Questions tagged [dust]

Questions about particulate matter found between stars, not to be confused with gas or ionised plasma. For planetary dust storms, use [dust-storm].

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38
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2answers
6k views

How can comets have tails if there's no air resistance in space?

I understand that solar radiation causes material to vaporize out of a comet into dust but why does the dust then trail behind the comet like a "tail"? Assuming gravity is the only applied force ...
16
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3answers
3k views

What is the difference between gas and dust in astronomy?

Is there a strict difference between gas and dust? In Earthly environment most things become gaseous if heated enough. The temperature of interstellar medium seems to range mostly between 10 and 10 ...
13
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1answer
446 views

What is the predominant element in the dust of the Sombrero Galaxy?

The Sombrero Galaxy contains a rather peculiar ring of dust orbiting it (seen as the dark ring on the outer edge). What is the prevalent element in this dust? Carbon?
12
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1answer
989 views

How did they make a video of the center of the galaxy, and what is it exactly that's flashing there?

The ESA video ESOcast 173: First Successful Test of Einstein’s General Relativity Near Supermassive Black Hole includes a clip of images of stars at the center of our galaxy orbiting around SgrA*, a ...
12
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2answers
271 views

How far apart is the dust in the Sombrero Galaxy's dust lane?

In his answer to this question, TildalWave made this remark: I think that first, we have to properly appreciate the size of the Sombrero Galaxy. It is roughly 50,000 light years (15 kilo parsecs) ...
11
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1answer
340 views

Was the "green star" event in NGC 3314 ever figured out or named?

from NGC 3314 Variable Object by By Bill Keel (University of Alabama, Tuscaloosa) and Lisa Frattare (Hubble Heritage Project, STScI). The object in question is circled. Comments below this answer led ...
10
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1answer
90 views

Any new info about solar flares hitting the Moon added by the LADEE mission?

This article from 2011 mentions simulations about the sputtering effect caused by a solar flare hitting the Moon: "We found that when this massive cloud of plasma strikes the moon, it acts like a ...
9
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1answer
122 views

Do we live in a galactic bubble?

I have heard a certain statement, which can be summarized succinctly into "we live in a local bubble", implying that solar system is located in an intestrellar dust underdensity region. This region ...
8
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1answer
372 views

Could rocks from Earth have reached the Kuiper belt, or Neptune at least? If so, how?

This answer (currently edit 3) to How certain are we that we have not sent life to other planets/moons? begins: First of all, rocks from Earth are probably just about everywhere in the Solar System. ...
8
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1answer
683 views

What is the origin of the dust near the sun?

note: Solar Probe+ is now officially Parker Solar Probe In https://space.stackexchange.com/q/17498/12102 I asked about the Solar Probe Plus mission. Reading a 2008 report I saw that there is an ...
8
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1answer
163 views

Why is there free magnesium in the ecliptic (if there is) and why would some be orbiting within the ecliptic plane but retrograde?

This answer to the question What direct or indirect observations of dust can one make by eye or with binoculars? mentions Brian May's thesis and it's connection to Zodical Light: Brian May (CBE): In ...
7
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1answer
285 views

How does V838 Monocerotis look today? Any subsequent light echo images, or is the party over?

This answer to the question V838 Monocerotis “light-echo” images morphed into nice video, but why so few original images? contains the following information below. There are other answers and more ...
7
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1answer
289 views

At what wavelengths can black hole Sagittarius A* be observed from Earth?

The supermassive black hole in the center of the Milky Way is blocked by dust and gas clouds as seen from where we are. Which wavelengths are blocked and which are most undisturbed for observation of ...
7
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0answers
97 views

Color index B-V of the dimming Betelgeuse

Using AAVSO light curve generator I have plotted V and B magnitudes of Betelgeuse in the past 150 days to see trend of B-V color index. If dust would be the cause of the recent drop in the star ...
6
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1answer
1k views

What cluster of stars is this with a "dark donut" to one side?

In the 2011 Sixty Symbols video Spy Satellites (from Deep Sky Videos) after about 01:44 amateur astrophotographer Nik Szymanek shows an image of a cluster of stars ...
6
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1answer
294 views

What is the physics of the "spinning dust" contribution to Cosmic Microwave Background measurements?

The lengthy paper Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Final Maps and Results mentions "spinning dust" about 51 times. It is a potential contributor to the measured ...
6
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1answer
124 views

What experiment does this "Tracing the History of Starlight" video try to explain?

The YouTube video Tracing the History of Starlight with NASA's Fermi Mission describes observation by the Fermi gamma ray telescope of EBL (extragalactic background light) gamma rays from 2,000 ...
5
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2answers
1k views

Interstellar Dust properties

While practicing for an upcoming examination, I ran into this problem: Which of the following best describes dust grains in the interstellar medium: They are a few hundred nanometers in size (size ...
5
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1answer
144 views

What is the distribution of organic compounds in the Milky Way Galaxy?

I imagine the answer is unknown for the entire galaxy, but I would appreciate a notion of the scales and locations of regions where astronomers have ventured at least a guess to the distribution of ...
5
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0answers
69 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 ...
4
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1answer
208 views

How many solar system objects that can really qualify as a KBO are likely to enter Pluto's Hill sphere each day?

A comment below Which celestial body is able to come closest to Pluto? says that Technically, many, many small Kuiper belt objects enter Pluto's Hill Sphere (or sphere of influence SOI) every day. ...
4
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1answer
113 views

Metals and dust locked into planets

I wonder what is the contribution of metals and dust locked into planets, with respect to the amount in the interstellar medium (ISM). In other words, when we measure the metallicity and the dust mass ...
4
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1answer
464 views

Why Free-Free emission is regarded as Thermal emission?

I read that thermal emission/radiation are the ones whose spectra is similar to that of a Black body radiation. Also thermal radiation depends solely on the temperature of the object. How can we ...
4
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1answer
308 views

Why dust is optically thin in Far Infrared wavelengths?

What is the actual meaning of the statement 'Dust is optically thin in the Far Infrared (FIR) over most of the Galaxy'? Kindly Help
4
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2answers
611 views

Is dust extinction/reddening caused by Rayleigh scattering or some other physics phenomenon (or both)?

I know from Rayleigh scattering that in the atmosphere redder photons are scattered less than bluer photons by the particles that both make up and are floating around in the atmosphere. This is why ...
4
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1answer
282 views

Estimating galactic dust extinction for medium band filters

I have a set of medium-band filters and I would like to compute $A_{\lambda}/E(B-V)$ for each filter which are not reported in the literatures. The magnitudes of the objects in the photometry ...
4
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2answers
304 views

Are micrometeorites cosmic dust?

Are micrometeorites just dust grains at high relative speed, or is there some difference between them and cosmic or interstellar or solar nebula dust? Dust as in the clouds which obscure parts of the ...
4
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1answer
106 views

Are there many faint meteors that are too faint to see with the naked eye?

I remember one time a while back looking at the night sky through night vision goggles. One interesting thing I noticed is that there appeared to be many very faint meteors in the sky practically all ...
4
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0answers
210 views

Why does titanium oxide around Betelgeuse produce this particular sawtooth-shaped absorption spectrum?

Betelgeuse Just Isn’t That Cool: Effective Temperature Alone Cannot Explain the Recent Dimming of Betelgeuse suggests that the recent dimming might be caused by increased optical absorption by dust ...
3
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1answer
160 views

Why is the "green" comet C/2014 Q2 (Lovejoy) red in this picture?

In this nice NYTimes 'survey article' "Our Vast Solar System and Its Many Explorers" there is a NEOWISE image of Comet C/2014 Q2 (Lovejoy). See here also. The NASA description of the image says: ...
3
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1answer
120 views

How do we know that the discovered M87 black hole isn't just a star surrounded by a dust disk?

To an untrained eye like mine, pictures of stars surrounded by dust discs look very much similar to the picture of the M87 black hole. Here are some pictures of these dust discs: And here is a ...
3
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1answer
164 views

Tongue-in-cheek quote on dust extinction

I remember hearing a quote or maybe rather an anecdote about a famous astronomer but I can't recall the exact wording and I also forgot who allegedly said it. Unfortunately, that has thwarted all my ...
3
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1answer
207 views

Why doesn't the equipartition theorem disallow spinning dust?

This excellent answer to the question What is the physics of the “spinning dust” contribution to Cosmic Microwave Background measurements? Is well sourced. The abstract of one of the papers there, ...
3
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1answer
71 views

How to estimate the temperature of an interplanetary dust grain?

I'm trying to solve this task: Estimate the equilibrium temperature of an interplanetary spherical dust grain if it is located at a distance of 3 AU. from the Sun, and the substance of the dust ...
3
votes
1answer
482 views

Absolute magnitudes with dust extinction

I have a distant $z\sim3$ galaxy with absolute AB magnitudes $M_B$ and $M_I$, where the central wavelengths of the $B$ and $I$ passbands are $\sim0.4\,\mu\text{m}$ and $\sim0.8\,\mu\text{m}$, ...
3
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1answer
68 views

Where does the dust on 67P/Churyumov-Gerasimenko come from?

As we (laymen) are told, comets lose gas and dust when they descent into the denser regions of the solar system. Seemingly so much and so large parts that they can even cause meteor showers like in ...
3
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0answers
33 views

Superconducting space dust; what transient fields could induce persistent current loops?

Science Alert's Superconductivity Has Been Discovered in Meteorites For The First Time quotes from Superconductivity found in meteorites (Wampler et al. PNAS March 23, 2020) The paper describes the ...
2
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2answers
195 views

V838 Monocerotis "light-echo" images morphed into nice video, but why so few original images?

This NYTimes video shows what I think is a series of real Hubble images which have been "morphed" artistically to appear to be continuously expanding. (also see The V838 Monocerotis Star Still Has ...
2
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2answers
119 views

What direct or indirect observations of dust can one make by eye or with binoculars?

The solar system and space in general has plenty of dust, and dust has major impacts on observing both visually and in radio astronomy. If I wanted to "see dust" in space, or see its effects, using ...
2
votes
1answer
141 views

How dark would the sun become if we traversed a Bok globule?

Bart Bok gave his name to dust clouds of 2-50 solar masses, which by their darkness may be 100 times more frequent than telescopes can detect. If the solar system traversed a Bok Globule, how dark ...
2
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1answer
786 views

What are the so called clouds of dust and gas made of?

We constantly read about "clouds of dust and gas" surrounding a (or being the initial state of a) star, but what elements constitute such dust and gas?
2
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1answer
293 views

Is Earth losing orbit? [duplicate]

Is the Earth losing or gaining distance from the sun overall? Could asteroids over time add weight to the Earth and push it farther from the sun more than having a degrading orbit around the sun? Does ...
2
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1answer
230 views

Why weren't the Hubble light-echo images of V838 Monocerotis supplemented by ground telescopes?

Drawing from this answer to V838 Monocerotis “light-echo” images morphed into nice video, but why so few original images? The V838 Monocerotis expansion (not a supernova) and the observation of the ...
2
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1answer
44 views

Is scattering efficiency of dust related to albedo?

I know that the scattering cross-sections of dust in comets depend on the scattering efficiency. A higher scattering efficiency leads to an increase in brightness. Therefore, does it mean that this ...
2
votes
1answer
99 views

carbonaceous content of galaxies?

There is a phrase in a Science Daily article which appears to be wrong: The Milky Way has a very high content of carbonaceous dust, which has been shown to be very rare in other galaxies. Is there ...
2
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0answers
48 views

Clarity on dust extinction terms and implementation: $R_V$,$ A_V$, and $E(B-V)$

I have created a model galaxy spectrum using STARBURST99 and want to compare it to an observed spectrum of a particular galaxy. I understand that I need to redden ...
1
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3answers
93 views

The name of a particular low extinction region

There is a region called Baade's window. I remember there is a similar region called "somebody's window", which also has a low amount of dust. Does anyone know the name?
1
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2answers
925 views

How do astronomers estimate the total mass of dust in clouds and galaxies?

As I understand it astronomers estimate the mass of stars by studying the orbits of their companions (other stars or planets). This helps them to derive relationships between the luminosities and ...
1
vote
1answer
46 views

What is the meaning of grain opacity and why does it affect the formation time of gas giants?

While doing research for my presentation on the formation of gas giants, more specifically the "core-accretion model", I have been stumbling across the term "grain opacity" and don'...
1
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0answers
16 views

what is the difference between Composite Stellar Population and Galaxy Spectral Energy Distribution?

I am reading Conroy et al. (2013), an extensive review on Stellar Population Synthesis technique, and I really can't get the difference between Composite Stellar Population and Spectral Energy ...