Precise stellar surface gravities from the time scales of...

Science Advances ^ | January 1, 2016 | Thomas Kallinger, Saskia Hekker, Rafael A. García, Daniel Huber, and Jaymie M. Matthews

[SunkenCiv]

We have demonstrated that the typical time scale of the combined granulation and oscillation variability is a reliable tracer of stellar surface gravity for stars with masses 0.8 to 3 times the mass of the Sun across a wide evolutionary range -- from main sequence stars with granulation time scales of minutes to hours to red giants with granulation time scales of days, including luminous red giants with time scales of weeks. We have tested this for a well-defined subsample of the Kepler catalog and found it to maintain a high accuracy, about six times better than that of the flicker method. In addition, it is more noise-tolerant than asteroseismology and gives a reasonably accurate surface gravity g for stars that are too faint for a reliable asteroseismic analysis. Therefore, the time scale technique makes it possible to study otherwise poorly understood stars, which will lead to better characterization of exoplanetary systems both individually and statistically.

[SunkenCiv]

full title, Precise stellar surface gravities from the time scales of convectively driven brightness variations

[ETL]

Hopefully this passage from the intro helps clarify what this is about...

"For spherical bodies such as stars, surface gravity (g) is proportional to mass divided by radius squared. Usually expressed as log g (where log denotes the decadic logarithm), it plays a key role in many aspects of astrophysics, from knowing stellar properties such as mass and radius to knowing the size of an exoplanet and whether it orbits in its star's habitable zone."

[SunkenCiv]

Thanks, I must have missed that on a search for that very thing. :’) Thanks gleeaikin for the original link, I’d have used it but for the push content/popups/spam.

[Eagles6]

Well Duh! who didn’t know that?/sarc

[sparklite2]

Adblock Plus.

[SunkenCiv]

:’)

[Gene Eric]

Well, that first sentence hurt my brain, but I was nonetheless intrigued...

V - combined granulation and oscillation variability
t - typical time scale
G - stellar surface gravity
M - main sequence stars
R - red giants
L - luminous R
h - granulation time scales of minutes to hours
d - granulation time scales of days
w - granulation time scales of weeks

We have demonstrated that Vt is a reliable tracer of G for stars with masses 0.8 to 3 times the mass of the Sun across a wide evolutionary range; specifically, from Mh to Rd including Lw.

We have demonstrated that the typical time scale of the combined granulation and oscillation variability is a reliable tracer of stellar surface gravity for stars with masses 0.8 to 3 times the mass of the Sun across a wide evolutionary range -- from main sequence stars with granulation time scales of minutes to hours to red giants with granulation time scales of days, including luminous red giants with time scales of weeks.

[SunkenCiv]

:’) THanks GE.

[Telepathic Intruder]

And?

[WhiskeyX]

“And?”

Such a capability opens the door to substantially improved measurements of stellar mass properties, internal stellar processes, and the properties of companion exoplanets.