# SONG policies

Below you will find the latest SONG policy document which include publication policies and general policies on the SONG project.

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# Latest published SONG papers

1/06 - 2021 |

## Paul Heeren: Precise radial velocities of giant stars. XV. Mysterious Nearly...

Using the Hamilton Échelle Spectrograph at Lick Observatory, we have obtained precise radial velocities (RVs) of a sample of 373 G- and K-giant stars over more than 12 years, leading to the discovery of several single and multiple planetary systems. The RVs of the long-period spectroscopic binary ε Cyg (HIP 102488) are found to exhibit additional regular variations with a much shorter period. We intend to improve the orbital solution of the ε Cyg system, and attempt to identify the cause of...

4/04 - 2021 |

## H. Korhonen: Observing the changing surface structures of the active K giant...

Aims. To study the spot evolution and differential rotation in the magnetically-active cool K-type giant star $\sigma$ Gem from broad-band photometry and continuous spectroscopic observations spanning 150 nights.Methods. We use high-resolution, high signal-to-noise ratio spectra obtained with the Hertzsprung SONG telescope to reconstruct surface (photospheric) temperature maps with Doppler imaging techniques. The 303 observations span 150 nights and allow for a detailed analysis of the spot...

18/02 - 2021 |

## K. Brogaard: Properties of the Hyades, the eclipsing binary HD27130, and the...

Eclipsing binary stars provide the means to derive accurate and precise masses and radii, from which insights into their evolution may be obtained. When they reside in star clusters, basic properties of even higher precision, along with additional information, can be extracted. Asteroseismology of solar-like oscillations offers similar possibilities for single stars. We wish to improve the previously established properties of the Hyades eclipsing binary HD 27130 and re-asses the...

14/10 - 2020 |

## O. Creevey: Sun-like Oscillations in the Population II giant HD 122563

We have been monitoring the metal-poor Population II giant, HD 122563, for radial velocity variations since 2016 using the SONG telescope on Tenerife. We have detected the global seismic quantity $\nu_{\rm max}$ which provides information related to the stellar parameters. By combining these data with complementary data, we derive a new precise surface gravity, radius and distance to the star. Our results are corroborated by using the parallax from Gaia DR2. We present these results and some...

29/07 - 2020 |

## Sai Prathyusha Malla: Asteroseismic masses of four evolved planet-hosting...

The study of planet occurrence as a function of stellar mass is important for a better understanding of planet formation. Estimating stellar mass, especially in the red giant regime, is difficult. In particular, stellar masses of a sample of evolved planet-hosting stars based on spectroscopy and grid-based modelling have been put to question over the past decade with claims they were overestimated. Although efforts have been made in the past to reconcile this dispute using asteroseismology,...

12/07 - 2020 |

20/09 - 2019 |

## Will M. Farr: Aldebaran b’s Temperate Past Uncovered in Planet Search Data

The nearby red giant Aldebaran is known to host a gas giant planetary companion from decades of ground-based spectroscopic radial velocity measurements. Using Gaussian Process-based Continuous Auto-Regressive Moving Average models, we show that these historic data also contain evidence of acoustic oscillations in the star itself, and verify this result with further dedicated ground-based spectroscopy using the SONG telescope and space-based photometry with the Kepler Space Telescope. From...