J/ApJ/935/L9 Close encounters to the Sun in Gaia DR3 (Bailer-Jones, 2022)
Stars that approach within one parsec of the Sun:
New and more accurate encounters identified in Gaia Data Release 3.
Bailer-Jones C.A.L.
<Astrophys. J. 935, L9 (2022)>
=2022ApJ...935L...9B 2022ApJ...935L...9B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, nearby ; Stars, distances ; Radial velocities ; Optical
Keywords: Space astrometry - Solar neighborhood
Abstract:
Close encounters of stars to the Sun could affect life on Earth
through gravitational perturbations of comets in the Oort cloud or
exposure to ionizing radiation. By integrating orbits through the
Galactic potential, I identify which of 33 million stars in Gaia DR3
with complete phase space information come close to the Sun. 61 stars
formally approach within 1pc, although there is high confidence in
only 42 (two thirds) of these, the rest being spurious measurements or
(in) binary systems. Most of the stars will encounter within the past
or future 6Myr; earlier/later encounters are less common due to the
magnitude limit of the Gaia radial velocities (RVs). Several close
encountering stars are identified for the first time, and the
encounter times, distances, and velocities of previously known close
encounters are determined more precisely on account of the
significantly improved precision of Gaia DR3 over earlier releases.
The K7 dwarf Gl 710 remains the closest known encounter, with an
estimated (median) encounter distance of 0.0636pc (90% confidence
interval 0.0595-0.0678pc) to take place in 1.3Myr. The new second
closest encounter took place 2.8Myr ago: this was the G3 dwarf
HD 7977, now 76pc away, which approached within less than 0.05pc of
the Sun with a probability of one third. The apparent close encounter
of the white dwarf UPM J0812-3529 is probably spurious due to an
incorrect RV in Gaia DR3.
Description:
The present paper continues a study to discover and characterize close
encounters, one that started with Hipparcos (Bailer-Jones,
2015A&A...575A..35B 2015A&A...575A..35B, Cat. J/A+A/575/A35; Paper I), then Gaia DR1
(Bailer-Jones 2018A&A...609A...8B 2018A&A...609A...8B, Cat. J/A+A/609/A8; Paper II) - both
complemented by non-Gaia data - and most recently Gaia DR2
(Bailer-Jones et al. 2018AJ....156...58B 2018AJ....156...58B, Cat. I/347; Paper III).
Since the first Gaia data release, astrometry has been in abundance
and the comparative lack of relative radial velocities (RVs) has been
the limiting factor of these studies - a complete reversal of the
pre-Hipparcos situation. Gaia DR3 (Gaia Collaboration et al., 2022,
Cat. I/355) now provides radial velocities for 34 million bright stars
(99% with G<15.7mag) with median uncertainties of 3.3km/s (central 90%
range 0.4±7.8km/s). This is nearly a fivefold increase in the number
of sources with radial velocities in Gaia DR2, and constitutes the
largest radial velocity survey to date.
Here I use these data to identify stars that approach within 1pc of
the Sun.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table12.dat 252 61 Perihelion (encounter) and additional parameters
(Tables 1 & 2) for all stars with a median
perihelion distance (dphmed) below 1pc
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
I/347 : Distances to 1.33 billion stars in Gaia DR2
(Bailer-Jones+, 2018)
J/A+A/609/A8 : Close encounters to the Sun in Gaia DR1 (Bailer-Jones, 2018)
J/A+A/575/A35 : Close star encounters (Bailer-Jones, 2015)
Byte-by-byte Description of file: table12.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Flag [b;d ] Source flag (1)
5- 6 I2 --- Seq [1/61] Sequential identifier
8- 26 I19 --- GaiaDR3 Gaia DR3 identifier (source_id) (2)
28- 34 F7.1 kyr tphmed Median perihelion time
36- 42 F7.1 kyr tph5 5% confidence interval bound on tph
44- 50 F7.1 kyr tph95 95% confidence interval bound on tph
52- 57 F6.4 pc dphmed Median perihelion distance
59- 64 F6.4 pc dph5 5% confidence interval bound on dph
66- 71 F6.4 pc dph95 95% confidence interval bound on dph
73- 78 F6.2 km/s vphmed Median perihelion velocity
80- 85 F6.2 km/s vph5 5% confidence interval bound on vph
87- 92 F6.2 km/s vph95 95% confidence interval bound on vph
94-100 F7.3 mas Plx Zeropoint-corrected Gaia DR3 parallax
102-106 F5.3 mas e_Plx Standard error of parallax
108-115 F8.3 mas/yr PM Gaia DR3 total proper motion (pm)
117-121 F5.3 mas/yr e_PM Standard error of PM (3)
123-129 F7.2 km/s RV Gaia DR3 radial velocity (radial_velocity)
131-135 F5.2 km/s e_RV Radial velocity error (radialvelocityerror)
137-139 I3 --- rv/vt Ratio, absolute radial velocity to
transverse velocity (4)
141-150 F10.7 mag Gmag Gaia DR3 G-band mean magnitude
(photgmean_mag)
152-161 F10.8 mag BP-RP Gaia DR3 BP-RP color (bp_rp)
163-179 F17.14 mag GMAG Absolute G-band magnitude (5)
181-191 F11.8 --- RUWE Renormalised unit weight error (ruwe)
193-194 I2 --- Solved Which parameters have been solved for?
(astrometricparamssolved)
196-197 I2 --- IPDfmp Percent of successful-IPD windows with more
than one peak (ipdfracmulti_peak)
199-209 F11.7 --- RVS/N Expected signal to noise ratio
(rvexpectedsigtonoise)
211-212 I2 --- o_RV Number of transits used to compute the
radial velocity (rvnbtransits)
214-231 F18.14 deg GLON Gaia DR3 Galactic longitude (l)
233-252 F20.16 deg GLAT Gaia DR3 Galactic latitude (b)
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Note (1): Flags as follows:
d = Encounter is dubious for a variety of possible reasons;
b = Indicates it is probably a wide-binary according to El-Badry et al.
(2021MNRAS.506.2269E 2021MNRAS.506.2269E), so may also not be reliable.
Note (2): Quantites with a label in brackets in the description are
taken directly from from the Gaia DR3 gaia_source table.
Note (3): The PM error, accounting for correlation, is given by the
expression (using the Gaia DR3 parameter labels):
ePM=sqrt((pmraerror*pmra)2+(pmdecerror*pmdec)2+
2*pmrapmdeccorr*pmraerror*pmra*pmdecerror*pmdec)/pmtot.
Note (4): The ratio of the current absolute radial velocity to the
current transverse velocity, the latter computed as 4.74047 PM/Plx.
Note (5): Absolute G-band magnitude calculated from Gmag+5log10(Plx/100),
where Plx is the zeropoint-corrected parallax in mas.
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Acknowledgements:
Coryn Bailer-Jones, calj(at)mpia.de
(End) Patricia Vannier [CDS] 16-Aug-2022