University of Alicante
Alicante: A family of stellar clusters in our Galaxy
This project is carried out within the following research group:
It is part of one of the lines of research we are carrying out: The study of stellar populations of young open clusters, which are groups of gravitationally bound stars of the same distance from Earth and have the same age. These objects allow us to study different current problems in Astrophysics: Galactic structure and evolution of massive stars.
We have discovered new clusters in our Galaxy that we have named Alicante. So far we have a family of 12 of these clusters. All of them have different characteristics and have a different population that allows us to study various topics.
Among them, we highlight some interesting systems: Alicante 1 which has a binary system, MYCam, candidate to be merged into a single object (considered one of the most interesting objects that populate our Galaxy by the BBC's Sky at night program) and others like Alicante 10, Alicante 8 ... which are among the most massive clusters in our Galaxy (Alicante 8 has been used in Steven Spielberg's science fiction series, Falling Skies)
When an astronomical object is discovered, in this case a star cluster, the designation of a name is made in the following way: if the discovery is made by only one person, the last name is put, and if it is made by more than one person, the name of the institution where they work is put. If there are several objects, they are designated with successive numbers: Alicante 1, Alicante 2, etc. In this way, we can mention some of the families that are traditionally known as Berkeley in the USA and Bochüm in Germany, to which the Alicante are now added, being the first Spanish institution that has a family of star clusters.
Our branch of work corresponds to observational astrophysics, so we usually write or collaborate in proposals for observing time that competitively win dozens of nights of observation at the most demanded telescopes in the world through their selection committees or the OPTICON program (Isaac Newton Group, GRANTECAN, Very Large Telescope, New Technology Telescope, Australian Astronomical Observatory, etc). This situation means that we have the opportunity, for many years, to be regular users of these magnificent facilities distributed
The article was published in 2008 in the magazine Astronomy and Astrophysics Negueruela & Marco, 2008, A&A, 492, 441;
In this work, which is part of the research carried out in Galactic Structure, a study was made of the only stellar association, called Cam OB3, which was thought to be part of the outermost arm of the Milky Way (Cygnus arm). The conclusion was that indeed this association of stars belonged to that arm and, in addition, we found the star cluster that belonged to it and that is Alicante 1. The distance at which they are found is 4.0 ± 0.4 kpc, so we have an estimate of the distance to that arm in that direction.
It is in the Camelopardalis constellation. Its coordinates are: RA: 03h 59m 18.3s; DEC: +57o 14' 13.7'' (J2000)
False colour image taken by the authors with the ALFOSC instrument of the Nordic Optical Telescope of the La Palma Observatory (NOT/ALFOSC)
Image taken in the filter and with the BUSCA instrument in the 2.2 m telescope in the Calar Alto Observatory
The article was published in 2003 in the magazine Astronomy and Astrophysics Negueruela, I. 2003, A&A, 408, 689;
In this work, the 3 brightest stars belonging to a very compact young cluster belonging to the Cassiopeia star association OB5 (Cas OB5), later called Alicante 2. One of them, BD +62 2296A is a supergiant of spectral type B2.5Ia. The closest to it, BD +62 2296B is a Wolf Rayet star of type WN4 and the third, BD +62 2296C, is a giant star of spectral type B0III. These are individual stars that do not form a binary or triple system. Such a concentration of very massive stars, which do not belong to a massive cluster in which a large number of slightly less massive stars should also appear, is very interesting in terms of the study of the formation and evolution of massive stars.
It is in the constellation Cassiopeia and its coordinates are: R.A.: 23h 47m 20.4s; DEC: +63o 13' 12'' (J2000)
Open cluster Alicante 5
The false colour composition image, which was obtained with the space telescope Spitzer, shows that the visible stars are part of a much larger population of extremely young stars, which is beginning to emerge from the cloud in which it has formed.
Open cluster Alicante 5, composition with false colors and inflatable
This image, which was obtained with the space telescope Spitzer, shows in the mid-infrared a bubble of interstellar dust known as N37. Inside this bubble, there is an extremely young cluster, Alicante 6, which has not yet fully emerged from the cloud.
Our recent work shows that star formation in this area has probably been induced by a very luminous star, spectral type O7 II, which is in the lower right corner of the image (being a very hot star it is hardly seen in the infrared).
Cluster Alicante 6, young, Fake colour composition of three images
Alicante 7, 8, 9, 10
Alicante 8,composition in 3 bands taken in the near infrared and corresponding to the UKIDSS data catalogue
These clusters are in the group of the most massive clusters in our Galaxy (they have a stellar content of more than 10,000 Solar Masses). They are located at a distance of 6 kpc and are grouped in the area of intersection of the bar with the spiral arm called Scutum-Crux. They are very far away and in a very high extinction zone, so we can only detect and study their brightest members which are the red supergiants. These objects emit most of their radiation in the infrared, so they must be observed with detectors that capture light in this wavelength range. If we try to observe them in the visible range nothing is captured, as if they did not exist.
Some articles about these clusters in the magazine Astronomy and Astrophysics:
- I. Negueruela, C. González-Fernández , A. Marco, J. S. Clark, and S. Martínez-Núñez. 2010. A&A, 513, A74
- I. Negueruela, C. González-Fernández , A. Marco, J. S. Clark. 2011. A&A, 528, A59
- I. Negueruela, A. Marco, C. González-Fernández, F. Jiménez-Esteban, J. S. Clark, M. Garcia & E.Solano. 2012. A&A. 547, A15
- C. González-Fernández & I. Negueruela. 2012. A&A, 539, A100
Alicante 11, 12
These clusters are published in the journal The Monthly Notices of the Royal Astronomical Society:
This work is framed within the investigations of Galactic Structure and Star Formation. We were studying a star formation region containing the open cluster called Stock 8 to investigate the extent of the Auriga OB2 star association and the possible star formation mechanisms existing in the area. As a result of the work, the Stock8 cluster has been discarded, placing it much closer to 2.8 kpc in the Perseus arm. In the region of Stock8 we have found two new clusters that are at the same distance as this one, which are Alicante 11 and Alicante 12.
Image taken in Aladin from the WISE Medium Infrared catalogue. The blue dots correspond to the stars in the Stock8 cluster and the yellow and green dots to the Alicante 11 and Alicante 12 clusters.