BO Microscopii

{{Starbox begin

| name=BO Microscopii

}}

{{Starbox image

| image = 250px

| caption = A visual band light curve for BO Microscopii, adapted from Cutispoto et al. (1997)

}}

{{Starbox observe

| epoch=J2000

| ra={{RA|20|47|45.00562}}

| dec={{DEC|−36|35|40.7698}}

| appmag_v=9.39

| constell=Microscopium

}}

{{Starbox character

| class=K3Ve

| b-v=

| u-b=

| variable=Flare star

}}

{{Starbox astrometry

| radial_v={{val|-5.64|2.03}}

| prop_mo_ra=18.735

| prop_mo_dec=−81.712

| pm_footnote=

| parallax=19.5983

| p_error=0.5745

| parallax_footnote=

| absmag_v=5.92

}}

{{Starbox detail

| mass={{val|0.82|0.08}}

| radius={{val|1.06|0.04}}

| luminosity=

| gravity=

| temperature={{val|4750|50}}

| metal_fe=−1.49

| rotation={{val|0.380|0.004}} days

| rotational_velocity=135

| age_myr={{val|33|5}}

}}

{{Starbox catalog

| names = {{odlist | name = Speedy Mic | V = BO Mic | CD = -37 13926 | CPD = -37 8883 | GSC = 07469-00997 | HD = 197890 | HIP = 102626 | PPM = 300614 | SAO = 212437 | TIC = 389423271 | TYC = 7469-997-1}}

}}

{{Starbox reference

|Simbad=HD+197890

}}

BO Microscopii (BO Mic) is a star in the constellation Microscopium located about {{convert|170|ly|pc e6AU|lk=on|abbr=off}} from the Sun. It has been dubbed "Speedy Mic" because of its very rapid rotation. The projected rotational velocity at the equator of this star is about {{convert|135|km/s|abbr=on}}, which, with an estimated inclination of 70° to the line of sight from the Earth, means it completes a rotation every {{convert|0.380|+/-|0.004|d|hour|abbr=off}}.

The photosphere of this star shows a high level of magnetic activity, with multiple star spots and prominences observed at the same time. As many as 25 prominences have been observed simultaneously, extending outward as far as 3.6 times the radius of the star. BO Mic is a flare star that undergoes sudden increases in X-ray and ultraviolet emissions. These events can emit a hundred times more energy than large solar flares. Speedy Mic is one of the most active stars in the vicinity of the Sun.

References

{{reflist|refs=

{{cite journal |last1=Cutispoto |first1=G. |last2=Kurster |first2=M. |last3=Pagano |first3=I. |last4=Rodono |first4=M. |title=UBV(RI)c Photometry of the Rapidly Rotating K-Type Star HD197890 = "Speedy Mic" |journal=Information Bulletin on Variable Stars |date=January 1997 |volume=4419 |page=1 |bibcode=1997IBVS.4419....1C |url=https://ui.adsabs.harvard.edu/abs/1997IBVS.4419....1C |access-date=28 January 2022}}

{{citation | display-authors=1 | last1=Torres | first1=C. A. O. | last2=Quast | first2=G. R. | last3=da Silva | first3=L. | last4=de La Reza | first4=R. | last5=Melo | first5=C. H. F. | last6=Sterzik | first6=M. | title=Search for associations containing young stars (SACY). I. Sample and searching method | journal=Astronomy and Astrophysics | volume=460 | issue=3 | pages=695–708 |date=December 2006 | doi=10.1051/0004-6361:20065602 | bibcode=2006A&A...460..695T |arxiv = astro-ph/0609258 | s2cid=16080025 }}

{{citation | last1=Holmberg | first1=J. | last2=Nordström | first2=B. | last3=Andersen | first3=J. | title=The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics | volume=501 | issue=3 |date=July 2009 | pages=941–947 | doi=10.1051/0004-6361/200811191 | journal=Astronomy and Astrophysics | bibcode=2009A&A...501..941H |arxiv = 0811.3982 | s2cid=118577511 }}

{{citation | display-authors=1 | last1=Wolter | first1=U. | last2=Robrade | first2=J. | last3=Schmitt | first3=J. H. M. M. | last4=Ness | first4=J. U. | title=Doppler imaging an X-ray flare on the ultrafast rotator BO Mic. A contemporaneous multiwavelength study using XMM-Newton and VLT | journal=Astronomy and Astrophysics | volume=478 | issue=1 | pages=L11–L14 |date=January 2008 | doi=10.1051/0004-6361:20078838 | bibcode=2008A&A...478L..11W |arxiv = 0712.0899 | s2cid=62827486 }}

{{citation | display-authors=1 | last1=Dunstone | first1=N. J. | last2=Barnes | first2=J. R. | last3=Collier Cameron | first3=A. | last4=Jardine | first4=M. | title=The coronal structure of Speedy Mic - I. A densely packed prominence system beyond corotation | journal=Monthly Notices of the Royal Astronomical Society | volume=365 | issue=2 | pages=530–538 |date=January 2006 | doi=10.1111/j.1365-2966.2005.09729.x | doi-access=free | bibcode=2006MNRAS.365..530D |arxiv = astro-ph/0510739 | s2cid=11048210 }}

{{citation

| display-authors=1

| last1=Wolter

| first1=U.

| last2=Schmitt

| first2=J. H. M. M.

| last3=van Wyk

| first3=F.

| title=Doppler imaging of Speedy Mic using the VLT. Fast spot evolution on a young K-dwarf star

| journal=Astronomy and Astrophysics

| volume=435

| issue=1