Lacaille 9352#Planetary system

{{Starbox image

| image = 280px

| caption = The neighborhood of the Solar System which also includes Lacaille 9352

| credit =

}}

{{Starbox observe

| epoch = J2000

| constell = Piscis Austrinus

| ra = {{RA|23|05|52.03579}}

| dec = {{DEC|−35|51|11.0552}}

| appmag_v = 7.34

}}

{{Starbox character

| class = M0.5V

| b-v = +1.50

| u-b = +1.18

| variable = Suspected

}}

{{Starbox astrometry

| radial_v = {{val|+8.31|0.13}}

| prop_mo_ra = {{val|+6765.995|fmt=commas}}

| prop_mo_dec = {{val|+1330.285|fmt=commas}}

| pm_footnote =

| parallax = 304.1354

| p_error = 0.0200

| parallax_footnote =

| absmag_v = 9.8

}}

{{Starbox detail

| mass = {{val|0.479|0.011|0.010}}

| radius = {{val|0.474|0.008}}

| rotational_velocity = 1

| luminosity = {{val|0.0368|0.0006}}

| temperature = {{val|3,672|36|34|fmt=commas}}

| habitable_inner = 0.16 AU

| habitable_outer = 0.40 AU

| metal_fe = {{val|−0.22|0.09}}

| gravity = 4.78

| age_gyr = 4.57

}}

{{Starbox catalog

| names=HD 217987, CD-36°15693, GCTP 5584, GJ 887, LHS 70, SAO 214301, LTT 9348, LFT 1758, Cordoba 31353, NSV 14420, HIP 114046, UGPMF 591

}}

{{Starbox reference

| Simbad = NAME+LACAILLE+9352

| NSTED = GJ-887

| ARICNS = 01887

}}

{{Starbox image

|image={{Location map|100x100|AlternativeMap=Piscis_Austrinus_constellation_map.svg

|alt=Lacaille 9352 is located in the constellation Piscis Austrinus.

|caption=Location of Lacaille 9352 in the constellation Piscis Austrinus|border=infobox|mark=Red_pog.png|width=300

|label=Lacaille 9352

|lat=23.1

|long=11.6

}}|caption=

}}

Lacaille 9352 (Lac 9352) is a red dwarf star in the southern constellation of Piscis Austrinus. With an apparent visual magnitude of 7.34, this star is too faint to be viewed with the naked eye except possibly under excellent seeing conditions. Parallax measurements place it at a distance of about {{Convert|10.74|ly|pc|abbr=off|lk=on}} from Earth. It is the eleventh closest star system to the Solar System and is the closest star in the constellation Piscis Austrinus. Its closest neighbour is the EZ Aquarii triple star system at about 4.1 ly away.

Properties

This star has the fourth highest known proper motion, (which was first noticed by Benjamin Gould in 1881) moving a total of 6.9 arcseconds per year. However, this is still a very small movement overall, as there are 3,600 arcseconds in a degree of arc. The space velocity components of this star are {{nowrap|(U, V, W)}} = {{nowrap|(−93.9, −14.1, −51.4) km/s}}. If the radial velocity (V_r) equals +9.7 km/s then about 2,700 years ago Lacaille 9352 was at its minimal distance of approximately {{Convert|10.63|ly|pc|abbr=on}} from the Sun.

The spectrum of Lacaille 9352 places it at a stellar classification of M0.5V, indicating it is a type of main sequence star known as a red dwarf. This was the first red dwarf star to have its angular diameter measured, with the physical diameter being about 47% of the Sun's radius. It has around half the mass of the Sun and the outer envelope has an effective temperature of about 3,670 K.

Planetary system

In June 2020, two super-Earth planets were reported, as well as a third signal with a period of 50.7 days that may be due to stellar activity—however, if this planet is real it may be located within the habitable zone. They were detected using the radial velocity method from observations with HARPS in Chile and HIRES in Hawaii.

Additionally, the star presents a difference on proper motion measurements taken by the Hipparcos and Gaia spacecrafts, suggesting the presence of an outer giant planet.

{{OrbitboxPlanet

| exoplanet = b

| mass_earth = {{val|4.2|0.6|p=≥ }}

| period = {{val|9.262|0.001}}

| semimajor = {{val|0.068|0.002}}

| eccentricity = {{val|0.09|0.09|0.06}}

| inclination =

}}

{{OrbitboxPlanet

| exoplanet = c

| mass_earth = {{val|7.6|1.2|p=≥ }}

| period = {{val|21.789|0.004|0.005}}

| semimajor = {{val|0.120|0.004}}

| eccentricity = {{val|0.22|0.09|0.10}}

| inclination =

}}

{{OrbitboxPlanet hypothetical

| exoplanet = d

| mass_earth = {{val|8.3|p=≳ }}

| period = ~50.7

| semimajor = ~0.21

| eccentricity = {{val|0.25|0.20|0.15}}

| inclination =

}}

References

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{{cite web | title=LACAILLE 9352 -- Pre-main sequence Star | work=SIMBAD | publisher=Centre de Données astronomiques de Strasbourg | url=http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+217987 | access-date=2010-01-20 }}

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| doi=10.1051/0004-6361/200911976

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{{cite web | title=ARICNS star page of Lacaille 9352 | publisher=Astronomisches Rechen-Institut Heidelberg | url=http://www.ari.uni-heidelberg.de/datenbanken/aricns/cnspages/4c01887.htm | access-date=2010-04-16 | archive-date=2012-09-16 | archive-url=https://web.archive.org/web/20120916104602/http://www.ari.uni-heidelberg.de/datenbanken/aricns/cnspages/4c01887.htm | url-status=dead }}

{{cite web | title= Annotations on NAME LACAILLE 9352 object | work=SIMBAD | publisher=Centre de Données astronomiques de Strasbourg | url=http://cdsannotations.u-strasbg.fr/annotations/simbadObject/1191721 | access-date=2010-04-16 }}

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{{Cite journal| journal=Nature | title=Why boring could be good for this star's two intriguing planets

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| doi=10.1038/d41586-020-01905-5

|url=https://www.nature.com/articles/d41586-020-01905-5| access-date=2020-06-30 | last1=Witze

| first1=Alexandra

| pmid=34168349

| s2cid=220507688

| url-access=subscription

}}

217987

114046

0887