Well, it is a start for eventually making an explanation, if perhaps a wrong turn. In fact they seem to me to accept it not because it fits well or isn’t suspect, but because it is the one hypothesis they can come up with. I note that there are a lot of small discrepancies between the model and the observations, making it even more suspect. The bulk of the dispersing photons starts out with absorption lines acquired in the equivalent deeper well, but I take it they are thermalized making the photosphere the imprinter of those lines. As such, they recommend future investigations target only specific sub-classes for comparison in order to limit such effects. Trying to tease out such small effects with such a diverse population of stars may simply not work. Ultimately, the team concludes that, regardless of the effect, the oddities observed here point to a limitation in the methodology. Yet, it is still somewhat suspect that this offset could so precisely counter the gravitational redshift. The team states that low mass stars made up the bulk of the survey due to their number and such stars are thought to undergo greater amounts of convection than most other types of stars. Namely, convection in the atmosphere of the stars would blueshift material. To explain this, the team turned to models of stars and determined that main sequence stars had a mechanism which could potentially offset the redshift with a blueshift. The two populations both showed the recessional velocity of the cluster, centered on 33.75 km/s. The team expected to find a discrepancy of ~0.6 km/s, yet when their results were processed, no such difference was detected. To negate the latter of these, they averaged the results of numerous stars of each type.
To eliminate effects of varying Doppler velocities, the team chose to study clusters, which have consistent velocities as a whole, but random internal velocities of individual stars. Thus, the team behind the new paper, led by Luca Pasquini from the European Southern Observatory, compared the shift among stars of the middling density of main sequence stars against that of giants. Thus, if astronomers wish to study the effects of gravitational redshift on stars of more normal density, other sources will be required. But because Earth also lies in the Sun’s gravitational well the amount of redshift if the photon were to escape from the distance of our orbit would only be 0.633 km/s leaving a distance of only ~0.003 km/s, a change swamped by other sources. Even larger observations have been made for neutron stars.įor stars like the Sun, the expected amount of redshift (if the photon were to escape to infinity) is small, a mere 0.636 km/s. It’s just expressed this way for convenience).
By examining the average amount of redshifts for white dwarfs against main sequence stars in clusters such as the Hyades and Pleiades, teams have reported finding gravitational redshifts on the order of 30-40 km/s (NOTE: the redshift is expressed in units as if it were a recessional Doppler velocity, although it’s not. $$\frac\right) =.9999958$$ and the frequency of the shifted photon is $4.Historically, gravitational redshifts have been detected on even more dense objects such as white dwarfs. At hyperphysics they give this general formula for a Schwarzschild background:
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