HD 190007

Lore & Background

The variability of HD 190007 was discovered by George Wesley Lockwood and colleagues from photometric data collected at Lowell Observatory between 1984 and 1995. It received its variable star designation, V1654 Aquilae, in 1997. The star is classified as a BY Draconis variable, showing a moderate level of magnetic activity in its chromosphere with a suspected activity cycle lasting 13.7 years. Its age is uncertain, and it displays a mild enhancement of metals.

The exoplanet HD 190007 b was first detected in 2020 using the radial-velocity method. Observations from the Roque de los Muchachos Observatory (2015–2019) provided 37 spectrographs, combined with 33 spectrographs from the W. M. Keck Observatory (1998–2014), flux measurements from the Fairborn Observatory over 20 years, and two-minute cadence data from the Transiting Exoplanet Survey Satellite in 2022. These data were used by M. Stalport and associates in 2023 to update the exoplanetary parameters.

Parallax measurements by Gaia place the star at a distance of 41.5 light-years from the Sun. It is drifting closer with a radial velocity of −30.3 km/s and is predicted to come within 3.6216 parsecs in 375,000 years. The star has 77% of the Sun's mass, 80% of its radius, and radiates 24% of the Sun's luminosity from its photosphere at an effective temperature of 4,610 K.

Reader's Guide

HD 190007 is significant as a nearby K-dwarf star hosting a confirmed exoplanet, HD 190007 b, discovered via radial-velocity observations. The planet has a minimum mass of 15.5 Earth masses and orbits its parent star every 11.7 days with moderate eccentricity. The star's BY Draconis variability and suspected 13.7-year activity cycle contribute to understanding magnetic activity in low-mass stars. The combination of long-term photometric monitoring, radial-velocity surveys, and space-based photometry from TESS has refined the planetary parameters. The star's predicted close approach to the Solar System in 375,000 years makes it an object of interest for future studies. Its moderate brightness (apparent magnitude 7.46) places it beyond naked-eye visibility but accessible to telescopic observation. The star's metal enhancement and uncertain age add to its astrophysical interest.

Did You Know?

• HD 190007 is predicted to come within 3.6216 parsecs of the Sun in 375,000 years.
• The exoplanet HD 190007 b has at least 15.5 times the mass of Earth.
• The star's rotation period is 28.6 days.
• HD 190007 was given the variable star designation V1654 Aquilae in 1997.