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天文館

臺北天文館學報(出版品)

臺北天文館學報第8期(English)

JTAM VOL. 8 (2010)


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Copyright & Content(pdf檔案)


FieldAuthorTitleReceived DateAccepted Date
Invited ArticlesSolar SystemShinsuke AbeHayabusa back to the Earth(pdf檔案)----
Refereed Paper Stars
IR
Ting-Hung Peng, Chung-Ming KoThe NIR colors of main sequence stars in 2MASS(pdf檔案)2009.10.192010.12.10
Refereed PaperHistory
Instrumentation
Education
Hsiang-Fu HuangThe Instructive Role of the Orrery in Astronomical Display(pdf檔案)2009.11.022010.12.06
Proceeding PaperISM
Radio
Louis Yang, Shih-Ping LaiProbing the magnetic field structure in star-forming regions through molecular line polarization(pdf檔案)2010.10.10--
Proceeding PaperISM
Radio
Nadia M. Murillo, Shih-Ping LaiResolving the two outflows from the Class 0 Protobinary VLA1623(pdf檔案)2010.10.20--
Proceeding PaperStars
Nebulae
IR
Ren-Shiang Sung, Shih-Ping LaiSearching for Very Low Luminosity Objects (VeLLOs) in the Taurus Molecular Cloud(pdf檔案)2010.10.20--
Proceeding PaperGalaxiesS. Foucaud, S. P. BamfordA new class of extremely star-forming galaxies at z<1.0(pdf檔案)2010.10.21--
Proceeding PaperStars
Nebulae
Tien-Hao Hsieh, Shih-Ping LaiPopulation of Young Stellar Objects in Nearby Molecular Clouds(pdf檔案)2010.10.25--


Invited Articles

Title:Hayabusa back to the Earth

Author:Shinsuke Abe

Keywords:Meteor, Asteroid, Spectroscopy, Hayabusa reentry capsule

Abstract:
   For about seven years since its launch by an M-V Launch Vehicle in May 2003, the Hayabusa asteroid sample return mission of the Japan Aerospace Exploration Agency (JAXA) successfully completed a great achievement by landing on the asteroid (25143) Itokawa, gathering rocks (dusts) there, and returning to the Earth with them while overcoming various troubles. Hayabusa ended on June 13, 2010, with the planned atmospheric reentry of the main spacecraft and its capsule. Both capsule and spacecraft reentered the atmosphere during midnight, showing fragmented bright fireballs in the sky over the Woomera Prohibited Area in the Australian desert. The main spacecraft disintegrated in the atmosphere, and the capsule reentered nominally and landed approximately 500 m from its targeted landing point. This paper reports on the preliminary result of our spectroscopic observation of a hypervelocity reentered spacecraft and its released capsule.

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Refereed Paper01

Title:The NIR colors of main sequence stars in 2MASS

Author:Ting-Hung Peng, Chung-Ming Ko

Keywords:2MASS, color-color diagram

Abstract:
   2MASS (Two Micron All Sky Survey) is an all sky NIR survey. Its PSC (point source catalogue) gives us an opportunity to find the mass function of main sequence stars across the sky, provided that we can identify the spectral type of the stars. Beseell & Brett (1988) have listed the intrinsic colors of main sequences and giants which are divided by about 40 spectral types. However, as pointed out by Finlator et al. (2000), the stars of different spectral types have similar infrared colors so that the classification of spectral types based on 2MASS (and NIR data in general) is difficult. Using the Michigan Catalogues (1975, 1978, 1982, 1988, 1999) on spectral types of main sequence stars, we attempt to find an empirical scheme to identify the spectral type of main sequence stars from PSC of 2MASS.

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Refereed Paper02

Title:The Instructive Role of the Orrery in Astronomical Display

Author:Hsiang-Fu Huang

Keywords:orrery, astronomy display, history of science communication, history of astronomy

Abstract:
   This article introduces the development of the orrery, which was an important visual aid of astronomy through the 18th century. The original orrery was invented by English clockmaker George Graham and Thomas Tompion in 1704, and this apparatus had been modified to become more complex. Through the entire 18th century, itinerant lecturers promoted the popularity of Newtonian natural philosophy, and their lecturing was based on the demonstration of instruments and experiments. The orrery was one of the apparatuses used in such philosophical lectures. Many 18th century lecturers, such as James Ferguson and Benjamin Martin, were also involved in the instrument-making trade, and had contributions to the improvement of the orrery. A joint collaboration between instrument business and philosophical lecturing was formed in 18th century marketplace, and this market was promoted by contemporary polite culture. By investigating the selected orrery items in the Royal Observatory Greenwich/National Maritime Museum collection, this study will show how the orrery combined instruction with entertainment in 18th century polite culture contexts.

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ASROC Symposium 2010 ProceedingsPR01

Title:Probing the magnetic field structure in star-forming regions through molecular line polarization

Author:Louis Yang, Shih-Ping Lai

Keywords:--

Abstract:
   The major problem of the most commonly used method for probing magnetic fields, the dust polarization observation, is that it is incapable of differentiating the field structure along the line of sight. Since every molecular transition has a particular critical density, measuring the molecular line polarizations, the Golreich-Kylafis effect (GK effect), provides a unique way to probe the three-dimensional structure in star-forming cores. Although currently it is very difficult to measure GK effect, the Acatama Large Millimeter/submillimeter Array (ALMA) will potentially enable routine observations of GK effect. In order to investigate the feasibility of the GK effect observations with ALMA, we develop a computer program for modeling molecular polarization with uniform magnetic field and velocity gradient. The program solves the radiative transfer equations for multiple transitions in the direction parallel and perpendicular to the magnetic field under the large velocity gradient approximation, and predicts the polari-zation percentage and direction of every transition. Here we demonstrate the results for CO, CS and SiO molecules in high-level transitions at different temperature and with different velocity gradient geometry and molecular cloud density. With this program, we can estimate the polarization of specific molecular transition for probing the mag-netic field geometry with ALMA.

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ASROC Symposium 2010 ProceedingsPR02

Title:Resolving the two outflows from the Class 0 Protobinary VLA1623

Author:Nadia M. Murillo, Shih-Ping Lai

Keywords:star formation, outflows, protobinary, VLA1623

Abstract:
   Protostellar outflows are important in the early stage of star formation, because they can transfer the angular momentum outward allowing further gravitational collapse to proceed. We study the Class 0 source VLA1623, embedded in the ρ Ophiuchi cloud. Previous high resolution observations have shown that VLA1623's continuum emission breaks up into two almost equal point sources with a separation of ~140AU (Looney et al. 2000) strongly suggesting that VLA1623 is a protobinary system. Our new observations were done using the Submillimeter Array (SMA) in compact configuration. Our data shows that VLA1623 has strong collimated outflows in 12CO J(3-2) with overlapping red- and blue-shifted morphology, which could imply that the outflow is located exactly on the plane of the sky. However, after studying the position and characteristics of the lobes from the channel map and P-V diagram, and comparing to previous studies and theoretical P-V diagrams, we conclude that VLA1623 presents two outflows, one emanating from each source. The envelope material traced in C17O (3-2) shows rotation perpendicular to the outflow axis. The material traced with SO (9-8) shows a velocity gradient similar to that of the outflows' central blue knot, suggesting a shock caused by the outflow.

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ASROC Symposium 2010 ProceedingsPR03

Title:Searching for Very Low Luminosity Objects (VeLLOs) in the Taurus Molecular Cloud

Author:Ren-Shiang Sung, Shih-Ping Lai

Keywords:stars: formation, stars: low-mass

Abstract:
   Observing protostars right after they formed from their parent cores is crucial for understanding the earliest phase of star formation. Discovered by Spitzer Space Telescope, Very Low Luminosity Objects (VeLLOs) are the faintest embedded sources currently known (internal luminosity, Lint < 0.1 solar luminosity), hence the best targets for studying the star formation in the earliest stage. On the other hand, VeLLOs could also be very low mass protostars or even proto brown dwarfs. Since Taurus is one of the closest clouds, it provides the best possible spatial resolution for investigating the nature of VeLLOs. We search for VeLLOs in Taurus adopting the color and luminosity criteria from Dunham et al. (2008), which are derived from known young Class 0 and early Class I objects. However, because the extinction in Taurus is very low, the contamination from background galaxies is especially high. Studying the previously identified VeLLO candidates, we found that [5.8] – [24.0] > 4 mag is a good criterion for eliminating galaxies. As a result, we select 9 VeLLO candidates in Taurus and all candidates have colors consistent with Class 0 or Class I sources. Further observations at submillimeter wavelengths are needed for confirming the YSO nature of these candidates.

Full Text(pdf檔案)


ASROC Symposium 2010 ProceedingsPR04

Title:A new class of extremely star-forming galaxies at z<1.0

Author:S. Foucaud, S. P. Bamford

Keywords:galaxy, galaxies: high-redshift, galaxies: evolution

Abstract:
   The detection of candidates for the first generation of galaxies in the distant Universe is hot topic in Astronomy. Young galaxies, forming their first stars, are an important contributor to the ionization of the gas between galaxies, as a result of their strong Lyman-α emission. A large number of these Lyman Alpha Emitters have been detected, at z=2 to z=8, but so far none of these correspond to the first generations of galaxies. However, the current paradigm of galaxy formation suggests that new galaxies are formed continuously. Therefore we should detect very young galaxies at any epoch.
   I will introduce a population of extremely star-forming and low mass galaxies at z<1.0, that we have identified using the latest generation of broad-band surveys. These objects, called ‘Peas’, appear to be in the act of building up their stellar mass and share many properties with young galaxies observed in the early Universe. The Peas may be the last remnants of a mode of star-formation common in the early Universe. Thanks to our technique, a large number of very young galaxies will be efficiently selectable at different epochs of the Universe, without the need for highly specialized imaging (e.g. narrow-band) or expensive spectroscopic surveys.

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ASROC Symposium 2010 ProceedingsPR05

Title:Population of Young Stellar Objects in Nearby Molecular Clouds

Author:Tien-Hao Hsieh, Shih-Ping Lai

Keywords:protostar, color-color diagram, color-magnitude digram

Abstract:
   We develop a new method to identify YSOs from star-forming regions using the photometry data of the Spitzer space telescope. Because SEDs of YSOs are similar to SEDs of background galaxies and Spitzer is sensitive enough to detect those galaxies, it has been difficult to separate YSOs and galaxies using only those photometry data. To solve this problem, previous works have developed several criteria according to the difference of the areas occupied by YSOs and galaxy sample in color-magnitude and color-color diagrams (hereafter CMD and CCD). However, different works used different CMDs and CCDs and defined criteria for separating YSOs and galaxies are often set by eyes. Here we develop a new method to measure the probability for a source to be a background galaxy; we calculate the density of pure galaxy sample in the multi-dimensional magnitude space and use the density as the probability of background galaxy. Our method is equivalent to use all CMDs and without artificial criteria. Thus, we can fairly identify the YSOs in the star-forming regions.

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