All Questions

15
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0answers
537 views

Terrestrial Exoplanet Skies – I've Built a Visual Sky Chart. Is it Accurate?

I'm an artist (and science enthusiast) and I've been trying to find a comprehensive resource that would help me clearly identify likely sky colors (as perceived by human vision) for exoplanets that ...
13
votes
0answers
422 views

Is it “weird” that all disc galaxies rotate once every billion years?

In a recent paper (Cosmic clocks: A Tight Radius - Velocity Relationship for HI-Selected Galaxies by Meurer, et al.), it was noted in the conclusion that: [This] implies a constant orbital time of ∼...
9
votes
0answers
442 views

How to determine scalar-to-tensor ratio r from CMB polarization spectrum?

CMB polarization spectrum can tell us about the primordial scalar and tensor perturbation. By analyze B and E mode angular spectrum power spectrum and temperature power spectrum we can determine the ...
8
votes
0answers
55 views

How uniformly is cometary debris distributed along the entire orbit of the comet?

Meteor showers occur when Earth passes through debris shed by a comet (if I get that right). Does this mean that the entire orbit of the comet is strewn with debris? I suppose that the debris follows ...
8
votes
0answers
170 views

Planning to revisit Arthur Eddington's experiment from 1919

As the fateful day draws closer, the United States will host a celestial event that comes once in three generations. I plan to witness this first hand at the exact center of greatest eclipse. In the ...
8
votes
0answers
387 views

Horseshoe orbits and integration in C

I'm studying a particular case of the restricted three-body problem. It's been found that some objects follow a horseshoe orbit pattern, and I'm trying to sort out something through an integration ...
8
votes
0answers
97 views

Estimating the tangential and cross component of the galaxy's shear using Gnomonic projection

I would like to know how I can estimate the tangential and cross component of the galaxy's shear using Gnomonic projection of the right ascension and declination ...
7
votes
0answers
52 views

What percentage of Helium-3 is primordial vs produced in stars

I tried to research but what I found is pretty limited. A very tiny but non zero percentage of primordial matter was Helium-3 or 3He. Stars produce 3He as part of the proton-proton chain but they ...
7
votes
0answers
132 views

How would astronomical seeing on Mars differ from that on Earth?

Astronomical seeing is the limiting factor for the resolution of all but the smallest Earthbound telescopes. Source Stunning advances in adaptive optics (along with it's predecessor speckle ...
7
votes
0answers
161 views

What fraction of a star's hydrogen store will be fused over its lifespan?

A main sequence star will fuse some of its hydrogen, but not all. In massive stars ($>1.5M_\odot$) the core is convective but the rest of the atmosphere radiative and hence does not mix much: as it ...
7
votes
0answers
179 views

What is the limiting abundances of elements at the end of the stelliferous era?

Is there any reputable published source on expected elemental abundances at the end of the era of stellar fusion? I am here interested in the contents of galaxies; much of intergalactic gas will be ...
7
votes
0answers
83 views

Do mixed type remnant collisions produce anything interesting?

The recent detection of a binary neutron star inspiraling and colliding raises an interesting question in my mind. Type Ia supernovae are believed to be caused by white dwarf/regular star pairs and/or ...
7
votes
0answers
66 views

How can maser emission be unpolarized?

I was reading that: However, unlike Galactic sources such as W3(OH), the emission is unpolarized and the 1667 MHz line is stronger than the 1665 MHz line. but how is this possible? Does not the ...
7
votes
0answers
55 views

Has the Kepler data been examined for light curves due to phase changes of non-transitting hot Jupiters and other?

I found this article http://www.epj-conferences.org/articles/epjconf/pdf/2011/01/epjconf_ohp2010_03005.pdf from 2011 announcing that two dozen secondary eclipses of "hot Jupters" have been seen in ...
6
votes
0answers
97 views

What object in the universe is most opaque to neutrinos?

I had this thought, and my first guess was "high density = lots of absorption, so I guess it's neutron stars" but this physics.se question about that has a great answer which covers why that's ...
6
votes
0answers
155 views

What are Kepler's laws (as he wrote them)?

There are of course many, many sources that quote Kepler's laws of planetary motion. This is preventing me from finding out what I really want to know: which is - what are Kepler's laws as he wrote ...
6
votes
0answers
77 views

Can the period of the planet transit across the sun be calculated in the same way the eclipse year is?

I read from Wikipedia$-$Eclipse cycle that the eclipse year, which is the period of Earth's hitting a certain node of its orbit around the sun, that is, the ecliptic, and the moon's orbit around Earth,...
6
votes
0answers
163 views

Gravitational eddies across the galaxy?

I read about natural gravitational eddies that travel in a wave that black holes have. They also have a strong magnetic field. Does those eddies follow magnetic field lines of the rotating black hole? ...
6
votes
0answers
83 views

Error propagation methods for orbit parameters

Recently I've encountered an article in our local astronomical popularization magazine. It is about a well known task of Sgr A*-black hole's mass estimation. The article is written as a step by step ...
6
votes
0answers
77 views

Need help understanding stellar spectroscopy data from ESO

The European Southern Observatory webpage has a web page that has tabular spectrogram data from A. J. Pickles, University of Hawaii. There are over 130 .dat files there. Each one represents a ...
6
votes
0answers
90 views

What is the farthest reported distance from observer from which a solar system body has occulted a star?

I originally wrote "...farthest distance from Earth..." but changed to "observer" in case the occultation was observed from a space telescope. It may not matter much but I didn't want to over-...
6
votes
0answers
158 views

Is the wind's intensity on Mars similar to Earth?

I've read that in Mars' poles, the winds can be as fast as 400 km/h, when the poles are exposed to sunlight because the frozen $CO_2$ sublimes. I know that the Martian atmosphere is much thinner than ...
5
votes
0answers
85 views

Is there any difference between M87's image and predictions?

Today, the EHT released (somewhat blurry as compared to simulations)images of M87 blackhole. Did the image contain anything which might lead to a correction to General Relativity or were all the ...
5
votes
0answers
56 views

Can anyone explain this odd Galactic dust filament near the LMC?

Perusing the Planck 353 GHz polarisation Aitoff projection I noticed an apparent magnetically driven dust filament rising abruptly from the Galactic ß-field in the Chameleon-Mensa S polar region. It ...
5
votes
0answers
59 views

Is the Ordovician meteor event detectable in the lunar cratering record?

Approximately 468 million years ago there were a large number of L-chondrite meteorites falling to Earth. This is called the Ordovician meteor event and was probably the result of a large collision in ...
5
votes
0answers
40 views

What is the relation between the saros (18 years, 11 days, 8 hours) and the period of lunar nodal precession (18.6 years)?

I am wondering. I am sure that they are related. How can we derive one from the other?
5
votes
0answers
75 views

Is Spherical Astronomy by W. M. Smart a good book on positional/spherical astronomy?

I'm a math undergrad, but I'm really interested in learning positional astronomy; However, the only well-referenced textbook I've come up with is Spherical Astronomy by W. M. Smart. I would like to ...
5
votes
0answers
93 views

Which astronomer set his beard on fire because he left the cap off his telescopes finder?

There is a famous story of an experienced astronomer setting his beard on fire because he left the cap off his telescopes finder. I know it's said to be true of Galileo, but I thing it's relatively ...
5
votes
0answers
39 views

Meade LX200GPS electronic RA movement very slow

I use a Meade 200 LX GPS. Last night between viewings it was placed in Sleep mode. On return the scope was making noises as if the motor was running. The scope was stationary, but had moved to what ...
5
votes
0answers
105 views

What EM spectrum can stars be most cheaply observed using Remote Sensing during the day?

I would like to augment my GPS navigation with remote sensing of 'the sky.' I am looking for any astronomical body that can be perceived during the day. Maybe Pulsars emit something easily detected, ...
5
votes
0answers
167 views

When the Moon formed and early on, did it orbit over the Earth's equator?

Or was it always at about 5.14 degrees inclination or has the inclination changed over time? See diagram. James K's answer to this question got me thinking about this, and I don't mean to call him ...
5
votes
0answers
48 views

Did the Juno mission locate Jupiter at the same precision as Saturn (4 km)?

Juno's low perijove should be great for measuring Jupiter's gravitational effect on Juno's orbit. Cassini together with VLBI has measured Saturn's location to within 4 km. Will Was Juno be able to ...
5
votes
0answers
94 views

Observatory control software

I'm setting up an observatory and I'm wondering what user-facing software would be best to use in terms of hardware control. There is a German mount, dome, focuser, filter wheel, various switches etc. ...
5
votes
0answers
99 views

Do differentials in the Earth's density cause the flyby anomaly?

The flyby anomaly is an occasional, unpredictable, and as yet unexplained discrepancy in acceleration of satellites when they pass close by the Earth. It causes an increase of up to 13 mm/s during ...
5
votes
0answers
105 views

Semimajor axis variations in co-orbital moons

I've been playing with simulations of co-orbital bodies similar to Saturn's moons Janus & Epimetheus- horseshoe orbits where the two bodies are of comparable mass- and I'm seeing some very odd ...
5
votes
0answers
401 views

What are the analysis steps in taking raw data from Kepler to a planetary system determination

I wish to get a concise list of the analysis steps required to take raw light data from a Kepler data set of a star through the steps needed to get to an analytical determination of the existence of a ...
5
votes
0answers
2k views

Exoplanet Temperature Calculations

I was given an exoplanet similar in size and distance to host star to our own earth. It's orbiting a star with luminosity six times our sun, the greenhouse coefficient 0.3, bond albedo 0.3. I need to ...
5
votes
0answers
92 views

Why can primordial tensor perturbations of the CMB be ascribed to gravitational waves?

Why can primordial tensor perturbations of the CMB be ascribed to gravitational waves? Is this attribution unique, or are there other mechanisms that could lead to the excitation of tensor modes? In ...
4
votes
0answers
32 views

How can we be certain that Ryugu is a remnant of the material that did not form planets?

As mentioned here, that Ryugu is a part of the Solar System material that did not get swept into forming a planet. But how can we be sure that it was not created later for example by an asteroid ...
4
votes
0answers
123 views

Is Optical VLBI theoretically feasible? If not why not?

There are plenty of optical interferometers in use with baselines of up to maybe 1km. As far as I can find out, they all work by directly collecting the light at all the telescopes, using mirrors to ...
4
votes
0answers
49 views

How open is China in sharing data from the Chang'e 4 mission?

It's really good to see that man (well, machine) has gone back to the moon again. Chang'e 4 is studying potential mantle material from the lunar depths and will be conducting radio astronomy in ...
4
votes
0answers
53 views

Does the orbital decay of Triton affect Neptune's rotation?

Just a quick question regarding Neptune. Because Phobos is spiraling in towards Mars, Mars' rotation speeds up. Does the same thing happen with Neptune's rotation?
4
votes
0answers
34 views

Strength of core-envelope coupling in stars

For a star with a given Zero-Age Main Sequence (ZAMS) mass, as a function of metallicity how strongly is the star's core coupled to its envelope? I understand that the core-envelope boundary is only (...
4
votes
0answers
48 views

Expansion of Jupiter's perturbing effects on Kepler's third law treatment of orbits?

Does anyone know any good reference for how this was done? I remember reading once about how Jupiter's gravitation can be treated as a perturbation, but I cannot find it again now. I think they ...
4
votes
0answers
31 views

How much is usually deposited in a Mars regional dust storm?

Is there any indication of how much dust is deposited, especially in areas that are not open where wind might produce a cleaning event?
4
votes
0answers
123 views

Are they really sure this isn't an Airy disk? How was that ruled out?

Are they sure this is a spherical shell of gas, and not just an Airy pattern? Image from: https://www.eso.org/public/images/eso0906b/ I get 180 pixels from center to the first minimum, and 72 pixels ...
4
votes
0answers
58 views

Can Einstein-Rosen bridges - if they exist - link two points of which one lies outside of the observable universe of the other?

So there's stuff very far away that is, due to expansion, accelerating away faster than the speed of light, so fast that its light will never reach us even with infinite time - and we can't reach that ...
4
votes
0answers
68 views

Detecting a Rogue Planet from Earth

This is for a novel. A rogue planet, is, by a one-in-a-zillion freak chance, on its way to collide with Earth. It has been drifting in interstellar space since its original formation (billions of ...
4
votes
0answers
67 views

“Pluto Time” for any solar system body

A while back NASA made a site called Pluto Time, where you can enter your address and find that "...moment near dawn and dusk each day, where the illumination on Earth matches that of high noon on ...
4
votes
0answers
60 views

Has the Penrose process ever been linked to an observed phenomenon in some way?

This answer mentions the Penrose process as a potential mechanism that could change the axis of the orbital angular momentum of an accretion disk around a black hole away from the original axis of the ...

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