HD 166191
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.jpg) Artist's impression of the collision of two planetesimals around HD 166191 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 18h 10m 30.34s |
| Declination | −23° 34′ 00.27″ |
| Apparent magnitude (V) | 8.35 ±0.02[1] |
| Characteristics | |
| Evolutionary stage | main-sequence star |
| Spectral type | F8 ±1[2] or G0V ±1[3] |
| Astrometry | |
| Radial velocity (Rv) | –7.23 ±0.36[4] km/s |
| Proper motion (μ) | RA: –4.931 ±0.025 mas/yr[4] Dec.: –39.349 ±0.019 mas/yr[4] |
| Parallax (π) | 9.8830±0.0232 mas[4] |
| Distance | 330.0 ± 0.8 ly (101.2 ± 0.2 pc) |
| Details[5] | |
| Mass | 1.6 M☉ |
| Radius | 2 R☉ |
| Luminosity | 4.1 L☉ |
| Temperature | 6000 K |
| Rotational velocity (v sin i) | 27 ±1 km/s |
| Age | ~10 Myr |
| Other designations | |
| CD-23 14016, HIP 89046, IRAS 18074-2334, 2MASS J18103033-2334003, TYC 6843-1557-1, WISE J181030.32-233400.6, PPM 267987, GSC 06843-01557, UCAC2 22300839, YZ 113 12544, AKARI-IRC-V1 J1810303-233401, MSX6C G007.4400-02.1430 | |
| Database references | |
| SIMBAD | data |
HD 166191 is a young late-F or early G-type star in the constellation Sagittarius. It is surrounded by a large amount of dust.[2][6] In 2019 it was reported in the Astronomer's Telegram that the star had brightened in the infrared, as was seen from Spitzer observations.[7] A study was published in 2022, reporting on the result of a follow-up campaign. This study showed that a dust cloud as large as the star did transit in front of it. This cloud was produced from a giant collision between two planetesimals.[5]
In early works the age of the system was not certain and ranged between 10–100 Myrs. The large amount of dust was interpreted as being produced by a recent collision of planetary embryos or by massive ongoing collisional grinding.[2] A later work did determine a younger age. The star was observed with ground-based spectroscopy and with Herschel. The researchers did find that the star is surrounded by a protoplanetary disk with a hole in the center. The silicate feature was also determined to be similar to primordial object. This would make the disk a so-called transitional disk, meaning it lies in between protoplanetary and debris disk.[3] Observations with the Submillimeter Array did however find a high amount of dust and only little amount of gas, indicating that the disk is a debris disk.[6] Another work determined that the disk is made up of two debris belts. An inner belt at ~0.27 AU with a temperature of about 760 Kelvin (K) and an outer belt at ~5 AU with a temperature of about 175 K.[5]
It was suggested that HD 166191 co-moves with HD 163296.[3] This was questioned in a later work.[5]
