How do we know the distance from the supernova?

[alpha2cen]

Only using red shift phenomena, can we learn the distance from the supernova ?

[insane_alien]

yes.

 

for reference, look up the hubble constant.

[alpha2cen]

How accurately can we learn the distance? From the supernova spectrum, do we use hydrogen red shift for obtaining the distance?

[RichIsnang]

Red shift will tell you the distance, also

Apparent magnitude - absolute magnitude = 5log(d/10)

 

Red shift will tell you the distance, also

Apparent magnitude - absolute magnitude = 5log(d/10)

[alpha2cen]

How many supernova did we find a year? Is it easy to find a supernova through a telescope? Which grade telescope are used to find it?

Edited June 16, 2012 by alpha2cen

[between3and26characterslon]

Type 1a supernovae occur when a white dwarf star accretes mass from its binary star until it reaches a point when it explodes. This always happens when the white dwarf reaches a particular mass so the resulting supernova is always the same brightness. This is the standard lightbulb and from this you can work out how far away an object is i.e. 2x distance = 1/4 brightness. If you were to measure the red shift of this supernova you would find a correlation with its distance. The distance can be calculated from the apparent brightness and inferred from the red shift.

 

So you work out how far away objects are, then measure their red shift, find the correlation and now you can estimate an objects distance just from its red shift.

[mr.spaceman]

Type 1a supernovae occur when a white dwarf star accretes mass from its binary star until it reaches a point when it explodes. This always happens when the white dwarf reaches a particular mass so the resulting supernova is always the same brightness. This is the standard lightbulb and from this you can work out how far away an object is i.e. 2x distance = 1/4 brightness. If you were to measure the red shift of this supernova you would find a correlation with its distance. The distance can be calculated from the apparent brightness and inferred from the red shift.

 

So you work out how far away objects are, then measure their red shift, find the correlation and now you can estimate an objects distance just from its red shift.

 

 

 

How can you learn that flesh coming from distant corners of the cosmos is 1a type of supernova?

 

I mean you don't know every binary star system, how can we learn that any far away explosion is precisely from 1a supernova?

 

 

[Spyman]

Type Ia supernovae have a characteristic light curve, their graph of luminosity as a function of time after the explosion.

 

This plot of luminosity (relative to the Sun, L0) versus time shows the characteristic light curve for a Type Ia supernova. The peak is primarily due to the decay of Nickel (Ni), while the later stage is powered by Cobalt (Co).

 

The similarity in the absolute luminosity profiles of nearly all known Type Ia supernovae has led to their use as a secondary standard candle in extragalactic astronomy. The cause of this uniformity in the luminosity curve is still an open question.

 

http://en.wikipedia.org/wiki/Type_Ia_supernova#Light_curve

[Alan McDougall]

Supernova are "Standard Candles" so they all blaze with the same brightness, so the brighter they are the closer they are, the dimmer they are the further they. Work out the distance of the nearest one using redshift and then use the brightness of this one to get a very close esitimate of the distances of other supernova using both Red Shift and bringtness as the tool

[Airbrush]

How can you learn that flesh coming from distant corners of the cosmos is 1a type of supernova?

 

I mean you don't know every binary star system, how can we learn that any far away explosion is precisely from 1a supernova?

 

To put it as simple as I can, because they have learned that the 1a type supernova always explodes when it reaches the same critical mass, so the explosion is always the same brightness, as already explained above more than once.

Edited July 5, 2012 by Airbrush

[alpha2cen]

Type Ia supernovae have a characteristic light curve, their graph of luminosity as a function of time after the explosion.

 

This plot of luminosity (relative to the Sun, L0) versus time shows the characteristic light curve for a Type Ia supernova. The peak is primarily due to the decay of Nickel (Ni), while the later stage is powered by Cobalt (Co).

 

The similarity in the absolute luminosity profiles of nearly all known Type Ia supernovae has led to their use as a secondary standard candle in extragalactic astronomy. The cause of this uniformity in the luminosity curve is still an open question.

 

http://en.wikipedia....ova#Light_curve

Earth rotation, revolution around the sun and the Galaxy rotation are considered?

[Spyman]

Earth rotation, revolution around the sun and the Galaxy rotation are considered?

In what way do you think they have an affect on the typical curve of luminosity for type 1a supernovae?

[alpha2cen]

In what way do you think they have an affect on the typical curve of luminosity for type 1a supernovae?

 

the Doppler effect? It will depend on the direction of the star and observing time.

[Spyman]

the Doppler effect? It will depend on the direction of the star and observing time.

The luminosity profiles over time is not a redshift phenomenon.

[alpha2cen]

The luminosity profiles over time is not a redshift phenomenon.

 

Blue shift or red shift might depends on star position, Earth position in the Solar system and latitude of the observatory.

So, obtained spectrum might firstly be corrected with a computer program for eliminating a movement effect about the observatory.

The factors effects are not so high than others?

Edited July 17, 2012 by alpha2cen

[Spyman]

Blue shift or red shift might depends on star position, Earth position in the Solar system and latitude of the observatory.

So, obtained spectrum might firstly be corrected with a computer program for eliminating a movement effect about the observatory.

The factors effects are not so high than others?

Earth has an rotational speed of 0.465 km/s at the equator and an average orbital speed of 29.78 km/s around the Sun which have a velocity of 220 km/s around the center of the Milky Way which is moving with around 552 km/s with respect to the cosmic microwave background radiation.

(Data collected from Wikipedia.)

 

Astronomers have all this data and of course their measurements are corrected to account for observatory movement when needed.

 

However the luminosity over time from a type 1a supernova is of brightness and not redshift so it is not affected by observatory movement.

 

The luminosity for type 1a supernovae is another way to measure distance and when compared to redshift they show that the expansion is accelerating.

 

Supernovae are useful for cosmology because they are excellent standard candles across cosmological distances. They allow the expansion history of the Universe to be measured by looking at the relationship between the distance to an object and its redshift, which gives how fast it is receding from us. The relationship is roughly linear, according to Hubble's law. It is relatively easy to measure redshift, but finding the distance to an object is more difficult. Usually, astronomers use standard candles: objects for which the intrinsic brightness, the absolute magnitude, is known. This allows the object's distance to be measured from its actual observed brightness, or apparent magnitude. Type Ia supernovae are the best-known standard candles across cosmological distances because of their extreme, and extremely consistent, brightness.

http://en.wikipedia.org/wiki/Dark_energy#Supernovae

[alpha2cen]

Earth has an rotational speed of 0.465 km/s at the equator and an average orbital speed of 29.78 km/s around the Sun which have a velocity of 220 km/s around the center of the Milky Way which is moving with around 552 km/s with respect to the cosmic microwave background radiation.

(Data collected from Wikipedia.)

 

Astronomers have all this data and of course their measurements are corrected to account for observatory movement when needed.

 

However the luminosity over time from a type 1a supernova is of brightness and not redshift so it is not affected by observatory movement.

 

The luminosity for type 1a supernovae is another way to measure distance and when compared to redshift they show that the expansion is accelerating.

 

Supernovae are useful for cosmology because they are excellent standard candles across cosmological distances. They allow the expansion history of the Universe to be measured by looking at the relationship between the distance to an object and its redshift, which gives how fast it is receding from us. The relationship is roughly linear, according to Hubble's law. It is relatively easy to measure redshift, but finding the distance to an object is more difficult. Usually, astronomers use standard candles: objects for which the intrinsic brightness, the absolute magnitude, is known. This allows the object's distance to be measured from its actual observed brightness, or apparent magnitude. Type Ia supernovae are the best-known standard candles across cosmological distances because of their extreme, and extremely consistent, brightness.

http://en.wikipedia....ergy#Supernovae

Thank you for good answer.

At the very far away star, a few number of photon would come form it. Does the redshift decrease the detector sensitivity(low energy photon)?

[ACG52]

At the very far away star, a few number of photon would come form it. Does the redshift decrease the detector sensitivity(low energy photon)?

 

Actually, from the very far away star, a great number of photons come from it. Type 1a supernovas can outshine the entire galaxy they are a part of.

Edited July 18, 2012 by ACG52

[alpha2cen]

Actually, from the very far away star, a great number of photons come from it. Type 1a supernovas can outshine the entire galaxy they are a part of.

 

When we got a picture of the nearest galaxy, Andromeda, it took 19 minute long. The telescope is not so wrong. It's on the Rocky mountains.

[Janus]

When we got a picture of the nearest galaxy, Andromeda, it took 19 minute long. The telescope is not so wrong. It's on the Rocky mountains.

 

I'm sorry, but I have no idea what you are trying to say here.

 

Are you saying that it took a 19 min exposure to take a picture of Andromeda?

 

If so, that was only so you could get a good resolution. Andromeda itself is visible by the unaided eye, you wouldn't need a 19 min exposure to notice that it had more than doubled its brightness.

 

Besides that, 19 minutes is not a long time compared to the light curve of a 1a supernova, which is measured in days.

[alpha2cen]

I'm sorry, but I have no idea what you are trying to say here.

 

Are you saying that it took a 19 min exposure to take a picture of Andromeda?

 

If so, that was only so you could get a good resolution. Andromeda itself is visible by the unaided eye, you wouldn't need a 19 min exposure to notice that it had more than doubled its brightness.

 

Besides that, 19 minutes is not a long time compared to the light curve of a 1a supernova, which is measured in days.

 

Is it not easy one to find a new supernova? How to scan all the stars in the sky? There would be some problems, i.e., Earth rotation, Earth position in the solar system, telescope focusing, light intensity, South or North hemisphere position, etc.

[Janus]

Is it not easy one to find a new supernova? How to scan all the stars in the sky? There would be some problems, i.e., Earth rotation, Earth position in the solar system, telescope focusing, light intensity, South or North hemisphere position, etc.

 

Again, What are you talking about, and what does it have to do with the original question?

 

We have many telescopes pointing at many different points of the sky pretty much all the time. We will catch a fair number of Supernovae. The fact that we might not catch all of them has no bearing on the question of how we use them to determine distance.

[alpha2cen]

Again, What are you talking about, and what does it have to do with the original question?

 

We have many telescopes pointing at many different points of the sky pretty much all the time. We will catch a fair number of Supernovae. The fact that we might not catch all of them has no bearing on the question of how we use them to determine distance.

 

Actually, is it easy to find the explosion of a new supernova?

Edited July 18, 2012 by alpha2cen

[Airbrush]

Actually, is it easy to find the explosion of a new supernova?

 

Supernovae happen very often, maybe one will be seen every few days. Does anyone know how often they happen?

 

"Although no supernova has been observed in the Milky Way since 1604, supernovae remnants indicate that on average the event occurs about once every 50 years in the Milky Way."

 

Since Billions of galaxies are visible to telescopes, supernovae are seen frequently.

 

http://en.wikipedia.org/wiki/Supernova

Edited July 19, 2012 by Airbrush

[Spyman]

At the very far away star, a few number of photon would come form it. Does the redshift decrease the detector sensitivity(low energy photon)?

I am sorry but I don't have such technical knowledge of antennas, receivers and amplifiers. But I would guess that the equipment needs to be different if the redshift is very large as from very distant objects and since we are able to view the cosmic microwave background radiation which have a redshift of 1089 compared to the highest observed redshift of an object with 'only' 8.6 for UDFy-38135539, I think the practical challenge lies more in measuring a more faded signal than one with a higher redshift.