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Questions tagged [star]

Questions regarding large spheres of plasma undergoing fusion.

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Celestron NexStar 130 SLT Computerized Telescope GoTo Not Accurate

I am trying to use a Celestron NexStar 130 SLT Computerized Telescope, but I am not able to use the GoTo function. I do the three start alignment, it confirms matches, I make sure the level is ...
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1answer
68 views

What area of Proxima Centauri would need to be occluded for the effect to be observable on Earth?

One of ideas of how Breakthrough Starshot could communicate data from Proxima Centauri is to have a massive swarm of the solar sail powered craft to pivot (with their sails) synchronously, taking ...
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4answers
3k views

Is parallax a “technique to measure the star distances” or a “tiny shift in star's position”?

I am not completely sure whether the Parallax is a "technique to measure the star distances" or a "tiny shift in star's position"? The a book says two points about Parallax: Astronomers have ...
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1answer
77 views

Information on the star at the centre of the Helix “Eye Of God” Nebula

Can someone please tell me what the mass (or size) of the star at the center of the Helix Nebula is, and how much larger it is than our own star (we call the Sun or Sol). Also, what is the name of ...
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2answers
114 views

Why is Proxima Centauri called Proxima Centauri?

It seems very logical, to call the star, closest to earth, "Proxima" ("Proximus" is Latin for "close" and the word for star, "stella", is feminin, hence "Proxima"), but there's one thing I don't ...
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2answers
64 views

Why is the metallicity of elliptical galaxies low?

As far as I understand, metallicities of old stars are usually low and those of new stars are usually high. If elliptical galaxies form after merger of galaxies, then surely that means the elliptical ...
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2answers
81 views

Why don't we see purple stars

I know that we don't see green stars because in blackbody radiation star doesn't produce one spectrum. The stars that have peaks in the green spectrum produce other spectrum in nearly same amout. ...
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60 views

What is the total number of stars in the universe? [duplicate]

I mean a total number of stars, not the only ones that we can see.
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1answer
45 views

Searching for stars with a given surface temperature and an absolute magnitude?

Do you have in mind any database/sites that I can search for stars that matches a given surface temperature and an absolute magnitude? For example, when I enter ...
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1answer
247 views

How do astronomers know if a planet is orbiting a star, or it's simply another star in the background?

For example, if astronomers photograph a "planet", which is in close proximity to a given star, then this "planet", could actually just be another "star" in the background, many light years away. It ...
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1answer
50 views

Could population III stars develop directly into population I stars?

Hundreds of millions of years after the Big Bang, the very first stars began to form consisting of mostly hydrogen, a bit of helium, and maybe some lithium. These stars lacked any "metals" (elements ...
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2answers
52 views

What is a type la supernova? [closed]

I’ve heard about them and know that they are used as standard candles, but what exactly are they? What makes them differ from other supernovae? Also, are they only special because of their use as ...
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2answers
2k views

Does a star fuse helium to beryllium on the main sequence?

When a star has finished fusing all its hydrogen into helium, it will then start fusing helium into beryllium and so on and so forth up until iron. When the star is fusing to beryllium, will the ...
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1answer
34 views

Is T Tauri a compulsory stage for stellar evolution?

Do all stars go from Protostar stage to T Tauri and then to Main Sequence or is T-Tauri stage only for certain stars? If only certain stars, is that those that are less than 3 solar masses which i ...
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3answers
149 views

Why do stars twinkle but planets don't [duplicate]

Many people say that stars twinkle because of Earth's atmosphere. However, the atmosphere is still there when we look at planets and don't see they twinkling. Is there a clear scientific consensual ...
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1answer
43 views

Are Symbiotic and Vampire Stars the same type of star or different?

Are Vampire Stars and Symbiotic Stars the same type of star or is there a difference? Vampire Stars siphon off hydrogen from its neighbour. According to https://www.cfa.harvard.edu/~kenyon/ss/, ...
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1answer
69 views

Light pollution and apparent magnitude of objects in solar system

Dust along the ecliptic scatters light, causing “light pollution” throughout the orbital plane of the solar system. If an object like, say, the sun's corona, had its brightness measured from above the ...
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1answer
132 views

Why does the sun appear 13x bigger through diffraction in Voyager 1 image from 1990, but not from Earth? [closed]

The sun in the Voyager 1 photo here from 1990 appears 13x bigger than its diameter, diffraction of course. On Earth, photographs of the sun do not make it appear 13x bigger. Why? A description of the ...
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1answer
71 views

Are there any optical method of viewing stars without “diffraction” making them appear larger? [closed]

In the 1700s, Edmond Halley and others discovered that stars appeared larger than they are, and attributed it to diffraction in the lens of an observer (telescope, eye) and/or in the Earth's ...
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1answer
63 views

In the closest stars, can you see the stellar corona?

Stars appear larger than they are, could that be the stellar corona here around Sirius, making it appear n-times larger than the stellar body? NASA recently mapped the solar corona to extending 12 ...
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1answer
58 views

Is the orbit of Sirius B based on observation, or derived from the variation in proper motion of Sirius A?

It is common to base models on deduction rather than empirical observation. The orbit of Sirius A is easily seen as variation in proper motion. The orbit of Sirius B, has it been observed, or is it ...
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1answer
72 views

Are there any good images of Sirius B at apastron in the Sirius system?

Sirius B has a distance to Sirius A of 11 arc seconds at apastron; are there any good images of it at that point in its orbit?
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2answers
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How does a blackhole burp?

Recently on the discovery channel I heard that a black hole burps matter out of it when it consumes more than it could process at a time. Given that even light cannot escape from a black hole, how ...
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1answer
52 views

Moving lights in the sky looks like they were moving coordinated [duplicate]

I was out with a couple friends a night and we looked up to the sky just watching the stars. I noticed what looked like a star moving then told my friends and they saw it too. After we saw the one ...
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3answers
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Can I sense a bright star pointing an eight foot antenna towards it?

If I connect an eight foot Yagi or other comparable sized antenna to my oscilloscope and point the antenna at a bright star will I see a voltage on my oscilloscope? I am not interested in turning the ...
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0answers
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Fast moving bright star with eliptic course, instant stop [duplicate]

Around 13 years ago I saw fast moving bright star with eliptic course which crossed half a sky in 1-2 sec and stopped instantly like it was a smashed like a bug, and didn't move for a while few ...
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2answers
81 views

Are there any stars that one day we could collide with?

I'm not talking about tomorrow but in the far far future could we say our Sun could collide with another star or otherwise within our current detectable range?
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1answer
53 views

Will comet 21P that just passed Earth on Sept 10 produce Draconid storm on Oct 9?

Comet 21P/Giaccobini-Zinner just made its closest pass to Earth and also made its Solar perihelion on the same day (Sept 10) which is roughly one month ahead of the annual Draconids meteor shower (Oct ...
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3answers
63 views

Hypothetically, if our sun was yellow would we still see “white” colours?

Hypothetically,if our sun was yellow would we still be able to see white colour on objects like snow,cotton etc.? Would we have the phenomenon of rainbow?
3
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1answer
69 views

Why does the adiabatic exponent decrease at the ionization zones?

The context is the ionization zones in stellar atmospheres or interiors, the Sun, for instance. The adiabatic exponent is the heat capacity ratio: $$\gamma = \frac{c_P}{c_V} = \frac{C_P}{C_V}$$ And,...
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1answer
59 views

Stellar core mass as a function of metallicity

Using Hurley's 2000 paper on Single Stellar Evolution, I have graphed the core mass of a star at three stages as a function of metallicity, Z, for a chosen ZAMS mass: at the beginning of the HG (MS), ...
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2answers
69 views

Classification and discovery of stars

How do astronomers find the difference between a 'Cephid Variable Star' and distinct normal stars with opaque objects blocking it's light, like stars with planets revolving around them while both ...
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1answer
62 views

How to find star location knowing latitude and LST

Newbie learning Astronomy and was curious how to locate a star giving a Latitude and LST. For example if my LST is 4:00 and my latitude is 20*N, how would I find where the Horsehead Nebula appears in ...
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3answers
101 views

Is there any definitive proof of stars being “born” in nebula formations?

Is there any absolute evidence of star formation inside of nebulae (AKA stellar nurseries) as is suggested and even stated as fact by many textbooks?
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2answers
92 views

Temperature gradient in stars

It is a well known fact that in stars, there exists a temperature gradiënt. The observational reason is because we perceived spectral lines in the otherwise continuous spectrum of a star. If this ...
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4answers
162 views

Why there are less massive stars than low mass stars?

What factor determines the selection of star mass? And how we know that the number of massive stars is less than the number of low mass stars?
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1answer
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Were all first generation stars of same mass and size?

If the density of the matter from which the first generation stars were made was homogeneous, so during the star formation nuclear fusion would have started around when they all reached to same ...
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1answer
47 views

What are these objects near Mirach

Night sky objects always interested me, nowadays Im trying to observe and photograph some of these objects. My phone is iPhone 6S, i used SkyGuide app to find positions, NightCap to photograph. Im ...
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1answer
58 views

Eccentricity and Inclination of a Star

I understand Planetary Eccentricity and Inclination. However when it applies to a star, does the centre or ecliptic plane refer to the Sun or the Galactic Centre? The star Sirius for example, 136....
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3answers
47 views

Ratios of magnitudes instead of differences

The color index in the photometric system is defined by the differences in magnitudes between two wavelength filters, which gives the ratio of intensities. For example, to determine the B-V index, you'...
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1answer
66 views

Orange light that rises quickly and moves of to the righ [duplicate]

I have recently noticed an orange "star" (or what I presume to be a star), rise above the hill line behind my home. It rises later than every other star and rises within a few hours while the other ...
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2answers
98 views

Dataset containing list of known globular clusters

Does anybody know if there is an existing dataset that consists of all known star clusters, their name, and their apparent dimensions or similar? Is it possible to make a query to, or download all ...
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1answer
100 views

We are in Green Lake, WI, 8/12/18, seeing bright orange “planet”/“star” almost due South, perhaps 20 degrees above horizon, what is it?

I have a “sky” app on my ipad and expected it to be Mars, but my app shows Mars just below horizon and closer to East. Oh, I should add that we saw this about 10:15 tonight. Hanging out watching ...
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Are there simplified M-L, M-R, and lifetime equations for non main sequence stars?

To give some context - I am trying to create a simple program that outputs the stellar properties of a star when given its initial mass and current age. e.g. Input Initial Mass = 2e30kg Age = 4.6 ...
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2answers
165 views

The formation of new stars as depicted in Feynman's lectures

I've stumbled upon this curious passage addressing the formation of stars in Feynman's lectures on physics: Whether we have ever seen a star form or not is still debatable. Figure 7–12 shows the ...
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1answer
363 views

Why is H_delta prominent in type A stars?

I understand factually that H$\delta$ lines are most prominent in type A stars and less so in more extreme types of stars on the H-R diagram. However I was wondering the reason for why they are not ...
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2answers
319 views

Currently proposed ways to distinguish between a really big planet and a really small star

The Next Big Future article Rogue Exoplanet 12.7 times bigger than Jupiter is 20 light years away Astronomers using the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) have made ...
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Almost unseeable light moving over nightsky. What is it? [duplicate]

Sometimes when I look up at the sky at night, I can see something moving. It’s so small that I barely can see it, but I can’t see it when I look directly at it. I need to look beside it to see it. It ...
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1answer
192 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?
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2answers
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Struggling to use my new telescope

I recently got my first telescope, a Bushnell reflector telescope. I spent a good while setting up my alignment. And I can see the moon perfectly! I went to look at another, Mars. I got it aligned in ...