X-Ray Emission from the Supergiant Shell in IC 2574

The M81 group member dwarf galaxy IC 2574 hosts a supergiant shell of current and recent star-formation activity surrounding a 1000 x 500 pc hole in the ambient Hi gas distribution. Chandra X-ray Observatory imaging observations reveal a luminous, L_x ~ 6.5 x 10^{38} erg/s in the 0.3 - 8.0 keV band, point-like source within the hole but offset from its center and fainter diffuse emission extending throughout and beyond the hole. The star formation history at the location of the point source indicates a burst of star formation beginning ~25 Myr ago and currently weakening and there is a young nearby star cluster, at least 5 Myr old, bracketing the likely age of the X-ray source at between 5 and ~25 Myr. The source is thus likely a bright high-mass X-ray binary --- either a neutron star or black hole accreting from an early B star undergoing thermal-timescale mass transfer through Roche lobe overflow. The properties of the residual diffuse X-ray emission are consistent with those expected from hot gas associated with the recent star-formation activity in the region.Comment: 5 pages, accepted for publication in the Astrophysical Journal Letter

STRUKTUR KOMUNITAS IKAN DI PADANG LAMUN PERAIRAN TERNATE, MALUKU UTARA

Lamun merupakan tumbuhan yang hidup terbenam di dalam laut dan penting untuk ekosistem pesisir. Fungsi penting padang lamun di antaranya yaitu sebagai spawning ground, feeding ground, dan tempat berlindung ikan.Wilayah perairan Ternate Maluku Utara dan sekitarnya merupakan salah satu lokasi penelitian COREMAP-CTI dan salah satu kajiannya mengenai ikan padang lamun. Tujuan penelitian ini untuk mengetahui struktur komunitas ikan di padang lamun perairan Ternate Maluku Utara. Pengumpulan data dilakukan dengan menggunakan metode Underwater Visual Census (UVC) selama 12 hari pada sepuluh stasiun penelitian.Berdasarkan hasil pengamatan di padang lamun perairan Ternate, Maluku Utara ditemukan sebanyak 1105 individu terdiri dari 56 jenis dari 22 famili. Berdasarkan hasil analisis struktur komunitas, nilai indeks keanekaragaman 1.69, indeks keseragaman 0.68, dan indeks dominansi 0.32 yang menunjukkan keanekaragaman spesies rendah dengan stabilitas komunitas yang labil.Seagrass is a plant that lives immersed in the sea and is important for coastal ecosystems. The important functions of seagrass include spawning ground, feeding ground, and fish shelter. Ternate, North Maluku waters and its surroundings are one of COREMAP-CTI research sites and one of the studies include seagrass fishes. The aim of this study was to determine the structure of seagrass fish community in Ternate waters of North Maluku. Data collection was carried out using the Underwater Visual Census (UVC) method for 12 days at ten site. Based on observations, the waters of Ternate, North Maluku has seagrass fish species that are still relatively high in diversity, we found 1105 individual fish consisting of 56 species from 22 families. Based on the results of community structure analysis, the diversity index value is 1.69, the similarity index is 0.68, and the dominance index is 0.32 which shows species diversity is generally classified as low with unstable community stability

DIVERSITAS IKAN PADA KOMUNITAS PADANG LAMUN DI PANTAI KEMA, SULAWESI UTARA.

Kondisi padang lamun di perairan Pantai Kema akan terus mengalami perubahan sebagai dampak negatif dari berbagai aktivitas penduduk setempat yang tidak konservatif. Akibatnya diversitas jenis ikan yang berasosiasi di dalamnya juga akan semakin berkurang. Akan tetapi, informasi mengenai diversitas spesies ikan padang lamun di daerah ini masih sangat terbatas. Oleh karena itu, pada bulan April 2014 dilakukan penelitian pada ikan padang lamun untuk mengetahui diversitas jenis dan kelimpahan ikan serta struktur komunitasnya. Pengambilan sampel dilakukan di empat stasiun dengan metode swept area menggunakan beach seine.  Hasil tangkapan seluruhnya adalah 2.621 individu ikan, terdiri atas 60 spesies dari 26 famili. Jumlah spesies ikan yang ditemukan secara spasial bervariasi dari 27- 47 spesies dengan total kelimpahan relatif  antara 14,08–34,91%. Famili Labridae dan Atherinidae merupakan famili paling dominan di semua stasiun dengan total kelimpahan relative sebesar 33,62% dan 25,45%. Tiga jenis yang paling umum ditemukan adalah Hypoatherina temminckii, Halichoeres papilionaceus dan Halichoeres melanurus. Komunitas ikan di padang lamun Pantai Kema termasuk kategori sedang (moderat) dengan stabilitas komunitasnya tidak stabil. Tipe asosiasi padang lamun yang berbeda mempengaruhi perbedaan keragaman jenis dan kelimpahan ikan yang hidup di dalamnya. Walaupun demikian, seluruh padang lamun di perairan pantai Kema masih dalam kondisi kondusif sebagai habitat ikan.Seagrass condition at Kema coastal area will continue to change as a negative impact of various activities of local people who are not conservative. As a result, the diversity of fish species is going to decrease. However, information about the diversity of seagrass fish species in this area is still limited. Therefore, in April 2014 a study of seagrass fish community structure was carried out to know the diversity of species, fish abundance and community structure. Sampling was carried out at four stations with swept area method using beach seine. A total of 2.621 individuals were collected, consisting of 60 species from 26 families. The number of fish species found spatially varies from 27 to 47 species with a total relative abundance of 14.08-34.91%. Labridae and Atherinidae families are the most dominant families in all stations with a total relative abundance of 33.62% and 25.45%. The three most common species are H. temminckii, H. papilionaceus and H. melanurus. Community structure of seagrass fish at Kema coastal area is moderate and unstable. The difference of seagrass beds association type affect the diversity of species and fish abundance. However, all seagrass beds at Kema coastal area are still conducive for fish habitat