Differential rotation and star-spot evolution on HK Aqr in 2001 and 2002

J R  Barnes; D J  James; A C  Cameron

doi:10.1111/j.1365-2966.2004.07949.x

Differential rotation and star-spot evolution on HK Aqr in 2001 and 2002

J R Barnes, D J James, A C Cameron

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38 Citations (Scopus)

Abstract

We present images of the rapidly rotating (P-rot = 0.431 d) M1.5Ve dwarf HK Aqr, from data obtained during 2001 and 2002. Star-spots are found distributed at a range of latitudes during both observing seasons, but unlike other solar-type rapid rotators of higher mass, HK Aqr does not show a strong polar cap at either epoch. In addition to the surface brightness images, we make use of the four-night time-base over which the 2002 observations were made, in order to derive an estimate of the latitudinal dependent rotation on HK Aqr. We find that the equator-lap-pole time lies in the range -1449 to +448 d. Although very small, we are therefore unable to determine whether the degree of differential rotation is in the solar or anti-solar sense.

Original language	English
Pages (from-to)	589-599
Number of pages	11
Journal	Monthly Notices of the Royal Astronomical Society
Volume	352
Issue number	2
DOIs	https://doi.org/10.1111/j.1365-2966.2004.07949.x
Publication status	Published - 1 Aug 2004

Keywords

line : profiles
methods : data analysis
techniques : miscellaneous
stars : activity
stars : individual : HK Aqr (Gl 890)
stars : late-type
DUAL-SITE OBSERVATIONS
DOPPLER IMAGES
MERIDIONAL FLOW
G DWARFS
PATTERNS
PROMINENCES
GLIESE-890
SUN

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10.1111/j.1365-2966.2004.07949.x

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title = "Differential rotation and star-spot evolution on HK Aqr in 2001 and 2002",

abstract = "We present images of the rapidly rotating (P-rot = 0.431 d) M1.5Ve dwarf HK Aqr, from data obtained during 2001 and 2002. Star-spots are found distributed at a range of latitudes during both observing seasons, but unlike other solar-type rapid rotators of higher mass, HK Aqr does not show a strong polar cap at either epoch. In addition to the surface brightness images, we make use of the four-night time-base over which the 2002 observations were made, in order to derive an estimate of the latitudinal dependent rotation on HK Aqr. We find that the equator-lap-pole time lies in the range -1449 to +448 d. Although very small, we are therefore unable to determine whether the degree of differential rotation is in the solar or anti-solar sense.",

keywords = "line : profiles, methods : data analysis, techniques : miscellaneous, stars : activity, stars : individual : HK Aqr (Gl 890), stars : late-type, DUAL-SITE OBSERVATIONS, DOPPLER IMAGES, MERIDIONAL FLOW, G DWARFS, PATTERNS, PROMINENCES, GLIESE-890, SUN",

author = "Barnes, {J R} and James, {D J} and Cameron, {A C}",

year = "2004",

month = aug,

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doi = "10.1111/j.1365-2966.2004.07949.x",

language = "English",

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pages = "589--599",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

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TY - JOUR

T1 - Differential rotation and star-spot evolution on HK Aqr in 2001 and 2002

AU - Barnes, J R

AU - James, D J

AU - Cameron, A C

PY - 2004/8/1

Y1 - 2004/8/1

N2 - We present images of the rapidly rotating (P-rot = 0.431 d) M1.5Ve dwarf HK Aqr, from data obtained during 2001 and 2002. Star-spots are found distributed at a range of latitudes during both observing seasons, but unlike other solar-type rapid rotators of higher mass, HK Aqr does not show a strong polar cap at either epoch. In addition to the surface brightness images, we make use of the four-night time-base over which the 2002 observations were made, in order to derive an estimate of the latitudinal dependent rotation on HK Aqr. We find that the equator-lap-pole time lies in the range -1449 to +448 d. Although very small, we are therefore unable to determine whether the degree of differential rotation is in the solar or anti-solar sense.

AB - We present images of the rapidly rotating (P-rot = 0.431 d) M1.5Ve dwarf HK Aqr, from data obtained during 2001 and 2002. Star-spots are found distributed at a range of latitudes during both observing seasons, but unlike other solar-type rapid rotators of higher mass, HK Aqr does not show a strong polar cap at either epoch. In addition to the surface brightness images, we make use of the four-night time-base over which the 2002 observations were made, in order to derive an estimate of the latitudinal dependent rotation on HK Aqr. We find that the equator-lap-pole time lies in the range -1449 to +448 d. Although very small, we are therefore unable to determine whether the degree of differential rotation is in the solar or anti-solar sense.

KW - line : profiles

KW - methods : data analysis

KW - techniques : miscellaneous

KW - stars : activity

KW - stars : individual : HK Aqr (Gl 890)

KW - stars : late-type

KW - DUAL-SITE OBSERVATIONS

KW - DOPPLER IMAGES

KW - MERIDIONAL FLOW

KW - G DWARFS

KW - PATTERNS

KW - PROMINENCES

KW - GLIESE-890

KW - SUN

U2 - 10.1111/j.1365-2966.2004.07949.x

DO - 10.1111/j.1365-2966.2004.07949.x

M3 - Article

SN - 0035-8711

VL - 352

SP - 589

EP - 599

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 2

ER -

Differential rotation and star-spot evolution on HK Aqr in 2001 and 2002

Abstract

Keywords

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