Potentially the biggest scientific story in history?

[barbos]

First of all, supernova standard candle is irrelevant here, they are for measuring distances to other galaxies. Second of all, there is no need for absolute brightness here, they are looking at changes in the brightness.

To measure change in something one needs to know something.

Yes, they measured it once and then compared to second measurement.
Scientists are not idiots.

 

[skepticalbip]

First of all, supernova standard candle is irrelevant here, they are for measuring distances to other galaxies. Second of all, there is no need for absolute brightness here, they are looking at changes in the brightness.

To measure change in something one needs to know something.

Indeed, something must be known to measure change. That is why measurements are made - so something will be known.

Here's an example of what is known from the measurements:



These light curves certainly indicate that there is some dimming events, dimming events that look very odd.

 

[fromderinside]

Great change is measured. Now relate those measures to the nature of the universe. Measurements related to normalizedflux whdcic, I believe, is realted to the standard candle. Oh wait. The standard candle is a relative measure in the first place and it isn't anchored to actual goings on one can recreate in the lab which leaves us speculating about what is a standard interstellar (brightness of a IA supernova) candle. You don't have an objective physical standard against which to relate your measurements. drat.

Look we accept that index because things tend to hold together when we use that event as a standard. Its just, well, that damn dark matter, space dust density, etc., may change everything, say, even how light appears to us when it arrives from the source.

 

[skepticalbip]

Great change is measured. Now relate those measures to the nature of the universe. Measurements related to normalizedflux whdcic, I believe, is realted to the standard candle. Oh wait. The standard candle is a relative measure in the first place and it isn't anchored to actual goings on one can recreate in the lab which leaves us speculating about what is a standard interstellar (brightness of a IA supernova) candle. You don't have an objective physical standard against which to relate your measurements. drat.

Look we accept that index because things tend to hold together when we use that event as a standard. Its just, well, that damn dark matter, space dust density, etc., may change everything, say, even how light appears to us when it arrives from the source.

I have no idea what you are asking... do you???

Kepler has light curves for up to a hundred thousand stars. Such light curves are all simply flat lines unless they have planets transiting (with the exception of Tabby's star - which is the reason for the interest). Here's an example of a light curve showing a planet (HAT-P-7 b) found by Kepler... notice it only shows a dimming of 0.006% during the transit but otherwise a flat light curve. It is apparently a large planet very close to the star since it blocks a significant percentage of the light and has an orbital period of only about 54 hours.



Is that what you are asking for or are you saying that astrophysicists don't have a clue what they are doing?

ETA:
I just noticed that you are apparently worried about absolute luminosity. That is irrelevant to what Kepler is looking for. You will note that the data have been normalized because absolute luminosity is not the concern. The concern is dimming caused by planetary transits and it doesn't matter if the star is a red dwarf or a blue giant or anything between.

 

[fromderinside]

ETA:
I just noticed that you are apparently worried about absolute luminosity. That is irrelevant to what Kepler is looking for. You will note that the data have been normalized because absolute luminosity is not the concern. The concern is dimming caused by planetary transits and it doesn't matter if the star is a red dwarf or a blue giant or anything between.

Exactly. Even though the best approach is to presume things are as they are nearby, If dark matter enters into observations of extreme scale and we don't have good evidence that such doesn't alter luminosity, doesn't interact with photons, then we can't use that 'safe' local presumption as an objective stand in. IOW is it safe to presume that transits millions of light years distant are the same as those within our solar system.

The question becomes are transits reliably evaluated by dimming across millions or billions of light years. We are looking at something outside our experience as evidenced by speculations relating to the article.

 

[skepticalbip]

ETA:
I just noticed that you are apparently worried about absolute luminosity. That is irrelevant to what Kepler is looking for. You will note that the data have been normalized because absolute luminosity is not the concern. The concern is dimming caused by planetary transits and it doesn't matter if the star is a red dwarf or a blue giant or anything between.

Exactly. Even though the best approach is to presume things are as they are nearby, If dark matter enters into observations of extreme scale and we don't have good evidence that such doesn't alter luminosity, doesn't interact with photons, then we can't use that 'safe' local presumption as an objective stand in. IOW is it safe to presume that transits millions of light years distant are the same as those within our solar system.

I assume you are talking about the hundreds (maybe thousands now) of Kepler finds excluding Tabby's star. It is a pretty damn safe premise. If those light curves are expanded there is much more data there that would take a hell of a lot of hand waving to explain as anything but a planet transiting the star not to mention the regularity and magnitude of dimming that is measured. As in the light curve posted earlier for HAT-P-7 b, much higher resolution of that data set is readily explained by the phases of that planet. Shown is a slow increase in intensity (as we see more reflected light as it approaches fully lit), then a drop in light (as the planet is eclipsed by the star), then back to full intensity (as the full planet emerges from eclipse), followed by a decrease in intensity (as the planet's unlit side revolves toward us), followed by another transit (as the planet transits and we see none of its illuminated side). It would take a hell of a lot of imagination and hand waving (most likely even special pleading) to offer any other scenario that could explain the data otherwise.

The question becomes are transits reliably evaluated by dimming across millions or billions of light years. We are looking at something outside our experience as evidenced by speculations relating to the article.

The article was only talking about Tabby's star. Its light curve is unique and has no explanation as yet. Its wild variations are obviously not due to a planet transit. What those variations are due to are currently unknown. Personally, I still wonder if couldn't be partly due to the star being an, as yet, unclassified type of variable star.

 

[barbos]

Great change is measured. Now relate those measures to the nature of the universe. Measurements related to normalizedflux whdcic, I believe, is realted to the standard candle. Oh wait. The standard candle is a relative measure in the first place and it isn't anchored to actual goings on one can recreate in the lab which leaves us speculating about what is a standard interstellar (brightness of a IA supernova) candle. You don't have an objective physical standard against which to relate your measurements. drat.

Look we accept that index because things tend to hold together when we use that event as a standard. Its just, well, that damn dark matter, space dust density, etc., may change everything, say, even how light appears to us when it arrives from the source.

You are drunk, aren't you?

 

[Angra Mainyu]

IOW is it safe to presume that transits millions of light years distant are the same as those within our solar system.

Kepler only looks for transits in the Milky Way. Moreover, it seems it doesn't look farther than 3000 light years from Earth.

 

[barbos]

Is that what you are asking for or are you saying that astrophysicists don't have a clue what they are doing?

Seems that way to me

 

[fromderinside]

IOW is it safe to presume that transits millions of light years distant are the same as those within our solar system.

Kepler only looks for transits in the Milky Way. Moreover, it seems it doesn't look farther than 3000 light years from Earth.

OK. Since the original Kepler looked only a few light hours (Venus, Mercury) in our solar system I guess my analogy would apply as millions of times a few light hours.

 

[Angra Mainyu]

OK. Since the original Kepler looked only a few light hours (Venus, Mercury) in our solar system I guess my analogy would apply as millions of times a few light hours.

I don't understand what you're trying to get at. Why does it matter what Kepler, the astronomer, looked at?
Your rationale was as follows:

Exactly. Even though the best approach is to presume things are as they are nearby, If dark matter enters into observations of extreme scale and we don't have good evidence that such doesn't alter luminosity, doesn't interact with photons, then we can't use that 'safe' local presumption as an objective stand in. IOW is it safe to presume that transits millions of light years distant are the same as those within our solar system.


The question becomes are transits reliably evaluated by dimming across millions or billions of light years. We are looking at something outside our experience as evidenced by speculations relating to the article.

You were talking about "extreme scale" and by that you meant at least millions of light years, not les than 3000 light years.
Now what is your argument, exactly?
You seem to be suggesting the transit method for detecting exoplanets is not reliable within 3000 light years.
But why would that be so?
Your suggestion - if that's what you're saying - begins to look like a sort of wide skepticism about most current astronomy.
By the way, many of the exoplanets have been confirmed by other methods.

In any event, that does not block the point that there is something anomalous about Tabby's star. After all, it's the only star Kepler found were that dimming happens, even though Kepler looked at a lot of stars.

 

[barbos]

These light curves certainly indicate that there is some dimming events, dimming events that look very odd.

Yes, it looks exactly as if something was covering it. Light output has well defined maximum level where star spends most of the time and then these dimming events
.
Intrinsically Variable stars don't have well defined maximum, they usually oscillate periodically, sometimes stochastically but they never have well defined base level from which they drop. Also these variation must correspond to spectrum variation and as far as I understand there are none in this Tabby's star.
Whatever it is, it's external to the star's body.

 

[DBT]

Looks like the long term dimming may have been due to the instruments being used and not the star itself:

Quote;
''Now, however, researchers suggest this seemingly century-long dimming trend might not be real. Instead, the apparent darkening may just be due to how astronomical instruments have changed over time.

In the new study, scientists pored over DASCH (Digital Access to a Sky Century @ Harvard) data. This is a collection of more than 500,000 photographic glass plates taken by astronomers at Harvard in Massachusetts between 1885 and 1993 that the university is digitizing.

"It is exciting that we have these century-old data, which are incredibly valuable for checks like this," study lead author Michael Hippke, an amateur astronomer from the German town of Neukirchen-Vluyn, told Space.com.

''The researchers looked not only at Tabby's Star, but also at a number of comparable stars in the DASCH database. Results showed that many of these other stars experienced a drop in brightness similar to that of Tabby's Star in the 1960s.

"That indicates the drops were caused by changes in the instrumentation, not by changes in the stars' brightness," study co-author Keivan Stassun at Vanderbilt University in Nashville, Tennessee, said in a statement.''

 

[barbos]

Looks like the long term dimming may have been due to the instruments being used and not the star itself:

Quote;
''Now, however, researchers suggest this seemingly century-long dimming trend might not be real. Instead, the apparent darkening may just be due to how astronomical instruments have changed over time.

In the new study, scientists pored over DASCH (Digital Access to a Sky Century @ Harvard) data. This is a collection of more than 500,000 photographic glass plates taken by astronomers at Harvard in Massachusetts between 1885 and 1993 that the university is digitizing.

"It is exciting that we have these century-old data, which are incredibly valuable for checks like this," study lead author Michael Hippke, an amateur astronomer from the German town of Neukirchen-Vluyn, told Space.com.

''The researchers looked not only at Tabby's Star, but also at a number of comparable stars in the DASCH database. Results showed that many of these other stars experienced a drop in brightness similar to that of Tabby's Star in the 1960s.

"That indicates the drops were caused by changes in the instrumentation, not by changes in the stars' brightness," study co-author Keivan Stassun at Vanderbilt University in Nashville, Tennessee, said in a statement.''

If true then previous study was unbelievably sloppy. But I don't quite understand this new study. They need to explain this effect itself and what was wrong with previous study.

 

[skepticalbip]

These light curves certainly indicate that there is some dimming events, dimming events that look very odd.

Yes, it looks exactly as if something was covering it. Light output has well defined maximum level where star spends most of the time and then these dimming events
.
Intrinsically Variable stars don't have well defined maximum, they usually oscillate periodically, sometimes stochastically but they never have well defined base level from which they drop. Also these variation must correspond to spectrum variation and as far as I understand there are none in this Tabby's star.
Whatever it is, it's external to the star's body.

There are quite a few types of variable stars. I was thinking of one more like the eruptive variables more along the lines of R Coronae Borealis but with much shorter periods of eruptive activity if such a thing is physically possible. Here is a light curve of that eruptive variable that does somewhat resemble what we see from Tabby's star but for the time scale.

light curve of R Coronae Borealis from 1980 to 1999

 

[Angra Mainyu]

Looks like the long term dimming may have been due to the instruments being used and not the star itself:

Quote;
''Now, however, researchers suggest this seemingly century-long dimming trend might not be real. Instead, the apparent darkening may just be due to how astronomical instruments have changed over time.

In the new study, scientists pored over DASCH (Digital Access to a Sky Century @ Harvard) data. This is a collection of more than 500,000 photographic glass plates taken by astronomers at Harvard in Massachusetts between 1885 and 1993 that the university is digitizing.

"It is exciting that we have these century-old data, which are incredibly valuable for checks like this," study lead author Michael Hippke, an amateur astronomer from the German town of Neukirchen-Vluyn, told Space.com.

''The researchers looked not only at Tabby's Star, but also at a number of comparable stars in the DASCH database. Results showed that many of these other stars experienced a drop in brightness similar to that of Tabby's Star in the 1960s.

"That indicates the drops were caused by changes in the instrumentation, not by changes in the stars' brightness," study co-author Keivan Stassun at Vanderbilt University in Nashville, Tennessee, said in a statement.''

But the 4-years dimming since 2009 seems solid, and it's faster than the long(er)-term dimming claimed by the original study that you cite.

https://astronomynow.com/2016/08/08/kepler-finds-tabbys-star-is-mysteriously-dimming/
http://www.skyandtelescope.com/astronomy-news/tabbys-star-weird-star-gets-weirder/

 

[barbos]

Yes, it looks exactly as if something was covering it. Light output has well defined maximum level where star spends most of the time and then these dimming events
.
Intrinsically Variable stars don't have well defined maximum, they usually oscillate periodically, sometimes stochastically but they never have well defined base level from which they drop. Also these variation must correspond to spectrum variation and as far as I understand there are none in this Tabby's star.
Whatever it is, it's external to the star's body.

There are quite a few types of variable stars. I was thinking of one more like the eruptive variables more along the lines of R Coronae Borealis but with much shorter periods of eruptive activity if such a thing is physically possible. Here is a light curve of that eruptive variable that does somewhat resemble what we see from Tabby's star but for the time scale.

light curve of R Coronae Borealis from 1980 to 1999
View attachment 7943
View attachment 7944

It looks similar. But there is a significant difference in spectral data. In case of eruptive stars you can determine what was erupted from star from spectra. In case of Tabby there appears no change in spectrum which suggests something which pretty opaque/solid/dense to most light including infrared. And star itself is not variable based on its characteristics.

 

[skepticalbip]

There are quite a few types of variable stars. I was thinking of one more like the eruptive variables more along the lines of R Coronae Borealis but with much shorter periods of eruptive activity if such a thing is physically possible. Here is a light curve of that eruptive variable that does somewhat resemble what we see from Tabby's star but for the time scale.

light curve of R Coronae Borealis from 1980 to 1999
View attachment 7943
View attachment 7944

It looks similar. But there is a significant difference in spectral data. In case of eruptive stars you can determine what was erupted from star from spectra. In case of Tabby there appears no change in spectrum which suggests something which pretty opaque/solid/dense to most light including infrared. And star itself is not variable based on its characteristics.

I think maybe you misunderstand what I was suggesting. I wasn't suggesting that it could be a R Coronae Borealis but only that it could be an irregular variable of a class we have not yet observed.

The reality is that we don't have a clue what is causing the dimming but it must be something between us and the star blocking the light, the source changing, some astronomical phenomena we are unaware of, or maybe a combination of all.

If there is something coming between us and the source then it is not in orbit because there is no repeating pattern and the combined cross section of them is huge with a combined cross section many times that of Jupiter. As Tabby suggested, maybe we are witnessing a gigantic space war and they are cleaning up the debris for recycling after each battle. But then she expects a natural explanation.

If it is an irregular variable star then is is a type we have not observed with characteristics we certainly don't understand.

Whatever it is, it is damned interesting because it is currently not explainable by any of our models.

 

[fromderinside]

I don't understand what you're trying to get at. Why does it matter what Kepler, the astronomer, looked at?
Your rationale was as follows:

Exactly. Even though the best approach is to presume things are as they are nearby, If dark matter enters into observations of extreme scale and we don't have good evidence that such doesn't alter luminosity, doesn't interact with photons, then we can't use that 'safe' local presumption as an objective stand in. IOW is it safe to presume that transits millions of light years distant are the same as those within our solar system.


The question becomes are transits reliably evaluated by dimming across millions or billions of light years. We are looking at something outside our experience as evidenced by speculations relating to the article.

You were talking about "extreme scale" and by that you meant at least millions of light years, not les than 3000 light years.
Now what is your argument, exactly?
You seem to be suggesting the transit method for detecting exoplanets is not reliable within 3000 light years.
But why would that be so?
Your suggestion - if that's what you're saying - begins to look like a sort of wide skepticism about most current astronomy.
By the way, many of the exoplanets have been confirmed by other methods.

In any event, that does not block the point that there is something anomalous about Tabby's star. After all, it's the only star Kepler found were that dimming happens, even though Kepler looked at a lot of stars.

Kepler telescope system is named after Kepler the one who initially measured transits. That is where I started.

Adjusting my argument to the range of the Kepler project is a simple thing. Others presume dust or other material intervening, I went with dust, aware that dark matter is a problem beyond dust.

Jumping in units from a couple light hours to three thousand light years is a change of millions, which, IMHO, is extreme scale.

 

[KeepTalking]

I don't understand what you're trying to get at. Why does it matter what Kepler, the astronomer, looked at?
Your rationale was as follows:


You were talking about "extreme scale" and by that you meant at least millions of light years, not les than 3000 light years.
Now what is your argument, exactly?
You seem to be suggesting the transit method for detecting exoplanets is not reliable within 3000 light years.
But why would that be so?
Your suggestion - if that's what you're saying - begins to look like a sort of wide skepticism about most current astronomy.
By the way, many of the exoplanets have been confirmed by other methods.

In any event, that does not block the point that there is something anomalous about Tabby's star. After all, it's the only star Kepler found were that dimming happens, even though Kepler looked at a lot of stars.

Kepler telescope system is named after Kepler the one who initially measured transits. That is where I started.

Adjusting my argument to the range of the Kepler project is a simple thing. Others presume dust or other material intervening, I went with dust, aware that dark matter is a problem beyond dust.

Jumping in units from a couple light hours to three thousand light years is a change of millions, which, IMHO, is extreme scale.

It wasn't a jump, it was a journey of 300 years. Kepler was making his transit observations during the dawn of the telescope. The space based Kepler Telescope is likely a million times more sensitive than those rudimentary telescopes, and can see well into the infrared range of light, which was impossible during Kepler's time.