40 research outputs found
Globular Cluster Formation in M82
We present high resolution mid-infrared (mid-IR; 11.7 and 17.65 micron) maps
of the central 400 pc region of the starburst galaxy M82. Seven star forming
clusters are identified which together provide ~ 15% of the total mid-IR
luminosity of the galaxy. Combining the mid-IR data with thermal radio
measurements and near- and mid-IR line emission, we find that these young
stellar clusters have inferred masses and sizes comparable to globular
clusters. At least 20% of the star formation in M82 is found to occur in
super-star clusters.Comment: 12 pages including three color figures; accepted for publication in
Ap
AAOmega spectroscopy of 29 351 stars in fields centered on ten Galactic globular clusters
Galactic globular clusters have been pivotal in our understanding of many
astrophysical phenomena. Here we publish the extracted stellar parameters from
a recent large spectroscopic survey of ten globular clusters. A brief review of
the project is also presented. Stellar parameters have been extracted from
individual stellar spectra using both a modified version of the Radial Velocity
Experiment (RAVE) pipeline and a pipeline based on the parameter estimation
method of RAVE. We publish here all parameters extracted from both pipelines.
We calibrate the metallicity and convert this to [Fe/H] for each star and,
furthermore, we compare the velocities and velocity dispersions of the Galactic
stars in each field to the Besan\c{c}on Galaxy model. We find that the model
does not correspond well with the data, indicating that the model is probably
of little use for comparisons with pencil beam survey data such as this.Comment: 6 pages, 5 figures, 4 tables. Accepted for publication in A&A. Data
described in tables will be available on CDS (at
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/530/A31) once publishe
Locating the Youngest HII Regions in M82 with 7 mm Continuum Maps
We present 7mm Very Large Array continuum images of the starburst galaxy M82.
On arcsecond scales, two-thirds of the 7mm continuum consists of free-free
emission from HII regions. In the subarcsecond resolution map, we identify 14
compact sources, including 9 bright HII regions with N_Lyc > 10^51 sec^-1. Four
of the HII regions have rising spectra, implying emission measures > 10^8 cm^-6
pc. Except for one compact source with peculiar features, all other compact
radio sources are found in dust lanes and do not have optical or near-infrared
continuum counterparts. Four regions of extended, high brightness (EM > 10^7
cm-6 pc) radio emission are found in our high resolution map, including some as
large as ~2", or 30 pc, representing either associations of small HII regions,
or sheetlike structures of denser gas. The good correlation between 7 mm
emission and Spitzer IRAC 8 micron continuum-removed PAH feature suggests that
PAH emission may track the recently formed OB stars. We find an excellent
correlation between molecular gas and star formation, particularly dense gas
traced by HCN, down to the ~ 45 pc scale in M82. We also find star formation
efficiencies (SFEs) of 1-10% on the same scale, based on CO maps. The highest
SFE are found in regions with the highest dense gas fractions.Comment: 18 pages, 10 figures. Accepted for publication in A
Origins Space Telescope: Baseline mission concept
The Origins Space Telescope will trace the history of our origins from the time dust and heavy elements permanently altered the cosmic landscape to present-day life. How did galaxies evolve from the earliest galactic systems to those found in the Universe today? How do habitable planets form? How common are life-bearing worlds? To answer these alluring questions, Origins will operate at mid-and far-infrared (IR) wavelengths and offer powerful spectroscopic instruments and sensitivity three orders of magnitude better than that of the Herschel Space Observatory, the largest telescope flown in space to date. We describe the baseline concept for Origins recommended to the 2020 US Decadal Survey in Astronomy and Astrophysics. The baseline design includes a 5.9-m diameter telescope cryocooled to 4.5 K and equipped with three scientific instruments. A mid-infrared instrument (Mid-Infrared Spectrometer and Camera Transit spectrometer) will measure the spectra of transiting exoplanets in the 2.8 to 20 μm wavelength range and offer unprecedented spectrophotometric precision, enabling definitive exoplanet biosignature detections. The far-IR imager polarimeter will be able to survey thousands of square degrees with broadband imaging at 50 and 250 μm. The Origins Survey Spectrometer will cover wavelengths from 25 to 588 μm, making wide-area and deep spectroscopic surveys with spectral resolving power R ∼ 300, and pointed observations at R ∼ 40,000 and 300,000 with selectable instrument modes. Origins was designed to minimize complexity. The architecture is similar to that of the Spitzer Space Telescope and requires very few deployments after launch, while the cryothermal system design leverages James Webb Space Telescope technology and experience. A combination of current-state-of-the-art cryocoolers and next-generation detector technology will enable Origins\u27 natural background-limited sensitivity
Origins Space Telescope: baseline mission concept
The Origins Space Telescope will trace the history of our origins from the time dust and heavy elements permanently altered the cosmic landscape to present-day life. How did galaxies evolve from the earliest galactic systems to those found in the Universe today? How do habitable planets form? How common are life-bearing worlds? To answer these alluring questions, Origins will operate at mid- and far-infrared (IR) wavelengths and offer powerful spectroscopic instruments and sensitivity three orders of magnitude better than that of the Herschel Space Observatory, the largest telescope flown in space to date. We describe the baseline concept for Origins recommended to the 2020 US Decadal Survey in Astronomy and Astrophysics. The baseline design includes a 5.9-m diameter telescope cryocooled to 4.5 K and equipped with three scientific instruments. A mid-infrared instrument (Mid-Infrared Spectrometer and Camera Transit spectrometer) will measure the spectra of transiting exoplanets in the 2.8 to 20 μm wavelength range and offer unprecedented spectrophotometric precision, enabling definitive exoplanet biosignature detections. The far-IR imager polarimeter will be able to survey thousands of square degrees with broadband imaging at 50 and 250 μm. The Origins Survey Spectrometer will cover wavelengths from 25 to 588 μm, making wide-area and deep spectroscopic surveys with spectral resolving power R ∼ 300, and pointed observations at R ∼ 40,000 and 300,000 with selectable instrument modes. Origins was designed to minimize complexity. The architecture is similar to that of the Spitzer Space Telescope and requires very few deployments after launch, while the cryothermal system design leverages James Webb Space Telescope technology and experience. A combination of current-state-of-the-art cryocoolers and next-generation detector technology will enable Origins’ natural background-limited sensitivity
The Origins Space Telescope
The Origins Space Telescope will trace the history of our origins from the time dust and heavy elements permanently altered the cosmic landscape to present-day life. How did galaxies evolve from the earliest galactic systems to those found in the universe today? How do habitable planets form? How common are life-bearing worlds? To answer these alluring questions, Origins will operate at mid- and far-infrared wavelengths and offer powerful spectroscopic instruments and sensitivity three orders of magnitude better than that of Herschel, the largest telescope flown in space to date. After a 3 year study, the Origins Science and Technology Definition Team will recommend to the Decadal Survey a concept for Origins with a 5.9-m diameter telescope cryo cooled to 4.5 K and equipped with three scientific instruments. A mid-infrared instrument (MISC-T) will measure the spectra of transiting exoplanets in the 2.8 20 m wavelength range and offer unprecedented sensitivity, enabling definitive biosignature detections. The Far-IR Imager Polarimeter (FIP) will be able to survey thousands of square degrees with broadband imaging at 50 and 250 m. The Origins Survey Spectrometer (OSS) will cover wavelengths from 25 588 m, make wide-area and deep spectroscopic surveys with spectral resolving power R ~ 300, and pointed observations at R ~ 40,000 and 300,000 with selectable instrument modes. Origins was designed to minimize complexity. The telescope has a Spitzer-like architecture and requires very few deployments after launch. The cryo-thermal system design leverages JWST technology and experience. A combination of current-state-of-the-art cryocoolers and next-generation detector technology will enable Origins natural background limited sensitivity