98 Aquarii

{{about|b¹ Aquarii|other star systems with this Bayer designation|b Aquarii}}

{{Starbox begin

| name = 98 Aquarii

}}

{{Starbox image

| image =

File:Aquarius IAU.svg

12px

| caption = Location of 98 Aquarii (circled)

}}

{{Starbox observe

| epoch = J2000

| ra = {{RA|23|22|58.22606}}

| dec = {{DEC|−20|06|02.0963}}

| appmag_v = +3.97

| constell = Aquarius

}}

{{Starbox character

| class = K0 III

| b-v = +1.089

| u-b = +0.948

| variable =

}}

{{Starbox astrometry

| radial_v = −6.5

| prop_mo_ra = −121.28

| prop_mo_dec = −97.59

| parallax = 19.96

| p_error = 0.23

| parallax_footnote =

| absmag_v =

}}

{{Starbox detail

| mass = 2.1

| radius = 14

| luminosity =

| gravity = 2.4

| temperature = 4,630

| metal_fe = −0.30

| rotational_velocity =

| age_gyr =

}}

{{Starbox catalog

| names= BD−20°6587, FK5 1612, HD 220321, HIP 115438, HR 8892, SAO 191858

}}

{{Starbox reference

|Simbad=98+Aqr

}}

98 Aquarii (abbreviated 98 Aqr) is a star in the equatorial constellation of Aquarius. 98 Aquarii is the Flamsteed designation, although it also bears the Bayer designation b¹ Aquarii. It is visible to the naked eye with an apparent visual magnitude of +3.97. The distance to this star, {{Convert|163|ly|pc|abbr=off|lk=on}}, is known from parallax measurements made with the Hipparcos spacecraft.

With over double the mass of the Sun, this is an evolved giant star that has a stellar classification of K0 III. The measured angular diameter of this star is {{nowrap|2.54 ± 0.13 mas}}. At the estimated distance of 98 Aquarii, this yields a physical size of about 14 times the radius of the Sun. The expanded outer envelope has an effective temperature of 4,630 K, giving it the orange glow of a K-type star.

References

{{reflist|refs=

{{citation | first=F. | last=van Leeuwen |date=November 2007 | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 |arxiv = 0708.1752 | s2cid=18759600 }}.

{{citation | display-authors=1 | last1=Melo | first1=C. H. F. | last2=de Laverny | first2=P. | last3=Santos | first3=N. C. | last4=Israelian | first4=G. | last5=Randich | first5=S. | last6=Do Nascimento | first6=J. D. Jr. | last7=de Medeiros | first7=J. R. | title=On the nature of lithium-rich giant stars. Constraints from beryllium abundances | journal=Astronomy and Astrophysics | volume=439 | issue=1 | pages=227–235 |date=August 2005 | doi=10.1051/0004-6361:20041805 | bibcode=2005A&A...439..227M | arxiv=astro-ph/0504133 | s2cid=10580797}}.

{{citation | last1=Houk | first1=Nancy | title=Michigan catalogue of two-dimensional spectral types for the HD stars | volume=4 | publication-place=Ann Arbor | publisher=Dept. of Astronomy, University of Michigan | date=1978 | bibcode=1988mcts.book.....H }}

{{citation | display-authors=1 | title=Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions | last1=Wielen | first1=R. | last2=Schwan | first2=H. | last3=Dettbarn | first3=C. | last4=Lenhardt | first4=H. | last5=Jahreiß | first5=H. | last6=Jährling | first6=R. | journal=Veroeffentlichungen des Astronomischen Rechen-Instituts Heidelberg | publisher=Astronomisches Rechen-Institut Heidelberg | issue=35 | date=1999 | volume=35 | page=1 | bibcode=1999VeARI..35....1W}}.

{{citation | last1=Jennens | first1=P. A. | last2=Helfer | first2=H. L. | title=A new photometric metal abundance and luminosity calibration for field G and K giants. | journal=Monthly Notices of the Royal Astronomical Society | volume=172 | pages=667–679 |date=September 1975 | issue=3 | bibcode=1975MNRAS.172..667J | doi=10.1093/mnras/172.3.667| doi-access=free }}.

{{citation | last1=Richichi | first1=A. | last2=Percheron | first2=I. | last3=Khristoforova | first3=M. | title=CHARM2: An updated Catalog of High Angular Resolution Measurements | journal=Astronomy and Astrophysics | volume=431 | pages=773–777 |date=February 2005 | issue=2 | doi=10.1051/0004-6361:20042039 | bibcode=2005A&A...431..773R | doi-access=free }}.

{{citation | first1=Kenneth R. | last1=Lang | title=Astrophysical formulae | volume=1 | series=Astronomy and astrophysics library | edition=3rd | publisher=Birkhäuser | date=2006 | isbn=3-540-29692-1 | url=https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41}}. The radius (R_*) is given by:

: $\begin{align} 2\cdot R_*
& = \frac{(50.1\cdot 2.54\cdot 10^{-3})\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\
& \approx 27.4\cdot R_{\bigodot}
\end{align}$

{{citation|title=The Colour of Stars |date=December 21, 2004 |work=Australia Telescope, Outreach and Education |publisher=Commonwealth Scientific and Industrial Research Organisation |url=http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html |access-date=2012-01-16 |archive-url=https://web.archive.org/web/20120222183238/http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html |archive-date=February 22, 2012 }}.

}}

Aquarii, b1

Aquarii, 098

Category:Aquarius (constellation)

Category:K-type giants