of perturbations (waves).

Can both have an underlaying common 'co-incedence' factor?

And thus yet another interesting paper:http://arxiv.org/abs/gr-qc/0509088

shows an analytical model of a radiating star undergoing gravitational collapse with non-vanishing shear, interesting papers.

 

[neutrino]

Astronomers have found a new type of neutron star. The objects send out short bursts of radio waves lasting just two to 30 milliseconds followed by "dark spells" lasting minutes to hours. Conventional plusars, in contrast, emit flashes of radio waves at regular intervals. The new objects -- dubbed "rotating radio transients" or RRATs -- were discovered by a team led by Maura McLaughlin from the Jodrell Bank Observatory at the University of Manchester in the UK. She believes that the RRATs may outnumber conventional radio pulsars by a ratio of four to one (Nature 439 817).

http://physicsweb.org/articles/news/10/2/9/1"

 

[wolram]

http://arxiv.org/abs/astro-ph/0604050

Authors: Smadar Naoz (1), Shay Noter (1), Rennan Barkana (1) ((1) Tel Aviv University)
Comments: 4 pages, 3 figures, submitted to PRL

Large telescopes have allowed astronomers to observe galaxies that formed as early as 850 million years after the Big Bang. We predict when the first galaxy that astronomers can observe formed in the universe, accounting for the first time for the size of the universe and for three essential ingredients: the light travel time from distant galaxies, Poisson and density fluctuations on all scales, and the effect of very early cosmic history on galaxy formation. We find that the first observable star is most likely to have formed 30 million years after the Big Bang (at redshift 65), much earlier than previously expected. Also, the first galaxy as massive as our own Milky Way likely formed when the universe was only 400 Myr old. We also show that significant modifications are required in current methods of numerically simulating the formation of the first galaxies.

 

[jdlawlis]

Chaisson and McMillan's Astronomy textbook gives the following explanation for the strong magnetic fields in neutron stars:

"The original field of the parent star is amplified as the collapsing core squeezes the magnetic field lines closer together, creating a magnetic field trillions of times stronger than the Earth's field."

However, don't neutron stars form by photodisintegration, where energetic photons split iron nuclei into smaller nuclei until only protons and neutrons remain? The protons then combine with electrons to form neutrons. As the electrons get consumed, electron pressure can no longer hold up the weight of the star, and it collapses. Where then, does the current come from to support a dynamo that fuels the magnetic field?

 

[shelanachium]

I gather at least some gamma-ray bursters are the result of neutron-star coalescence, when a neutron star binary radiates gravitational waves, losing energy till the stars fuse.

In many cases the result will be a black hole, but before this forms there should be some ejecta; in principle this could be examined spectroscopically in the afterglow of such events.

Because neutron-stars are by definition neutron-rich, I have often wondered whether the ejecta might include superheavy elements, whose most stable isotopes must be far more neutron-rich than familiar nuclei. They may not form in supernovae because of the extreme fissionability of fermium and immediately succeeding elements (see my comments on superheavy elements in nuclear physics forum). If long-lived superheavies are ever formed, perhaps more likely 'top-down' from already neutron-rich matter than 'bottom-up' in supernovae. As neutron-star coalescence is very rare, this would explain rarity of long-lived superheavies, should they exist at all.

 

[WhyIsItSo]

To clarify, I am seeking a mathematical model upon which I can build a program which could populate a fictitious E0 (or spherical dwarf) galaxy with a plausible distribution of stars. I am not looking for the outlying stuff, just the main central sphere and disc portions.

From extensive reading I understand that the bulk of luminous bodies will be within the sphere, but I don't know what kind of ratios are realistic.

If there is any data regarding types of stars most likely for a given region of a galaxy, that would be useful also.

This model need not be rigorous; just good enough to use to make a realistic "looking" galaxy.

 

[SCKnight14]

Okay, I'm writing a science-fiction story, and I'm trying to make it as realistic as possible, which means, the story is going to be plausible. Thus, I'm trying to figure out how to make an alien world be realistic. The planet is going to be Earth-like (to a certain extent), but there are going to be a lot of differences. For example, the star is not going to be a G main sequence star, and the planet isn't going to be the third planet, etc.

Here goes:
1) Star is a K0V star, meaning its mass is around .79 solar masses.
2) The planet is the fourth from the star, and lies approximately 0.562 AU, and has a mass of about 0.936 EM (Earth Mass). The star's HZ (habitable zone) is between 0.477 - 0.846 AU.
3) The planet has a nitrogen-oxygen atmosphere, just like Earth's atmosphere, but it also has much more argon and helium in its atmosphere than Earth does.
4) The planet is basically cold, with average surface temperature of between 4.4° C and 14.1° C (between 39.9° F and 57.4°F). It has very few clouds.
5) The planet has a large concentration of cobalt, since the lifeforms on the planet have indigo-colored blood, which is the result of their blood bimetallic hemoglobin, which is cobalt and iron (by the way, cobalt turns blue when it oxidizes).

Now, here's my question:
What would the planet's sky look like? What color would it have? I read in some books and articles that planets orbiting orange or red stars would have a green or greenish-blue sky. However, I'm not sure if this is correct (the book was a Star Trek roleplaying game book a friend loaned me a while back, and we all know how 'realistic' Star Trek is). Does anyone mind helping me out, please?

In addition, this topic can be used to figure out what other worlds' skies would look like as well.

 

[astonomy101]

I am having difficulty understanding the concept of Doppler imaging as used to detect and study starspots.

With regards to the conventional Doppler imaging,

so far what i have understood is that a spectral absorption line from a star is observed over time, and if the star is rotating sufficiently fast then the spectral line will be broad enough to observe any distortion caused by the existence of spots.

These spots cause a distortion because they are of lower temperature, therefore reducing the line absorption at the spectral line under observation. The reason for this is that particular absorption lines can be observed only for a certain range of temperatures and if the temperature drops then less absorption occurs.

The above is what i have understood as the explanation for the below diagram:

http://helene.ethz.ch/research/stars/starspots/results/DI_atom_anim.gif

Moving onto Zeeman doppler imaging...well i can't seem to understand this. What i have picked up is that the spectral (absorption) lines are split due to the strong magnetic field at starspots (Zeeman effect), the size of the splitting reveals the magnitude of the magnetic field at that point. As seen below:

As to the direction of the field, i don't know how we can tell this.Also, what do the horizontal lines below represent?

And i am drawing a blank as to what the second profile below represents:

I appreciate that from this we can tell that the two spots are of opposite polarity but i can't quite tell what i am looking at.

Is my explanation so far is correct?

Why is Zeeman Doppler imaging used rather than just plain Doppler imaging?

 

[ThomasEdison]

http://www.physorg.com/news187288162.html

This article mentioned interesting gravity waves from these close together binarys. It also mentioned a plume of matter jetting from one star to the other.

I know very little about astronomy so forgive how naive this may sound.
So my question is:
What about the electric current between these two objects?



The picture shows a plume of matter jetting from one of the binarys to the other. Would a massive electric charge be running up and down this plume? I mean truly cataclysmic looking lightning (although I don't think there is lightning without an atsmosphere.) However there would be star dust and gas to arc I would think. Would this binary act like a gigantic generator?


Can anyone explain what is happening electrically in a close together binary star such as this where it appears they actually share matter with each other?

 

[Scott S]

I've created an XL spreadsheet to update star coordinates from J2000 to the current date and time. Unfortunately, I have some issue after about 150 successful formulae. My bug is somewhere in conversion to Local Hour Angle and dealing with refraction and then converting to Altitude/azimuth.
Quite embarrasing after all that good work.
This is not homework and I've checked the bugger using Meeus and now I'm just frustrated.
If anyone is willing to take a look at the spreadsheet, I've attached a copy of the offending page. Any pointers in the proper direction would be MASSIVELY appreciated.
Thanks, Scott.

Edit; The bugger is too big to upload.
Anyone interested in looking her over can e-mail me at ssz0407@msn.com.

 

[jess_vander]

I'm really stuck with this last question...im not quite sure where to start...any help would be greatly appreciated! for a) I am not sure what to use for the mass of the star and the radius..do i have to subtract the two radii?

When a massive star is at the end of its life, the inner core that is perhaps 2 solar masses shrinks in radius from a size of around 0.01 solar radii to a radius of just 20 km.

a) Calculate that the gravitational potential energy of the core EPOTENTIAL = −0.6GM2
R before and after the collapse.

b) The total energy of the star is conserved during this collapse: ETOTAL = EOTHER + EPOTENTIAL. This implies that the difference is liberated as other forms of energy. Calculate the amount of energy liberated.

c) How important is it to know the original radius of the core before collapse?

d) The liberated energy goes into heat, expanding the outer layers of the star at very high speed, neutrinos and light. Assume that just 0.1 percent of this energy emerges as light over a period of 100 days. Determine the luminosity of the star over this period.

e) Convert this luminosity to solar luminosities. For comparison the entire Milky Way galaxy has a luminosity of around 2 × 1010 Solar Luminosities.

 

[FunkyDwarf]

Ola,

I have a question regarding material discussed in this paper:
http://www.ias.ac.in/jarch/jaa/3/325-334.pdf

and also in others:
http://www.springerlink.com/content/q3773x7626424383/
http://onlinelibrary.wiley.com/doi/10.1002/asna.2113090417/abstract

Firstly: Eqn 20 in the first paper depics the g00 component of the Schwarzschild exterior metric with a coefficient of 9 which as far as i know shouldn't be there (and isn't in their equation 11). Is this an error/missprint or am i missing something? While it seems like a misprint, if one generates a metric using their A,B and R (which is really a parameter which i relable lambda; a is the radius of the object) then in the case where r=a the metric g11 part of the metric does not correspond to the corrsponding component of the Schwarzschild metric (i realize the original discrepancy was in the other component but...)

Second question: I am not currently able to login to retrieve the full pdf of the 3rd link, but in the abstract they suggest an upper limit on the mass to ensure physical reasonableness (a>1.46 r_s). Is it fair to say then that even in this 'superdense' case one cannot take the metric arbitarily close to the black hole limit? Is there such an interior metric which allows this without breaking energy conditions (as the Florides metric appears to do)?

Cheers!
-G

 

[Dembadon]

http://Earth'sky.org/space/a-brilliant-but-solitary-superstar" mentions the possibility that a superstar, VFTS 682, might've been "ejected" from a nearby star cluster, R 136.

Apart from my amazement about the sheer size (and temperature) of this star, I'm curious about what would have to happen for something so massive to be moved in any manner. I've little-to-no knowledge of astrophysics, so I'll do my best to follow, but the only thing I can think of at the moment would be an explosion. Hopefully I don't offend anyone with my attempts to make something that I'm sure is incredibly complex out to be so simple. Feel free to tell me if I'm in-over-my-head.

 

[ImaLooser]

The Coriolis effect manifests as Rossby waves in the superfluid core of a neutron star. Such waves are "unstable due to gravitational waves," (amazing!) though they are somewhat damped by viscosity.

I also read that the Coriolis force dominates in BECs. http://iopscience.iop.org/1367-2630/12/9/093001/pdf/1367-2630_12_9_093001.pdf It also claims that another paper ("Rogue waves as spatial energy concentrators in arrays of nonlinear waveguides" Yuliy V. Bludov, Vladimir V. Konotop, and Nail Akhmediev) shows that this phenomenon is strongly correlated with rogue waves, as seen in the oceans of Earth. Amazing! Unfortunately it costs $40 or so to read that paper, the title seems to have nothing to do with it, and they won't even give an abstract for free. Hmmmph.

 

[ImaLooser]

Topological Currents in Neutron Stars:
Kicks, Precession, Toroidal Fields, and Magnetic Helicity
James Charbonneau and Ariel Zhitnitsky
Department of Physics & Astronomy, University of British Columbia
Journal of Cosmology and Astroparticle Physics, August 2010

http://arxiv.org/pdf/0903.4450.pdf


There's also a slide show at
http://www.phas.ubc.ca/~james/papers/wnppc09.pdf

and a PhD thesis at
http://www.phas.ubc.ca/~james/papers/jcharbonneau_PhD_thesis.pdf

The idea is this: There are a great many neutrons in a neutron star and some of these undergo decay. This produces mostly (only?) left-spin electrons. This excess will move in the direction of magnetic flux, inducing a current.

This seems reasonable to me. Then in a neutron star core there will be a current flowing wherever there is sufficient magnetic flux. This is what interests me. Does that seem right?
I also wonder about the magnitude of this current.

(He goes further and proposes things that will happen if the star has no significant electron-absorbing crust, but this case is not in my interest.)

 

[Romulo Binuya]

**"Stars are spherical balls of gas, and so you might think that when they end their lives and explode, that explosion would look like a uniform ball expanding out with great power," said Fiona Harrison, the principal investigator of NuSTAR at the California Institute of Technology (Caltech) in Pasadena. "Our new results show how the explosion's heart, or engine, is distorted, possibly because the inner regions literally slosh around before detonating."**
http://www.nasa.gov/jpl/nustar/supernova-explosion-20140219/#.UwUUA6ZFu0E

What made the inner regions of a collapsing star to slosh? Is the core which is supposed to be impervious and resistive to deformation due to degeneracy pressure would slosh too? Perhaps it will, considering that it generates shock waves that ultimately rips the star apart.