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Questions tagged [spectral-type]

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Query spectral type for absolute magnitude

I'm working on a project with stars where, given their spectral type (such as B0IV), I want to be able to know its approximate absolute magnitude. I have searched online and found data sources like ...
J minding's user avatar
24 votes
3 answers
3k views

Did the Sun's light always peak in the green wavelengths?

So, I know the sun is getting brighter over it's lifespan and I'm wondering how that affects its emission spectrum. The reason I'm asking this is because I find it weird that plants reflect green ...
Elhammo's user avatar
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2 votes
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Sloan Digital Sky Survey - Obtaining Spectral and Photometric Datasets

I am working on a soft computing (fuzzy logic), genetic algorithm, explainable AI (XAI) classification system for astronomical objects from the Sloan Digital Sky Survey. The dataset I am currently ...
todd45040's user avatar
3 votes
1 answer
133 views

Is WASP-12 a F-type star or a G-type star?

I saw in Wikipedia that WASP-12 is a star with spectral type of G0V while they said its temperature is 6360 K. Does that mean it must be a star with spectral type of F7V or F6V? Its size is not like a ...
Iwanttobeabillionare sofucking's user avatar
2 votes
2 answers
83 views

What does G0Vp mean?

I know that "G0V" refers to stars with spectral type G0 but some stars have spectral type G0Vp. What does the extra "p" in there mean?
Iwanttobeabillionare sofucking's user avatar
1 vote
1 answer
108 views

What are probabilities of finding a star with the specific stellar type?

I am a programming tutor, and with my student we were writing a program simulating a flight through the cosmos. I thought that it would be great to make the circles representing stars more realistic. ...
v010dya's user avatar
  • 111
7 votes
2 answers
1k views

Are main-sequence G9 stars habitable?

Our sun is a G-type main-sequence star. Specifically, it is classed as a G2 star. Meanwhile, 18.8 lightyears away, is a star called sigma draconis, or Alsafi to use its more common name. Modern ...
user98816's user avatar
  • 469
3 votes
1 answer
130 views

Stellar classification spectral lines: chemical abundance vs temperature

I'm an amateur who watched the Cosmos episode on Cecilia Payne's contributions to stellar classification, which I liked. I've been going down a rabbit hole on this and and I have a question for ...
Stephen's user avatar
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3 votes
2 answers
248 views

Why the Sun is white if it is G2?

I know it's a simple question, but even I progressed in astronomy, I always had this question. So, I know the Sun, in the MK classification system, it's G2: yellow. But I also know the sun, in visible ...
Artur Carneiro Barroso's user avatar
4 votes
2 answers
784 views

Does the luminosity of a star have the form of a Planck curve?

Figure shows the intensity of the radiant energy emitted from stars A and B over a unit time according to the wavelength. The area between the graph and the horizontal axis is S and 4S, respectively. ...
빛나는밤's user avatar
2 votes
1 answer
60 views

Strange spectral types in star catalogs

I'm collecting different star catalogs I've found in the Internet to make my own and I noticed some "strange" peculiarity in how those catalogs describe spectral type of a star. Namely: ...
Felix.leg's user avatar
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5 votes
1 answer
239 views

Reason for different surface temperatures of Tau Ceti and Epsilon Indi at similar properties

While looking at a list of nearby stars, I noticed that the spectral classes were not always consistent compared to the masses (and radii) of the main sequence stars. Especially the comparison between ...
vinyazu's user avatar
  • 51
1 vote
1 answer
379 views

Convert from spectral type to RGB color?

I'm writing a night sky simulator and I want to render stars using the correct color. Is there a formula that converts a two-character code (as seen in the Yale Star Catalog) to a RGB value?
prideout's user avatar
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9 votes
2 answers
2k views

How do I say the luminosity class aloud?

I have need to say the spectral type of a star for a poster presentation I'm making, which includes the luminosity class. However, I've been unable to determine the standard way of doing so, and ...
mknote's user avatar
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1 vote
0 answers
49 views

What color would stars have with an apparent magnitude of ~-30? [duplicate]

The light of the Sun is white because our eyes are evolved to work with it as the primary light source. Other stars look white in the night sky because they are too faint to activate the color ...
Yora's user avatar
  • 197
5 votes
1 answer
203 views

What does a + (plus) mean in stellar classification?

I've noticed some stellar classifications might look like this: A0IV+G: (HD 70003) F3IV+F0IV (HD 82434) ...
aggregate1166877's user avatar
11 votes
1 answer
1k views

Spectral class and luminosity of hydrogen bomb explosions?

Since hydrogen bombs detonating are like tiny little stars, I wonder what luminosity and spectral classification they would get if one were to categorize them like this. E.g. Starfish Prime and the ...
John's user avatar
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1 vote
1 answer
215 views

What happened to NS spectral types after OBAFGKM?

What happened to NS after OBAFGKM? The full mnemonic was "O Be a Fine Girl Kiss Me Now Sweetheart" a few decades ago as I remember. I think it was that way in "The Larousse ...
Harry Powell's user avatar
2 votes
3 answers
2k views

What is a hard spectral state vs. a soft spectral state?

In X-ray astronomy, the source is considered to be in the hard or soft spectral state. So what is the meaning of the hard spectral state? What are the soft state and hard state in spectroscopy?
Monkey King's user avatar
5 votes
3 answers
821 views

How would the characteristics of a habitable planet change with stars of different spectral types?

The tidal forces a habitable planet experiences increase with decreasing spectral type. So a habitable planet orbiting a smaller, less massive, and cooler star would experience much stronger tidal ...
user199374's user avatar
6 votes
3 answers
162 views

Does "spectral type" and "stellar classification" refer to the same thing?

Should the tags stellar-classification and spectral-type be merged? has been asked in meta two weeks ago. It requires some careful consideration but so far no response has been forthcoming, so I'm ...
uhoh's user avatar
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6 votes
2 answers
341 views

Why is the Sun less massive than other G2V stars?

The Wikipedia page for G-type main-sequence stars lists the expected mass and temperature for stars of each sub-classification: $$\begin{array}{c|c|c|} & \text{Mass ($M_\odot$) } & \text{...
user177107's user avatar
  • 2,689
2 votes
1 answer
121 views

Is there a luminosity class for brown dwarfs?

I've been reading about brown dwarfs, and checking their spectral types, and I noticed that they do not have a luminosity class (V, VI, etc). So I am wondering, do brown dwarfs have a luminosity class,...
WarpPrime's user avatar
  • 6,673
3 votes
1 answer
120 views

What does the "a" at the end of a spectral type mean?

Looking at the chart for spectral type peculiarities (here), I noticed that the letter a was missing from the chart. This seems to be an error, as the star Vega has spectral type A0Va, with the a ...
WarpPrime's user avatar
  • 6,673
4 votes
1 answer
532 views

Are the sub-spectral types (1,...9) based on temperature or spectral lines?

The spectral type of stars has an OBAFGKM class, along with a number, from 0 to 9. According to Wikipedia, (sample shown below), the lower the number, the hotter and more massive the star, but ...
WarpPrime's user avatar
  • 6,673
4 votes
4 answers
4k views

What spectral type of star has an absolute magnitude of exactly 0?

We know that Vega is the star that serves as the zero point for the UBV color scale, and has an apparent magnitude of nearly zero (+0.02). But its absolute magnitude is +0.58, making it rather far ...
WarpPrime's user avatar
  • 6,673
11 votes
2 answers
1k views

Is there an O1 or O0 star?

Okay, we've seen the super hot Wolf-Rayet stars, especially WR 102 and 142, and the "slash stars," many of which are early O (O2-4.5/WN). We know the temperatures of these Wolf Rayet stars. ...
WarpPrime's user avatar
  • 6,673
0 votes
1 answer
818 views

Relation between age and spectral type of star

Does the spectral type of a star change as it ages? Since its temperature changes, I suppose the spectral type should also change, but I'm a bit confused about this. Also, is the spectral type ...
Shakti's user avatar
  • 43
8 votes
3 answers
1k views

Determine spectral type of star from its properties

How can I determine spectral type of star, if I know all its another properties? For Example, Rigel A has spectral type B8Ia. Rigel has temperature 12 500 K. ...
Michal's user avatar
  • 323
5 votes
1 answer
741 views

Would a red dwarf star resemble our own Sun at sunset to an observer on a nearby planet?

Suppose you're observing a red dwarf star at Noon from the surface of an Earth-like planet orbiting in the red dwarf's habitable zone, so that the red dwarf's luminosity is equal to our own Sun. Aside ...
RobertF's user avatar
  • 183
2 votes
1 answer
504 views

Is there a relationship between stars' absolute magnitude, spectral class and relative location in a cluster?

I am interested to know whether a pattern has been observed with regard to the characteristics of a star (in particular, its absolute magnitude and spectral class) and its location relative to others ...
POD's user avatar
  • 121
2 votes
1 answer
93 views

Has J been used by itself as a spectral type?

While answering the question "Why have brown dwarf classes been dubbed L, T and Y?" I noticed that in the paper Kirkpatrick et al. (1999) "Dwarfs Cooler than 'M': The Definition of Spectral Type 'L' ...
user avatar
22 votes
2 answers
5k views

Do we know a star that is similar to the Sun when it would be a red giant?

In about 5 billion years the Sun is predicted to become a red giant and have more than 200 times its current size, reaching a radius of about 5 AU when largest. I wonder what spectral class the Sun ...
user30007's user avatar
  • 1,226
1 vote
0 answers
74 views

How are Y-dwarf spectral subtypes defined?

It is often stated that the spectral subtype indicates the relative position between spectral types, e.g. G5 being halfway from the start of spectral type G to the beginning of spectral type F. Given ...
user avatar
2 votes
0 answers
60 views

Spectral Class Breakdown

Where can I get a more detailed breakdown of Spectral Classes. Wikipedia only has it at Letter level rather than sublevel. For example, https://en.wikipedia.org/wiki/Stellar_classification has B ...
MiscellaneousUser's user avatar
2 votes
1 answer
167 views

Examples of absorption lines for main sequence stars

Where might I find a detailed table or figure containing the absorption lines and their corresponding wavelengths for each type of main sequence star? I'm trying to get the chemical abundance of ...
bajotupie's user avatar
-1 votes
1 answer
78 views

Compare this planet to Earth and determined its habitability (can humans live in this environment?) [closed]

I'm given this set of data and I need to describe the habitability. Would this not be habitable since the temperature of the albedo and the equilibrium is similar to Earth's or does the Spectral Type ...
Kevin Wang's user avatar
10 votes
2 answers
385 views

Can Jupiter's nightside be classified as spectral type Y?

As far as I am aware, the latest spectral types that have been assigned are around Y2, for objects like WISE 0855-0714 that have temperatures around 250 K or so. I've also seen several directly-imaged ...
user avatar
11 votes
1 answer
528 views

How does a star's rotation affect a star on the main sequence?

I searched and have found that the questions mainly focus on neutron stars, white dwarfs and black holes. This was not what I want. Basically, the bigger the star's mass is, the more intense its ...
Christmas Snow's user avatar
6 votes
0 answers
119 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 ...
Lakey's user avatar
  • 161
4 votes
2 answers
98 views

Stellar electromagnetic signatures

By using only the electromagnetic signature of a star, could a star be distinguished with reliable accuracy from any other star? To elaborate a little, say we have a collection of about 200,000 stars. ...
BenjaminF's user avatar
  • 273
2 votes
2 answers
573 views

Can someone explain this diagram showing the spectral type distribution of bright stars

Can someone explain this diagram? The text is in Dutch, free translation: "You are given a graph: a histogram of the 10 000 most apparent bright stars. Explain 1, 2 and 3." The fact that the number ...
Stijn D'hondt's user avatar
1 vote
3 answers
3k views

B-V to U-B colour index

Is there a formula to convert the B-V index to U-B index or are they totally different and separate observations and can't be convert like you can with Fahrenheit->Celsius? (Updated) I know F->C ...
MiscellaneousUser's user avatar
3 votes
1 answer
191 views

Why is TiO special?

Red spectra of M stars are dominated by TiO(Titanium oxide) bands, which have become the primary means of establishing spectral types.see ApJ Why is TiO special? There should be much more Silicon ...
questionhang's user avatar
  • 3,137
0 votes
1 answer
154 views

Solar Spectral Types and Dwarf Stars

On the following page, http://www.uni.edu/morgans/astro/course/Notes/section2/spectraltemps.html It mentions Main, Giants and SuperGiants. However for Dwarf Stars (e.g. D, Sd) , do I apply Main ...
MiscellaneousUser's user avatar