68 research outputs found
The post-outburst photometric behaviour of V838 Mon
The unusual eruptive variable discovered in Monoceros in 2002 January
underwent dramatic photometric and spectroscopic changes in the months prior to
its 2002 June-August conjunction with the Sun. Optical and infrared (IR)
photometry obtained at the South African Astronomical Observatory (SAAO)
between 2002 January and June (JD 2452280-440) is presented here in an analysis
of the star's post-outburst behaviour. The light curve indicated 3 eruptions
took place in 2002 January, February and March. SAAO echelle spectra obtained
in the week prior to the March maximum indicated the ejection of a new shell of
material. JHKL photometry obtained during 2002 April showed the development of
an IR excess due to the formation of a dust shell. The shell appears to be
largely responsible for the rapid fade in the optical flux during 2002
April-May (Delta V > 6 mag within 3 weeks). Blueing of the optical colours
during the decline is likely due either to the revealing of an emission line
region surrounding V838 Mon, or the unveiling of the progenitor or a
spatially-close early-type star.Comment: 7 pages, 7 figures - accepted for MNRA
A method for establishing taxonomic research priorities in a megadiverse country
A coordinated strategy for biosystematics research that addresses the needs of end-users can improve the relevance and impact
of research products. The basic types of information that taxonomists provide, common to all organisms, are the names,
descriptions, and a mechanism for identifying components of biodiversity, and associated data such as distribution information.
This information is provided through taxonomic research.
A biosystematics research strategy has been developed in South Africa to focus on the main gaps in taxonomic
knowledge. A prioritisation process has been developed and applied to plants, but can potentially be used for all organisms.
The methodology for development of the taxonomic priorities to formulate a research strategy is described. Determining
priorities for taxonomic research and development of the strategy will facilitate bridging the gaps among compilers, users
and implementers of taxonomic information, and streamline the taxonomy-conservation impediment.Botanical Education Trust.http://www.mapress.com/phytotaxahb201
History and drivers of plant taxonomy in South Africa
The development of plant taxonomy in South Africa from about 1600 to 2015 is reviewed, with emphasis on the main driving
factors that have influenced the research direction, techniques used, and choice of taxonomic research topic. In addition,
key personalities and important historical events are highlighted. The early scientific interest in the flora of South Africa
and, by implication, its taxonomy was initially driven by curiosity. Exploration of plants for economic purposes especially
for medicinal use and later, agriculture, drove the scientific development of botany and formed the foundation of formal
botany in the country. Establishment of botanical gardens and herbaria influenced botanical research, in particular the field of
taxonomy. Technological advances lead to increased modernisation of taxonomy as new sources of information derived from
other fields of botany were incorporated into taxonomic research. Funding priorities and availability of financial resources
influence the taxonomic research that is conducted, and international initiatives that impact on priorities in biodiversity
science have further impact on taxonomy. At present the predominant culture of taxonomy is directed towards electronic
dissemination of taxonomic information, leading to increased accessibility and connectivity. Strategic planning of plant
taxonomy in South Africa has become more formal as relevance and impact of research products increasingly need to be
justified with respect to the financial costs of conducting taxonomic research.The University of Pretoria is thanked for financial support.http://www.mapress.com/j/pt/am2016Plant Scienc
Proposal to conserve the family name Asphodelaceae (Spermatophyta : Magnoliidae : Asparagales)
Asphodelaceae c omprises a round 12 genera a nd about 1060
species (Africa, Mediterranean basin, Arabian Peninsula, west and
central Europe, Madagascar, Central Asia, Australia, New Zealand),
Hemerocallidaceae some 19 genera with about 117 species (tropical
and temperate Eurasia, Australia, New Zealand, several Pacific
islands, Madagascar, western South America, southern Africa),
while Xanthorrhoeaceae s.str. has one genus with some 28 species
(restricted to Australia, including Tasmania). The Angiosperm Phylogeny
Group (APG II in Bot. J. Linn. Soc. 141: 399–436. 2003 &
APG III in 161: 105–121. 2009) combine these three families into
Xanthorrhoeaceae s.l., although APG II provided the option to also
use Asphodelaceae and Hemerocallidaceae, under the system of socalled
“bracketed families”. APG III, however, did away with this
option, thus leaving Xanthorrhoeaceae as the only choice.http://www.botanik.univie.ac.at/iapt/s_taxon.phpam201
The correct name of Aloe plicatilis, the fan aloe, in the genus Kumara (Asphodelaceae: Alooideae), again
The combination Kumara plicatilis (L.)
Klopper & Gideon F.Sm. recently published for
the fan aloe [Aloe plicatilis (L.) Burm.f.], is a synonym
of Kumara plicatilis (L.) G.D.Rowley, the
latter having priority due to earlier valid publication.Die kĂĽrzlich fĂĽr die "fan aloe"
[Aloe plicatilis (L.) Burm. f.] publizierte Kombination
Kumara plicatilis (L.) Klopper & Gideon
F.Sm. ist ein Synonym von Kumara plicatilis (L.)
G.D.Rowley, welche Prioriät aufgrund der gültigen
frĂĽheren Publikation hat.http://www.bcss.org.uk/journal.htmlam201
Plant taxonomic capacity in South Africa
South Africa’s exceptionally rich and diverse flora faces challenges in terms of utilisation, management and conservation;
these actions are underpinned by taxonomic research. The principal purpose of this review is to determine whether South
Africa has the human capacity and resources to conduct taxonomic research that is required to support end-users of plant
taxonomic information, and to identify shortages of capacity or resources that might prove to be an obstacle for plant taxonomic
research. From an analysis of the existing gaps in taxonomic information, current research trends, and resources, it
is apparent that there is a critical shortage of human capacity in South Africa to conduct plant taxonomic research for the
benefit of biodiversity and society. Training institutions need to ensure the supply of suitably trained graduates including
concentrating on those who meet Employment Equity targets. The need for more taxonomists is clearly justified, but may not
be a priority in a country that already has such shortages of capacity in education and social services. Aside from lobbying for
more jobs to be created, there is an urgent need to utilise available resources (human and other) effectively, and to implement
a strategy for taxonomic research to ensure that priority activities are conducted.http://www.mapress.com/phytotaxaam201
Creating an online world flora by 2020 : a perspective from South Africa
At the 10th Conference of the Parties of the Convention on Biodiversity (CBD), which was held in Nagoya, Japan, in October 2010, an updated Global Strategy for Plant Conservation (GSPC) was adopted as part of the plan of work of the CBD. Target 1 of the GSPC aims to produce an online Flora for all the plants of the world by 2020. Governments that have ratified the CBD will have to report over the next several years on progress towards achieving this challenging target. Floras are still widely regarded as a means of providing descriptive information and identification tools for the plants that occur in a specified region. Historically, Floras have included identification keys; scientific names with authorship for all taxa known to occur in the area; synonymy; descriptions; distributions within the region in question; specimen citations; habitat; literature references; and illustrations. Of these, nomenclature, descriptions, identification tools, illustrations and distributions are critical components. The approach being taken by South Africa, a biodiversity-rich country, in working towards achieving Target 1 of the GSPC by 2020 is presented and discussed, outlining a methodology that may be of practical use to other countries. We hope this will urge other countries to consider how they might meet this challenging conservation target.http://link.springer.com/journal/10531hb201
The correct names for species of aloe sect. Chortolirion (Asphodelaceae: Alooideae)
The correct names and synonymy for species of Aloe sect. Chortolirion (A. Berger) Boatwr. & J.C. Manning (Asphodelaceae:
Alooideae) are provided. This treatment recognises four species in this section, namely A. welwitschii, A. barendii,
A. jeppeae and A. subspicata. Aloe subspicata and A. welwitschii are treated as conspecific by some authors.http://www.botanik.univie.ac.at/iapt/s_taxon.phpam201
The GW Vir instability strip in the light of new observations of PG 1159 stars. Discovery of pulsations in the central star of Abell 72 and variability of RX J0122.9-7521
We present the results of new time series photometric observations of 29
pre-white dwarf stars of PG 1159 spectral type, carried out in the years
2014-2022. For the majority of stars, a median noise level in Fourier amplitude
spectra of 0.5-1.0 mmag was achieved. This allowed the detection of pulsations
in the central star of planetary nebula Abell 72, consistent with g-modes
excited in GW Vir stars, and variability in RX J0122.9-7521 that could be due
to pulsations, binarity or rotation. For the remaining stars from the sample
that were not observed to vary, we placed upper limits for variability. After
combination with literature data, our results place the fraction of pulsating
PG 1159 stars within the GW Vir instability strip at 36%. An updated list of
all known PG 1159 stars is provided, containing astrometric measurements from
the recent Gaia DR3 data, as well as information on physical parameters,
variability, and nitrogen content. Those data are used to calculate
luminosities for all PG 1159 stars to place the whole sample on the theoretical
Hertzsprung-Russell diagram for the first time in that way. The pulsating stars
are discussed as a group, and arguments are given that the traditional
separation of GW Vir pulsators in "DOV" and "PNNV" stars is misleading and
should not be used.Comment: Accepted for publication in ApJ
A revised generic classification for Aloe (Xanthorrhoeaceae subfam. Asphodeloideae)
The predominantly southern African Xanthorrhoeaceae subfam. Asphodeloideae (Asphodelaceae subfam. Alooideae) has long been regarded as comprising seven so-called alooid genera (Aloe, Astroloba, Chortolirion, Gasteria, Haworthia, Lomatophyllum, Poellnitzia). A reassessment of the classification of the traditionally broadly circumscribed genus Aloe, a charismatic Old World group of leaf succulents, has necessitated nomenclatural adjustments. We propose a narrower generic concept for Aloe s. str. and the recognition of segregate genera to reflect accumulating evidence for monophyletic groups: here, the genus Kumara is reinstated and the new genera Aloidendron and Aloiampelos are established. New combinations are made in Aloe for the three species of Chortolirion.http://www.mapress.com/phytotaxahb2016Plant Scienc
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